TBC TERT-BUTYLPYROCATECHOL

Petrochemical monomer producers, synthetic rubber plants (manufacturing SBR 1502, PBR, NBR, and CR), and composite resin formulators systematically prefer TBC Tert-Butylpyrocatechol over hydroquinone, phenothiazine, and aromatic amine inhibitors because TBC Tert-Butylpyrocatechol has a very low vapor pressure (boiling point 285 °C, staying entirely in the liquid monomer phase rather than distilling overhead into vapor spaces), does not introduce nitrogen or sulfur catalyst poisons into downstream Ziegler-Natta or anionic polymerizations, and can be stripped quantitatively from monomers just prior to polymerization simply by washing with dilute aqueous sodium hydroxide (NaOH) or passing through an activated alumina bed. Furthermore, supplying TBC Tert-Butylpyrocatechol as an 85% w/w eutectic liquid solution in demineralized water (TBC 85% Water) or methanol (TBC 85% Methanol) depresses the freezing/crystallization point from +53 °C (for 100% pure solid TBC) down to +10 °C (in water) or below -30 °C (in methanol), enabling effortless ambient-temperature metering pump injection at tank farms and marine terminals.

Supplied commercially by Ataman Kimya in both 100% Pure Solid Crystalline Flakes / Pastilles (assay >= 99.0% w/w, melting point 52 to 56 °C, color <= 50 APHA in molten state) and 85% w/w Liquid Solutions in Water or Methanol (active TBC content 84.0% to 86.0% w/w, color <= 70 to 100 APHA, density ~1.045 g/cm3 at 20 °C), TBC Tert-Butylpyrocatechol is manufactured under strict quality controls to prevent trace iron discoloration and ensure immediate radical-scavenging reactivity. Matching the correct physical form (100% Solid Flakes versus 85% Aqueous versus 85% Methanolic Liquid) and dissolved oxygen protocol for TBC Tert-Butylpyrocatechol guarantees safe, gel-free monomer logistics and precise resin cure control.

CAS Number: 98-29-3 (1,2-Benzenediol, 4-(1,1-dimethylethyl)-; 4-tert-Butylpyrocatechol; 4-tert-Butylcatechol; Unspecified isomer reference CAS: 27213-78-1)
EC Number: 202-653-9 (EINECS 202-653-9; EU REACH Registered substance: 4-tert-butylpyrocatechol)
Molecular Formula: C10H14O2 (Condensed Structural Formula: (CH3)3C-C6H3(OH)2 or C6H3[C(CH3)3]-1,2-(OH)2)
Molecular Weight: 166.22 g/mol (Exact Monoisotopic Mass: 166.0994 g/mol)
INCI Name: t-BUTYL HYDROQUINONE is a different isomer (CAS 1948-33-0); TBC Tert-Butylpyrocatechol (CAS 98-29-3, 4-tert-Butylcatechol) is strictly an industrial monomer inhibitor, polymer stabilizer, and chemical intermediate (prohibited in cosmetics under EU Regulation EC No 1223/2009 Annex II Entry 342)
E Number: Not assigned (Industrial petrochemical monomer inhibitor, synthetic rubber process stabilizer, and resin additive; not a food additive, whereas TBHQ E319 is the 1,4-hydroquinone isomer CAS 1948-33-0)
Melting Point: 52.0 to 56.0 °C (125.6 to 132.8 °F, typically 53.0 to 55.0 °C) for 100% Pure Solid TBC Tert-Butylpyrocatechol (CAS 98-29-3); Solidification / Crystallization Point of 85% w/w TBC in Water: +8.0 to +12.0 °C (+46.4 to +53.6 °F); Solidification Point of 85% w/w TBC in Methanol: <= -30.0 °C (-22.0 °F)
Boiling Point: 285.0 °C (545.0 °F) at 101.3 kPa (760 mmHg) atmospheric pressure for pure TBC Tert-Butylpyrocatechol (159.0 °C at 2.67 kPa / 20 mmHg; 85% aqueous solution boils initially at ~102 to 105 °C due to water evaporation; Closed-Cup Flash Point of pure TBC: 151.0 °C / 303.8 °F; Cleveland Open-Cup Flash Point: ~165.0 °C)
Viscosity: Not applicable for 100% solid flakes at 20 °C (in molten liquid state at 60 °C, dynamic viscosity of pure TBC Tert-Butylpyrocatechol is ~16 to 22 mPa·s); for 85% w/w TBC in Water at 20 °C, dynamic viscosity is approximately 90 to 135 mPa·s (cP, and ~35 mPa·s at 40 °C); for 85% w/w TBC in Methanol at 20 °C, dynamic viscosity is ~15 to 25 mPa·s
Density: True solid density of 100% pure TBC Tert-Butylpyrocatechol crystals at 20 °C: ~1.080 to 1.090 g/cm3 (Apparent bulk density of flakes/pastilles: 550 to 650 g/L); Molten liquid density of pure TBC at 60 °C: 1.042 g/cm3; Liquid density of 85% w/w TBC in Water at 20 °C: 1.040 to 1.050 g/cm3 (typically 1.045 g/cm3); Liquid density of 85% w/w TBC in Methanol at 20 °C: 0.990 to 1.005 g/cm3

Most Frequently Encountered Synonyms:
TBC Tert-Butylpyrocatechol
TBC TERT-BUTYLPYROCATECHOL
4-tert-Butylpyrocatechol
4-tert-Butylcatechol
p-tert-Butylpyrocatechol
p-tert-Butylcatechol
para-tert-Butylcatechol
tert-Butylpyrocatechol
tert-Butylcatechol
TBC
4-tert-Bütilkateşol
p-tert-Bütilpirokateşol
Tersiyer Bütil Pirokateşol (TBC)
Stiren ve Bütadien Polimerizasyon İnhibitörü TBC
UN 3261 (Solid) / UN 3265 (Liquid Solution)
CAS 98-29-3
EC 202-653-9

WHAT IS TBC TERT-BUTYLPYROCATECHOL?

Known across international petrochemical monomer refining, synthetic rubber manufacturing, polymer logistics, and thermoset resin commerce as TBC Tert-Butylpyrocatechol, 4-tert-Butylpyrocatechol, 4-tert-Butylcatechol, PTBC, or simply TBC (and in Turkish industrial trade as TBC Tersiyer Bütil Pirokateşol, 4-tert-Bütilpirokateşol, or Stiren/Bütadien Polimerizasyon İnhibitörü TBC), TBC Tert-Butylpyrocatechol is a sterically substituted ortho-dihydric phenol (catechol derivative) carrying the IUPAC name 4-(1,1-dimethylethyl)benzene-1,2-diol (CAS No. 98-29-3, EC / EINECS No. 202-653-9, molecular formula C10H14O2, molar mass 166.22 g/mol). Universally recognized as the global standard storage and transport polymerization inhibitor for Styrene Monomer (SM), 1,3-Butadiene (BD), Isoprene, Chloroprene, and Divinylbenzene, TBC Tert-Butylpyrocatechol is supplied by Ataman Kimya in three industrial commercial formats: (1) TBC 100% Pure Solid Crystalline Flakes / Pastilles (or molten liquid in heated isotanks), (2) TBC 85% w/w Liquid Solution in Demineralized Water, and (3) TBC 85% w/w Liquid Solution in Methanol (or Toluene/Styrene).

Why TBC Tert-Butylpyrocatechol Is the Global Standard Inhibitor for Styrene and 1,3-Butadiene Over Hydroquinone and MEHQ:
In petrochemical plants and tank farms, reactive vinyl and conjugated diene monomers—above all Styrene (C8H8) and 1,3-Butadiene (C4H6)—undergo spontaneous thermal and trace-peroxide-initiated free-radical polymerization during storage. If uninhibited, styrene and butadiene polymerize exothermically (liberating ~70 to 75 kJ/mol of heat), leading to catastrophic runaway tank-car explosions or insoluble cross-linked 'popcorn polymer' fouling that ruptures steel distillation columns and pipelines! TBC Tert-Butylpyrocatechol outperforms competing phenolic inhibitors for three fundamental reasons:

- 1. Distinction of TBC Tert-Butylpyrocatechol from Unsubstituted Hydroquinone (HQ, 1,4-Benzenediol, CAS 123-31-9): Unsubstituted hydroquinone is polar and almost completely insoluble in non-polar hydrocarbon monomers like styrene (< 0.05% at 20 °C) and liquid 1,3-butadiene, crystallizing out at cold winter temperatures. By contrast, attaching the lipophilic tertiary-butyl group (-C(CH3)3) at the C-4 position in TBC Tert-Butylpyrocatechol increases hydrocarbon solubility by more than 1,000-fold: TBC Tert-Butylpyrocatechol is soluble to > 50% w/w in styrene monomer at 25 °C and remains completely dissolved in liquid 1,3-butadiene and isoprene even at -20 °C

- 2. Distinction of TBC Tert-Butylpyrocatechol from MEHQ (4-Methoxyphenol, CAS 150-76-5) and BHT (2,6-Di-tert-butyl-4-methylphenol, CAS 128-37-0): Monohydric MEHQ is the standard inhibitor for polar acrylic and methacrylic acid/ester monomers, whereas BHT is a weak antioxidant. However, in less polar conjugated monomers like styrene and 1,3-butadiene, the ortho-dihydroxy (1,2-catechol) group of TBC Tert-Butylpyrocatechol has a much lower O-H bond dissociation energy (~330 kJ/mol vs. ~355 kJ/mol for MEHQ) because the resulting ortho-semiquinone radical is stabilized by an intramolecular hydrogen bond from the adjacent -OH group! As a result, at 60 °C, TBC Tert-Butylpyrocatechol scavenges monomer peroxyl radicals 25 times faster than hydroquinone and 50 to 100 times faster than MEHQ or BHT!

- 3. Critical Distinction of TBC Tert-Butylpyrocatechol (CAS 98-29-3) from TBHQ (tert-Butylhydroquinone, CAS 1948-33-0): Procurement teams must never confuse TBC Tert-Butylpyrocatechol (4-tert-butyl-1,2-benzenediol, CAS 98-29-3, an ortho-catechol monomer inhibitor) with TBHQ (2-tert-butyl-1,4-benzenediol, CAS 1948-33-0, a para-hydroquinone food oil antioxidant E319). TBC Tert-Butylpyrocatechol is a far more potent monomer radical inhibitor and has a much higher solubility in liquid hydrocarbons and water eutectic blends.

CHEMICAL STRUCTURE, RADICAL-SCAVENGING MECHANISM AND THE DISSOLVED OXYGEN REQUIREMENT

Understanding how TBC Tert-Butylpyrocatechol arrests free-radical chain polymerization at just 10 to 50 ppm in Styrene and 50 to 200 ppm in 1,3-Butadiene—and why dissolved molecular oxygen (O2) is mandatory for its operation—is essential for safe monomer storage and resin formulation:

Intramolecular Hydrogen-Bond Activation of the 1,2-Catechol Moiety:
In TBC Tert-Butylpyrocatechol, the two hydroxyl groups occupy adjacent ortho positions (C-1 and C-2) on the benzene ring, while the electron-donating tert-butyl group (+I inductive effect) sits at C-4. In the ground state, one phenolic -OH group forms a five-membered intramolecular hydrogen bond with the oxygen atom of the adjacent -OH group, while the other -OH proton is strongly activated for homolytic hydrogen atom transfer (HAT). When a free radical extracts a hydrogen atom from TBC Tert-Butylpyrocatechol, the resulting 4-tert-butyl-2-hydroxyphenoxyl (ortho-semiquinone) radical is resonance-stabilized across the aromatic ring and locked by a strong intramolecular hydrogen bond (~18 kJ/mol stabilization energy), making it completely incapable of initiating a new polymer chain!

