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Propargyl alcohol anhydrous, a low-water grade for moisture-sensitive synthesis steps, is a colorless to pale yellow liquid that carries a triple bond at one end and a primary alcohol group at the other. Its CAS number is 107-19-7 and its molecular formula is C₃H₄O. The water content is assured by an upper limit defined in the manufacturer’s specification; in commercial grades this limit is mostly between 0.1% and 0.5% at most. Because it is flammable and toxic, it should be used only by trained personnel.
Propynol, the alcohol component that combines with an isocyanate in the production of the IPBC mold inhibitor used in paints, coatings and wood preservatives, calls for a low-water grade at that step, since water would consume the isocyanate and form a urea by-product. In aqueous nickel plating baths and acid inhibitor packages, on the other hand, water is the medium itself; in these uses the standard grade can also be considered as needed.
Hydroxymethylacetylene, a building block for pharmaceutical and agrochemical intermediates, supplies the propargyl unit in sulfonamides such as sulfadiazine, in fosfomycin, and in active substances such as clodinafop-propargyl and propargite. The moisture limit can be critical in steps involving bases, organometallic reagents or isocyanates. This product can be supplied by ATAMAN KİMYA; for technical information and requests, contacting ATAMAN KİMYA is recommended.
WHAT IS PROPARGYL ALCOHOL ANHYDROUS?
Propargyl alcohol anhydrous is the commercial grade of prop-2-yn-1-ol in which the water content is deliberately kept low. The substance has the structure HC≡C–CH₂OH. Its chemical identity is the same as that of the standard grade; the difference lies in the controlled moisture level and the analytical and document details tied to it.
The anhydrous grade is a product whose water content is held below a defined upper limit. In the commercial documents examined, two suppliers state at most 0.1% water, while a laboratory grade states at most 0.5% water by the Karl Fischer method. The limit and the measurement method appear in the product’s certificate of analysis.
The assurance of quality is therefore the water limit in the specification and the measurement method that verifies it. Karl Fischer titration is widely used for this purpose.
The substance mixes with water in all proportions. Because no separate water phase forms, moisture that enters the product cannot be seen by eye; for this reason the water level is followed by measurement and protected by closed packaging.
With water it forms an azeotrope boiling at about 97.5 °C. The Merck Index gives the mixture as about 39.5 parts propargyl alcohol and 60.5 parts water by weight, while a 1948 patent reports about 45.5%. The difference depends on the source and the measurement. In either case ordinary distillation cannot remove the water completely.
Drying is therefore a real step of production. The substance emerges from the aqueous medium as a by-product of butynediol in the Reppe synthesis. The old patent describes that the methods of the day reached at most 97% purity, and that azeotropic drying with benzene, removal of formaldehyde with acidified methanol and distillation under a vacuum of about 70 mmHg raised it to about 99.5%.
In another patent, the distillate of a product recovered from a dimethyl sulfoxide medium contained 85.9% propargyl alcohol and 10.5% water; the 1.0% water in the feed passed into the overhead product together with the propargyl alcohol.
Among market grades, purity is mostly in the range of 98–99.9%. BASF states at least 99.3% purity. Two suppliers write at least 99.5% and 99.6% purity together with at most 0.1% water, while Thermo Scientific gives at least 98.5% purity and at most 0.5% water.
It must not be confused with substances of similar name. Allyl alcohol (CAS 107-18-6) has a double bond, while propyl alcohol (CAS 71-23-8) is a saturated alcohol. Propargyl bromide, propargylamine and propargyl acrylate are likewise separate products derived from propargyl alcohol.
The hazard profile is the same as that of the standard grade: in the harmonized classification the substance is flammable, toxic and corrosive. It can polymerize uncontrollably with heat, light, bases and oxidizers.
In France in 2018, a drum kept for a long time above 30 °C polymerized and exploded; the incident is a reminder that storage temperature is decisive.
COMMON PRODUCT AND CHEMICAL NAMES OF PROPARGYL ALCOHOL ANHYDROUS:
Propargyl Alcohol Anhydrous
Anhydrous Propargyl Alcohol
Propargyl Alcohol Anhydr.
Anhydr. Propargyl Alcohol
Propargyl Alcohol, Anhydrous
Propargyl Alcohol
Propargylic Alcohol
2-Propyn-1-ol
Prop-2-yn-1-ol
2-Propynol
Prop-2-ynol
3-Propynol
Propynol
Propynyl Alcohol
2-Propynyl Alcohol
Ethynyl Carbinol
Ethynylmethanol
Acetylene Carbinol
Acetylenyl Carbinol
Hydroxymethylacetylene
1-Hydroxy-2-propyne
3-Hydroxy-1-propyne
3-Hydroxypropyne
1-Propyn-3-ol
Propiolic Alcohol
Agrisynth PA
107-19-7
The first five names are commercial expressions describing the low-water grade of the same substance. “Anhydrous” is the usual catalog term, and “anhydr.” is its common abbreviation. These words name the quality level, not the substance.
The remaining names write the chemical identity in different systems. Prop-2-yn-1-ol is the systematic name; 2-propyn-1-ol and 3-propynol arise from a numbering difference, while ethynyl carbinol describes the structure as a methanol derivative.
The word propargyl denotes the –CH₂–C≡CH group. Propargyl bromide, chloride and amine, which carry the same group, are separate chemicals and are not names of propargyl alcohol. Agrisynth PA is a trade name.
Codes such as NA 1986 and UN 1986 have found their way into the synonym lists of some catalogs; they are not substance names but old transport numbers. The current number in most documents is UN 2929. 107-19-7 in the list is the CAS number.
Stating the CAS number and the highest required water level together with the name in the order makes it easier to reach the right product. Information on purity, moisture and packaging is found in the product documents.
