Process for halogenation of aldehydes and production of oximes therefrom

摘要

In the halogenation under reflux conditions of an unhalogenated aldehyde of the formula <IMAGE> with Cl2, Br2 or I2, the aldehyde and halogen are continuously fed into a reactor at a molar ratio of halogen to unhalogenated aldehyde between about 0.8:1 and about 1.1:1 and water is continuously fed into the unhalogenated reactor at a rate of between about 1% and about 20% by weight of aldehyde. The product alpha -haloaldehyde is thiohydrocarbylated and then oximated to form a 2-hydrocarbylthioaldoxime of the formula <IMAGE> with improved yield and quality because of the improved yield and quality of unhalogenated alpha -haloaldehyde. An exemplary process includes the chlorination of isobutyraldehyde (IBA) to form alpha -chloroisobutyraldehyde (CIBA), the thiomethylation of CIBA to form 2-methyl-2 methylthio-propionaldehyde (MTIBA) and the oximation of MTIBA to form 2-methylthio-propionaldehyde oxime (aldicarb oxime or ADO).