Phosphoric Acid → Aldicarb [ISO]

Participants

Reaction Steps

Into a one liter glass resin kettle equipped with a metal pitched-blade agitator, a pressure-equalizing dropping funnel with Teflon® tube for subsurface addition, a thermometer and a dry ice/acetone cooled condenser was added 66.5 grams (0.50 mole) of 2-methyl-2-(methylthio) propionaldehyde oxime and 112 milliliters of water. After cooling the mixture to a temperature of 2° C.-3° C. with a water/salt/ice bath, 0.52 grams (0.005 mole) of triethylamine was added to the kettle under a nitrogen atmosphere. A stoichiometric amount of methyl isocyanate (29.5 milliliters, 0.50 mole) was then added over a period of 30 minutes at a temperature of 4° C.-14° C. with vigorous stirring. The water/salt/ice bath was removed and the mixture was stirred for an additional 75 minutes at a temperature of 10° C.-18° C. after which an additional 2.0 milliliters (0.03 mole) of methyl isocyanate was added and the mixture stirred for an additional period of 30 minutes. The water/salt/ice bath was then put back in place and 2.9 grams of phosphoric acid in 10 milliliters of water was added in a slow stream subsurface. The resulting solid product was filtered off on a sintered glass funnel and rinsed with hexane to give 104.4 grams (wet weight) of a fluffy white powder. High pressure liquid chromatographic analysis (internal standard) indicated the following: 84.00 percent 2-methyl-2-(methylthio) propionaldehyde O-(methylcarbamoyl) oxime (89.1 percent yield based on aldicarb oxime) and 2.38 percent 2-methyl-2-(methylthio) propionaldehyde oxime; 13.62 percent water content was determined by Karl Fischer titration.

Provenance & Evidence