CAS NO, EC / EINECS NO AND CHEMICAL IDENTIFICATION OF PROPARGYL ALCOHOL ANHYDROUS
Product name: Propargyl Alcohol Anhydrous / Anhydrous Propargyl Alcohol
Grade definition: Low-water propargyl alcohol (the water limit varies by manufacturer)
Common abbreviation: PA (used especially in the corrosion literature)
Chemical name: Prop-2-yn-1-ol (2-propyn-1-ol)
CAS No: 107-19-7
EC / EINECS No: 203-471-2
EU index number: 603-078-00-X
Molecular formula: C₃H₄O
Molecular weight: 56.06 g/mol
Structural notation: HC≡C–CH₂OH; SMILES: C#CCO
Chemical class: Acetylenic (alkynyl) primary alcohol
Main functions: Synthesis intermediate, acid corrosion inhibitor component, nickel plating additive, chlorinated solvent stabilizer
The harmonized EU classification, under index number 603-078-00-X, is given as flammable liquid category 3 (H226), acute toxicity category 3 by the oral, dermal and inhalation routes (H301, H311, H331), skin corrosion category 1B (H314) and long-term aquatic hazard category 2 (H411). Some supplier documents show stricter classifications.
Most documents use UN 2929, class 6.1 with subsidiary hazard 3 for transport. The customs position is 2905.29 for unsaturated acyclic alcohols; the detailed code should be verified for the product and country.
The water limit is a quality parameter, not identification data. Standard and anhydrous grades carrying the same CAS number differ in moisture, some impurities and document details; this difference is stated in measurable form in the order text.
CHEMICAL STRUCTURE AND MOLECULAR PROPERTIES OF PROPARGYL ALCOHOL ANHYDROUS
The defining feature of the structure is its two ends. At one end of the chain lies a triple bond between two sp-hybridized carbons, and at the other a methylene carbon bearing the hydroxyl. Because the C≡C–C axis is linear, the hydroxymethyl group sits at the end of this linear unit.
The hydroxyl group determines its relationship with water. The oxygen and the hydroxyl hydrogen can form hydrogen bonds with water molecules. This is why the substance mixes with water in all proportions and why the logarithm of its octanol-water partition coefficient is about –0.38.
The same property makes drying difficult. Because water and alcohol are bound to each other, moisture cannot be removed by a single-step phase separation. This is the reason processes such as azeotropic distillation and vacuum are needed in production.
The triple bond contains one sigma and two pi bonds. This electron-rich region attaches to metal surfaces, coordinates with metals and undergoes addition reactions. Because the terminal C–H bond is attached to an sp carbon, it is markedly acidic compared with alkanes.
This acidity also explains why moisture causes trouble. Terminal alkynes are deprotonated with strong bases and organometallic reagents, and these reagents react with water first. Consequently, in such a step every water molecule in the medium consumes part of the reagent used.
The hydroxyl group is a primary alcohol with an estimated pKa of about 13.6. Its aqueous solution behaves close to neutral: one document gives pH 7 at 50 g/L, another pH 3 at 500 g/L. This difference comes from concentration; pH should not be taken as a product property without stating the concentration.
The molecule is neutral and covalent and contains no ionic component. The hydroxymethyl carbon is at the alcohol level and the carbons of the triple bond are at the alkyne level. Oxidation leads first to propynal and then to propiolic acid.
The structure is strained. With heat, light, bases, oxidizers and peroxides the triple bond can polymerize spontaneously. The Merck Index states that the substance polymerizes on heating and with caustic, while its acidified aqueous solutions resist this tendency.
An old purification patent gives the same observation from another angle: in neutral or basic medium the substance can decompose to formaldehyde. For this reason, about 1% hydrochloric acid and succinic acid were added during concentration in the old methods.
This point matters for the anhydrous grade: a dehydrated, neutral liquid behaves differently from an acid-stabilized aqueous solution. Stability depends on the supplier’s stabilizer system and the storage temperature; stabilizer information is obtained from the supplier.
The hydroxyl can form carbamates, esters or ethers, and with halogens it can be converted to propargyl halides. The triple bond, in turn, is used in reactions such as Sonogashira coupling and copper-catalyzed azide–alkyne cycloaddition. The water tolerance of these reactions should be assessed individually.
PHYSICAL AND CHEMICAL PROPERTIES OF PROPARGYL ALCOHOL ANHYDROUS
General technical properties:
The values below vary with the manufacturer, the grade and the measurement method. The information is general; it does not replace product-specific TDS and SDS documents.
Physical appearance: Clear, mobile liquid; ranges from colorless to pale yellow (straw-colored); mild geranium-like odor
Chemical character: Polar, neutral, acetylenic primary alcohol; terminal alkyne; prone to polymerization with heat, light and bases
Molecular formula: C₃H₄O
Molecular weight: 56.06 g/mol
CAS No: 107-19-7
EC / EINECS No: 203-471-2
Water content (the distinguishing parameter of the anhydrous grade): The limit is defined in the manufacturer’s specification. For example, two supplier documents state at most 0.1% water (one together with at least 99.5% purity, the other with at least 99.6%); there is also a laboratory grade stating at most 0.5% water by the Karl Fischer method. The measurement method and the limit are given in the certificate of analysis
Purity (assay): Commercial grades are mostly at least 98–99.9% (gas chromatography). For example TCI states at least 98.0%, Merck at least 99.0%, BASF at least 99.3%, and a pharmaceutical intermediate supplier at least 99.65%; these are product-specific specification values
Formaldehyde: At most 0.1% in one manufacturer’s specification; an impurity from the production route that should be requested separately, like water
Color: At most 20 Hazen in one manufacturer’s specification
Stabilizer: The commercial material may contain a stabilizer; information on type and amount is obtained from the supplier
Density: Relative density 0.948–0.950 at 20 °C; one manufacturer gives 0.9485. A value of d₄²⁰ 0.9715 also appears in the Merck Index
Refractive index: n20/D about 1.429–1.435
Melting point: About –48 to –53 °C according to documents; one manufacturer gives –58 °C
Boiling point: About 112–115 °C at normal pressure; the Merck Index gives values at reduced pressure such as 70 °C (148 mmHg) and 40 °C (35 mmHg)
Azeotrope with water: Boils at about 97.5 °C; the composition is about 39.5% (Merck Index) to 45.5% (1948 patent) propargyl alcohol by weight
Flash point: About 33 °C in a closed cup; 36–37.5 °C in open cup and other methods
Autoignition temperature: About 365 °C
Explosion limits: In air by volume, lower limit 3.4%, upper limit 70% (three documents); 1.9–86.2% in two documents
Vapor pressure: About 1.54 kPa at 20 °C, that is about 11.6–12 mmHg; some databases give 15.6 mmHg
Vapor density: About 1.93–1.94 relative to air
Solubility in water: Miscible in all proportions; one document gives about 1,000 g/L at 20 °C
Solubility in organic solvents: Miscible or soluble with ethanol, ether, acetone, chloroform, benzene, ethyl acetate and tetrahydrofuran; not miscible with aliphatic hydrocarbons
pH (aqueous solution): About 7 in a 50 g/L solution (TCI), 3 in a 500 g/L solution at 20 °C (Merck). A single value should not be accepted without the concentration
Octanol-water partition coefficient: log Pow about –0.38
Decomposition: Stable under normal conditions; polymerizes with heat, light, bases, peroxides and oxidizers. Carbon oxides form in a fire
Reactivity: Incompatible with phosphorus pentoxide, strong acids and bases, oxidizers, amines, isocyanates, acid chlorides and anhydrides; attacks many plastics
Flammability rating: NFPA 704 health 4, flammability 3, instability 3
Short Description of Physical Properties
It is a liquid lighter than water, mobile and quite volatile at room temperature. Because the flash point is about 33 °C, it gives off ignitable vapors even in a cool store; the vapors are about 1.9 times heavier than air and collect at floor level.
