GB1173359A - Preparation of Unsaturated Aliphatic Compounds - Google Patents

Abstract

1,173,359. Preparation of unsaturated aliphatic compounds. E.I. DU PONT DE NEMOURS & CO. June 2, 1967 [June 3, 1966; April 25, 1967], No. 25523/67. Heading C2C. An unsaturated aliphatic compound is prepared by dehydrohalogenating an aliphatic compound containing at least 2 C atoms with an inorganic alkaline material in an aqueous medium in the presence of a quaternary ammonium compound as catalyst. The inorganic alkali may be NaOH and the catalyst preferably has the general formula R 1 R 2 R 3 R 4 NCl, wherein R 1 , R 2 and R 3 are C 1-20 aliphatic radicals and R 4 is a C 8- 20 aliphatic radical or a benzyl radical which is optionally substituted. It is preferred that at least one of the groups R 1 , R 2 or R 3 contains a hydroxy or ether group #- to the N- atom. By the process 2,3-dichlorobutadiene-1,3 may be prepared from 2,3, 4-trichlorobutene-1. In the examples, chloroprene (2-chloro-1,3- butadiene) is prepared from 3,4-dichlorobutene-1 using a wide range of catalysts including those of the general formula R 1 (CH 3 ) 3 NCl, e.g. octyltrimethyl ammonium chloride or R 1 (benzyl) (CH 3 ) 2 NCl, e.g. stearylbenzyldimethyl ammonium chloride. Commercial catalysts such as "Aliquat, " "Hyamine," "Arquad" (Registered Trade Mark) and "Triton" (Registered Trade Mark) are also employed. The catalyst is used at 0À01-10% based on the weight of the halogenated aliphatic compound and the molar ratio of alkali: said aliphatic compound is 0À5:1 up to 20:1.