Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Patent
1994-04-28
1995-10-10
Killos, Paul J.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
560 55, 502478, 502465, C07C 6976
Patent
active
054572266
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/EP93/02317 Aug. 27, 1993.
The present invention is concerned with the manufacture of cinnamic acid derivatives which, owing to their UV-B absorbing properties, are suitable as UV-B filters for cosmetic agents, e.g. sunscreen agents.
R. F. Heck in Org. Reactions, vol. 27, chapter 2, pages 345-389 (1982) describes, inter alia, the preparation of cinnamic acid derivatives by reacting haloaromatics with acrylic acid derivatives in the presence of palladium compounds as homogeneous catalysts and of bases, e.g. secondary or tertiary amines. Disadvantages of this reaction are, that the for the most part expensive homogeneous palladium catalysts can not be recovered in a simple manner after the reaction and that the reaction time is relatively long. For example, a 68 percent yield of methyl pmethoxycinnamate is achieved after 5 hours when p-iodoanisole is vinylated with methyl acrylate in the presence of palladium acetate and tri(n-butyl)amine [see also R. F. Heck and J. P. Nolley, Jr., J. Org. Chem. 37, 2310 (1972)].
U.S. Pat. No. 4,970,332 also describes the reaction of piodoanisole (and other palkoxyiodobenzenes) with alkyl acrylates in order to prepare corresponding cinnamic acid derivatives. In this case, the reaction is carried out in the presence of a heterogeneous palladium catalyst (palladium on a carrier material) and a trialkylamine and the palladium catalyst can be recovered by filtration. However, as in the above Heck process, the reaction time is relatively long, for example 2 to 4 hours in the preparation of 2ethylhexyl pmethoxycinnamate. A further disadvantage is that the process is limited to the use of trialkylamines as the bases.
The object of the present invention is to carry out such alkenylations more rapidly, with higher yields and with a wider choice of amines. This object has surprisingly been achieved by carrying out the reaction of the haloaromatic with the acrylic acid derivative inter alia in the presence of an alkanoic acid ammonium salt formed from an alkanoic acid and a primary, secondary or tertiary amine as defined in more detail hereinafter.
The process in accordance with the invention for the manufacture of a cinnamic acid derivative of the general formula ##STR2## wherein R.sup.1 signifies hydrogen or C.sub.1-8 -alkyl and C.sub.1-4 -alkoxy-C.sub.1-10 -alkyl, ##STR3## wherein R.sup.1 has the significance given above, and X is iodine, or can also be bromine, when R.sup.2 is hydrogen, palladium catalyst and in the presence of the alkanoic acid ammonium salt formed from a C.sub.2-5 -alkanoic acid and a mono-, di- or trialkylamine of the general formula -alkyl and or morpholine (V), with the proviso that in the case of the manufacture of the cinnamic add derivative of formula I in which R.sup.2 signifies hydrogen the reaction can be carried out in the presence of the mono-, di- or trialkylamine of formula IV or of the optionally N-(C.sub.1-4 -alkyl)substituted pyrrolidine, piperidine or morpholine (V) in place of the alkanoic acid ammonium salt defined above.
Under the term "alkyl" used in respect of the above formulae I, II, III and IV there are to be understood, depending on the number of carbon atoms, not only straight-chain but also branched-chain alkyl groups. Methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert.butyl, n-pentyl, tert.pentyl, neopentyl, n-hexyl, n-heptyl, 2-ethylhexyl, 1,1,3,3-tetramethylbutyl, n-nonyl and n-decyl are examples of such alkyl groups. The term "alkoxy", as part of the alkoxyalkyl group (R.sup.2), signifies such groups in which the alkyl part has the previous significance. Examples of pyrrolidine, piperidine and morpholine, each of which can be N-substituted, are the unsubstituted heterocycles themselves and N-methylpyrrolidine, N-ethylpiperidine and N-methylmorpholine.
As heterogeneous catalysts there especially come into consideration palladium on charcoal, palladium on siliceous earth, palladium on alumina and palladium on barium sulphate; other palladium catalysts of the palladium on carrier material type ca
REFERENCES:
patent: 4970332 (1990-11-01), Caskey
R. F. Heck, "Organic Reactions" Textbook, vol. 27, Chapter 2, pp. 345-389 (1982).
Givaudan-Roure Corporation
Gould George M.
Johnston George W.
Killos Paul J.
Waddell Mark E.
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