A Facile, Catalytic Deoximation Method Using Potassium Bromide and Ammonium Heptamolybdate in the Presence of Hydrogen Peroxide in an Aqueous Medium

Abstract

A simple, mild and efficient procedure for the cleavage of a wide range of ketoximes and aldoximes to the corresponding carbonyl compounds in an aqueous medium using catalytic amounts of potassium bromide and ammonium heptamolybdate tetrahydrate in combination with 30% hydrogen peroxide is described.

Key words

oximes - potassium bromide - ammonium heptamolybdate tetrahydrate - hydrogen peroxide

References

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24

Typical Deoximation Procedure: To a thoroughly stirred soln of (NH₄)₆Mo₇O₂₄·4H₂O (296 mg, 0.24 mmol) in H₂O (0.5 mL) was added 30% H₂O₂ soln (1.2 mL). After stirring for 10 min, a soln of KBr (29 mg, 0.24 mmol) in H₂O (0.5 mL) was added followed by a drop of HClO₄ (0.1 mL) whereupon the reaction mixture assumed a yellow coloration. Benzaldehyde oxime (145 mg, 1.2 mmol) was slowly added and the resulting mixture was stirred for 3 h (monitored by TLC); the mixture turned almost colorless. The reaction mixture was washed successively with 5% NaHSO₃ soln (2 × 2 mL) and H₂O (2 mL), and was then extracted with EtOAc (2 × 10 mL) and dried (Na₂SO₄). The concentrated extract was subjected to column chromato-graphy (silica gel, 60-120 mesh; light petroleum) to yield benzaldehyde (120 mg, 95%). Its identity was confirmed by co-TLC (and superimposable IR spectrum) with an authentic sample.