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Mono T-butyl hydroquinone presents as white to light tan crystalline powder or flakes with a characteristic mild phenolic odor.
The compound exhibits polymorphism with at least two crystalline forms identified.
The orthorhombic form is most common with unit cell dimensions a=8.92Å, b=10.34Å, c=10.56Å.
The tert-butyl group provides steric hindrance that significantly influences both physical properties and antioxidant behavior compared to unsubstituted hydroquinone.
IUPAC Name: 2-(1,1-Dimethylethyl)-1,4-benzenediol
Common Industrial Names: Mono-tert-butylhydroquinone, MTBHQ, TBHQ
Alternative Chemical Names: Tert-butylhydroquinone, 2-tert-butyl-1,4-dihydroxybenzene, 2-(tert-butyl)hydroquinone
Food Additive Designation: E319, INS 319
CAS Registry Number: 1948-33-0
EC Number: 217-752-2
FEMA Number: 2183
UN Number: 3077 (Environmentally hazardous substance)
Molecular Architecture:
Molecular Formula: C₁₀H₁₄O₂
Structural Representation: (CH₃)₃C–C₆H₃(OH)₂ (1,4)
SMILES Notation: CC(C)(C)C1=CC(=C(C=C1)O)O
Molecular Mass: 166.22 g/mol
Exact Mass: 166.0994 Da
Physical Property Data:
Melting Point: 126.5-128.5°C (pure form)
Boiling Point: 295-300°C (with decomposition)
Flash Point: 171°C (closed cup)
Density: 1.05 g/cm³ at 25°C
Vapor Pressure: 0.01 hPa at 25°C
Solubility:
Water: 0.5 g/L at 20°C
Ethanol: 600 g/L at 20°C
Propylene glycol: 450 g/L at 20°C
Soybean oil: 50 g/L at 25°C
Acetone: >1000 g/L at 20°C
pKa Values: pKa₁ = 9.95, pKa₂ = 11.75 (25°C)
Log P (octanol/water): 3.30
Refractive Index: 1.541 (for melt at 130°C)
Chemical Behavior and Antioxidant Mechanism:
MTBHQ functions as a highly effective primary antioxidant through multiple protective mechanisms:
Free Radical Scavenging Activity:
The compound acts as a hydrogen atom donor, terminating free radical chain reactions:
ROO• + ArOH → ROOH + ArO•
ArO• (semiquinone radical) is resonance-stabilized and relatively unreactive, preventing further propagation. The tert-butyl substituent provides steric protection to the phenolic OH groups while maintaining electron-donating character through hyperconjugation.
Metal Chelation Capability:
MTBHQ demonstrates moderate metal-chelating activity, particularly for Fe³⁺ and Cu²⁺ ions, forming complexes with stability constants log K ~ 8-10. This secondary antioxidant activity prevents metal-catalyzed oxidation initiation.
Synergistic Effects:
When combined with citric acid, ascorbic acid, or tocopherols, MTBHQ exhibits pronounced synergistic antioxidant effects. The synergism factor can reach 3-5x for certain food matrices.
Thermal Stability:
Decomposition begins at approximately 200°C with rapid degradation above 250°C. The main decomposition pathway involves elimination of isobutylene followed by quinone formation.
Industrial and Food Applications:
Food Preservation Systems:
Maximum permitted levels (EU): 200 mg/kg in fats/oils for frying, 100 mg/kg in dehydrated potato products
Typical use levels: 0.01-0.02% based on fat/oil content
Primary applications:
Vegetable oils (soybean, canola, sunflower) - extends shelf life 3-5x
Fried snack foods - reduces rancidity development
Meat products (especially cooked, cured meats) - prevents warmed-over flavor
Bakery products with high-fat content
Nutraceutical oils (fish oil, flaxseed oil) - protects omega-3 fatty acids
Polymer Stabilization:
Rubber industry: Antioxidant in synthetic rubbers (SBR, BR, NBR) at 0.5-1.5%
Adhesives: Prevents oxidative degradation in pressure-sensitive adhesives
Petroleum products: Additive in lubricating oils and greases
Analytical Characterization:
Spectroscopic Methods:
UV-Vis Spectroscopy: λmax = 290 nm (ε = 3600 L·mol⁻¹·cm⁻¹) in ethanol
FT-IR Spectroscopy: ν(O-H) 3300-3400 cm⁻¹ (broad), aromatic ν(C-H) 3050 cm⁻¹, ν(C=C) aromatic 1600, 1500 cm⁻¹, δ(O-H) 1370 cm⁻¹, ν(C-O) 1250 cm⁻¹
NMR Spectroscopy:
¹H NMR (DMSO-d₆): δ 8.70 (s, 2H, OH), 6.70 (d, 1H, H-3), 6.65 (dd, 1H, H-5), 6.50 (d, 1H, H-6), 1.30 (s, 9H, t-Bu)
¹³C NMR (DMSO-d₆): δ 149.2 (C-1,4), 140.5 (C-2), 121.0 (C-6), 116.5 (C-3), 115.0 (C-5), 34.0 (C(CH₃)₃), 29.5 (CH₃)
Chromatographic Methods:
HPLC Analysis: C18 column, mobile phase methanol/water/acetic acid (60:39:1), flow 1.0 mL/min, UV detection at 290 nm, retention time ~6.5 minutes
GC-MS: After silylation with BSTFA, characteristic ions m/z 166 (M⁺), 151 (M⁺–CH₃), 123 (M⁺–C₃H₇)
Regulatory Status and Safety:
FDA Status: Generally Recognized As Safe (GRAS) for food use (21 CFR 172.185)
EFSA Evaluation: Acceptable Daily Intake (ADI) 0-0.7 mg/kg body weight (2016)
JECFA: ADI 0-0.2 mg/kg body weight
LD₅₀ Values: Oral rat: 700-1000 mg/kg; Dermal rabbit: >2000 mg/kg
Ecotoxicity: LC₅₀ Daphnia magna: 3.2 mg/L (48h)
SAFETY INFORMATION ABOUT MONO T-BUTYL HYDROQUINONE
First aid measures:
Description of first aid measures:
General advice:
Consult a physician.
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
If inhaled:
If breathed in, move person into fresh air.
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately.
Wash off with soap and plenty of water.
Consult a physician.
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
If swallowed:
Do NOT induce vomiting.
Never give anything by mouth to an unconscious person.
Rinse mouth with water.
Consult a physician.
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment.
Avoid breathing vapours, mist or gas.
Evacuate personnel to safe areas.
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste.
Keep in suitable, closed containers for disposal.
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place.
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles.
Faceshield (8-inch minimum).
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
Skin protection:
Handle with gloves.
Gloves must be inspected prior to use.
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product.
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices.
Wash and dry hands.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls.
If the respirator is the sole means of protection, use a full-face supplied air respirator.
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions.
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company.
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product
