Carbon Dioxide → HCID 20519912, compound

Participants

Reaction Conditions

Reaction Steps

A reactor was charged with 1,457.5 g of 3-chloro-4-isopropoxyphenylhydrazine hydrochloride and 5.5 l of toluene to which was slowly added 971.7 g of pyridine while stirring at 10°-15° C. The temperature was lowered to 5°-10° C. and 667.3 g of ethyl chloroformate was added over about 3 hours. The resulting mixture was stirred at 10°-20° C. for 2 hours, was washed with water and dried over MgSO4, and after filtration, evaporated to 4 liters. This solution was slowly added over about 3 hours to a stirred mixture of 3.7 l of toluene and 693 g of phosgene at 10°-15° C. The resulting mixture was stirred for about 3 hours at room temperature, then slowly heated to 85° C. to remove excess phosgene. The remaining mixture was cooled to 10° C. and 540 g of dimethylamine was added over about 3 hours while stirring and cooling to maintain a temperature of 10°-20° C. After stirring at room temperature for about 30 minutes, a solid product was filtered and washed with ether. The filtrate was evaporated to dryness, leaving a solid product. Washing the filter cake with water, left an oily residue which was triturated with ether to yield a white solid. To this solid combined with that obtained by evaporation of the filtrate was added 4.5 l of water, 960 g of 50% sodium hydroxide and 2.2 l of ethanol. The resulting mixture was heated at reflux for about 5 hours and then allowed to cool to room temperature. To this mixture 1.5 l of concentrated hydrochloric acid was slowly added while stirring. Carbon dioxide gas evolved. The resulting solution was then made basic by adding 500 ml of 50% sodium hydroxide while stirring. The resulting tan solid was filtered, air dried, triturated with hexane-ether (90:10) solution and, after filtration, dried to yield 957.3 g of solid product semicarbazide; melting point 73°-74° C.

Provenance & Evidence