Process for halogenation of aldehydes and production of oximes therefrom

Claim 1

In a process for preparing a 2-hydrocarbylthioaldoxime of the formula ##STR13## where R' and R" independently are alkyl of 1 to 4 carbons, and R''' is a hydrocarbon radical of 1 to 18 carbon atoms selected from the group consisting of alkyl, cycloalkyl, alkenyl, cycloalkenyl and aryl or a substituted hydrocarbon radical of the above group, said process comprising the halogenation under reflux conditions of an unhalogenated aldehyde of the formula ##STR14## with a halogenating agent selected from Cl 2 , Br 2 and I 2 , to form an α-haloaldehyde of the formula ##STR15## where X is Cl, Br or I and R' and R" are as defined above, and the thiohydrocarbylation of said α-haloaldehyde with a thiol salt of the formula R'''SM, where R''' is as defined above and M is an alkali or alkaline earth metal to form an α-formyl sulfide of the formula ##STR16## and the oximation of the said α-formyl sulfide to form said 2-hydrocarbylthioaldoxime, the improvement wherein the halogenation under reflux conditions of the unhalogenated aldehyde comprises continuously feeding the unhalogenated aldehyde and halogenating agent into a reactor at a molar ratio of halogenating agent to unhalogenated aldehyde of between about 0.8:1 and about 1.1:1 and continuously feeding water into the reactor at a rate of between about 1% and about 20% by weight of unhalogenated aldehyde and wherein the thiohydrocarbylation step includes reacting an α-haloaldehyde having less than about 1% by weight of homopolymers and copolymers of unreacted unhalogenated aldehyde.