The recommendation of cold storage has nothing to do with freezing; the melting point is very low. The real reason is sensitivity to heat and air. For the anhydrous grade, the recommendation also matters with regard to moisture.
Its relationship with water is the key to measuring quality. Because the substance mixes with water in all proportions and forms no separate phase, moisture cannot be detected visually. A method such as Karl Fischer and a documented limit are therefore needed.
There are small differences between documents. The melting point is written as –48 to –58 °C, the flash point as 33 to 37.5 °C and the relative density as 0.948 to 0.9715. The differences come from the method, the temperature, the purity and the literature source. Binding values should be sought in the certificate of analysis.
HOW DOES PROPARGYL ALCOHOL ANHYDROUS WORK AT THE MOLECULAR LEVEL?
The substance does not behave the same way in every application. In one place it attaches to a metal surface, in another it steers crystal growth on a cathode, and in another it offers two different chemical handles in synthesis, as an alcohol and as an alkyne. The importance of water content changes accordingly.
In aqueous media: acid inhibition and nickel plating
In concentrated acid the steel surface is positively charged and acid anions approach it. Propargyl alcohol binds to the surface through the pi electrons of the triple bond and the hydroxyl oxygen, slowing the anodic and cathodic reactions together. In time the molecules on the surface polymerize to give a hydrophobic film.
A study on iron in sulfuric acid calculated that each adsorbed molecule displaces about three water molecules and that the adsorption free energy is about –31.2 kJ/mol. In another study, about 97% protection was obtained at 0.05% by weight in 4 M HCl at 80 °C.
In a nickel bath it behaves as a secondary (Class II) brightener. It attaches to the cathode surface with its pi electrons and slows the reduction of nickel ions at protruding points; pits fill and the surface levels out. Because Class II additives raise internal stress, they are balanced with primary brighteners such as saccharin.
What these two applications have in common is that the solution is water to begin with. A small amount of moisture does not affect the result; the anhydrous grade shows its real value in synthesis steps.
Where dryness matters: synthesis
Through its hydroxyl group, propargyl alcohol is converted with butyl isocyanate into propynyl butylcarbamate, which is iodinated to give IPBC. The isocyanate also reacts with water: first carbamic acid forms, then carbon dioxide and an amine, and the amine combines with a second isocyanate to give a disubstituted urea.
An IPBC patent mentions this side reaction and stresses using the isocyanate fresh. In the carbamate step moisture is a competitor that both consumes the isocyanate and generates urea impurity; low-water propargyl alcohol is therefore preferred.
The iodination step, in most methods, is run in an aqueous medium or in water containing a surfactant. Water itself is not a problem at this stage; what matters is that the preceding carbamate step was completed cleanly.
In deprotonations with strong bases and organometallic reagents the situation is harsher. While the terminal alkyne hydrogen and the alcohol hydrogen react with these reagents, the water in the medium consumes the same reagent. In such steps the moisture limit is set by the needs of the process, not by a catalog value.
The dryness required for palladium- and copper-catalyzed couplings and for copper-catalyzed azide–alkyne cycloaddition is more flexible. Some of these reactions can also be run in water-containing media; even so, the catalyst system, base and solvent choice determine water tolerance, and it should be tested separately in each process.
Stabilization in chlorinated solvents
Trichloroethylene decomposes with metal, moisture and heat to form acid. When propargyl alcohol is added with co-stabilizers such as pyrrole at 0.005–1% by weight, preferably 0.05–0.5%, it slows this decomposition. In an accelerated test the acidity rose to 494 ppm in the unstabilized solvent, whereas it stayed at 93 ppm in a solvent containing 0.1% propargyl alcohol, 0.05% pyrrole and a small amount of amine.
Since moisture is counted among the causes of decomposition, the stabilizer’s own moisture load is also a parameter; this information is obtained from the supplier.
WHICH SECTORS USE PROPARGYL ALCOHOL ANHYDROUS?
The anhydrous grade stands out especially in moisture-sensitive synthesis steps. In the fields below the substance is used with different functions.
Chemistry and fine chemicals
This is the most prominent field. Propargyl halides, esters, ethers, propiolic acid and various alkyne derivatives are obtained from this three-carbon building block. In steps involving bases, organometallic reagents or isocyanates, the water limit becomes decisive.
Pharmaceuticals and biotechnology
It is an intermediate in the preparation of sulfonamide antibacterials such as sulfadiazine, of fosfomycin and of some antiviral precursors. It is not a component of the final drug but an early link in the production chain. High purity, low water and batch consistency stand out in this field.
Agriculture
It provides the propargyl group in the structure of herbicides such as clodinafop-propargyl and acaricides such as propargite. Propargite is not approved in the EU.
