Ester cinnamates

It may be prepared synthetically by reducing cinnamic aldehyde diacetate, and saponifying the resulting cinnamyl esters. Cinnamic alcohol is a crystalline body, although commercial specimens frequently contain traces of impurities which prevent crystallisation. It has the following characters —... 

Phenethyl alcohol is qualitatively and quantitatively one of the most important fragrance substances that belongs to the class of araliphatic alcohols. Its lower homologue (benzyl alcohol) and higher homologue (dihydrocinnamic alcohol) also have characteristic odor properties, but are more frequently used in the form of their esters. Cinnamic alcohol, the most important unsaturated araliphatic alcohol, is valuable for both fragrances and flavors. 

Acrylate ester - [CINNAMIC ACID.CINN AMALDEHYDE AND CINN AMYL ALCOHOL] (Vol 6)... 

CjH6.CHO + CH3.COOC2H5 = CjHj.CH CH.COOCjHj + H.O Benzaldehyde Acetic ester Cinnamic ester... 

Other preparations of 2-iminothiazolidin-4-ones which are discussed in the review by Brown utilize the reactions of thiourea with a-hydroxy acids,ethyl diazoacetate,glycidic esters, - cinnamic acid, unsaturated diacids (fumaric, maleic, and citraconic) or their esters or imides, and propiolic esters. There has been considerable controversy in the literature surrounding the propiolic ester synthesis since many workers have proposed that the products are 1,3-thiazines (see Section IV, B, 1). The pertinent papers in this controversy have been summarized by Cain and Warrener. Nagase has recently settled the argument in favor of the 2-iminothiazolidin-4-... 

Cinnamic acid derivatives 960—see also 2,4-Dimethoxycinnamic acid esters Cinnamic acids—see Hydroxycinnamic adds, tratts-4-Hydroxy-a-cyanocinnamic acid Circular dichroism 992 Claisen condensation,... 

The E)- Z) photoisomerization of a, 8-unsaturated esters/ cinnamic esters/ butenoic esters/ anddienoic esters is catalyzed by Bp3-OEt2 ovEthylahiminum Dichloride. The latter two reactions also involve the photodeconjugation of a, 8-unsaturated esters to /3,)/-unsaturated esters. The BFs-MeOH complex is used for the isomerization of 1- and 2-butenes to form equal quantities of cis- and tran5-but-2-enes/ the BF3-OEt2-acetic acid complex is not as effective. 

Cinnamic acid, 2,4-diisopropyl-, ethyl ester. See Ethyl diisopropylcinnamate Cinnamic acid-1,5-dimethyl-1-vinyl-4-hexenyl ester Cinnamic acid-1,5-dimethyl-1-vinyl-4-hexen-1-yl ester. See Linalyl cinnamate Cinnamic acid, o-hydroxy-, 5-lactone. See Coumarin... 

Synonyms Acetic acid, cinnamyl ester Cinnamic acetate 3-Phenylallyl acetate y-Phenylallyl acetate 2-Phenyl-2-propen-1-ol acetate... 

This oil consists principally of benzyl cinnamate and benzyl benzoate, with a small amount of free benzoic and cinnamic acids. Dihydro-benzoic acid is also probably present in the form of esters. Cinnamic alcohol, vanillin, and farnesol are also present in very small amoilnt. 

Misidentification of source plants involved in chemical analysis before 1986, except for authenticated cultivated E. purpurea, renders earlier chemical studies unreliable. Components attributed to E. angustifolia, which may instead have involved E. pallida, include flavonoid components of the leaves essential oil constituents, including echinolone, humu-lene, caryophyllene epoxide, and various polyacetylene components. Four sesquiterpene esters (cinnamates of echinadiol, epox-yechinadiol, echinaxanthol, and dUiydroxy-nardol) attributed to E. purpurea in fact do not occur in Echinacea but are constituents of Parthenium integrifolium. Chemical work by R. Bauer and coworkers at Munich and Diisseldorf now makes distinction of source species in commercial supplies possible. 

Cinnamic acid can be readily esterified by the Fischer-Speier method without any risk of the addition of hydrogen chloride at the double bond. Proceed precisely as for the preparation of ethyl benzoate (p. 104), using 20 g. of cinnamic acid and 20 ml. of rectified spirit. When the crude product is poured into water, a sharp separation of the ester is not readily obtained, and hence the addition of about 10 ml. of carbon tetrachloride is particularly desirable. Finally distil off the carbon... 

Methyl, ethyl, n-propyl, isopropyl, n-hutyl, benzyl, cyclohexyl esters of formic, acetic, oxalic, succinic, tartaric, citric, benzoic, salicylic (and other substituted benzoic acids), phthalic and cinnamic acids phenyl esters of acetic, benzoic and salicylic acids. 

As a general guide, however, it may be noted that the following have fairly easily recognisable odours methyl and ethyl formate methyl and ethyl acetate (apples) methyl and ethyl benzoate methyl salicylate (oil of winter-green) and ethyl salicylate methyl and ethyl cinnamate. (It is however usually impracticable to distinguish by odour alone between the methyl and ethyl esters of a particular acid.) Methyl and ethyl o. alate, and methyl and ethyl phthalate are almost odourless. Succinic and tartaric esters have faint odours. 

The cinnamate ester prepared as above (23.2 g. 79 mmol) was added as a solid slowly to refluxing xylene (500 ml) over a period of 3 h at a rate that prevented accumulation of unreacted azidocinnamate in the solution (monitored by gas evolution through a gas bubbler). The solution was refluxed for an additional 2 h after gas evolution ceased. The reaction mixture was cooled and the solvent removed in vacuo. The residue was recrystallized from methanol to give pure product (20.7 g, 99% yield). 