The Two-Step Radical-Trapping Cycle and Why Dissolved Oxygen (O2) Is Essential:
During storage of Styrene or 1,3-Butadiene, thermal self-initiation (such as the Mayo Diels-Alder dimerization of styrene) generates carbon-centered alkyl/styryl radicals (R·):
- Why TBC Reacts Slowly with Carbon-Centered Radicals (R·) in the Absence of Oxygen: Under strictly anaerobic (100% oxygen-free) conditions, carbon-centered styryl or butadienyl radicals (R·) are nucleophilic and react very slowly with phenolic O-H bonds (rate constant k_inh ~10^1 to 10^2 L/mol·s), allowing monomer polymerization to proceed!
- Instantaneous Conversion of R· to Peroxyl Radicals (ROO·) by Dissolved Oxygen: When a trace concentration of dissolved molecular oxygen (O2, typically 15 to 50 ppm in the liquid monomer, maintained by blanketing storage tanks with a 5%–8% O2 in N2 gas mixture or dry air where flammability limits permit) is present, O2 reacts at diffusion-controlled speed (k ~10^8 to 10^9 L/mol·s) with carbon-centered radicals (R·) to form electrophilic peroxyl radicals: R· + O2 --> ROO·.
- Rapid Two-Electron Scavenging of ROO· by TBC Tert-Butylpyrocatechol: Electrophilic peroxyl radicals (ROO·) react instantaneously with TBC Tert-Butylpyrocatechol (rate constant k_inh ~10^6 L/mol·s—10,000 times faster than with R·!):
  Step A: ROO· + TBC (Ar(OH)2) --> ROOH + Ar(OH)O· (resonance-stabilized ortho-semiquinone radical).
  Step B: A second peroxyl radical (ROO·) or molecular O2 reacts with the ortho-semiquinone radical: ROO· + Ar(OH)O· --> ROOH + 4-tert-Butyl-1,2-benzoquinone (stable ortho-quinone).
   Furthermore, the generated 4-tert-butyl-1,2-benzoquinone is itself a direct trap for carbon-centered radicals (R·), giving a stoichiometric inhibition factor (f) of >= 2.0 radical chains terminated per molecule of TBC Tert-Butylpyrocatechol!

Why TBC 85% in Water Forms a Stable Liquid Eutectic at +10 °C:
Although 100% pure TBC Tert-Butylpyrocatechol is a crystalline solid melting at 52 to 56 °C (and TBC is only sparingly soluble in large volumes of cold water at ~0.4% w/w), adding just 15% w/w water to 85% w/w molten TBC Tert-Butylpyrocatechol creates a reverse hydrated hydrogen-bonded liquid phase (water-in-catechol hydrogen-bonded complex) whose crystallization point drops by > 42 °C down to +8 to +12 °C! Similarly, dissolving 85% w/w TBC Tert-Butylpyrocatechol in 15% w/w methanol depresses the crystallization point below -30 °C for arctic winter outdoor dosing systems.
4. Effortless Alkaline Caustic Washing or Alumina Removal Prior to Polymerization:
Because TBC Tert-Butylpyrocatechol is a diprotic weak acid (pKa1 = 9.53, pKa2 ~13.0) with a high water-to-hydrocarbon partition coefficient once deprotonated into the water-soluble sodium catecholate anion, polymer plants can strip TBC Tert-Butylpyrocatechol from Styrene or 1,3-Butadiene down to < 0.5 ppm prior to polymerization simply by washing the monomer with a 5%–10% aqueous sodium hydroxide (NaOH) solution or passing the dry monomer through a fixed bed of activated alumina (Al2O3)!

INDUSTRIAL PRODUCTION AND MANUFACTURING PROCESSES

Commercial TBC Tert-Butylpyrocatechol (CAS 98-29-3) is manufactured via the selective Friedel-Crafts mono-alkylation of Pyrocatechol (1,2-Dihydroxybenzene, CAS 120-80-9) with Isobutylene (2-Methylpropene) or tert-Butanol:

Step 1: Catalytic Friedel-Crafts Alkylation of Catechol: High-purity molten pyrocatechol (1,2-benzenediol, synthesized by catalytic hydroxylation of phenol with hydrogen peroxide) is reacted with isobutylene gas (CH2=C(CH3)2) or tert-butyl alcohol ((CH3)3COH) at 80 to 130 °C in the presence of a regioselective solid-acid catalyst (such as macroreticular sulfonic-acid ion-exchange resin, activated acid clay, phosphoric acid, or heterogeneous heteropolyacid/zeolite catalyst). Because the two hydroxyl groups on C-1 and C-2 direct electrophilic substitution to the sterically unhindered C-4 para position rather than the crowded C-3 ortho position, 4-tert-butylpyrocatechol is formed with > 92%–95% selectivity (alongside minor 3-tert-butylcatechol and 3,5-di-tert-butylcatechol byproducts, which are transalkylated back to the 4-isomer).

Step 2: Multi-Stage High-Vacuum Fractional Distillation (under Nitrogen): The crude reaction product is neutralized/filtered and fractionally distilled in a stainless-steel or glass-lined vacuum column at 150 to 170 °C under 10 to 25 mbar absolute pressure under a strict oxygen-free nitrogen blanket (preventing oxidative quinone darkening) to isolate water-white molten TBC Tert-Butylpyrocatechol with >= 99.0%–99.7% purity and melt color <= 30–50 APHA.

Step 3: Flaking/Pastillation (100% Solid Grade) or Precision Blending (85% Liquid Grades): For the 100% solid grade, molten TBC Tert-Butylpyrocatechol is solidified on a nitrogen-blanketed chilled stainless-steel flaker/pastillator into uniform white-to-cream crystalline flakes or pastilles, or drummed as a molten liquid that solidifies in the drum. For the liquid dosing grades, molten TBC Tert-Butylpyrocatechol is blended under nitrogen with 15.0% +/- 0.5% w/w deoxygenated demineralized water (to produce TBC 85% in Water) or 15.0% +/- 0.5% w/w anhydrous methanol (to produce TBC 85% in Methanol) and filtered through 1-micron cartridges into lined drums or IBCs.
Ataman Kimya supplies all three commercial grades of TBC Tert-Butylpyrocatechol (100% Solid Flakes/Fused, 85% in Water, and 85% in Methanol) from ready stock to petrochemical, synthetic rubber, and resin plants.

PHYSICAL AND CHEMICAL PROPERTIES OF TBC TERT-BUTYLPYROCATECHOL

Quantitative physical constants, thermodynamic properties, and analytical specification ranges for commercial TBC Tert-Butylpyrocatechol (CAS 98-29-3, EC 202-653-9) across 100% Pure Solid and 85% Liquid grades are detailed below with their standard ASTM, ISO, and DIN test methods:
Chemical Identity and Registry Numbers of TBC Tert-Butylpyrocatechol: 4-tert-Butylpyrocatechol / 4-tert-Butylcatechol / 4-(1,1-Dimethylethyl)-1,2-benzenediol; CAS No. 98-29-3; EC / EINECS No. 202-653-9
Molecular Formula and Molar Mass of TBC Tert-Butylpyrocatechol: C10H14O2 ((CH3)3C-C6H3-1,2-(OH)2); Molecular Weight = 166.22 g/mol
Physical State and Appearance of TBC Tert-Butylpyrocatechol:
- TBC 100% Pure Grade (at 20 °C): White to pale cream or light tan crystalline solid flakes, pastilles, or fused crystalline mass (melts above 53 °C into a clear colorless to pale yellow liquid)
- TBC 85% in Water Grade (at 20 °C): Clear, colorless to pale yellow or light amber homogeneous viscous liquid
- TBC 85% in Methanol Grade (at 20 °C): Clear, colorless to pale yellow mobile liquid
Odor of TBC Tert-Butylpyrocatechol: Characteristic mild phenolic odor
Assay / Active TBC Content (Capillary GC or UV/Titrimetric Assay):
- TBC 100% Pure Solid Grade: >= 99.0% w/w 4-tert-Butylpyrocatechol (typical batch value: 99.3% to 99.8% w/w; 3-tert-butyl isomer <= 0.3%; 3,5-di-tert-butyl isomer <= 0.3%; free catechol <= 0.2%)
- TBC 85% in Water Grade: 84.0% to 86.0% w/w 4-tert-Butylpyrocatechol + 14.0% to 16.0% w/w demineralized water
- TBC 85% in Methanol Grade: 84.0% to 86.0% w/w 4-tert-Butylpyrocatechol + 14.0% to 16.0% w/w methanol
Color on Pt-Co (APHA / Hazen) Scale (ASTM D1209 / ISO 6271):
- TBC 100% Grade (Molten at 60 °C or 10% in Methanol): <= 50 to 80 APHA (typical fresh batch: 20 to 45 APHA)
- TBC 85% Liquid Grades (As-is at 20 °C): <= 70 to 100 APHA
Melting Point / Crystallization Point of TBC Tert-Butylpyrocatechol (ISO 1218 / ASTM D1493):
- TBC 100% Pure Grade: Melting Point = 52.0 to 56.0 °C (125.6 to 132.8 °F; Solidification Point >= 52.0 °C)
- TBC 85% in Water Grade: Crystallization / Freezing Point = +8.0 to +12.0 °C (+46.4 to +53.6 °F)
- TBC 85% in Methanol Grade: Crystallization / Pour Point = <= -30.0 °C (-22.0 °F)
Boiling Point and Vapor Pressure of TBC Tert-Butylpyrocatechol:
- Boiling Point (100% Pure TBC): 285.0 °C (545.0 °F) at 101.3 kPa (760 mmHg); 159.0 °C at 2.67 kPa (20 mmHg)
- Vapor Pressure (100% Pure TBC): 0.0036 hPa (0.36 Pa / 0.0027 mmHg) at 25 °C; 0.28 hPa at 60 °C; 1.33 hPa at 109 °C (extremely low volatility compared to Styrene b.p. 145 °C or 1,3-Butadiene b.p. -4.4 °C!)
Flash Point and Auto-Ignition Temperature of TBC Tert-Butylpyrocatechol:
- TBC 100% Pure Grade: Pensky-Martens Closed Cup Flash Point (ASTM D93) = 151.0 °C (303.8 °F); Cleveland Open Cup = ~165.0 °C; Auto-Ignition Temperature = ~435.0 °C (815 °F)
- TBC 85% in Water Grade: No flash point below boiling of water (> 100 °C; flash point of dehydrated residue ~151 °C)
- TBC 85% in Methanol Grade: Closed-Cup Flash Point = ~23.0 to 26.0 °C (governed by the 15% methanol co-solvent; Flammable Liquid Category 3)
Density / Specific Gravity of TBC Tert-Butylpyrocatechol:
- TBC 100% Pure Solid: True crystal density = 1.085 g/cm3 at 20 °C; Molten liquid density = 1.042 g/cm3 at 60 °C; Bulk density of flakes = 550 to 650 g/L
- TBC 85% in Water: Liquid density = 1.040 to 1.050 g/cm3 (typically 1.045 g/cm3) at 20 °C
- TBC 85% in Methanol: Liquid density = 0.990 to 1.005 g/cm3 at 20 °C
Dynamic Viscosity of TBC Tert-Butylpyrocatechol:
- TBC 100% Molten Liquid at 60 °C: ~18 mPa·s (cP)
- TBC 85% in Water: ~95 to 130 mPa·s (cP) at 20 °C; ~35 mPa·s at 40 °C
- TBC 85% in Methanol: ~15 to 25 mPa·s (cP) at 20 °C
Acid Dissociation Constant (pKa in Water at 25 °C) and Aqueous pH of TBC Tert-Butylpyrocatechol:
- pKa1 = 9.53; pKa2 ~ 13.0; pH of saturated aqueous solution (~0.4% w/w at 20 °C) = 5.2 to 6.2
Solubility Profile of TBC Tert-Butylpyrocatechol (at 25 °C):
- In Water: Sparingly soluble in bulk cold water (~4.0 g/L = 0.4% w/w at 20 °C; ~20 g/L at 80 °C), yet forms a 100% miscible reverse-hydrated liquid phase at 85% w/w TBC + 15% w/w water, and is freely soluble (> 300 g/L) in alkaline aqueous NaOH or KOH solutions (via sodium catecholate salt formation)!
- In Organic Solvents & Monomers (at 25 °C): Freely soluble in Styrene Monomer (> 55% w/w), Toluene (> 50% w/w), Methanol (> 85% w/w), Ethanol (> 80% w/w), Acetone (> 80% w/w), Diethyl Ether, Ethyl Acetate, and liquid 1,3-Butadiene or Isoprene
Octanol-Water Partition Coefficient (Log Kow, OECD 107): 1.98 (moderately lipophilic, low bioaccumulation potential, BCF < 20 L/kg)
Trace Metal Purity: Iron (Fe) <= 1.0 to 2.0 mg/kg (ppm; ultra-low iron prevents dark blue-black iron-catecholate complex coloration).