Paints, coatings and wood preservation
It does not enter directly as a component; it is the raw material of the IPBC mold inhibitor. IPBC is used in dry-film preservatives, wood preservatives and some adhesives. The quality of the raw material may affect the purity and color of the product.
Metalworking, pickling and oil and gas
It reduces metal loss and hydrogen uptake in pickling of steel in HCl or H₂SO₄; it is a component of inhibitor packages in well acidizing. Because the medium is aqueous, water content is not a deciding parameter in these sectors; the standard grade is mostly used.
Galvanic and electroplating
In nickel baths it is a secondary brightener and leveling additive, often present inside a commercial additive package at very low amounts. Because the bath is aqueous, the water limit is not decisive here either.
Polymers, solvents and special fields
It is used in preparing alkyne-containing monomers and functional polymers, in stabilizing chlorinated hydrocarbons (especially trichloroethylene), in solder flux, in aerospace paint strippers and as a laboratory reagent. In the laboratory the anhydrous grade is preferred for sensitive experiments.
Food, cosmetics, textiles, paper and detergents are not among the typical fields of use of this substance.
IS PROPARGYL ALCOHOL ANHYDROUS USED IN COSMETIC, FOOD AND PHARMACEUTICAL APPLICATIONS?
Short answer: it is not used in cosmetics or food; in pharmaceuticals it is only a synthesis intermediate. The anhydrous grade does not change this result. The three fields need to be seen separately.
Cosmetics
It has no defined INCI name for a cosmetic function and the substance is not regarded as a cosmetic ingredient. It causes severe skin burns and can be fatal through skin absorption. Its use in leave-on or rinse-off products is therefore unacceptable.
A fragrance raw-material database does not consider it suitable for fragrance use. The cosmetic preservative IPBC is synthesized from propargyl alcohol; however, IPBC is a separate substance, and this chain does not mean that propargyl alcohol can be used in cosmetics.
Food
It is not a food additive and has no E number. It is not added directly to food. A food and flavor database does not consider it suitable for use as a flavoring, and it is not listed in the Food Chemicals Codex either.
No record permitting its use in food-contact materials has been found.
Pharmaceuticals
It is not present in medicines as an active or excipient substance. Supplier sources present it as an intermediate in the synthesis of drugs such as sulfonamide-type antibacterials and fosfomycin.
The intermediate must not carry over into the final product as a residue. Because propargyl alcohol has been found mutagenic in some tests, drug manufacturers carry out impurity control according to international harmonization guidelines.
No pharmacopoeia monograph has been found in the sources examined. The quality of a product to be used in drug synthesis, including its water limit, is determined by the specification between the buyer and the manufacturer.
INDUSTRIAL APPLICATIONS OF PROPARGYL ALCOHOL ANHYDROUS
The effect of water content differs in every application. Below, the purpose, the function of the substance, water sensitivity and limitations of use are given together for each application.
Production of the IPBC mold inhibitor
The purpose is to obtain IPBC, which is used in paints, coatings, wood preservatives, adhesives and some personal care products. Here propargyl alcohol is the alcohol component of the first step. It reacts with butyl isocyanate to give propynyl butylcarbamate; the intermediate is then iodinated.
Water sensitivity is high, but only in the carbamate step. The isocyanate gives carbamic acid with water, which breaks down into carbon dioxide and an amine; the amine in turn leads to the formation of a urea with a second isocyanate. Each water molecule thus consumes reagent and produces impurity. A patent recommends using the isocyanate preferably within about 24 hours after distillation.
The reason for preference is that a low-water raw material protects carbamate yield and product color. The limitation is that isocyanate and iodine chemistry require closed systems and trained personnel.
Pharmaceutical and agrochemical intermediates
The purpose is to add a propargyl or alkyne unit to the target molecule. The alcohol group can form esters, ethers and carbamates; the triple bond is used in coupling reactions. In active substances such as clodinafop-propargyl and propargite, the propargyl group is a direct part of the structure.
Water sensitivity varies with the step. In a step starting with a base or an organometallic reagent moisture directly affects yield; in aqueous operations it is unimportant. A pharmaceutical intermediate supplier stresses at least 99.65% purity; values such as water, formaldehyde and color are limited separately according to the buyer’s own step.
The reason for preference is that it is a small and relatively inexpensive source of an alkyne. The limitation is high toxicity and side reactions that increase at low purity.
Fine chemistry requiring bases and organometallic reagents
The purpose is to remove the alcohol or terminal alkyne hydrogen with a strong base and to attach the resulting species to another molecule. The acidity of the terminal C–H bond makes this possible. The same acidity means that the same reagent will also react with water.
Water sensitivity is at its highest level in this application. Moisture in the medium consumes part of the reagent used and upsets the stoichiometry. The anhydrous grade therefore gains most meaning here; even so, the buyer should determine by measurement the limit needed for their own step.
The limitation is that dryness is protected not only by the product document but also by the opened container and the inert gas practice.
Acid inhibitor concentrates (oil well acidizing, steel pickling)
The purpose is to limit the attack of concentrated HCl or H₂SO₄ on steel pipe, tubing and equipment. Propargyl alcohol and its derivatives are components of inhibitor packages; one patent describes using a mixture containing 80–90% propargyl alcohol by weight at 0.5–20% of the acid fluid. In stainless steel, 98.3–99.9% protection has been reported at 0.05–0.10% by volume in HCl.
Water sensitivity is low. The application medium is water-based acid, and a certain amount of moisture in the concentrate does not change the result. The effect is determined by temperature, acid type and concentration, and the presence of synergists (iodide, copper, chromium).
The limitation is the toxicity of the substance and its harm to the aquatic environment. In this application the standard grade is mostly used.
Nickel plating baths
The purpose is to obtain a bright and smooth deposit. Propargyl alcohol and its ethoxylated derivative are added in very small amounts together with primary brighteners such as saccharin; in the patent literature the total acetylenic additive is in the range of 0.01–0.5 g/L. Because the bath is aqueous to begin with, water sensitivity is almost negligible.
