Glycol ethers, oxidative addition solvents

Ethylene oxide is used for manufacture of ethylene glycol, the latter being an antifreeze compound as well as a raw material for production of polyethylene terephthalate used in the manufacture of polyester fibers for preparation of surfactants for the manufacture of ethanolamines for production of ethylene glycols used in plasticizers, solvents, and lubricants and for making glycol ethers used as jet-fuel additives and solvents. 

Propylene oxide and 1,2-butylene oxide cyclic ethers find their largest use as chemical intermediates. Both oxides react readily with dilute amounts of mineral acids (e.g., hydrochloric acid) to form the chlorohydrin addition product. This reactivity with acid make these epoxy solvents valuable acid acceptor-type stabilizers for several chlorinated solvents. Trace amounts of hydrogen chloride from chlorinated solvent degradation is immediately neutralized by reaction with the propylene or 1,2-butylene oxide stabilizer. Reaction of propylene oxide with an alcohol or phenol in the presence of an acid catalyst yields the monoether of propylene glycol (see Chapter 13 for the glycol ethers). 

In the United States, the minimum requirements for a brake fluid are laid down in SAE 1703 MVSS 116 (DOT-3, DOT-4). Fluids meeting these requirements are nowadays manufactured by blending the following components solvents (glycol ethers), lubricants (e.g., polyglycols), and oxidation and corrosion inhibitors together with antiwear additives. 

Most acetate esters, however, are produced from acetaldehyde using the Tishchenko reaction. In addition, ether acetates are used as solvents for nitrocellulose, acrylic lacquers, varnish removers, and wood stains. First, glycol monoethers are produced from ethylene oxide or propylene oxide with alcohol, which are then esterified with acetic acid. The three major products are ethylene glycol monoethyl ether acetate (EEA), ethylene glycol monobutyl ether acetate (EBA), and propylene glycol monomethyl ether acetate (PMA, more commonly known as PGMEA in semiconductor manufacturing processes, where it is used as a resist solvent). This application consumes about 15% to 20% of worldwide acetic acid. Ether acetates, for example EEA, have been shown to be harmful to human reproduction. 

Butylene oxide is used principally as an HCl acceptor in stabilizer formulations for 1,1,1-trichloroethane, a dry-cleaning and metal-cleaning solvent. It is also used as a pharmaceutical intermediate and as a comonomer in making nonionic surfactants and copoly(alkylene oxide)s. Other uses include preparation of gasoline additives, butanol amines, butylene glycols, and their ether and ester derivatives. 

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