WHY EACH IMPORTANT PROPERTY OF TBC TERT-BUTYLPYROCATECHOL MATTERS IN PRACTICE

Monomer plant engineers, marine terminal operators, synthetic rubber chemists, and UPR resin formulators track specific quantitative parameters on a TBC Tert-Butylpyrocatechol COA because each property governs process safety and polymer quality:
- High Hydrocarbon Solubility (> 50% in Styrene at 25 °C) Coupled with High Alkaline Water Extractability (pKa1 = 9.53): An ideal monomer inhibitor must stay 100% dissolved in non-polar hydrocarbon monomers during sub-zero winter pipeline transport, yet be 100% removable right before polymerization. Because TBC Tert-Butylpyrocatechol carries both a C-4 tert-butyl tail and weakly acidic C-1/C-2 catechol hydroxyls (pKa1 = 9.53), it dissolves effortlessly in cold Styrene and 1,3-Butadiene, but when the monomer is contacted with a 5% aqueous NaOH wash (pH 13.5), TBC Tert-Butylpyrocatechol deprotonates into the water-soluble sodium 4-tert-butylcatecholate ion and extracts quantitatively into the aqueous waste layer!
- Low Color (<= 50 to 80 APHA) and Ultra-Low Trace Iron (Fe <= 1–2 ppm): When TBC Tert-Butylpyrocatechol oxidizes in air or contacts trace ferric iron (Fe3+ from rusty carbon-steel pipes), it forms reddish-yellow 4-tert-butyl-1,2-benzoquinone and dark blue-black iron(III)-catecholate complexes. High-purity, low-APHA TBC Tert-Butylpyrocatechol supplied by Ataman Kimya ensures that inhibited Styrene Monomer retains its crystal-clear water-white specification (APHA <= 10 at 10–15 ppm TBC).
- Low Volatility (Boiling Point 285 °C, Vapor Pressure 0.36 Pa at 25 °C): ensures that TBC Tert-Butylpyrocatechol remains in the liquid monomer phase during vacuum distillation in styrene and butadiene recovery columns, preventing reboiler fouling and bottom-tray polymer build-up.
- Liquid Eutectic Freezing Point Depression (+10 °C for TBC 85% in Water; <= -30 °C for TBC 85% in Methanol): Eliminates the need to melt solid drums of 100% TBC (melting point 54 °C) in steam rooms, allowing direct closed-loop metering pump injection of TBC Tert-Butylpyrocatechol into monomer rundown lines and marine tankers!

HOW DOES TBC TERT-BUTYLPYROCATECHOL WORK AT THE MOLECULAR AND PROCESS LEVEL?

TBC Tert-Butylpyrocatechol protects reactive monomers and thermoset resins through four interconnected chemical mechanisms:
- 1. Peroxyl Radical Scavenging (Hydrogen Atom Transfer, HAT) in Oxygenated Monomers: In stored Styrene, 1,3-Butadiene, or Isoprene containing 15 to 50 ppm dissolved oxygen, thermally generated monomer radicals (M·) react instantaneously with O2 to form monomer peroxyl radicals (MOO·). Rather than adding to another monomer double bond to form explosive polymeric peroxides (which propagate at slow rate k_p ~10–100 L/mol·s), MOO· abstracts a hydrogen atom from TBC Tert-Butylpyrocatechol at k_inh ~10^6 L/mol·s—terminating the kinetic chain before even a single monomer unit can polymerize!
- 2. Ortho-Quinone In-Situ Generation and Carbon-Radical Trapping: Each molecule of TBC Tert-Butylpyrocatechol oxidized by two peroxyl radicals converts into one molecule of 4-tert-butyl-1,2-benzoquinone (TBBQ). Unlike para-benzoquinone, ortho-4-tert-butyl-1,2-benzoquinone acts as an active radical spin trap and retardation co-agent for carbon-centered radicals (M·) in oxygen-depleted dead zones or distillation reboilers, extending protection across both liquid-phase and low-oxygen regimes.

- 3. Decomposition of Hydroperoxides & Suppression of 'Popcorn Polymer' Seeds in 1,3-Butadiene and Isoprene: In conjugated diene monomers (1,3-butadiene, isoprene, chloroprene), trace oxygen without an inhibitor forms insoluble, cross-linked, free-radical-rich 'popcorn polymer' seeds that grow exponentially by absorbing monomer and can burst steel pipes with forces exceeding 300 bar! Dosing 50 to 200 ppm of TBC Tert-Butylpyrocatechol scavenges both alkoxyl (RO·) and peroxyl (ROO·) radicals at the popcorn seed interface, arresting seed nucleation and growth.
- 4. Gel-Time & Pot-Life Stabilization in Unsaturated Polyester Resins (UPR) and Vinyl Ester Resins: When added at 50 to 500 ppm to styrene-diluted Unsaturated Polyester Resins (UPR) or Vinyl Ester Resins, TBC Tert-Butylpyrocatechol prevents premature room-temperature gelation during 6–12 months of drum storage, and provides a clean, sharply defined induction period (gel time) once MEKP (methyl ethyl ketone peroxide) and cobalt octoate accelerator are added—without reducing final Barcol hardness after cure!

WHAT PROBLEMS CAN TBC TERT-BUTYLPYROCATECHOL HELP SOLVE?

Petrochemical engineers, synthetic rubber producers, and resin formulators deploy TBC Tert-Butylpyrocatechol to prevent six critical industrial hazards and quality failures:
Runaway exothermic polymerization and tank explosions in Styrene Monomer storage and marine transport prevented by TBC Tert-Butylpyrocatechol
Uninhibited Styrene Monomer self-polymerizes slowly at ambient temperature and accelerates adiabatically above 50–65 °C into a violent thermal runaway (reaching > 300 °C and rupturing tanks). Maintaining 10 to 50 ppm of TBC Tert-Butylpyrocatechol (along with 15–50 ppm dissolved O2) arrests radical chains completely during months of bulk tank storage and ocean transit.
Destructive 'popcorn polymer' fouling and peroxide buildup in 1,3-Butadiene and Isoprene units prevented by TBC Tert-Butylpyrocatechol
In butadiene extraction units and synthetic rubber plants (SBR 1502, PBR, NBR, SBS), uninhibited dienes form explosive polymeric peroxides and expanding popcorn polymer that plugs columns and cracks valves. Injecting 50 to 200 ppm TBC Tert-Butylpyrocatechol into rundown tanks and recycle streams prevents peroxide accumulation and popcorn growth.

Insolubility and winter precipitation of Hydroquinone in non-polar hydrocarbon monomers solved by TBC Tert-Butylpyrocatechol
Hydroquinone has poor solubility in cold styrene, vinyltoluene, divinylbenzene, and liquid butadiene, precipitating out on tank bottoms and leaving the bulk monomer unprotected. The C-4 tert-butyl group of TBC Tert-Butylpyrocatechol guarantees complete miscibility in all hydrocarbon monomers down to sub-zero temperatures.
Premature in-can gelling and erratic gel-time drift in Unsaturated Polyester (UPR) and Vinyl Ester Resins solved by TBC Tert-Butylpyrocatechol
UPR and vinyl ester resins often suffer from downward gel-time drift or premature gelation during warm summer storage (> 35 °C). Adding 50 to 300 ppm of TBC Tert-Butylpyrocatechol stabilizes shelf life and allows exact adjustment of room-temperature MEKP/cobalt gel times without compromising peak exotherm or cure speed.

Solid inhibitor handling hazards and steam-melting bottlenecks solved by TBC 85% Liquid Grades
Handling and melting solid drums of 100% pure TBC (melting point 54 °C) exposes operators to corrosive dust/vapors and risks thermal oxidation darkening if overheated. Using Ataman Kimya's TBC 85% in Water (freezing point +10 °C) or TBC 85% in Methanol (freezing point <= -30 °C) allows closed, automated liquid metering directly from drums or IBCs at ambient temperature.

Catalyst poisoning in downstream polymerization caused by non-removable amine or sulfur inhibitors avoided by TBC Tert-Butylpyrocatechol
Aromatic amine or phenothiazine inhibitors leave residual nitrogen and sulfur that poison Ziegler-Natta, metallocene, or anionic butyl-lithium catalysts. TBC Tert-Butylpyrocatechol contains only carbon, hydrogen, and oxygen (C10H14O2) and strips down to < 0.5 ppm via simple caustic NaOH washing or alumina adsorption.

BENEFITS FOR THE MANUFACTURER AND END USER

Sourcing TBC Tert-Butylpyrocatechol from Ataman Kimya delivers decisive safety, operational, and economic advantages:
Benefits of TBC Tert-Butylpyrocatechol for the Monomer, Rubber & Resin Manufacturer:
- 25x Faster Radical-Scavenging Kinetics than Hydroquinone: Protects reactive monomers at ultra-low dosages (10 to 50 ppm in Styrene; 50 to 200 ppm in 1,3-Butadiene).
- Unlimited Hydrocarbon Monomer Solubility: Dissolves instantaneously in styrene, divinylbenzene, butadiene, isoprene, and aromatic solvents without crystal dropout.
- Easy Quantitative Removal Before Polymerization: Washes out completely with 5%–10% aqueous NaOH or adsorbs onto activated alumina beds when inhibitor-free monomer is needed, or can be overridden directly with a slight excess of free-radical initiator in emulsion SBR polymerization.
- Ready-to-Pump 85% Liquid Eutectic Options (Water or Methanol): Eliminates drum-melting ovens and enables precision closed-loop dosing pump automation.
- Ultra-Low Iron & Low APHA Color: Guarantees water-white monomer color compliance (APHA <= 10–15 in inhibited styrene).

