Epichlorohydrin

Brief Overview

Epichlorohydrin is a volatile and flammable, clear, colorless, liquid, chlorinated cyclic ether with an irritating, chloroform-like odor that emits toxic fumes of hydrochloric acid and other chlorinated compounds when heated to decomposition. Epichlorohydrin is used in the manufacture of epoxy resins, synthetic glycerin and elastomers. Exposure to epichlorohydrin irritates the eyes, skin and respiratory tract, and can cause chemical pneumonitis, pulmonary edema, and renal lesions. This substance also affects the blood. Epichlorohydrin is reasonably anticipated to be a human carcinogen and may be associated with an increased risk of developing respiratory cancer.

Manufacturing Process

Epichlorohydrin is commercially prepared by high temperature chlorination of propylene to allyl chloride, followed by chlorohydration with hypochlorous acid to form isomeric glycerol dichlorohydrins. The mixture is subsequently dehydrochlorinated with alkali to yield epichlorohydrin.

Epichlorohydrin is also synthesized by chlorohydrination of allyl chloride which is obtained by high-temperature chlorination of propylene. Byproducts of chlorination are cis- and trans-1,3-dichloropropene and 1,2-dichloropropane. Glycerol dichlorohydrins are made from allyl chloride, with 1,2,3-trichloropropane being obtained as a byproduct. Finally, epichlorohydrin is produced from the glycerol-dichlorohydrin mixture by treatment with base.

Plastic Industry

Epichlorohydrin is used for the synthesis of polyols, reactants for the manufacture of rigid polyurethane foams.

Resins

Epichlorohydrin is primarily used to manufacture epoxy resins. Epoxy resins are generally produced by reacting a polyhydric phenol with an aliphatic chlorohydrin or simple aliphatic epoxide. The most familiar epoxy is obtained by condensing epichlorohydrin with bisphenol A, resulting in a basic epoxy resin molecule. Major advantages of epoxy resins include corrosion resistance, solvent and chemical resistance, hardness, and adhesion.

Epichlorohydrin is also used to produce both anion- and cation-exchange resins. Water-insoluble anion-exchange resins having good stability are prepared by reacting epichlorohydrin with ethylenediamine or a higher homolog. Strong base anion-exchange resins can be produced by reacting epichlorohydrin with polymeric tertiary amines. Epichlorohydrin-based anion exchangers are used successfully to purify drinking water and to clean polluted air. Cation-exchange resins are produced by condensing epichlorohydrin with polyhydroxy phenols and by sulfonating the product.

Textile Industry

In the textile industry, epichlorohydrin is used to modify the carboxyl groups of wool. The resulting product has a longer and improved resistance to moths. Epichlorohydrin is also used to prepare protein-modified, wool-like fibres, which have an affinity for acid dyes and which exhibit resistance to both mold and insects. Furthermore, epichlorohydrin is used to prepare dyeable polypropylene fibres and to dye polyolefin, polyacrylonitrile, polyvinyl chloride, polyvinyl alcohol, and other fibres. It is also used to impart wrinkle resistance and to prepare anti-static agents and textile sizing. Derivatives of epichlorohydrin show utility as levelling, dispersion, softening, emulsifying, and washing agents.

Surface Active Agents

Many epichlorohydrin-based, surface-active agents are useful in cosmetics and shampoos, and as detergents, sudsing agents, water softeners, and de-emulsifiers.

Papers, Inks and Dyes

Epichlorohydrin polyhydroxy compounds and their esters are useful in the production of special printing inks and textile print pastes. These products yield flexible films that are chemically inert to caustic soda and other chemical solutions. Epichlorohydrin adducts are useful as filler retention aids, paper coatings, flocculants, and anti-static agents. Paper and paperboard products with improved printability, pigment retention, folding endurance, and gloss also are prepared with epichlorohydrin reaction products.

Plasticizers

Epichlorohydrin can be used to form vinyl polymer plasticizers, solvents for food and flavouring, and plasticizers for polyurethanes.

Agricultural Products

When reacted with alcohols or the sodium salts of alkylphenols, epichlorohydrin will form products that are useful in insecticides, bactericides, and fungicides.

Other Applications

Asphalt improvers, corrosion inhibitors, electrical insulation for wire, fire-retardant urethanes, hair conditioning rinses, liners for polyethylene bottles, linoleum and linoleum cements, lubricant additives, petroleum production aids, pharmaceuticals, photographic film bases, rubber latex coagulation aids, waterproofing compounds, zinc electroplating compounds.