Imperial Chemical Industries Limited

Robert J Lindsay

Ian Ferguson

Alan T Costello

Martin E Fakley

A process of isolating dihydroxyacetone which is a useful intermediate in organic chemistry as well as being a sun-tanning agent. The process comprises passing a reaction mixture containing dihydroxyacetone in an organic solvent through at least one thin film evaporator to distil dihydroxyacetone separately from the solvent.

Isolation process

1-Cyano-3-[2',2'-(dihalogeno and/or trifluoromethyl)vinyl]-2,2-dimethylcyclopropanes are converted into the corresponding 1-amides and 1-carboxylic acids by reaction with sulphuric acid and water, or into the corresponding 1-carboxylic acid esters by reaction with sulphuric acid, water and a lower alkanol. High yields are obtained.

Process for preparing cyclopropane carboxylic acids

Process for the preparation of 1-lower alkoxycarbonyl-3-(.beta.,.beta.-dichlorovinyl)-2,2-dimethylcyclopropanes from the corresponding 1-cyano-1-carboxylic acid ester by hydrolysis, decarboxylation of the free carboxylic acid, reaction of the cyclopropane nitrile with a lower aliphatic alcohol and anhydrous hydrogen chloride, followed by alcoholysis or hydrolysis of the reaction product so obtained to give the desired ester or carboxylic acid. Includes a method for the separation of essentially pure cis- and trans-isomers from the mixed nitriles. The products are useful intermediates for the preparation of pyrethroid insecticides.

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Manchester, United Kingdom

Robert J Lindsay