APPLICATIONS OF TBC TERT-BUTYLPYROCATECHOL

TBC Tert-Butylpyrocatechol (4-tert-Butylpyrocatechol / 4-tert-Butylcatechol, CAS 98-29-3) is utilized across eight critical industrial applications:
TBC Tert-Butylpyrocatechol is extensively utilized as the primary Polymerization Inhibitor and Antioxidant Stabilizer for Styrene Monomer (SM), Alpha-Methylstyrene, Vinyltoluene, and Divinylbenzene (DVB) during distillation, storage, and marine/rail transport.
TBC Tert-Butylpyrocatechol is used for the Stabilization of Conjugated Diolefin Monomers—specifically 1,3-Butadiene, Isoprene, Chloroprene (2-Chloro-1,3-butadiene), and Piperylene—to prevent explosive peroxide formation and popcorn polymerization.
Also, TBC Tert-Butylpyrocatechol is utilized in Synthetic Rubber Manufacturing (including Emulsion SBR 1502 / 1500, Solution SBR, Polybutadiene BR, Nitrile NBR, and Polychloroprene CR) as a recycle-monomer inhibitor and short-stopping / antioxidant co-stabilizer.

For Unsaturated Polyester Resins (UPR), Vinyl Ester Resins, Gelcoats, and Putty/SMC/BMC Molding Compounds, TBC Tert-Butylpyrocatechol is widely used as a shelf-life stabilizer and room-temperature gel-time modifier.
In Polyurethane (PU) Foam Catalyst Packages and Polyether Polyols, TBC Tert-Butylpyrocatechol is employed as an antioxidant and scorch-preventing radical scavenger.
Furthermore, TBC Tert-Butylpyrocatechol is utilized as a Process Inhibitor in Reactive Distillation Columns, Petrochemical Steam Crackers (C4/C5 pygas recovery), and Vinyl Acetate / Acrylate Monomer Recovery Units.
TBC Tert-Butylpyrocatechol is also used as a Stabilizer for Chlorinated Hydrocarbons, Allyl Monomers, and Specialty Adhesives/Coatings.
 In Fine Chemical, Pharmaceutical, and Agrochemical Synthesis, TBC Tert-Butylpyrocatechol serves as a reactive ortho-catechol building block for synthesizing crown ethers, catecholamine/benzodioxole derivatives, corrosion inhibitors, and metal-chelating ligands.

WHICH INDUSTRIES USE TBC TERT-BUTYLPYROCATECHOL?

- The Petrochemical Monomer Refining and Bulk Chemical Terminal Industry relies on TBC Tert-Butylpyrocatechol to inhibit Styrene, 1,3-Butadiene, Isoprene, and Divinylbenzene during production, storage, and shipping.
- The Synthetic Rubber and Elastomer Manufacturing Industry (SBR, BR, NBR, SBS, SIS, and CR plants) utilizes TBC Tert-Butylpyrocatechol to stabilize fresh and recycled monomer streams against popcorn polymer fouling.
- The Thermoset Composite Resin Industry (Unsaturated Polyester Resin UPR, Vinyl Ester, Gelcoat, and SMC/BMC producers) uses TBC Tert-Butylpyrocatechol to control resin pot life, shelf stability, and MEKP cure gel times.
- The Polyurethane (PU) Catalyst, Polyol, and Foam Additive Industry deploys TBC Tert-Butylpyrocatechol as a radical-scavenging antioxidant stabilizer.
- The Specialty Monomer, Ion-Exchange Resin (Styrene-DVB copolymer), and Adhesive Manufacturing Industry uses TBC Tert-Butylpyrocatechol for high-crosslinker monomer stabilization (500 to 1,500 ppm in Divinylbenzene).
- The Fine Chemical and Specialty Intermediate Synthesis Industry utilizes TBC Tert-Butylpyrocatechol (4-tert-Butylcatechol) as a substituted 1,2-benzenediol synthon.

USE OF TBC TERT-BUTYLPYROCATECHOL IN STYRENE, 1,3-BUTADIENE AND SYNTHETIC RUBBER PLANTS

- Styrene Monomer (SM) Storage and Marine Transport Stabilization with TBC Tert-Butylpyrocatechol (10 to 50 ppm): Globally, commercial Styrene Monomer (CAS 100-42-5) is inhibited at the refinery rundown tank with 10 to 15 ppm w/w of TBC Tert-Butylpyrocatechol for cool/temperate pipeline and short-term tank storage (< 25 °C), and boosted to 15 to 50 ppm w/w (typically 20 to 45 ppm) of TBC Tert-Butylpyrocatechol for warm-climate storage (> 30 °C) or long-distance ocean tanker voyages. Because TBC Tert-Butylpyrocatechol is consumed slowly as it neutralizes thermally generated peroxyl radicals (typical depletion rate is ~0.5 to 2.0 ppm per week at 25–35 °C), tank-farm laboratories monitor active TBC Tert-Butylpyrocatechol concentration weekly by ASTM D4590 (colorimetric NaOH/alcohol extraction spectrophotometry at 490 nm) and top up with TBC 85% Liquid whenever levels fall below 10 ppm!
- 1,3-Butadiene, Isoprene, and Chloroprene Stabilization with TBC Tert-Butylpyrocatechol (50 to 200 ppm): Liquefied 1,3-Butadiene (CAS 106-99-0) and Isoprene (CAS 78-79-5) stored in pressurized spheres or refrigerated tanks are dosed with 50 to 200 ppm w/w (typically 100 to 150 ppm) of TBC Tert-Butylpyrocatechol (usually injected as TBC 85% in Methanol or TBC 85% in Water/Hydrocarbon). In synthetic rubber plants (such as E-SBR 1502 or NBR emulsion polymerization), when unreacted 1,3-butadiene and styrene are flashed and steam-stripped from the latex at 60% conversion for recycle, 50 to 100 ppm of TBC Tert-Butylpyrocatechol is injected into the monomer recovery condensers to prevent popcorn polymer from plugging the recycle compressors and condensers.
- Divinylbenzene (DVB) and Vinyltoluene Stabilization with TBC Tert-Butylpyrocatechol (500 to 1,500 ppm): Because bifunctional Divinylbenzene (DVB 55%, 63%, and 80% grades) cross-links 20 times faster than styrene, DVB is stabilized with 800 to 1,500 ppm (0.08% to 0.15% w/w) of TBC Tert-Butylpyrocatechol.

USE OF TBC TERT-BUTYLPYROCATECHOL IN UNSATURATED POLYESTER RESINS (UPR), PU CATALYSTS AND FINE SYNTHESIS

- Unsaturated Polyester Resins (UPR) and Vinyl Ester Resins with TBC Tert-Butylpyrocatechol (50 to 500 ppm): When molten unsaturated maleate/fumarate polyester alkyd is thinned (let down) into Styrene Monomer at 80–110 °C, hydroquinone or toluhydroquinone is used as the hot-thinning inhibitor, while 50 to 300 ppm of TBC Tert-Butylpyrocatechol is added during cooling or final adjustment to trim the ambient MEKP + Cobalt Octoate gel time (e.g., from 8 minutes out to a target of 20 to 35 minutes) and extend ambient drum shelf life beyond 6 to 12 months. In room-temperature cobalt-accelerated cures, TBC Tert-Butylpyrocatechol provides cleaner, more linear gel-time extension with less yellow/pink discoloration than hydroquinone.
- Polyurethane Amine/Tin Catalyst Stabilization & Fine Chemical Synthesis: Dosed at 0.05% to 0.50% w/w in polyurethane tertiary-amine/organotin catalyst blends and specialty polyols to prevent air-induced peroxide discoloration; reacted with alkyl halides, epoxides, or acyl chlorides in organic synthesis to produce substituted 1,2-benzodioxoles, catechol ethers, and specialty antioxidants.

FORMULATION AND PROCESS CONSIDERATIONS WHEN USING TBC TERT-BUTYLPYROCATECHOL

To ensure 100% safe monomer storage and trouble-free dosing when working with TBC Tert-Butylpyrocatechol, plant engineers must strictly observe four critical operational rules:
- 1. Mandatory Dissolved Oxygen (15 to 50 ppm O2) in Inhibited Monomers: TBC Tert-Butylpyrocatechol REQUIRES dissolved molecular oxygen (minimum 10 to 15 ppm O2, optimal 15 to 50 ppm O2 in Styrene) to function effectively! Never blanket a TBC-inhibited Styrene or Divinylbenzene storage tank with 100% pure oxygen-free Nitrogen for prolonged periods without maintaining 5%–8% O2 in the vapor space (or periodic air/O2 sparging), because if dissolved oxygen drops below 3–5 ppm, TBC Tert-Butylpyrocatechol loses > 90% of its radical-trapping speed!
- 2. Choosing Between TBC 85% in Water vs. TBC 85% in Methanol vs. TBC 100% Solid Flakes:
  - Choose TBC 85% in Water (freezing point +8 to +12 °C, non-flammable flash point > 100 °C) for standard Styrene Monomer plants, marine terminals, and UPR resin plants where methanol contamination is undesirable and dosing lines are kept above +15 °C.
  - Choose TBC 85% in Methanol (freezing point <= -30 °C) for sub-zero winter outdoor tank farms and refrigerated 1,3-Butadiene / Isoprene spheres where water droplets would freeze into ice crystals and plug injection nozzles!
  - Choose TBC 100% Pure Solid Flakes when zero water and zero methanol can be tolerated (e.g., preparing custom stock solutions in dry styrene, toluene, or polyol).
- 3. Gentle Thawing of TBC 85% in Water (+25 to +40 °C) If Chilled Below +10 °C: If drums or IBCs of TBC 85% in Water are exposed to winter temperatures below +8 to +10 °C, partial crystallization of TBC hydrates may occur. Warm the sealed container gently in a warm room at +25 to +40 °C (never exceed 50–60 °C or use open flames) and roll/circulate until 100% clear and homogeneous before pumping, because a partially frozen drum has a depleted TBC concentration in the supernatant liquid!
- 4. Materials of Construction (316L Stainless Steel / HDPE / Glass / PTFE): Never store or pipe concentrated TBC Tert-Butylpyrocatechol in unlined carbon steel, cast iron, copper, or brass (iron forms dark blue-black complexes and catalyzes oxidation; copper catalyzes quinone formation). Use AISI 316L or 304 stainless steel, baked phenolic-lined steel, high-density polyethylene (HDPE), glass, and PTFE/Viton seals.

