Prepn. of nematocidal cis-1,3-dichloropropene - from still-bottoms of allyl chloride synthesis by selective halogenation

摘要

(I), mainly cis-isomer, is prepd. from the still-bottoms resulting from the prodn. of allyl chloride by chlorinating propylene, by (i) selectively halogenating C6 olefins in the still-bottoms with Cl2 or Br2; and (ii) separating cis-(I) by distillation and concurrently or subsequently is isomerising the trans-(I) in the still bottoms to form an equilibrium mixture of cis- and trans- (I), separating cis-(I) and continuing the isomerisation and separation until the desired conversion has been achieved. (I) is a known nematocide, the cis-isomer having twice the activity of the trans-isomer.