Chemical industry portal

1,2-propanediol

Product name 1,2-propanediol
Synonyms propylene glycol
GOST no data
CAS 57-55-6

Propylene glycol, also known as 1,2-propanediol is a colorless, odorless, slightly sweetish, viscous, highly hygroscopic liquid. It is fully miscible with water, methanol, ethanol, acetone, diethyl ether, chloroform; boundedly soluble in benzene. Propylene glycol forms azeotropic mixtures with aniline (bp 179.5°C; 43% wt of propylene glycol), o-xylene (135.8°C; 10.0% wt), toluene (110.5°C; 1.5% wt).

Since the molecule of propylene glycol contains a chiral carbon atom C2, it exists in either of two optically active forms (dextrorotatory and sinistrorotatory isomers). Industrial propylene glycol is a racemic mixture. Pure optical isomers may be prepared by hydration of pure (D) or (L) propylene oxide.

Propylene glycol is a diatomic alcohol. It can form mono- and di- ethers and esters being treated with alcohols or acids respectively. It also reacts with alkali metals and alkalis to form corresponding salts (glycolates). 1,2-Propylene glycol dehydrates in the presence of acids or alkalis to form dimethyl-1,4-dioxanes (mixture of isomers). Catalytic dehydratation of 1,2-propanediol at 250°C results in propionic aldehyde.

Propylene glycol reacts with propylene oxide to give the mixture of di-, tri-, tetra- and polypropylene glycols. The yield of products depends on the ratio of reagents and reaction conditions.

1,2-Propanediol is considerably less toxic than ethylene glycol, moreover it is used as a food additive.

Production.

Main industrial method for propylene glycol synthesis is hydration of propylene oxide. Non-catalytic hydration is conducted at 200-220°C, catalytic process proceed at 150-180°C and 1.5-1.8 MPa in presence of ion-exchange resins or small amounts of sulfuric acid or alkali. Final product contains of 20% 1,2-propanediol and 1.5% of dipropylene glycol and small amounts of other polypropylene glycols. Pure propylene glycol can be obtained after rectification.

Propylene glycol synthesis by hydration of propylene oxide


Uses.

  • as a moisturizer to maintain moisture in medicines, cosmetics, food, and tobacco products;
  • as a flavoring agent in Angostura and Orange bitters;
  • as a solvent for food colors and flavourings;
  • as a humectant food additive, labeled as E number E1520;
  • as a carrier in fragrance oils;
  • as a food grade antifreeze;
  • in smoke machines to make artificial smoke for use in firefighters training and theatrical productions;
  • in hand sanitizers, antibacterial lotions, and saline solutions
  • as a main ingredient in many cosmetic products, including baby wipes, bubble baths, and shampoos
  • as the primary ingredient in the "Paint" inside a Paintball;
  • as a base ingredient in aircraft deicing fluid and some automobile antifreezes;
  • in cryonics;

  • Manufacturer(s) OJSC Himprom Kemerovo
    Chemical structure of propylene glycol

    FIND PRODUCT
    Find chemicals by name, GOST or CAS number

    Russian version
    Unauthorized copying, processing or reproduction of any and all information published on this website prohibited.
    © 2000-2010 All rights reserved
    Powered by CHEMINDUSTRY.RU group
    Contact us