TYPICAL USE LEVELS AND INITIAL FORMULATION APPROACHES FOR TBC TERT-BUTYLPYROCATECHOL

Typical commercial dosage levels for TBC Tert-Butylpyrocatechol (calculated as 100% active TBC; multiply by 1.18 when dosing TBC 85% Liquid) depend on the monomer, temperature, and storage duration:
- In Styrene Monomer (SM) Temperate Pipeline & Short-Term Tank Storage (< 25 °C), TBC Tert-Butylpyrocatechol is dosed at 10 to 15 ppm w/w (10 to 15 g active TBC per metric ton of Styrene, with 15–50 ppm dissolved O2).
- In Styrene Monomer Warm-Climate Storage (> 30 °C) and Long-Distance Marine Tanker Voyages, TBC Tert-Butylpyrocatechol is utilized at 20 to 50 ppm w/w (20 to 50 g active TBC per metric ton of Styrene).
- In Liquefied 1,3-Butadiene (BD), Isoprene, and Chloroprene Storage & Recycle Streams, TBC Tert-Butylpyrocatechol is incorporated at 50 to 200 ppm w/w (typically 100 to 150 ppm active TBC).
- In Vinyltoluene and Alpha-Methylstyrene Monomers, TBC Tert-Butylpyrocatechol is applied at 15 to 50 ppm w/w.
- In Divinylbenzene (DVB 55%, 63%, and 80% Crosslinker Grades), TBC Tert-Butylpyrocatechol is used at 800 to 1,500 ppm w/w (0.08% to 0.15% w/w).
- In Unsaturated Polyester Resins (UPR), Vinyl Ester Resins, and Gelcoats, TBC Tert-Butylpyrocatechol is dosed at 50 to 500 ppm w/w (0.005% to 0.05% w/w) to adjust MEKP/cobalt gel time and extend shelf life.
- In Polyurethane Catalyst Packages and Specialty Polyether Polyols, TBC Tert-Butylpyrocatechol is employed at 500 to 3,000 ppm w/w (0.05% to 0.30% w/w).
The four laboratory and pilot plant frameworks below illustrate preliminary evaluation and quality-control protocols for TBC Tert-Butylpyrocatechol by qualified technical personnel.

EXAMPLE 1: STYRENE MONOMER STORAGE STABILIZATION, ASTM D4590 SPECTROPHOTOMETRIC TBC MONITORING AND TOP-UP PROTOCOL WITH TBC TERT-BUTYLPYROCATECHOL

Purpose: To prepare a 1.0% w/w master stock solution of TBC Tert-Butylpyrocatechol in Styrene Monomer, dose bulk Styrene to a target of 15 ppm (or 30 ppm for warm transit), monitor weekly TBC depletion via ASTM D4590 colorimetric extraction, and verify zero polymer formation (ASTM D2121) over 60 days at 35 °C.
Initial dosing and stock-solution parameters (per 1,000 kg = 1.0 metric ton of Styrene Monomer, density 0.906 g/cm3):
- Uninhibited or Low-TBC Distilled Styrene Monomer (CAS 100-42-5, purity >= 99.8%, initial TBC = 5.0 ppm, dissolved oxygen = 25 ppm via 6% O2 / 94% N2 gas blanket): 1,000.0 kg
- TBC Tert-Butylpyrocatechol 85% w/w Liquid in Water (or TBC 100% Flakes dissolved at 1.0% w/w in fresh Styrene Monomer; to raise TBC from 5.0 ppm to 30.0 ppm = +25.0 g active TBC/ton = +29.4 g of TBC 85% Liquid/ton): 29.4 g of TBC 85% Liquid (or 2,500 g of a 1.0% w/w active TBC-in-styrene stock solution)
Laboratory monitoring and evaluation procedure:
- Stage 1 (Stock Dosing & Homogenization): Meter the 29.4 g of TBC 85% Liquid (or 2,500 g of 1.0% TBC-in-styrene stock solution) into the 1,000 kg Styrene Monomer recirculation loop and circulate for 30 minutes until homogeneous.
- Stage 2 (ASTM D4590 Colorimetric TBC Assay): Take a 10.0 mL sample of the inhibited Styrene Monomer and extract with 0.15N NaOH in aqueous methanol (or add NaOH/octanol reagent per ASTM D4590). In alkaline solution in the presence of air, extracted TBC Tert-Butylpyrocatechol oxidizes rapidly into a pink-red quinonoid anion with an absorption maximum at 490 nm. Measure absorbance at 490 nm on a UV-Vis spectrophotometer against a 0 to 50 ppm TBC calibration curve: confirm active TBC concentration is 30.0 +/- 1.0 ppm.
- Stage 3 (Accelerated 35 °C Aging & ASTM D2121 Polymer Content Check): Store sealed oxygenated aliquots at 35 °C for 60 days, testing active TBC and polystyrene content (by methanol turbidity / gravimetry per ASTM D2121) every 7 days: verify that as long as TBC Tert-Butylpyrocatechol remains >= 10–12 ppm and dissolved O2 is >= 15 ppm, polystyrene content remains <= 5 to 10 ppm (crystal clear, APHA <= 10).

EXAMPLE 2: CAUSTIC WASHING AND ACTIVATED ALUMINA REMOVAL OF TBC TERT-BUTYLPYROCATECHOL FROM STYRENE OR 1,3-BUTADIENE PRIOR TO POLYMERIZATION

Purpose: To strip 45 ppm of TBC Tert-Butylpyrocatechol from inhibited Styrene Monomer (or 150 ppm from 1,3-Butadiene) down to < 0.5 ppm immediately prior to laboratory or pilot-plant polymerization using either alkaline NaOH extraction or fixed-bed activated alumina adsorption.
Initial monomer feed and stripping media (per 1,000.0 g of inhibited Styrene Monomer):
- Inhibited Styrene Monomer containing 45.0 ppm w/w TBC Tert-Butylpyrocatechol: 1,000.0 g (approx. 1,104 mL)
- Method A (Alkaline Caustic Extraction Wash): 3 x 150.0 g aliquots of 5.0% w/w aqueous Sodium Hydroxide (NaOH) solution, followed by 2 x 150.0 g aliquots of deoxygenated demineralized water (pH 7.0)
- Method B (Dry Activated Alumina Column Stripping, Zero Wastewater): 50.0 g of basic Activated Alumina (Al2O3, 80–200 mesh, calcined at 250 °C) packed in a jacketed glass/stainless-steel column under nitrogen
Laboratory evaluation procedure:
- For Method A (Caustic Wash): Contact the 1,000.0 g of 45 ppm TBC-inhibited Styrene Monomer with 150.0 g of 5% aqueous NaOH in a separatory funnel or mixer-settler for 5 minutes and allow phases to separate. Observe that deprotonated sodium 4-tert-butylcatecholate partitions into the lower aqueous caustic phase (turning it pale pink-amber). Repeat twice more with fresh 5% NaOH, wash twice with demineralized water until the aqueous layer is neutral (pH 7.0), and dry over anhydrous Na2SO4 or molecular sieves.
- For Method B (Alumina Bed): Percolate the 1,000.0 g of dry 45 ppm TBC-inhibited Styrene downward through the 50.0 g basic activated alumina column at a liquid hourly space velocity (LHSV) of 4 to 6 h-1 under nitrogen: the ortho-catechol groups of TBC Tert-Butylpyrocatechol chemisorb onto surface Al-O sites as an orange-brown band at the top of the bed, while water-white, inhibitor-free Styrene exits the bottom!
- Verify by ASTM D4590 spectrophotometry that residual TBC Tert-Butylpyrocatechol in the stripped monomer is < 0.5 ppm, and immediately blanket the uninhibited monomer with nitrogen and charge to the polymerization reactor within < 2 hours.

EXAMPLE 3: GEL-TIME ADJUSTMENT AND 50 °C SHELF-LIFE STABILIZATION OF AN UNSATURATED POLYESTER RESIN (UPR) OR VINYL ESTER RESIN WITH TBC TERT-BUTYLPYROCATECHOL

Purpose: To extend the 25 °C MEKP/Cobalt gel time of a pre-accelerated orthophthalic/isophthalic Unsaturated Polyester Resin (UPR) from 9 minutes out to a target molding window of 25 +/- 2 minutes without reducing peak exotherm or cured Barcol hardness using TBC Tert-Butylpyrocatechol.
Initial UPR resin formulation ladder (per 1,000.0 g of 65% alkyd / 35% styrene UPR base resin):
- Unsaturated Polyester Resin in 35% Styrene Monomer (pre-accelerated with 0.20% w/w of 6% Cobalt Octoate, baseline unadjusted gel time with 1.5% MEKP at 25 °C = 9.0 minutes): 1,000.0 g
- TBC Tert-Butylpyrocatechol Stock Solution (10.0% w/w solution of TBC 100% Flakes dissolved in Styrene Monomer or Propylene Glycol):
  - Batch 1 (Control, +0 ppm added TBC): 0.00 g stock solution
  - Batch 2 (+100 ppm active TBC = 0.10 g TBC/kg): 1.00 g of 10% TBC stock solution
  - Batch 3 (+200 ppm active TBC = 0.20 g TBC/kg): 2.00 g of 10% TBC stock solution
  - Batch 4 (+300 ppm active TBC = 0.30 g TBC/kg): 3.00 g of 10% TBC stock solution
Laboratory evaluation procedure:
- Stir the 1.00 g, 2.00 g, and 3.00 g of 10% TBC Tert-Butylpyrocatechol stock solution into Batches 2, 3, and 4 for 15 minutes at 25 °C.
- Take 100.0 g of each resin batch in a 25 °C water bath, catalyze with 1.50 g (1.5% w/w) of standard Methyl Ethyl Ketone Peroxide (MEKP, 9% active oxygen), and record SPI Gel Time, Time to Peak Exotherm, and Peak Exotherm Temperature (ASTM D2471): verify that Batch 1 gels in 9.0 min, Batch 2 (+100 ppm TBC) gels in ~16.5 min, Batch 3 (+200 ppm TBC) hits the exact target gel time of ~25.0 min (with Peak Exotherm remaining >= 175 °C and 24-hour Barcol 934-1 hardness >= 42, identical to Control!), and Batch 4 (+300 ppm TBC) gels in ~34.0 min.
- Place uncatalyzed sealed cans of Batches 1–4 in a 50 °C oven (accelerated dark storage stability test): verify that +200 ppm TBC Tert-Butylpyrocatechol doubles the uncatalyzed 50 °C pot life from 14 days to > 32 days!

EXAMPLE 4: INHIBITION OF POPCORN POLYMER AND PEROXIDE FORMATION IN 1,3-BUTADIENE / ISOPRENE RECYCLE STREAMS WITH TBC 85% IN METHANOL

Purpose: To evaluate low-temperature miscibility (-20 °C) and inhibition of peroxide and popcorn polymer growth in liquid Isoprene (or 1,3-Butadiene) using TBC Tert-Butylpyrocatechol (85% in Methanol).
Initial monomer test setup (per 500.0 g of distilled Isoprene monomer in pressure glass autoclaves):
- Freshly Distilled Isoprene Monomer (2-methyl-1,3-butadiene, CAS 78-79-5, boiling point 34 °C, containing 20 ppm dissolved O2 and seeded with 0.50 g of active cross-linked diene popcorn polymer seed): 500.0 g
- TBC Tert-Butylpyrocatechol (dosed as TBC 85% in Methanol at 100 ppm active TBC = 0.050 g active TBC = 0.059 g of TBC 85% M per 500 g monomer): 59.0 mg
Laboratory evaluation procedure:
- Verify that the TBC 85% in Methanol stock solution remains crystal-clear and free-flowing at -25 °C, and dissolves instantaneously in cold Isoprene at -20 °C without phase separation or ice crystal formation.
- Hold the TBC-inhibited Isoprene autoclave (containing the 0.50 g popcorn seed) and an uninhibited control autoclave at 40 °C for 14 days: verify that whereas the uninhibited control exhibits rapid popcorn seed mass multiplication (> 500% weight gain) and dangerous active peroxide accumulation (> 150 ppm as H2O2 by iodometric titration ASTM E299), the autoclave inhibited with 100 ppm TBC Tert-Butylpyrocatechol shows zero popcorn seed growth (< 1% weight change) and peroxide content <= 5 ppm!