Stabilization of chlorinated solvents
The purpose is to prevent trichloroethylene used in vapor degreasing from decomposing and forming acid under metal, moisture and heat. Propargyl alcohol is added at 0.005–1% by weight together with co-stabilizers such as pyrrole and a very small amount of amine.
Water sensitivity is a logical parameter in this application; because moisture is counted among the causes of decomposition, the stabilizer is not wanted to carry moisture. Because trichloroethylene use is restricted in many regions, the application has shrunk.
Polymer modification and click chemistry
The purpose is to give polymers and surfaces a triple-bond function and to join it with azide-containing molecules. Propargyl alcohol is the raw material of monomers such as propargyl acrylate and ethers. Water sensitivity varies with the catalyst system; control of residual copper and toxic monomers is limiting.
PRECAUTIONS IN THE USE OF PROPARGYL ALCOHOL ANHYDROUS
In the anhydrous grade two matters are handled together: the hazards of the substance itself and keeping it dry. Correct packaging and handling keep the water value on the document intact until the moment of use. The main points:
• Water uptake: Because the substance mixes with water in all proportions, moisture in the air enters as the lid is opened. If a container taken from the cold is opened before reaching room temperature, condensation forms on the surface
• Number of openings: As a large package is opened repeatedly, the risk of moisture and polymerization increases. Small packages or septum containers are preferred; opened containers should be consumed quickly
• Inert gas: Filling the headspace with dry nitrogen or argon keeps both moisture and oxygen away
• Drying on one’s own: The Merck Index reports that the substance polymerizes with caustic, and an old patent reports that it decomposes to formaldehyde in neutral or basic medium. Trials with basic drying agents should therefore not be made; if necessary, a suitable grade should be requested from the supplier
• Water determination: The Karl Fischer method is common, and the method should be agreed in advance between buyer and seller. Because aldehydes can affect this method, the effect of impurities such as formaldehyde on the measurement should be discussed with the laboratory
• General hazards: The liquid is absorbed quickly through the skin and can be fatal; it causes permanent eye damage. The flash point is about 33 °C. It polymerizes with heat, light, bases and oxidizers; it is incompatible with strong acids and bases, amines, isocyanates and salts of copper, silver and mercury. A closed system, grounding and appropriate protective equipment are required
• Materials and waste: Stainless steel, glass and phenolic-lined containers are preferred; aluminum, rubber and epoxy coatings are avoided. The substance is toxic to aquatic life; waste must be disposed of by licensed firms
• Regulation: Classification, labeling, transport, occupational exposure and KKDİK/REACH obligations should be checked for the target country
This section is written for general information. The current safety data sheet and technical data sheet of the product to be used should be taken as the basis.
STARTING FORMULATION APPROACHES FOR PROPARGYL ALCOHOL ANHYDROUS
The examples in this section show, at a conceptual level, the paths that can be followed in evaluating the anhydrous grade. They are not validated commercial recipes, production instructions or regulation-compliant final formulas.
The substance is toxic, flammable, corrosive and prone to polymerization; accompanying substances such as isocyanates and organometallic reagents are also hazardous in their own right. For this reason full component tables, mixing order, temperature and duration are not given; only levels and evaluation criteria that appear in published sources are mentioned.
Every study must be carried out with trained personnel, in closed systems and in authorized laboratories. The common question is this: for which application is which water limit really needed?
EXAMPLE 1: WATER DETERMINATION AND MONITORING OF MOISTURE UPTAKE IN ANHYDROUS GRADE BATCHES
Purpose: To verify the documented water limit of an anhydrous grade batch and to monitor how opening the package, storage temperature and headspace gas change the water content over time.
Starting approach:
Batches: at least two suppliers or batches; those whose documents state a water limit (for example at most 0.1% or at most 0.5%)
Water determination: Karl Fischer method; the choice of an aldehyde-compatible reagent is determined with the laboratory
Storage variables: 2–8 °C and room condition below 30 °C; under nitrogen and in air
Opening frequency and sampling method: tested as a separate variable
Evaluation approach:
• The initial water value is compared with the value on the certificate of analysis
• Water determination is repeated at set intervals; the increase is followed according to the number of openings and the storage condition
• Color and purity (gas chromatography) are also recorded; yellowing or an increase in viscosity is noted as a sign of polymerization
Safety and quality note: Cold containers must be brought to room temperature before opening. Work should be done in a fume hood with butyl rubber gloves, goggles and a face shield. Sample residues must be disposed of as hazardous waste.
EXAMPLE 2: EVALUATING WATER TOLERANCE IN CARBAMATE FORMATION
Purpose: In a step where propargyl alcohol gives a carbamate with an isocyanate, to compare the effect of batches with different water contents on conversion, urea by-product and color.
Starting approach:
Propargyl alcohol batches: at least three batches with different water limits
Isocyanate: from the same production, fresh and of the same quality (in the literature, use within about 24 hours after distillation is preferred)
Catalyst type and amount: held constant according to the user’s own process (in the literature, tin catalyst about 0.001–1%)
Solvent, temperature and duration: held constant according to the user’s own model
Evaluation approach:
• The input water value of each batch is recorded by the Karl Fischer method
• Conversion, carbamate yield and disubstituted urea content are compared by chromatography
• From the results, the highest water limit the process really requires is determined and written into the purchasing specification
Safety and quality note: Isocyanates are respiratory sensitizers and are incompatible with propargyl alcohol; work must be done only in a closed system and with trained personnel. The risk of heat release and polymerization must be considered.
EXAMPLE 3: COMPARING STANDARD AND ANHYDROUS GRADES IN AN ACID INHIBITOR CONCENTRATE
Purpose: To compare the performance of the standard and anhydrous grades in an acid inhibitor concentrate; to show their effects on corrosion rate, hydrogen uptake and concentrate stability.
Starting approach:
Grades: standard and anhydrous propargyl alcohol; purity limits similar, water limits different
Acid medium: about 15% HCl or 0.5 M H₂SO₄; held constant
Propargyl alcohol level: in the literature about 0.05–0.10% by volume (stainless steel in HCl); screened stepwise
Synergist: potassium iodide or a small amount of copper or chromium ions; evaluated as a separate variable
Evaluation approach:
• Corrosion rate is calculated from the weight loss of metal coupons; polarization and impedance measurements are added
• The prepared concentrate is stored for a set time; appearance, color and effectiveness are measured again
• The results provide a basis for choosing the grade best suited to the application
Safety and quality note: Work should be done in a fume hood or closed system, taking hydrogen evolution and acid vapor into account. Spent acid solution must be disposed of as waste in accordance with regulations. If possible, a ready-made inhibitor solution should be used instead of the pure substance.
