Preparation method of rocuronium bromide

[0037] Embodiment 1 of the present invention provides a kind of preparation method of rocuronium bromide, comprises the steps:

[0038](1) Preparation of Compound III

[0039] Pump 72kg of dichloromethane into the reaction kettle at 25°C-30°C, start stirring, add 1.6kg of starting materials, stir and disperse; add 0.63kg of acetyl chloride dropwise, after dropping, keep the temperature of the material liquid at 25°C-30°C and stir React for 5 to 8 hours, the reaction solution is not processed, directly dropwise add 4.1kg of 10% hydrochloric acid solution to the reaction solution, after the drop is complete, keep the reaction at 25°C to 30°C for 20 hours, let stand and separate, remove 46.7kg of the organic layer, Add about 20.6 kg of 10% sodium carbonate aqueous solution to the remaining reaction solution to adjust pH=7 to 9, separate the organic phase, add 3.8 kg of silica gel to the organic phase, stir and absorb for 10 min, filter under reduced pressure, and then use 32.3 kg of

[0044] In this embodiment, except step 3 is changed to "the mass ratio of dichloromethane to methyl tert-butyl ether-ethyl acetate in the dichloromethane-methyl tert-butyl ether-ethyl acetate system is 8:20:20" , all the other are with embodiment 1.

[0046] In this embodiment, except that step 3 is changed to "the mass ratio of dichloromethane to methyl tert-butyl ether-ethyl acetate in the dichloromethane-methyl tert-butyl ether-ethyl acetate system is 3:25:25" , all the other are with embodiment 1.