COMPATIBILITY AND INCOMPATIBILITY OF TBC TERT-BUTYLPYROCATECHOL

Evaluating chemical and materials compatibility is critical when handling TBC Tert-Butylpyrocatechol in monomer tank farms, chemical plants, and resin reactors:
- Full Compatibility of TBC Tert-Butylpyrocatechol with Monomers, Hydrocarbons, and Alcohols: Completely miscible and chemically compatible with Styrene, Alpha-Methylstyrene, Vinyltoluene, Divinylbenzene, 1,3-Butadiene, Isoprene, Chloroprene, Acrylic/Methacrylic Esters, Unsaturated Polyester and Vinyl Ester Resins, toluene, xylene, ethylbenzene, methanol, ethanol, isopropanol, acetone, and polyether polyols.
- Compatibility of TBC Tert-Butylpyrocatechol with Co-Inhibitors and Retarders: Fully compatible with hydroquinone (HQ), 4-methoxyphenol (MEHQ), 2,6-di-tert-butyl-4-methylphenol (BHT), para-benzoquinone (PBQ), phenothiazine (PTZ), and stable nitroxide radicals (TEMPO / 4-hydroxy-TEMPO) in multi-stage distillation column inhibition packages.

- Severe Incompatibility of TBC Tert-Butylpyrocatechol with Strong Oxidizers, Strong Bases, and Acid Chlorides/Anhydrides: Keep concentrated TBC Tert-Butylpyrocatechol strictly segregated from strong oxidizing agents (concentrated nitric acid, hydrogen peroxide > 30%, organic peroxides like pure MEKP/BPO, permanganates, chlorates, and chromates), which oxidize TBC exothermically. Mixing concentrated TBC directly with concentrated strong alkalis (NaOH, KOH, amines) generates exothermic neutralization heat and causes rapid air-oxidation of the catecholate salt into dark black-brown humic quinone polymers.
- Incompatibility with Unlined Carbon Steel, Iron, and Copper Alloys: Contact with iron (Fe2+/Fe3+) or rust forms intense blue-black iron-catecholate complexes that discolor monomers; contact with copper or brass accelerates oxidative degradation. Always use 316L/304 stainless steel, HDPE, baked phenolic linings, glass, and PTFE/Viton gaskets.

SIMILAR PRODUCTS AND ALTERNATIVES TO TBC TERT-BUTYLPYROCATECHOL

When designing a monomer storage, distillation column, or resin stabilization program, engineers compare TBC Tert-Butylpyrocatechol (CAS 98-29-3) against MEHQ (4-Methoxyphenol, CAS 150-76-5), Hydroquinone (HQ, CAS 123-31-9), BHT (Butylated Hydroxytoluene, CAS 128-37-0), TBHQ (tert-Butylhydroquinone, CAS 1948-33-0), and TEMPO / DNBP distillation inhibitors.

TBC TERT-BUTYLPYROCATECHOL AND MEHQ (4-METHOXYPHENOL / HYDROQUINONE MONOMETHYL ETHER, CAS 150-76-5)

MEHQ (4-Methoxyphenol, C7H8O2, MW 124.14 g/mol, melting point 54–56 °C) is the standard storage inhibitor for polar acrylic and methacrylic acid and ester monomers (such as glacial acrylic acid, methyl methacrylate, and butyl acrylate).
However, in non-polar conjugated hydrocarbon monomers like Styrene, 1,3-Butadiene, Isoprene, and Divinylbenzene, TBC Tert-Butylpyrocatechol is vastly superior to MEHQ for three reasons: (1) The 1,2-catechol structure of TBC Tert-Butylpyrocatechol scavenges styryl/butadienyl peroxyl radicals 50 to 100 times faster than the single hindered -OH group of MEHQ, allowing Styrene to be stabilized with just 10–15 ppm TBC (vs. 100–200 ppm needed for MEHQ); (2) TBC Tert-Butylpyrocatechol has a lower acidity (pKa 9.53) and higher partition ratio into aqueous NaOH than MEHQ, making TBC much easier to strip completely by caustic washing; and (3) TBC Tert-Butylpyrocatechol is supplied as a convenient 85% liquid eutectic in water (+10 °C freezing point), whereas MEHQ is a solid that cannot form an 85% liquid hydrate.

TBC TERT-BUTYLPYROCATECHOL AND HYDROQUINONE (HQ / 1,4-BENZENEDIOL, CAS 123-31-9)

Hydroquinone (1,4-Benzenediol, C6H6O2, MW 110.11 g/mol, melting point 172 °C) is an unsubstituted para-dihydric phenol used in water-soluble monomers and hot UPR thinning.
However, Hydroquinone is practically insoluble in non-polar hydrocarbon monomers (< 0.05% in styrene and insoluble in liquid 1,3-butadiene or isoprene) and has a radical-scavenging rate constant 25 times slower than TBC Tert-Butylpyrocatechol at 60 °C. The C-4 tert-butyl group and ortho-catechol geometry of TBC Tert-Butylpyrocatechol provide complete hydrocarbon solubility (> 50% in styrene) and 25-fold higher inhibition power.

TBC TERT-BUTYLPYROCATECHOL AND BHT (2,6-DI-TERT-BUTYL-4-METHYLPHENOL, CAS 128-37-0)

BHT (Butylated Hydroxytoluene, C15H24O, MW 220.35 g/mol) is a sterically hindered monohydric phenol widely used as an antioxidant in plastics, rubbers, fuels, and lubricating oils.
While BHT prevents slow oxidative aging in finished polymers, its two bulky ortho-tert-butyl groups sterically hinder the -OH group so severely that BHT reacts too slowly to stop rapid vinyl or diene monomer polymerization on its own. TBC Tert-Butylpyrocatechol has an unhindered, intramolecularly activated ortho-catechol group that traps monomer radicals instantaneously.

TBC TERT-BUTYLPYROCATECHOL AND TBHQ (TERT-BUTYLHYDROQUINONE, CAS 1948-33-0)

TBHQ (2-tert-Butyl-1,4-benzenediol, C10H14O2, MW 166.22 g/mol, melting point 127–129 °C) is the 1,4-para-positional isomer of TBC Tert-Butylpyrocatechol and is used primarily as a food-grade frying oil antioxidant (E319) and biodiesel stabilizer.
Because TBHQ is a high-melting solid (128 °C vs. 54 °C for TBC), has much lower solubility in non-polar styrene/butadiene at low temperatures, cannot form an 85% liquid aqueous eutectic at room temperature, and has a slower radical-trapping rate in styrene than the 1,2-ortho-catechol isomer, TBC Tert-Butylpyrocatechol (CAS 98-29-3) is universally specified for monomer and synthetic rubber inhibition.

TBC TERT-BUTYLPYROCATECHOL AND 4-HYDROXY-TEMPO / PHENOTHIAZINE IN DISTILLATION COLUMNS

Stable nitroxide radicals (such as 4-Hydroxy-TEMPO, CAS 2226-96-2) and Phenothiazine (PTZ, CAS 92-84-2) are true anaerobic inhibitors that trap carbon-centered radicals (R·) directly in oxygen-free high-temperature vacuum distillation columns.
However, TEMPO and PTZ are expensive, impart orange/dark color or nitrogen/sulfur contamination to the finished monomer, and cannot be removed easily by simple caustic washing. Therefore, petrochemical plants use TEMPO/retarder packages inside the distillation column reboiler, and dose clean, sulfur-free, nitrogen-free TBC Tert-Butylpyrocatechol into the overhead distilled monomer product for all storage and customer shipping!

QUALITY GRADES, QUALITY CONTROL AND PURCHASING CRITERIA FOR TBC TERT-BUTYLPYROCATECHOL

When qualifying TBC Tert-Butylpyrocatechol (CAS 98-29-3) from Ataman Kimya, procurement and Quality Control laboratories select from three standardized commercial physical grades:
- 1. TBC 100% Pure Solid Flakes / Pastilles / Fused Grade: White to pale cream crystalline flakes or fused solid with 4-tert-Butylpyrocatechol Assay >= 99.0% w/w (typical >= 99.4%), Melting/Solidification Point 52.0 to 56.0 °C, Molten Color <= 50 to 80 APHA, Water Content <= 0.1%–0.2%, Free Catechol <= 0.2%, and Trace Iron (Fe) <= 1–2 ppm. Ideal for preparing custom anhydrous stock solutions in styrene, toluene, or UPR resins.
- 2. TBC 85% in Water Liquid Grade (TBC 85 AQ): Ready-to-pump clear pale-yellow liquid eutectic containing 84.0% to 86.0% w/w active TBC Tert-Butylpyrocatechol and 14.0% to 16.0% w/w demineralized water, Color <= 70 to 100 APHA, Density (20 °C) 1.040–1.050 g/cm3, Viscosity (20 °C) ~95–130 mPa·s, and Crystallization Point +8.0 to +12.0 °C. The global standard liquid dosing grade for Styrene Monomer plants, marine terminals, and UPR producers.
- 3. TBC 85% in Methanol Liquid Grade (TBC 85 M): Ready-to-pump mobile liquid containing 84.0% to 86.0% w/w active TBC Tert-Butylpyrocatechol and 14.0% to 16.0% w/w anhydrous methanol, Color <= 70 to 100 APHA, Density (20 °C) ~0.995 g/cm3, Viscosity (20 °C) ~15–25 mPa·s, and Crystallization Point <= -30.0 °C. Ideal for sub-zero winter outdoor dosing skids and cryogenic/refrigerated 1,3-Butadiene and Isoprene spheres.
Incoming Quality-Control (QC) Parameters to Verify on Every Shipment of TBC Tert-Butylpyrocatechol:
- Verify the Chemical Identity and CAS / EC Numbers of TBC Tert-Butylpyrocatechol (CAS 98-29-3 / EC 202-653-9).
- Verify Active 4-tert-Butylpyrocatechol Content by GC (>= 99.0% for Solid; 84.0%–86.0% for 85% Liquid grades) and Water/Methanol Balance by Karl Fischer / GC.
- Verify Color on the Pt-Co / APHA Scale (<= 50–80 APHA for 100% grade; <= 70–100 APHA for 85% liquid grades) to ensure zero quinone oxidation or iron contamination.
- Verify Crystallization / Solidification Point (52–56 °C for 100% Solid; +8 to +12 °C for 85% Water; <= -30 °C for 85% Methanol).
- Verify Complete Clarity of a 10% w/w Solution in Styrene Monomer or Toluene (and < 1–2 ppm Trace Iron content).

