Synthesis of alkene-2-ones

Details Synthesis of alkene-2-ones Synthesis of alkene-2-ones

1999-12-13

2001-05-01

Richter, Johann (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Oxygen containing

Reexamination Certificate

active

06225506

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to the synthesis of alkene-2-ones. More particularly, the invention relates to the synthesis of 5-hexen-2-one.
BACKGROUND OF THE INVENTION
It is known to produce 5-methyl-5-hexen-2-one by the reaction of 2,4-pentanedione methallyl chloride in ethanolic potassium carbonate. Boatman, S., et al,
Org. Synth.
Coll. Vol. 5:767-768. The comparative boiling points of the product and the ethanol solvent may preclude direct distillate of the product from the reaction mixture. Yields of 47% to 52% have been reported.
SUMMARY OF THE INVENTION
Pursuant to this invention, 2,4-alkane diones are converted to alkene-2-ones by treating with a 2-alkene halide in the presence of an alkylene glycol which has a boiling point higher than the boiling point of the alkene-2-one product. The use of glycol instead of ethanol as in the prior art eliminates the need for aqueous quenching and phase extraction, and facilitates the direct distillation of low boiling alkene-one products from the higher boiling ethylene glycol, wherein a true “one pot” procedure with direct distillation of the product from the reaction mixture is provided.
GENERAL DESCRIPTION OF THE INVENTION
The invention is generally illustrated by the equation:
wherein X is a halogen, R and R′ are alkyl groups, preferably C
1
to C
10
alkyl groups, which may be identical or different, and n is 1 to 4. The boiling point of the alkylene glycol is below that of the alkene-2-one product.
The reactants and the alkylene glycol are selected to provide a reaction mixture from which the desired product may be distilled directly. Preferably, equimolar amounts of alkane dione and 2-alkene halide are used. An initial reaction temperature in the range of about 20° C. to about 40° C. is appropriate. The temperature is then preferably raised to about 60° C. to about 90° C. after a time period of one or two hours to complete the reaction.
Pursuant to a preferred embodiment of the invention, allyl chloride is reacted with acetylacetone and K
2
CO
3
in an ethylene glycol medium to produce 5-hexen-2-one.


REFERENCES:
patent: 3983175 (1976-09-01), Tamai et al.
patent: 4602117 (1986-07-01), Lantzch

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