Pyrolytic Decomposition. The pyrolytic decomposition at 350—460°C of castor oil or the methyl ester of ricinoleic acid spHts the ricinoleate molecule at the hydroxyl group forming heptaldehyde and undecylenic acids. Heptaldehyde, used in the manufacture of synthetic flavors and fragrances (see Elavors and spices Perfumes) may also be converted to heptanoic acid by various oxidation techniques and to heptyl alcohol by catalytic hydrogenation. When heptaldehyde reacts with benzaldehyde, amyl cinnamic aldehyde is produced (see Cinnamic acid, cinnamaldehyde, and cinnamyl... 

Nearly all uses and appHcations of benzyl chloride are related to reactions of the active haUde substituent. More than two-thirds of benzyl chloride produced is used in the manufacture of benzyl butyl-phthalate, a plasticizer used extensively in vinyl flooring and other flexible poly(vinyl chloride) uses such as food packaging. Other significant uses are the manufacture of benzyl alcohol [100-51-6] and of benzyl chloride-derived quaternary ammonium compounds, each of which consumes more than 10% of the benzyl chloride produced. Smaller volume uses include the manufacture of benzyl cyanide [140-29-4], benzyl esters such as benzyl acetate [140-11-4], butyrate, cinnamate, and saUcylate, benzylamine [100-46-9], and benzyl dimethyl amine [103-83-8], and -benzylphenol [101-53-1]. In the dye industry benzyl chloride is used as an intermediate in the manufacture of triphenylmethane dyes (qv). First generation derivatives of benzyl chloride are processed further to pharmaceutical, perfume, and flavor products. 

Phenyl-2-propenoic acid [621 -82-9] commonly referred to as cinnamic acid, is a white crystalline soHd having a low intensity sweet, honeylike aroma. It has been identified as a principal constituent in the botanical exudates from Styrax IJquidamber orientalis) Benzoin Styrax ben in Pern Balsam [Myroxylon pereirae and Tolu Balsam (]Ayro>ylon balsamum) (4,5). In these, as well as numerous other natural products, it exists both as the free acid and in the form of one or more of its esters, as for example, methyl cinnamate, ben2yl cinnamate [103 1 -3] and cinnamyl cinnamate. 

Cinnamic acid undergoes reactions that are typical of an aromatic carboxyhc acid. Using standard methodology, simple esters are easily prepared and salts are formed upon neutrali2ation with the appropriate base. Hydrogenation of cinnamic acid under mild conditions leads to 3-phenylpropanoic acid [501-52-0] whereas under forcing conditions, such as under high pressure in presence of a nickel catalyst, complete saturation to 3-cyclohexylpropanoic acid [701-97-3] is readily accompHshed (8). 

Esters of cinnamic acid are used more extensively than the acid itself, and can be converted to the acid by standard hydrolysis protocols. The Claisen condensation between benzaldehyde and the appropriate acetate ester provides a direct, high yield route to the simple esters. 

Cinnamate ester yields of 70—95% have been realized, but the substrates are expensive when compared with those employed in the standard Claisen approach. 

Economic Aspects. There are no pubhshed production figures for cinnamic acid. Most of the manufactured acid is consumed internally to generate a series of cinnamate esters for flavor and fragrance appHcations. With this in mind, it was possible to estimate a 1990 usage in the range of 175 metric tons. The cinnamic acid that does find its way into the marketplace has been sold for 12—14/kg in dmm quantities. 

When heated in the presence of a carboxyHc acid, cinnamyl alcohol is converted to the corresponding ester. Oxidation to cinnamaldehyde is readily accompHshed under Oppenauer conditions with furfural as a hydrogen acceptor in the presence of aluminum isopropoxide (44). Cinnamic acid is produced directly with strong oxidants such as chromic acid and nickel peroxide. The use of t-butyl hydroperoxide with vanadium pentoxide catalysis offers a selective method for epoxidation of the olefinic double bond of cinnamyl alcohol (45). 

Health and Safety. Cinnamyl alcohol has been evaluated by FEMA and given GRAS status (FEMA No. 2294). Two of its esters, cinnamyl cinnamate (FEMA No. 2298) and cinnamyl acetate (FEMA No. 2293), ate also used extensively in flavor and fragrance compositions. Cinnamyl alcohol has also been tested by RIFM (48) and found to be safe for use. There have been reported cases of irritation and several manufacturers market a desensitized alcohol for use in fragrance appHcations. 

Esters can be obtained from halogenated olefins using a metal carbonyl catalyst (87), eg, /n j -l-bromo-2-phenylethylene is treated with nickel carbonyl in the presence of methanol to afford the corresponding methyl cinnamate (see Cinnamic acid). 

The addition of benzonitrile oxide to acrylic acid gave only the 4-carboxylic acid (441) (59MI41601), while addition to cis- and trans-cinnamic esters gave cis and trans diastereomeric pairs of 4-carboxylic acids (442) (Scheme 100) (59MI41600). Arbisono repeated the experiment and, when methyl c/s-cinnamate was used, in addition to the 4-carboxylic acid some 5-carboxylic acid (442) was isolated (66MI41600). The reaction of vinyl bromides with benzonitrile oxide yielded only an isoxazole and not a bromoisoxazoline (Scheme 101) (78JCR(S)192). 

An interesting footnote to the general synthesis of macrocyclic crown ether-type esters is found in the work of Ors and Srinivasan . These workers used cinnamate esters and diesters as precursors to large ring lactones. Depending on orientation, either truxil-... 

The addition of diazomethane to unsaturated esters (1), as ethyl acrylate, methyl crotonate and ethyl cinnamate, was investigated by Auwers who showed that the primary addition product is a A -pyrazoline (2) which rearranges spontaneously to the conjugated A -pyrazoline (3). 

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