STORAGE AND HANDLING OF TBC TERT-BUTYLPYROCATECHOL

Warehouse and Tank Storage Conditions for TBC Tert-Butylpyrocatechol: Store TBC Tert-Butylpyrocatechol in tightly sealed original nitrogen-blanketed drums, IBC totes, or 316L stainless-steel bulk tanks in a cool, dry, well-ventilated indoor storage area away from direct sunlight, heat sources, strong alkalis, and oxidizers:
- Storage Temperature for TBC 100% Solid Flakes: Store below +30 to +35 °C in a dry, cool warehouse so the flakes (melting point 52–56 °C) do not soften, sinter, or fuse into a solid block.
- Storage Temperature for TBC 85% in Water: Maintain warehouse and dosing-line temperature strictly between +15 °C and +30 °C! Below +10 to +12 °C, TBC 85% in Water begins to crystallize. If partial crystallization occurs during cold winter transport, warm the closed drum or IBC gently in a warm room or water bath at +25 to +40 °C (never exceed 50 °C) and mix/circulate thoroughly until 100% clear and homogeneous before drawing off liquid!
- Storage Temperature for TBC 85% in Methanol: Remains liquid down to -30 °C; store below +30 °C in a flameproof flammable-liquid storage area away from ignition sources.
Nitrogen Blanketing to Prevent Air Oxidation Darkening: Because concentrated TBC Tert-Butylpyrocatechol slowly absorbs oxygen from humid air to form reddish-brown 4-tert-butyl-1,2-benzoquinone (increasing APHA color over time), always purge the headspace of partially used drums, IBCs, and bulk dosing tanks with dry Nitrogen gas (N2) and reseal bungs immediately! (Note: Nitrogen blanketing is used on the concentrated TBC storage drum itself to keep its APHA color water-white, whereas 15–50 ppm dissolved O2 is maintained in the large Styrene Monomer tank where TBC is diluted to 15 ppm!). When stored unopened under nitrogen in original containers, TBC Tert-Butylpyrocatechol has a certified shelf life of 12 to 24 months.

FIRST AID MEASURES AND SAFETY INFORMATION FOR TBC TERT-BUTYLPYROCATECHOL

First Aid Measures for TBC Tert-Butylpyrocatechol (4-tert-Butylpyrocatechol, CAS 98-29-3):
WARNING — Concentrated TBC Tert-Butylpyrocatechol is corrosive to skin and eyes, harmful if swallowed or in contact with skin, and a potent skin sensitizer (may cause phenolic skin depigmentation / chemical leukoderma upon repeated skin contact!):
- Skin Contact with TBC Tert-Butylpyrocatechol: Immediately remove all contaminated clothing and shoes! Wash or flush the contacted skin immediately with polyethylene glycol 300/400 (PEG 400 decontamination solution, if available on site for phenolic burns) or with copious running lukewarm water and mild soap for at least 15 to 20 minutes. Do NOT use organic solvents (like methanol or toluene) to wash skin, as solvents accelerate dermal absorption! Obtain immediate medical attention for chemical burns.
- Eye Contact with TBC Tert-Butylpyrocatechol: TBC Tert-Butylpyrocatechol causes severe eye burns and risk of serious corneal damage (GHS Skin Corr. 1B / Eye Dam. 1, H314 / H318). Immediately flush the eyes with plenty of lukewarm low-pressure running water or sterile eyewash saline for at least 15 to 20 minutes while holding the eyelids wide open and removing contact lenses if present; call an ophthalmologist or emergency physician immediately!
- Inhalation of TBC Tert-Butylpyrocatechol Dust, Vapors, or Mists: If dust from 100% solid flakes or vapor/mist from heated or sprayed liquid TBC is inhaled, move the exposed person immediately into fresh air, keep them warm and at rest in a half-upright position, administer oxygen if breathing is difficult, and seek immediate medical care.

- Ingestion of TBC Tert-Butylpyrocatechol: If swallowed, rinse the mouth thoroughly with water and have the conscious person drink 1 to 2 small glasses of water. Do NOT induce vomiting (risk of esophageal perforation from corrosive catechol!); never give anything by mouth to an unconscious person, and transport immediately to a hospital.
Workplace Safety, GHS Classification, and Toxicological Profile of TBC Tert-Butylpyrocatechol:
Under European Union CLP Regulation (EC) No 1272/2008 and UN GHS, TBC Tert-Butylpyrocatechol (CAS 98-29-3, EC 202-653-9) is classified as:
- Acute Toxicity Oral Category 4 (H302: Harmful if swallowed; Rat oral LD50 ~815 mg/kg bw)
- Acute Toxicity Dermal Category 4 (H312: Harmful in contact with skin; Rat dermal LD50 ~1,331 mg/kg bw)
- Skin Corrosion Category 1B and Serious Eye Damage Category 1 (H314: Causes severe skin burns and eye damage; H318: Causes serious eye damage)
- Skin Sensitization Category 1 (H317: May cause an allergic skin reaction; also known to cause occupational melanocyte depigmentation / vitiligo-like leukoderma if skin contact occurs)

- Aquatic Acute Category 1 (H400: Very toxic to aquatic life, M-factor = 1) and Aquatic Chronic Category 2 (H411: Toxic to aquatic life with long lasting effects). (Note: TBC 85% in Methanol additionally carries Flammable Liquid Category 3 H226 and Methanol STOT SE 1 H370 hazard statements).
Personal Protective Equipment (PPE) for Handling TBC Tert-Butylpyrocatechol:
Always use closed-loop transfer pumps, dip tubes, and dry-disconnect couplings when dosing liquid TBC 85% to eliminate operator exposure. Operators must wear a full-face chemical splash shield over tightly fitting safety goggles (EN 166), long-cuff impervious butyl rubber, neoprene, or laminated barrier gloves (EN 374, breakthrough time > 480 min), acid/phenol-resistant chemical suit and apron, safety boots, and a combination organic-vapor/particulate respirator (EN 14387 Type A-P2/P3) whenever handling open drums or flakes. Keep emergency eye-wash stations, safety showers, and PEG 400 skin-decontamination bottles immediately adjacent to TBC dosing skids!
Commercial Packaging and International Transport Classification for TBC Tert-Butylpyrocatechol:

- Packaging Formats Supplied by Ataman Kimya:
  - TBC 100% Pure Solid Flakes / Pastilles: 25 kg net UN-certified polyethylene-lined fiber drums or heavy-duty PE bags inside UN steel/fiber drums; 190–200 kg net baked-phenolic-lined steel drums (for fused solid grade).
  - TBC 85% in Water & TBC 85% in Methanol Liquid Grades: 200 kg net UN-certified baked epoxy-phenolic lined tight-head steel drums or high-molecular-weight HDPE drums (4 drums per pallet = 800 kg net), 1,000 kg net UN composite IBC totes, and stainless-steel portable tank containers (T7/T11).
- Dangerous Goods Transport Classification (ADR / RID / IMDG / IATA):
  - For TBC 100% Pure Solid Flakes: UN 3261, Proper Shipping Name: CORROSIVE SOLID, ACIDIC, ORGANIC, N.O.S. (contains 4-tert-Butylpyrocatechol), Class 8, Packing Group II (or III depending on specific test dossier), Marine Pollutant: Yes (Environmentally Hazardous).
  - For TBC 85% in Water Liquid Solution: UN 3265, Proper Shipping Name: CORROSIVE LIQUID, ACIDIC, ORGANIC, N.O.S. (contains 4-tert-Butylpyrocatechol), Class 8, Packing Group II, Marine Pollutant: Yes.
  - For TBC 85% in Methanol Liquid Solution: UN 2924, Proper Shipping Name: FLAMMABLE LIQUID, CORROSIVE, N.O.S. (contains Methanol and 4-tert-Butylpyrocatechol), Class 3 (Subsidiary Risk 8), Packing Group II / III, Marine Pollutant: Yes.

WHAT SHOULD BE CONSIDERED WHEN PURCHASING TBC TERT-BUTYLPYROCATECHOL?

When sourcing TBC Tert-Butylpyrocatechol (CAS 98-29-3) from Ataman Kimya for monomer stabilization, synthetic rubber manufacturing, UPR/vinyl ester resin production, or fine chemical synthesis, procurement and plant engineering teams should specify six key technical parameters in their Request for Quotation (RFQ):

Physical Form and Solvent Carrier (100% Solid Flakes vs. 85% in Water vs. 85% in Methanol): Specify whether your dosing system requires TBC 85% in Water (the standard non-flammable liquid grade for Styrene and UPR plants operating above +15 °C), TBC 85% in Methanol (for sub-zero winter outdoor tank farms and refrigerated 1,3-Butadiene / Isoprene units down to -30 °C), or TBC 100% Pure Solid Flakes / Fused (for water-free and methanol-free custom solutions and chemical synthesis).

Target Monomer or Resin System: Indicate whether TBC Tert-Butylpyrocatechol will be used to inhibit Styrene Monomer, 1,3-Butadiene, Isoprene, Chloroprene, Divinylbenzene, Unsaturated Polyester / Vinyl Ester Resins, or Polyurethane Catalysts.

Maximum APHA Color and Trace Iron Ceiling: For water-white Styrene Monomer and clear optical/gelcoat resins, specify low APHA color (<= 50–80 APHA) and ultra-low trace iron (Fe <= 1–2 ppm).

Packaging Format and Closed-Loop Dip-Tube / Bung Requirements: Specify 25 kg fiber/PE drums (for 100% flakes), 200 kg lined steel or HDPE drums, or 1,000 kg UN IBC totes (for 85% liquid grades), and state if specific drum bung threads (2-inch buttress vs. NPS) are required for your closed-loop chemical metering pumps.

Dangerous Goods Transport Mode (ADR Road, IMDG Sea, or Rail) and Nitrogen Blanketing: Confirm delivery location and preferred Incoterms for UN Class 8 / Class 3+8 hazmat logistics.

Required Documentation: Request the grade-specific Technical Data Sheet (TDS), 16-section CLP/GHS Safety Data Sheet (SDS), and batch Certificate of Analysis (COA).

