Cyclohexanone Oxime → Hydroxylammonium ammonium sulfate

The aqueous ammonium bisulfate phase freed from organic products such as cyclohexanone oxime and cyclohexanone may be used directly or, for example, after treatment with carbon for the removal of the final traces of organic components, in the catalytic hydroxylamine synthesis in place of sulfuric acid. Here again there is produced a hydroxylammonium/ammonium sulfate solution which may then be used for the oximation process. The aqueous ammonium bisulfate solution formed during oximation may, of course, be passed to the hydroxylamine synthesis as formed or, if desired, in a diluted or concentrated form. The oxime phase produced by the oximation reaction may be used directly, without post-oximation or purification, to particular advantage for catalytic rearrangement to caprolactam in the gas phase, the catalyst being, say, boron oxide/aluminum oxide.