反应详情

A mixture of 40 g (22 mmol) of ethyl o-chlorobenzimidate and 22.2 g (21 mmol) of 2,6-lutidine in 500 ml of petroleum ether (b.p. 100°-130° C.) is treated with 27.2 g (25 mmol) of ethyl chloroformate and the whole is then heated at reflux temperature for about 16 hours. The precipitated salt is subsequently filtered off, the filtrate is evaporated under reduced pressure and the residue is recrystallized from diethyl ether. In this manner there is obtained ethyl (o-chloro-α-ethoxybenzylidene)carbamate, m.p. 65°-66° C.; 1H--NMR (CDCl3, 60 MHz): 4.02 (q,OCH2CH3), 4.58 (q, OCH2CH3); mass spectrum: 220(100).

1. temperaturethe whole is then heated
2. temperatureat reflux temperature for about 16 hours
3. filtrationThe precipitated salt is subsequently filtered off
4. customthe filtrate is evaporated under reduced pressure
5. customthe residue is recrystallized from diethyl ether