TBC TERT-BUTYLPYROCATECHOL SUPPLY FROM ATAMAN KİMYA

TBC Tert-Butylpyrocatechol—4-tert-Butylpyrocatechol / 4-tert-Butylcatechol identified under CAS No. 98-29-3 and EC No. 202-653-9 (Molecular Formula C10H14O2)—is supplied by Ataman Kimya across all three industrial formats (TBC 100% Pure Solid Flakes/Fused, TBC 85% w/w in Water, and TBC 85% w/w in Methanol) for petrochemical monomer plants and storage terminals, synthetic rubber producers (SBR, BR, NBR, CR), unsaturated polyester and vinyl ester resin manufacturers, polyurethane catalyst blenders, and specialty chemical synthesizers.
Companies planning to source TBC Tert-Butylpyrocatechol (or complementary monomer inhibitors and antioxidants including MEHQ 4-Methoxyphenol, Hydroquinone HQ, BHT, TBHQ, and Phenothiazine) from Ataman Kimya can share their target physical grade, monomer or resin system, and packaging requirements to confirm stock availability, hazardous-goods logistics, and commercial quotation details.
Sharing the following information in a quotation request for TBC Tert-Butylpyrocatechol facilitates rapid technical matching by the Ataman Kimya team:
- Requested physical grade of TBC Tert-Butylpyrocatechol (TBC 85% in Water, TBC 85% in Methanol, or TBC 100% Pure Solid Flakes/Fused)
- Target application (Styrene Monomer storage/marine transit, 1,3-Butadiene/Isoprene/SBR plant, Divinylbenzene, UPR/Vinyl Ester resin gel-time adjustment, or fine synthesis)
- Required analytical specifications (Assay >= 99.0% or 85.0% +/- 1.0%, APHA color ceiling, and crystallization point)
- Estimated order quantity (spot pallet/IBC shipment and annual consumption forecast) and preferred UN-certified packaging
- Delivery destination, preferred Incoterms, and required technical documentation (TDS, SDS, and batch COA for TBC Tert-Butylpyrocatechol)

FREQUENTLY ASKED QUESTIONS ABOUT TBC TERT-BUTYLPYROCATECHOL

 What is TBC Tert-Butylpyrocatechol and why is it the global benchmark inhibitor for Styrene and 1,3-Butadiene?
TBC Tert-Butylpyrocatechol (4-tert-Butylpyrocatechol or 4-tert-Butylcatechol, CAS 98-29-3, EC 202-653-9, formula C10H14O2, MW 166.22 g/mol) is a sterically substituted ortho-dihydroxybenzene carrying two adjacent hydroxyl groups (-OH at C-1 and C-2) and a bulky tert-butyl group at C-4. It is the global standard polymerization inhibitor for Styrene, 1,3-Butadiene, Isoprene, and Divinylbenzene because its C-4 tert-butyl group provides unlimited solubility in non-polar hydrocarbons down to sub-zero temperatures, while its intramolecularly hydrogen-bonded 1,2-catechol group scavenges monomer peroxyl radicals 25 times faster than hydroquinone and 50–100 times faster than MEHQ.

 Why does TBC Tert-Butylpyrocatechol require dissolved oxygen (15 to 50 ppm O2) in the monomer to work effectively?
Like all phenolic inhibitors, TBC Tert-Butylpyrocatechol reacts relatively slowly with carbon-centered monomer radicals (R·) under strictly oxygen-free conditions, but reacts instantaneously (k ~10^6 L/mol·s) with oxygen-centered peroxyl radicals (ROO·). When 15 to 50 ppm of dissolved molecular oxygen (O2) is maintained in the liquid monomer (using a 5%–8% O2 in N2 gas blanket or periodic air injection), O2 converts any thermally formed carbon radical (R·) immediately into a peroxyl radical (ROO·), which TBC Tert-Butylpyrocatechol neutralizes on contact!

 What is the difference between TBC 100% Solid Flakes, TBC 85% in Water, and TBC 85% in Methanol?
100% pure TBC Tert-Butylpyrocatechol is a crystalline solid that melts at 52 to 56 °C, requiring heated rooms or solvent dissolution before pumping. By blending 85% w/w TBC Tert-Butylpyrocatechol with 15% w/w demineralized water (TBC 85% in Water), a liquid hydrogen-bonded eutectic is formed whose freezing point drops to +8 to +12 °C, allowing direct ambient-temperature metering pump injection without flammable solvents. For cold winter outdoor tank farms or refrigerated 1,3-Butadiene spheres (< 0 °C), TBC 85% in Methanol provides a freezing point below -30 °C.

 What happens if a drum of TBC 85% in Water partially freezes in cold winter weather (< +10 °C), and how should it be thawed?
If TBC 85% in Water cools below +8 to +12 °C during winter transit, solid TBC hydrate crystals precipitate out at the bottom of the drum, leaving the upper liquid layer depleted in active TBC! Never pump from a partially crystallized drum. Instead, place the sealed drum or IBC in a warm room or warm water bath at +25 to +40 °C (never exceed 50 °C or apply open flames) until 100% melted, and roll or circulate the drum thoroughly to restore a uniform 85.0% w/w concentration before use.

 How is TBC Tert-Butylpyrocatechol removed from Styrene or 1,3-Butadiene prior to polymerization?
Because TBC Tert-Butylpyrocatechol is a weak acid (pKa1 = 9.53), it can be stripped from Styrene or 1,3-Butadiene down to < 0.5 ppm simply by washing the monomer with a 5% to 10% aqueous sodium hydroxide (NaOH) solution (which converts TBC into water-soluble sodium 4-tert-butylcatecholate in the aqueous waste layer) followed by a water rinse, or by passing the dry monomer through a fixed bed of basic activated alumina (Al2O3). In many free-radical emulsion polymerizations (such as SBR 1502), low levels of TBC (10–15 ppm) do not even need to be removed and are simply overcome by a slight stoichiometric excess of free-radical initiator.

 What are the standard ppm dosage levels of TBC Tert-Butylpyrocatechol in Styrene, 1,3-Butadiene, Divinylbenzene, and UPR Resins?
In Styrene Monomer, 10 to 15 ppm w/w active TBC is standard for temperate storage (< 25 °C), and 20 to 50 ppm w/w is used for warm summer storage (> 30 °C) or ocean tanker shipping. In 1,3-Butadiene and Isoprene, 50 to 200 ppm w/w is standard to prevent peroxide and popcorn polymer formation. In reactive Divinylbenzene (DVB), 800 to 1,500 ppm w/w is used. In Unsaturated Polyester Resins (UPR) and Vinyl Ester Resins, 50 to 500 ppm w/w is dosed to extend shelf life and adjust MEKP/cobalt gel times.

 How is active TBC Tert-Butylpyrocatechol concentration measured in inhibited Styrene Monomer?
Active (unoxidized) TBC Tert-Butylpyrocatechol in Styrene Monomer is measured rapidly by the standard ASTM D4590 colorimetric method (or ASTM D7882 HPLC): extracting the styrene sample with alkaline NaOH/alcohol oxidizes TBC into a pink-red quinone anion whose absorbance at 490 nm is directly proportional to active ppm of TBC (from 1 to 100 ppm).

 What is the difference between TBC Tert-Butylpyrocatechol (CAS 98-29-3) and TBHQ (tert-Butylhydroquinone, CAS 1948-33-0)?
TBC Tert-Butylpyrocatechol (CAS 98-29-3) is the 1,2-ortho-dihydroxy isomer (4-tert-butyl-1,2-benzenediol, melting point 54 °C), whereas TBHQ (CAS 1948-33-0) is the 1,4-para-dihydroxy isomer (2-tert-butyl-1,4-benzenediol, melting point 128 °C). TBC Tert-Butylpyrocatechol has far higher solubility in cold liquid hydrocarbon monomers, forms an 85% liquid eutectic with water at +10 °C, and traps styryl/diene peroxyl radicals much faster than TBHQ.

 What safety and PPE precautions are required when handling concentrated TBC Tert-Butylpyrocatechol?
Concentrated TBC Tert-Butylpyrocatechol is corrosive to skin and eyes (H314/H318), harmful if swallowed or absorbed through skin (H302/H312), a skin sensitizer (H317), and can cause occupational skin depigmentation (chemical leukoderma). Always use closed-loop metering pumps, wear chemical splash goggles plus a face shield, butyl or neoprene barrier gloves, and a chemical apron, and keep PEG 400 decontamination solution and safety showers at the dosing station.

 How can petrochemical plants, synthetic rubber producers, and resin manufacturers source TBC Tert-Butylpyrocatechol and request COA, TDS, and SDS documents from Ataman Kimya?
Customers can procure TBC Tert-Butylpyrocatechol (CAS 98-29-3, EC 202-653-9) in TBC 100% Pure Solid Flakes (25 kg drums), TBC 85% in Water (200 kg drums / 1,000 kg IBCs), and TBC 85% in Methanol (200 kg drums / 1,000 kg IBCs)—complete with batch-specific Certificates of Analysis (COA), Technical Data Sheets (TDS), and GHS/CLP Safety Data Sheets (SDS)—directly from Ataman Kimya by calling +90 216 577 10 10 or emailing info@atamankimya.com.

TBC TERT-BUTYLPYROCATECHOL – TECHNICAL SUMMARY

TBC Tert-Butylpyrocatechol—known across global petrochemical, synthetic rubber, and polymer resin commerce as 4-tert-Butylpyrocatechol, 4-tert-Butylcatechol, p-tert-Butylcatechol, 4-(1,1-Dimethylethyl)-1,2-benzenediol, TBC, PTBC, and 4-tert-Bütilpirokateşol, and identified under CAS No. 98-29-3 and EC / EINECS No. 202-653-9—is the industry-benchmark free-radical polymerization inhibitor and antioxidant stabilizer with the molecular formula C10H14O2 ((CH3)3C-C6H3-1,2-(OH)2) and a molecular weight of 166.22 g/mol. Synthesized via the para-selective Friedel-Crafts alkylation of pyrocatechol with isobutylene and high-vacuum fractional distillation under nitrogen, TBC Tert-Butylpyrocatechol pairs a lipophilic C-4 tert-butyl group (providing > 50% w/w solubility in non-polar hydrocarbon monomers down to sub-zero temperatures) with an intramolecularly hydrogen-bonded C-1/C-2 ortho-catechol moiety that scavenges monomer peroxyl radicals 25 times faster than hydroquinone and strips quantitatively upon alkaline NaOH washing (pKa1 = 9.53) or activated alumina percolation.

Supplied by Ataman Kimya in three standardized commercial formats—TBC 100% Pure Solid Crystalline Flakes / Fused (assay >= 99.0% w/w, melting point 52 to 56 °C, boiling point 285 °C, molten color <= 50 to 80 APHA), TBC 85% w/w Liquid Solution in Demineralized Water (crystallization point +8 to +12 °C, density 1.045 g/cm3, viscosity ~95–130 mPa·s at 20 °C), and TBC 85% w/w Liquid Solution in Methanol (crystallization point <= -30 °C, density ~0.995 g/cm3)—TBC Tert-Butylpyrocatechol prevents runaway thermal polymerization, peroxide accumulation, and destructive popcorn polymer formation across Styrene Monomer (10 to 50 ppm), 1,3-Butadiene and Isoprene (50 to 200 ppm), Chloroprene, Vinyltoluene, and Divinylbenzene (800 to 1,500 ppm). Beyond monomer logistics and synthetic rubber (SBR, BR, NBR, CR) recycle streams, TBC Tert-Butylpyrocatechol serves as a precision gel-time modifier and pot-life stabilizer in Unsaturated Polyester Resins (UPR) and Vinyl Ester Resins, an antioxidant in polyurethane catalysts, and a versatile ortho-catechol chemical intermediate.
For technical grade selection (100% Solid Flakes vs. 85% in Water vs. 85% in Methanol), monomer inhibition dosing guidance, current warehouse stock availability, Technical Data Sheet (TDS), Safety Data Sheet (SDS), and batch Certificate of Analysis (COA) documentation, or to request a commercial quotation for TBC Tert-Butylpyrocatechol tailored to your petrochemical, rubber, or resin plant requirements, you can contact Ataman Kimya directly through the communication channels below. Our technical sales team will gladly assist you with UN-certified packaging and specialized logistics support.

Ataman Chemicals
Phone: +90 216 577 10 10
Email: info@atamankimya.com