74124-79-1

6066-82-6

28920-43-6

74124-79-1

102774-86-7

1. 8 kg (1.25 kmol) of N-hydroxybutanediimide is added to the reactor kettle in a single addition, stirred well, and the temperature in the kettle is maintained at -2°C to 0°C. 2. 300 kg (1.62 kmol) of tributylamine and 450 kg of tetrahydrofuran are mixed in a high level tank and then slowly added to the reactor over a period of 10 to 11 hours in an amount of 50 to 57 kg per hour, maintaining the kettle temperature at not more than 5°C. 3. Due to the exothermic nature of the reaction, after the addition of tributylamine, the reaction vessel was warmed up to room temperature and the reaction was continued for 7.5 h. A large number of white solid crystals (N,N'-disuccinimidyl carbonate) were observed to precipitate out of the reaction solution. 4. Filtration of the reaction mixture: the reaction material was homogeneously introduced into a totally closed centrifuge within 1 h and dried under N2 protection. Subsequently the solids in the centrifuge were washed in two batches with 100 kg of tetrahydrofuran solvent at about 0°C and dried to give 120 kg of wet product. 5. The wet product was dried in a vacuum oven at 40 to 45°C for 7 to 8 hours to constant weight to give 95 kg of white crystalline powder with an HPLC purity of 99.1%. The filtrate obtained by centrifugal separation was used in the next step of the reaction. 6. The centrifugal filtrate and washing solvent from step 3 were combined and introduced into a 2000 L distillation unit. The tetrahydrofuran solvent was removed under vacuum at 0 to 5°C, maintaining the kettle temperature at 40 to 42°C. 7. 7. After removal of the tetrahydrofuran, 230 kg of ethylene dichloride was added, stirred at 40°C and held at 50°C for 0.5 hours. The reaction mixture was subsequently washed three times with 160 kg of water. 8. The phases were separated and the dichloromethane phase was added to a 500 L autoclave for subsequent processing.