US Patent 6235935
Method of Manufacturing High Purity Oximes from Aqueous Hydroxylamine and Ketones
Abstract:
High purity oximes are prepared from aqueous hydroxylamine and ketones reacted at ambient temperature without addition of impurities such as salts or acids.
Example 1:
Acetone Oxime
50ml of high purity acetone was added to 100ml of high purity 50% hydroxylamine/50% water (by weight), and stirred magnetically. The mix was left to reach equilibrium by sitting a few hours to reach ambient temperature. 50ml of 98% formic acid in water was then added to the mixture to give a pH of 6.0-6.2 and mixed to reach equilibrium. The crystalline product was filtered. The mix was left to stir for another 24 hours. The formed crystals were filtered and added to those already collected.
Purification proceeded as follows:
The crystals were dissolved in a non-polar solvent (perfluorocyclohexane) by heating and cooled overnight at RT to recrystallize. The material was then filtered and washed with the solvent. The oxime had; MP: 61-63*C; Yield: 85-90%.
Notes of the Reaction:
Other acids may be used to adjust the pH to 6.0-6.2. However, with inorganic acids, ionic impurities may be added.
Acid %Yield
H2 87.5
HNO3 835
HCl 76.7
Acetic 78.6
Citric 78.6
Example 2:
Acetyl Acetone Dioxime
50ml of high purity acetyl acetone was gradually added to 100ml of high purity 50%hydroxylamine/50%water in a glass beaker and stirred with a magnetic stirrer overnight at RT. The product separated as crystals. They were purified as in Example 1. Yield: 1.54g (83%); MP: 140-144*C
Example 3:
Cyclohexanone Oxime
50ml of high purity cyclohexanone was gradually added to 100ml of high purity 50%hydroxylamine/50%water in a glass beaker and stirred overnight at RT. The oxime separated as crystals. Yield: 1.55g (95%), MP: 86-90*C
References Cited:
US Patents:
3429920
3941840
4128579
4929756
5117060
5254734
5300689
5488161
Other References:
CA 127:81069 (1997)
