What is Propargyl Alcohol? – Chemical name, structure, synthesis, and CAS No

Propargyl alcohol turns up in two very different places: in the drum of corrosion inhibitor a steel mill pumps into its pickling line, and in the reaction train that makes pharmaceuticals and vitamins. The same small, reactive molecule does both jobs. It is also the textbook example of a wider structural class, the propargylic alcohols, so this page defines both the compound and the position.

Propargylic alcohol: definition

A propargylic alcohol is an alcohol in which the hydroxyl (–OH) group is attached to a carbon atom directly adjacent to a carbon–carbon triple bond (an alkyne). That –OH-bearing carbon is the propargylic position: the sp³ carbon next to the C≡C. Its general form is HC≡C–CH(OH)–, the alkyne analogue of an allylic alcohol (where the –OH sits next to a C=C double bond).

A homopropargylic alcohol has the hydroxyl group two carbons away from the alkyne, on the carbon once removed from the propargylic position. Its general form is HC≡C–CH₂–CH(OH)–. The prefix homo- signals one extra carbon (a –CH₂– spacer) between the –OH and the triple bond.

So the position is defined by how far the –OH sits from the triple bond: propargylic = OH adjacent to the alkyne (one carbon, the propargylic position); homopropargylic = OH two carbons away from the alkyne. Propargyl alcohol — the specific compound this page is named for — is the simplest propargylic alcohol: 2-propyn-1-ol, HC≡C–CH₂–OH.

Propargylic vs homopropargylic alcohol

The two terms describe where the hydroxyl sits relative to the carbon–carbon triple bond. The propargylic carbon is the one bonded directly to the alkyne; moving the –OH one carbon further out gives the homopropargylic case.

One useful clarification: propargylic alcohol (the class, hydroxyl adjacent to an alkyne) is not the same as propargyl alcohol (the specific compound, 2-propyn-1-ol). Propargyl alcohol is simply the smallest member of the propargylic-alcohol family. The propargylic position matters in synthesis because the carbon next to the triple bond is activated — it is more reactive toward substitution and a common handle for further chemistry, in the same way the allylic position next to a double bond is.

What is propargyl alcohol?

The short answer: propargyl alcohol (2-propyn-1-ol, CAS 107-19-7) is a colorless, water-miscible liquid alkyne alcohol with the formula C3H4O and a molecular weight of 56.06 g/mol. Its reactive terminal carbon-carbon triple bond makes it two things at once: a powerful corrosion inhibitor for steel in acid, and a versatile building-block intermediate in chemical synthesis.

Key properties

Property values are from public chemical data and RawSource’s typical product specification; the Certificate of Analysis for the lot you buy governs the exact figures.

What is propargyl alcohol used for?

Two roles dominate, both driven by the reactive triple bond:

• Corrosion inhibitor for steel in acid. It adsorbs and polymerizes into a protective film on carbon steel, protecting tubing, casing, and equipment during oil-well acidizing and acid pickling. This is its best-known industrial use, covered in detail in how propargyl alcohol inhibits corrosion.
• Chemical synthesis intermediate. The terminal alkyne is a handle for further reaction, so propargyl alcohol is a building block in the manufacture of pharmaceuticals (including fosfomycin and sulfadiazine routes), vitamin A, acrolein and allyl chemistry, agrochemicals, and other fine chemicals.

It also serves as a reactive solvent and a stabilizer in certain formulations.

How is propargyl alcohol made?

Industrially it is produced by the Reppe reaction: formaldehyde reacts with acetylene over a copper-acetylide catalyst, giving propargyl alcohol along with butynediol. The propargyl alcohol is then separated and purified to the high assay industrial buyers need.

Is propargyl alcohol hazardous?

Yes — it carries the GHS signal word Danger. It is a flammable liquid and vapor, toxic if swallowed, in contact with skin, or if inhaled, causes severe skin burns and eye damage, and is toxic to aquatic life with long-lasting effects.

It is handled strictly as a bulk industrial chemical with full engineering controls and PPE, and it can polymerize on contact with heat, acids, oxidizers, or some metals. Always work from the current Safety Data Sheet, and treat transport classification as a per-shipment determination rather than a fixed label.

Buying propargyl alcohol in bulk

Industrial buyers take propargyl alcohol by the drum, IBC tote, and ISO tank. RawSource supplies bulk propargyl alcohol (CAS 107-19-7) at a 99.9%+ typical assay with full CoA and SDS documentation, into oil and gas and industrial manufacturing. The corrosion-inhibitor mechanism is in how it inhibits corrosion, and the acid-service detail in acidizing and pickling. To source propargyl alcohol for corrosion inhibition or acidizing, request a quote.

Frequently asked questions

What is a propargylic alcohol?

A propargylic alcohol is an alcohol in which the hydroxyl (–OH) group is attached to a carbon atom directly adjacent to a carbon–carbon triple bond (an alkyne). That carbon is the propargylic position. The general structure is HC≡C–CH(OH)–, and the simplest example is propargyl alcohol itself.

What is a homopropargylic alcohol?

A homopropargylic alcohol has the hydroxyl group two carbons away from the alkyne — one carbon past the propargylic position, with a –CH₂– spacer between the –OH carbon and the triple bond. The general structure is HC≡C–CH₂–CH(OH)–; 3-butyn-1-ol (HC≡C–CH₂–CH₂–OH) is the simplest example.

What is the propargylic position?

The propargylic position is the sp³ carbon directly adjacent to a carbon–carbon triple bond. It is the alkyne analogue of the allylic position (the carbon next to a double bond), and it is activated toward substitution, which is why it is a common reactive handle in synthesis. A propargylic alcohol is an alcohol with its –OH on this carbon.

Is propargyl alcohol the same as propargylic alcohol?

Not quite. Propargyl alcohol is one specific compound, 2-propyn-1-ol (HC≡C–CH₂–OH, CAS 107-19-7). Propargylic alcohol is the broader class: any alcohol with its hydroxyl on the carbon adjacent to an alkyne. Propargyl alcohol is the simplest member of that class.

What is propargyl alcohol used for?

Mainly as a corrosion inhibitor for steel in acid (oil-well acidizing and acid pickling) and as a reactive intermediate in chemical synthesis, including pharmaceutical, vitamin, and agrochemical routes. It also acts as a reactive solvent.

Is propargyl alcohol flammable?

Yes. It is a flammable liquid with a flash point around 34 °C and a wide flammability range, so it is stored and handled away from heat, sparks, and open flame.

Is propargyl alcohol soluble in water?

Yes, it is miscible with water in all proportions, and also soluble in many common organic solvents.

What is the boiling point of propargyl alcohol?

About 114 °C. Its melting point is roughly −48 to −52 °C, and it has a density near 0.97.

How is propargyl alcohol synthesized?

Industrially by the Reppe reaction of formaldehyde with acetylene over a copper catalyst, which also yields butynediol; the propargyl alcohol is then separated and purified.

Editorial note. This article is general reference information for industrial and professional use, not safety or transport advice. Property figures are public chemical data and typical product ranges; the Certificate of Analysis governs the material you buy. Propargyl alcohol is a hazardous material — consult the current Safety Data Sheet (SDS) before handling, and verify transport classification for your specific shipment. RawSource makes no warranty, express or implied, and assumes no liability for use of this information.

RawSource Editorial

Commercial & Sourcing Desk