SIMILAR PRODUCTS AND ALTERNATIVES TO PROPARGYL ALCOHOL ANHYDROUS
Options are evaluated according to the application’s water sensitivity, chemical function, toxicity and regulation. The standard grade of the same substance is the closest option; different substances are weighed separately for function and safety. No substance replaces it in every application.
STANDARD GRADE PROPARGYL ALCOHOL
The same chemical, offered in a grade with a wider water limit. It is often sufficient in acid inhibition, in nickel plating and in water-tolerant syntheses. It may offer an advantage in price and availability.
The limitation is moisture-sensitive steps. In steps involving bases, organometallic reagents or isocyanates, the water value of the standard grade may come out high. The decision should rest on the water tolerance the buyer has measured in their own step.
2-METHYL-3-BUTYN-2-OL AND 3-BUTYN-2-OL
2-Methyl-3-butyn-2-ol is a tertiary alcohol carrying a terminal alkyne; its boiling point is about 104 °C. A dermal LD50 of about 1,420 mg/kg in rabbits is reported; it is used as a coating additive and as an acetylene carrier.
3-Butyn-2-ol is the secondary alcohol analogue with an added methyl group. Its toxicity is similar (one source gives an LD50 of about 57 mg/kg), so it brings no safety gain.
2-BUTYNE-1,4-DIOL AND ETHOXYLATES
2-Butyne-1,4-diol is a dihydroxy, hygroscopic solid; propargyl alcohol forms as a by-product, at about 5%, in its Reppe production. In nickel plating both are secondary brighteners. Ethoxylated propargyl alcohol is less volatile and should be verified as a separate substance. None of them replaces propargyl alcohol in synthesis.
ALLYL ALCOHOL AND ACID INHIBITOR ALTERNATIVES
Allyl alcohol is a similar small alcohol with a double bond; it too is toxic and flammable, and it does not give the same performance in acid inhibition. Cinnamaldehyde-based systems and indolizine derivatives are acid inhibitor options that contain no acetylenic alcohol; at high temperature and in concentrated acid, propargyl alcohol is still the reference component.
OTHER PROPARGYLATION SOURCES IN SYNTHESIS
Propargyl bromide and 3-chloropropyne are reactive halides that attach the propargyl group directly. They derive from the same substance, but they are alkylating agents and irritants. If esterification through the alcohol group is possible, propargyl alcohol is preferred directly.
QUALITY CONTROL AND PURCHASING CRITERIA FOR PROPARGYL ALCOHOL ANHYDROUS
The binding specification is always in the technical data sheet of the manufacturer offering the product and in the batch certificate of analysis. The main parameters in quality control:
• Water content: The main criterion of the anhydrous grade. It is determined by the Karl Fischer method; two suppliers state at most 0.1% and one laboratory grade at most 0.5%. The limit and the method should be written together, and the effect of impurities such as formaldehyde on the measurement should be discussed with the laboratory
• Purity: Determined by gas chromatography. Commercial specifications mostly show at least 98–99.9%; BASF states at least 99.3%, Merck at least 99.0%, two Asian suppliers at least 99.5% and 99.6%, and a pharmaceutical intermediate supplier at least 99.65%
• Formaldehyde: An impurity from the production route; one manufacturer gives at most 0.1%. It matters both for safety and for subsequent reactions
• Color: One manufacturer states at most 20 Hazen. Yellowing can be a sign of aging or polymerization
• Density and refractive index: Relative density at 20 °C about 0.948–0.950, n20/D about 1.429–1.435. They give a quick check for identity verification
• Stabilizer: Information on type and amount should be obtained from the supplier, as it may affect synthesis or plating
• Metal ions: Ions such as iron and copper can affect plating, acid inhibition and the tendency to polymerize. A limit should be requested according to the use
• Batch information: Production date, batch number, package type and net quantity should be asked. In a batch kept for a long time, water and purity should be measured again
• Documents: SDS, TDS, a batch-specific certificate of analysis and transport information should be requested
The manufacturer’s typical values must not be confused with the binding specification. Parameters specific to solids, such as bulk density and particle size, do not apply to this liquid.
STORAGE AND TRANSPORT OF PROPARGYL ALCOHOL ANHYDROUS
A dry, cool, well-ventilated store away from ignition sources is required. The substance is sensitive to heat, light and air; many suppliers recommend storage under dry inert gas in the tightly closed original package. In the anhydrous grade every opening of the lid can lead to moisture uptake, so the package is handled with care.
The temperature limit varies by document. TCI recommends 0–10 °C, CDH, Molekula and Thermo Scientific 2–8 °C, Merck 2–30 °C, and another source below 30 °C. The reason for cold storage is not freezing but the risk of polymerization. A container must not be opened before it reaches room temperature; otherwise moisture condensing on the surface can get into the product.
An incident report from France describes a polymerization explosion in a drum kept above 30 °C for a long time. The advice that stands out is to keep opened drums under nitrogen and consume them within a few weeks, and to store unopened drums below 30 °C.
Suitable packaging is clean stainless steel, glass and phenolic-lined containers. Aluminum, rubber and epoxy coatings are avoided; the substance attacks many plastics. Suppliers report drum and bulk shipment options from 0.5 kg to 200 kg.
It is not stored together with phosphorus pentoxide, strong acids and bases, oxidizers, amines, isocyanates, acid chlorides and anhydrides. Contact with salts of copper, silver and mercury can lead to explosive metal acetylides. The store is kept apart from food and feed areas.
For transport, most documents give UN 2929, class 6.1 (subsidiary hazard 3). The packing group may be I (TCI, CDH, Sigma-Aldrich, Molekula) or II (Loba, Henan Haiyuan, Thermo Scientific); UN 1986 / NA 1986 is also seen on some pages. For each shipment the current SDS and the ADR, IMDG or IATA rules should be taken as the basis.
