Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Reexamination Certificate
1998-11-24
2001-05-22
Killos, Paul J. (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
Reexamination Certificate
active
06235935
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an improved method for making oximes. The method uses aqueous hydroxylamine and a ketone.
2. Brief Description of the Prior Art
Oximes of general formula R
1
R
2
C═NOH, where R
1
and R
2
are alkyl or an alkoxy groups, are used extensively as intermediates in manufacturing of other products.
U.S. Pat. No. 3,429,920 describes a method for producing oximes from ketones by using a hydroxylamine salt in a buffered solution of a weak acid and a salt of the weak acid. This method is complicated and time consuming, and adds impurities.
SUMMARY OF THE INVENTION
The present invention provides a simple, convenient method for preparing oximes, using an aqueous hydroxylamine and ketone solution.
This method has several advantages over the traditional methods: (a) it is fast and spontaneous therefore giving a high production yield; and (b) it does not need a long and difficult process or costly apparatus.
Briefly, in the preferred embodiment, a high purity oxime such as acetone oxime, CH
3
—C(CH
3
)═NOH, can be prepared using free hydroxylamine base and a ketone. In some cases, the reaction proceeds spontaneously, and with other reactants the media must be acidified in order to initiate reaction. A 50% by weight aqueous solution of hydroxylamine base is mixed with high purity ketone. The crystalline oxime material can be filtered and recrystallized using an inert fluorocarbon solvent for further purification.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention is a method for making high purity oximes using an aqueous hydroxylamine solution and ketones. The examples given below use acetone, acetyl acetone (2, 4pentanedione), and cyclohexanone to yield acetone oxime, acetyl acetone dioxime, and cyclohexanone oxime, but the method has also been used with methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, and cylcopentanone to yield the corresponding oximes. Of these examples, only acetone requires acidification, as discussed below. When acidification is required, preferably a high purity organic acid such as formic, acetic, citric, or oxalic acid is used. Inorganic acids, such as hydrochloric, sulfuric, nitric, or phosphoric acids, may be used but may lead to unwanted ionic or inorganic contaminants. Those skilled in the art will recognize that analogous ketones may be used to create other oximes.
REFERENCES:
patent: 3429920 (1969-02-01), de Rooij
patent: 3941840 (1976-03-01), Rotaru
patent: 4128579 (1978-12-01), Berthold
patent: 4929756 (1990-05-01), Kuma
patent: 5117060 (1992-05-01), Witzeman
patent: 5254734 (1993-10-01), Kanda et al.
patent: 5300689 (1994-04-01), Krbechek et al.
patent: 5488161 (1996-01-01), Krbechek
C.A. 127:81069 (1997).
Russell Jin Wang
Sahbari Javad J.
Jaffer David H.
Killos Paul J.
Pillsbury & Winthrop LLP
Silicon Valley Chemlabs, Inc.
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