Hydroxylamine → Hydroxylamine, sulfate (1:1)

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Reaction Steps

In the subsequent oil/aqueous phase separation step, a reaction mixture after the oxime-forming step is separated into an oil phase and an aqueous phase to obtain the oil phase in which cyclododecanone oxime is dissolved. In the step, it is also preferred to add the rearrangement solvent (on the premise that it goes into oil phase) and carry out the oil/aqueous phase separation, which will be explained in detail for the dehydration/solvent preparation step. The oil phase and the aqueous phase can be separated by a commonly used separation method such as standing separation, centrifugation separation and cyclone separation, but in an industrial continuous process, a reaction mixture is transferred from an oxime-forming reactor to a separator, where the oil and the aqueous phases are separated and drained. Depending on the type of the oxime-forming reactor, the oil phase and the aqueous phase may be drained separately from the reactor. When oxime formation is conducted using an aqueous solution of hydroxylamine sulfate (hydroxylamine prepared by Rashig method, also called as ammonium sulfite method, where an aqueous solution of ammonium nitrate is reduced by sulfur dioxide in the presence of hydrogen sulfate ions, into hydroxyamide-N,N-disulfate, which is then hydrolyzed to obtain hydroxylamine sulfate) and ammonia water, ammonium sulfate is obtained as a byproduct from the separated aqueous phase. This ammonium sulfate is called as oxime ammonium sulfate, which is purified more easily than ammonium sulfate as a byproduct in the rearrangement step described in “BACKGROUND ART” (called as rearrangement ammonium sulfate) and can be thus sold in the market. When hydroxylamine prepared by HPO method wherein hydroxylamine phosphate is prepared is used, ammonium sulfate is not formed even in the oxime-forming step. Furthermore, for the purpose of recovering the oxime-formation solvent dissolved in the aqueous phase, the oxime-formation solvent and cyclododecanone oxime may be extracted with a hydrophobic solvent from the aqueous phase.

Provenance & Evidence