In bulk shipment it should be verified that tanks and lines are clean, moisture-free and of compatible material.
SAFETY INFORMATION ON PROPARGYL ALCOHOL ANHYDROUS
The anhydrous grade is neither safer nor more hazardous than the standard grade; the hazard profile is the same. The information below is intended for the general reader:
• Classification: In the harmonized EU classification, flammable liquid category 3 (H226), acute toxicity category 3 (H301, H311, H331), skin corrosion category 1B (H314) and long-term hazard to the aquatic environment category 2 (H411). Some suppliers classify more severely (H300, H310, H330, H341, H372)
• Acute toxicity: Oral LD50 in rats about 20–70 mg/kg, dermal in rabbits about 16–88 mg/kg. It carries a skin notation; absorption through the skin can be fatal
• Skin and eyes: The undiluted liquid can cause second-degree burns within minutes and permanent eye damage; it is a lachrymator
• Inhalation: The vapors irritate the nose, throat and lungs. Occupational limits vary by country; NIOSH and ACGIH give 1 ppm (skin)
• Fire and reactivity: The flash point is about 33 °C. For fire fighting, carbon dioxide, alcohol-resistant foam or dry chemical powder is used; a strong water jet is not recommended. It can polymerize with heat, light, bases, peroxides and oxidizers; ignition with phosphorus pentoxide has been reported
• Personal protective equipment: Closed system or fume hood; gloves approved in the SDS and with permeation data (for example butyl rubber), face protection or sealed goggles, protective clothing and, when necessary, respiratory protection. An eyewash and an emergency shower must be available
• Spills and first aid: The area is evacuated, ignition sources are shut off, the substance is collected with an inert absorbent and not released to the sewer. On contact, clothing is removed, skin and eyes are washed for at least 15 minutes, and medical help and a poison information center are called immediately
• Environment and waste: LC50 for fish about 1.53 mg/L; not released to water and soil, disposed of by licensed firms
This section is for general information; it does not replace the product-specific SDS.
WHAT TO CONSIDER WHEN BUYING PROPARGYL ALCOHOL ANHYDROUS?
The supply chain is shaped around a few manufacturers in China and BASF. In selection, continuity, document quality and safety are evaluated together with price.
• Water limit: Ask what maximum percentage of water is defined in the specification, by which method it is measured, and what value appears on the batch certificate
• Suitability for the application: The anhydrous grade is preferred in moisture-sensitive steps involving bases, organometallic reagents or isocyanates; in applications in aqueous media (acid inhibition, nickel plating) the standard grade can also be considered
• Correct identity: CAS 107-19-7, prop-2-yn-1-ol. Ethoxylate, 2-(prop-2-ynyloxy)ethanol, 3-butyn-2-ol and propargylamine are different substances
• Packaging and moisture protection: Small packages or septum containers reduce the number of openings; the headspace gas and lid sealing should be asked
• Documents: Current SDS, TDS, batch-specific certificate of analysis, transport documents; the classification and packing group in the SDS should agree with the shipping documents
• Regulation and logistics: Poisons and hazardous substances legislation, KKDİK/REACH, hazardous goods transport rules and, if needed, the cold chain should be checked by the buyer
• Total cost: Cold storage, hazardous goods freight, protective equipment, waste and training costs are added to the unit price
For critical applications, a preliminary trial with a sample before ordering and verification of the water value in one’s own laboratory are recommended.
SUPPLY OF PROPARGYL ALCOHOL ANHYDROUS FROM ATAMAN KİMYA
For technical information, quotations and product requests on propargyl alcohol anhydrous, contacting ATAMAN KİMYA is recommended. Sharing the intended use, the required grade and the order conditions in the request allows the right product to be determined quickly.
The current stock status, grade, purity, water content, formaldehyde level, stabilizer information, origin, packaging, transport conditions and documents of the product should be confirmed with ATAMAN KİMYA before ordering. Writing the CAS number 107-19-7 together with the product name in the order prevents confusion.
Sharing the following information in a quotation request makes it easier to evaluate the right product:
• Sector of use and final application
• Required water limit and measurement method (for example Karl Fischer), and purity, formaldehyde and color limits
• Need for a stabilizer or expectation of a stabilizer-free grade
• Required CAS number (107-19-7) and, if any, brand or product code
• Estimated order quantity, package type and size, storage and unloading facilities
• Requested documents: SDS, TDS, certificate of analysis and transport documents
The contact page on the company’s website can be used for ATAMAN KİMYA contact details.
FREQUENTLY ASKED QUESTIONS ABOUT PROPARGYL ALCOHOL ANHYDROUS
What is propargyl alcohol anhydrous?
It is the grade of prop-2-yn-1-ol in which the water content is kept low. It is a colorless to pale yellow liquid with the formula HC≡C–CH₂OH and a geranium-like odor, and it is used especially in water-sensitive syntheses.
What does propargyl alcohol anhydrous mean?
It means a propargyl alcohol grade whose water content is kept below a defined upper limit. Commercial documents state, for example, at most 0.1% or at most 0.5% water. The limit and the measurement method are given in the certificate of analysis.
What is the CAS number of propargyl alcohol anhydrous?
It is 107-19-7. Standard and anhydrous grades carry the same number; the difference lies in the water limit and the documents.
What is the EC / EINECS number of propargyl alcohol anhydrous?
It is 203-471-2. In the harmonized EU classification it appears with index number 603-078-00-X.
What is the chemical formula of propargyl alcohol anhydrous?
It is C₃H₄O. The molecular weight is 56.06 g/mol.
Is propargyl alcohol anhydrous used in cosmetics or food?
No. It is not a cosmetic ingredient and has no INCI name; it is not a food additive and has no E number. The cosmetic preservative IPBC is synthesized from this substance, but it is a separate substance.
What is the difference between anhydrous and standard propargyl alcohol?
The chemical is the same; the difference is water content, the document details tied to it, and price. The anhydrous grade matters in steps involving bases, organometallic reagents or isocyanates; in aqueous applications such as acid inhibition and nickel plating the standard grade can also be used.
