Preparation of angelic acid or esters thereof

Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters

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Details

560217, 560220, 560221, 562598, 549499, 203 38, C07C 67333, C07C 51353

Patent

active

046136800

DESCRIPTION:

BRIEF SUMMARY
FIELD

The present invention relates to preparation of angelic acid or esters thereof. More particularly, it is concerned with angelic acid or esters thereof, perfume compositions and novel esters of angelic acid.


BACKGROUND

Angelic acid is a known compound which is chemically (Z)-2-methyl-2-butenoic acid and is represented by the formula ##STR2##
Angelic acid and a part of its esters are contained in natural essential oils, especially in essential oil of chamomile flower in a higher content, are fragrant as they are and are useful as perfume materials.
However, no proposal has been made for the synthetic method of these materials suitable for practical use.
It is an object of this invention to provide a process for preparing angelic acid or esters thereof by simple procedures with formation of by-products inhibited.
Another object of the invention is to provide novel perfume compositions.
A further object of the invention is to provide novel esters of angelic acid.


DISCLOSURE OF THE INVENTION

According to the present invention, angelic acid or esters thereof are prepared by isomerizing tiglic acid or an ester thereof in the presence of an organic sulfinic acid. ##STR3##
In the above formulae (1) and (2), R is H or an ester radical.
According to the invention, there are also provided perfume compositions containing angelic acid or an ester thereof and novel esters of angelic acid represented by the formulae (3)-(15) below. ##STR4##
Dotted lines in the above general formulae indicate that a double bond exists on either of the lines.


PREFERRED EMBODIMENTS

Tiglic acid or esters of tiglic acid represented by the general formula (1) which are used as the starting material in the process of the present invention are compounds contained in natural essential oils, for example, in essential oil of gardenia. The compounds are of fragrance per se and are useful as perfume materials. There are also known several processes by which these compounds are chemically prepared. Tiglic acid and certain esters thereof chemically prepared are commercially available. A typical process for the preparation of tiglic acid and esters thereof is described, for example, by R. E. Buckles in Chem. Rev., 55, 659-677 (1955).
These compounds may therefore be made available by known means for the process of the invention.
Their ester radicals in tiglic esters, that is, R in the above-mentioned general formula (1) which in nature do not participate in the reaction may be any one, and it is usually preferred to employ a substituted or unsubstituted saturated or unsaturated hydrocarbon radical containing not more than 20 carbon atoms. As examples of them are mentioned saturated or unsaturated hydrocarbon radicals such as an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group or an aralkyl group or substituted hydrocarbon radicals containing, for example, a hydroxyl group, an alkoxy group or an ester group.
As examples of the esters of tiglic acid used in the process of the invention are mentioned, but not limited to, the methyl ester, the ethyl ester, the n-butyl ester, the iso-butyl ester, the sec-butyl ester, the n-amyl ester, the iso-amyl ester, the neopentyl ester, the 2-methylbutyl ester, the n-hexyl ester, the 3-methylpentyl ester, the 2-methyl-2-propenyl ester, the cis-3-hexenyl ester, the gelanyl ester, the neryl ester, the linalyl ester, the citronellyl ester, the 2-methyl-2-butenyl ester, the trans-3-hexenyl ester, the 3-methyl-2-butenyl ester, the .beta.-phenylethyl ester, the .alpha.-phenylethyl ester, the furfuryl ester.
Since the process of the invention involves a geometrical isomerization reaction of the double bond, those containing an ester radical capable of forming isomers by the reaction may afford a complex mixture as the reaction product. The lower alkyl esters are particularly preferred due to easiness in the reaction and availability.
The organic sulfinic acid used as the catalyst in the process of the invention is a compound represented by the general formula (16) below. n in the general f

REFERENCES:
Toray Industries, Inc. Chemical Abstracts, vol. 97 (1982) #181, 761v and p. 1471CS.
Kirk-Othmer Encyclopedia of Chemical Technology 2nd. Ed. (1965), vol. 8, p. 356.
Gibson, T. W. et al. J. Org. Chem., vol. 41 (1976) pp. 791-793.
The Merck Index (1976) 9th Ed., pp. 681 and 9156, Merck & Co., publ.
March, Jerry Advanced Organic Chemistry, 2nd Ed. 113-114, (1977).
CRC Handbook of Chemistry and Physics (1976-7) 57th Ed., p. C-232 CRC Press.
Nozaki, H. et al. Tetrahedron, vol. 23 (1967) pp. 2173-2179.
Hackh's Chemical Dictionary (1969) McGraw-Hill, Publ. at p. 681.

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