PREPARATION OF MONOHALOACETYL HALIDES

1374324 Monohaloacyl halides MONSANTO CO 29 Sept 1972 [30 Sept 1971 4 Aug 1972] 45054/72 Heading C2C Monohaloacyl halides are prepared by reacting an optionally substituted ketene with Cl 2 , Br 2 , I 2 or an interhalogen compound thereof in the presence of, as a liquid solvent, one or more lactones of formula wherein R, R1, R2, R3, R4, R5, R6, R7, R8 and R9 are each hydrogen, halogen, C 1-6 alkyl, phenyl, benzyl, alkylphenyl or alkylbenzyl in which each alkyl group has up to 6 carbon atoms and a, b and c are each 0 or 1. The ketene and halogen or interhalogen compound are preferably introduced concurrently into the lactone using a molar ratio of halogen (or interhalogen) to ketene of between 1 : 1 and 1À3 : 1. The required lactone may be formed in situ from the corresponding unsaturated lactone by addition of the halogenating agent. The process may be effected continuously or batchwise. Examples describe the halogenation of ketene, methyl ketene and phenyl ketene with Cl 2 , Br 2 and IC1 to produce the corresponding monohaloacyl halides. Acyl halides and dihaloacyl halides are obtained as by-products. Exemplified and specified lactones are: #-propiolactone, γ- and #-valerolactones, γ-butyrolactone, #-caprolactone, and α-butyl-, #-chloro-, #-phenyl and #-para-tolyl-γ-butyrolactones. Comparative experiments use as solvents: methyl, ethyl, butyl and hexyl acetates, carbon tetrachloride, 1,2-dichloroethylene, acetonitrile, benzonitrile and nitromethane.