What is propargyl alcohol anhydrous used for?
It is used as a building block in moisture-sensitive alkyne and alcohol syntheses, above all for IPBC and for pharmaceutical and agrochemical intermediates. It may also appear as an acid inhibitor, a nickel brightener and a solvent stabilizer.
Which sectors use propargyl alcohol anhydrous?
In fine chemicals, pharmaceuticals, agrochemicals, the paint and wood preservation chain (IPBC), oil and gas, metalworking, electroplating and polymer modification. It is not an ingredient in cosmetics and food.
What is propargyl alcohol anhydrous good for?
It is a building block offering both alcohol and alkyne functions in synthesis; it protects steel in acid and gives brightness in a nickel bath.
How does propargyl alcohol anhydrous react with isocyanates?
The alcohol group gives a carbamate with the isocyanate; this is the first step of IPBC production. Because water in the medium consumes the isocyanate and forms a urea by-product, the low-water grade is preferred in this step.
How does propargyl alcohol anhydrous work in acid corrosion?
It attaches to the steel surface with the pi electrons of the triple bond and the hydroxyl oxygen, slows the anodic and cathodic reactions, and in time forms a hydrophobic film. Because the medium is aqueous, water content is not a deciding factor in this application.
Is propargyl alcohol anhydrous soluble in water?
Yes, it mixes with water in all proportions. For this reason the moisture level is followed by measurement.
Can propargyl alcohol be made anhydrous by distillation with water?
Not completely by simple distillation; the substance forms an azeotrope with water boiling at about 97.5 °C (about 39.5–45.5% propargyl alcohol by weight). Azeotropic drying and vacuum distillation are used in production.
Is propargyl alcohol anhydrous a hazardous substance?
Yes, it is highly hazardous: toxic, corrosive, flammable and harmful to the aquatic environment. Being anhydrous does not reduce the hazard. A closed system, suitable protective equipment and the product-specific SDS are essential.
Why can propargyl alcohol anhydrous be fatal through skin absorption?
Because the molecule is small, polar and miscible with water, it passes quickly through the skin. A dermal LD50 of about 16–88 mg/kg in rabbits is reported.
Is propargyl alcohol anhydrous registered under REACH?
The substance has a harmonized classification in the EU and has notifications in the ECHA inventory. The registration number and scope should be confirmed from the ECHA database and the supplier, and the KKDİK status in Türkiye separately.
What is the physical appearance of propargyl alcohol anhydrous?
It is a colorless to pale yellow, clear and mobile liquid; its odor resembles geranium. The flash point is about 33 °C.
What is the UN number of propargyl alcohol anhydrous?
Most documents give UN 2929, class 6.1 (subsidiary hazard 3); the packing group is I or II depending on the document. The current SDS should be checked for each shipment.
Why do water and formaldehyde matter in propargyl alcohol anhydrous?
Water consumes the reagent in steps involving isocyanates and strong bases. Formaldehyde is an impurity from the production route and matters for both safety and reactions. Limits vary by supplier, for example at most 0.1%.
What does the price of propargyl alcohol anhydrous depend on?
It depends on the water and formaldehyde limits, purity, packaging, order quantity and transport requirements.
Is there an alternative to propargyl alcohol anhydrous?
The standard grade may be sufficient in moisture-insensitive applications. 2-Butyne-1,4-diol in nickel plating, cinnamaldehyde-based systems in acid inhibition, and alkynes such as 2-methyl-3-butyn-2-ol in synthesis can be considered; none replaces it in every job.
How should propargyl alcohol anhydrous be stored?
In a cool, dry and ventilated place, under dry inert gas and in the tightly closed original package; most suppliers recommend 2–8 °C or at most 30 °C. A cold container should be opened at room temperature, and opened containers should be consumed quickly.
Which documents should be requested when buying propargyl alcohol anhydrous?
The SDS, the TDS and the batch-specific certificate of analysis including the water value are the basic documents. Depending on the application, a quality statement, a transport document and regulatory information should also be requested.
Which technical properties matter when buying propargyl alcohol anhydrous?
Water content and measurement method, purity, formaldehyde, color, relative density, refractive index and stabilizer information. Packaging, production date and batch consistency should also be asked.
PROPARGYL ALCOHOL ANHYDROUS – TECHNICAL SUMMARY
Chemical name: Prop-2-yn-1-ol; propargyl alcohol (low-water grade)
Common names: Propargyl Alcohol Anhydrous, Anhydrous Propargyl Alcohol, Propargyl Alcohol Anhydr., 2-Propyn-1-ol, Ethynyl Carbinol, Propynol
CAS No: 107-19-7
EC / EINECS No: 203-471-2
Molecular formula: C₃H₄O
Molecular weight: 56.06 g/mol
Chemical class: Acetylenic primary alcohol; terminal alkyne
Physical appearance: Colorless to pale yellow, clear, mobile liquid; geranium-like odor
Water content: Upper limit defined in the manufacturer’s specification; at most 0.1% and at most 0.5% in commercial examples (Karl Fischer); the limit and the method are given in the certificate of analysis
Main properties: Relative density about 0.95 (20 °C), boiling point about 112–115 °C, flash point about 33 °C, miscible with water in all proportions; azeotrope with water at about 97.5 °C
Main functions: Synthesis intermediate (alcohol and alkyne building block), acid corrosion inhibitor component, nickel plating secondary brightener, chlorinated solvent stabilizer
Important application areas: IPBC production, pharmaceutical and agrochemical intermediates, fine chemistry requiring bases and organometallic reagents, click chemistry and polymer modification, acid inhibitor packages, nickel plating
Parameters critical for quality control: Water content, purity, formaldehyde, color, relative density, refractive index, stabilizer, metal ions
Storage: In a cool, dry and ventilated place, under dry inert gas, in the closed original package; mostly cold; a cold container is brought to room temperature before opening
Regulation: Harmonized EU classification H226, H301, H311, H331, H314, H411; for transport UN 2929, class 6.1 (3), packing group I or II depending on the document; not an ingredient in cosmetics and food; REACH and KKDİK status should be confirmed with the supplier.
