Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1999-02-02
2000-09-05
Richter, Johann
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C07C 4545
Patent
active
061145874
DESCRIPTION:
BRIEF SUMMARY
INTRODUCTION
The present invention describes the preparation of .alpha.-alkyl cinnamaldehydes and preferably, the preparation of .alpha.-n-amylcinnamaldehyde (Jasmine aldehyde), through aldolic condensation catalyzed by zeolite type solid acids.
.alpha.-n-amylcinnamadehyde is a substance with a violent scent and it is commonly used in perfumery. The production of .alpha.-n-amylcinnamaldehyde can be carried out through aldolic condensation between heptanal and benzaldehyde using alkaline catalysts.
A difficulty with aldol condensation is that both reagents can undergo side reactions giving rise to by-products that reduce the yield of alkyl cinnamaldehyde and that furthermore they can provide an unpleasant scent, thus reducing the quality of the perfume. One of these undesired reactions is self-condensation of n-alkyl aldehyde, which can be inhibited to a great extent, by keeping the concentration of this reagent relative to that of the benzaldehyde in the reaction mixture very low. Therefore, this methodology requires long addition times of heptanal, leading to the use of batch reactions with long reaction times and renders impractical the use of plug-flow continuous reactors.
Further by-products that are formed in these conditions are those resulting from the limited stability of benzaldehyde which tends to disproportionate via the Cannizzaro reaction to yield Benzes alcohol and benzoic acid, which in turn reacts with the alkaline catalyst, and therefore, causing the neutralization of the catalyst.
BACKGROUND OF THE INVENTION
A. Weissenborn in East German patent 11,191 (1956) describes a produce for the preparation of Jasmine aldehyde wherein the catalysts are Ni, Co or Fe salts of carboxylic acids. The reaction is carried out at the temperature range of 180-190.degree. C., in the presence of toluene in order to facilitate azeotropic distillation of the water and the heptanal is added slowly to the reaction mixture. Yields around 80% of Jasmine aldehyde are obtained.
R. Mahrwald and H. Schick in East German patent DD 287,712 (1991) describe a procedure wherein the aldolic condensation between heptanal and benzaldehyde is accomplished in the presence of Titanium compounds (tetraisopropiltitanium) and toluene as the azeotropic agent. Yields around 56% of Jasmine aldehyde are obtained.
L. S. Payne in European patent 392,579 (1990) describes a procedure for the selective preparation of .alpha.-cinnamaldehydes by aldolic condensation in two phases, using glycols (especially ethylene glycol) as solvents and sodium or potassium hydroxides as catalysts. Yields around 90% of .alpha.-cinnamaldehyde are obtained.
P. Mastagli et al. in Bull. Soc. Chim. France, 1955, p. 268, describe the preparation of Jasmine aldehyde using anionic exchange resins (IR-4B) as catalysts. The yields obtained varied between 2 and 12%.
The same author describes in Compt. Rend. 1957 vol. 244, p. 207, a process starting from n-alkyl aldehyde and benzaldehyde acetals using as a catalyst a mixture of an acid catalyst (cationic exchange resin) and a basic catalyst (anionic exchange resin) in order to produce the hydrolysis and aldolic condensation respectively. The yields obtained varied between 5 and 28%.
A. Sakar et al. in Ind. J. Chem., 1986, vol. 25,p. 656 accomplish aldolic condensation using potassium carbonate and a phase transfer catalyst such as benzyltriethylammonium chloride. On the other hand, D. Abenhaim et al in Synthetic Comm., 1994, vol. 24, p. 1199 carry out condensation using the same type of catalysts but under microwave effect. In both cases yields around 80% of Jasmine aldehyde are obtained.
BRIEF DESCRIPTION OF THE INVENTION
This invention describes the selective obtainment of .alpha.-alkyl cinnamaldehydes and specifically, Jasmine aldehyde, by direct reaction between the acetal of n-alkyl aldehyde (heptanal) and benzaldehyde where zeolites and zeotypes with medium and large pore diameters with 10 and preferably 12 member rings, as well as mesoporous molecular sieves are used as acid catalysts.
The process involves
REFERENCES:
patent: 5475162 (1995-12-01), Brandvold et al.
patent: 5637774 (1997-06-01), Beavers
Durr, 1956, Ann de Chim 13:85-114.
Durr, 1953, Academie des Sciences 28:1012+1014.
Mastagli et al., 1957, Academie des Sciences7:207-9.
Sarkar et al., 1986, Indian J. Chem.
Abenhaim et al., 1994, Synthetic Communications, 24(9):1199-1205.
Canos Avelino Corma
Climent Olmedo M.sup.a Jose
Guil Lopez Rut
Iborra Chornet Sara
Primo Millo Jaime
Consejo Superior de Investigaciones Cientificas
Padmanabhan Sreeni
Richter Johann
Universidad Politeonica de Valencia
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