4-Methoxybenzyl isothiocyanate was prepared as follows:
Take 300.0g of 4-methoxybenzylamine (2.19mol) and 309.2g of triethylamine (3.06mol) in a 5000mL three-necked round-bottomed flask, add 1000mL of ethyl acetate, and set it in an ice bath to cool down and mechanically stir. When the temperature of the mixture was reduced to 0 C ~ 5 C, 299.2 g of CS2 (3.93 mol) was slowly added dropwise with a constant-pressure dropping funnel with magnetic stirring while dropping, and the temperature of the reaction solution was controlled to be below 30 C. The reaction solution was then cooled at room temperature and mechanically stirred. After the dropwise addition, the reaction was magnetically stirred at room temperature (10-30 degree range) for one hour; at this temperature, 471.9 g of BOC anhydride (2.16 mol) and 0.18 g of DMAP (0.06% of the amount of allyl amine) catalyst were added to the reaction solution, and the reaction was stirred for 1.5 h at 302.5 C.
At the end of the reaction, the reaction solution was washed with the acid solution for two times, and the washing The total amount of acid consumed was 1.5 times that of triethylamine, and then washed with saturated brine to neutral. The organic phase was concentrated by evaporation, and the acid washed crude product was obtained. Acid wash crude, placed in a flask, electric heating jacket heating, rotary vane vacuum pump, collect 130 ~ 145 / 10mmHg of the fraction, the distillation of crude 4-methoxybenzyl isothiocyanate.
