Cw-Cinnamic acids

Two polymorphic forms of cw-cinnamic acid have been characterized using 3C CPMAS NMR. ... 

When heated at I20°C in concentrated aqueous alkaline solution./3-chloro-cw-cinnamic acid is converted into phenylacetylene. A dehydrohalogenation followed by a decarboxylation would explain this sequence, but more probably a direct dehalogenative decarboxylation occurs as such reactions are observed in the absence of vinylic hydrogen, e.g. 

It stands out that the photochemistry is also dependent of the crystalline phases where the topochemical relations between nearest-neighbor molecules are not the same in the pure guest crystals and in the TOT clathrates. When the TOT/cw-stilbene clathrate was irradiated, photoconversion to trans-stilbene occurred smoothly with the additional formation of small amounts of phenanthrene and of an unidentified product. On the contrary the TOT/tru j-stilbene clathrate remained unchanged when irradiated for long periods of time. In the majority of cases, crystalline cw-cinnamic acid derivatives are entirely converted to tran -isomers on irradiation and the trans-to-cis isomerization is not observed However both TOT clathrates with the trans- and cis-isomers of methyl cinnamate photoisomerized under similar conditions. It is noteworthy that these clathrates and those of the stilbenes (Sect. 2.1.4) are isomorphous. 

Kinetics of the reaction of diazodiphenylmethane (92) in a wide range of alcohols with pyridine and pyridine-A -oxide 3- and 4-carboxylic acids (84)-(87), 4-substituted benzoic acids (88)," cw -substituted cinnamic acids (89), 2-(4-phenyl-substituted)cyclohex-l-enyl carboxylic acids (90), and 4 -substituted-biphenyl-2-carboxylic acids (91)" have been reported. Comparison of the new results for 4-substituted benzoic acids with the published results of data for 3-substituted benzoic acids was made, " and it was concluded that the most important solvent property influencing the rate of reaction appears to be the polarity of the alkyl group expressed as Taft s polar constant a. Transmission coefficients in the cinnamic acids (89) were compared with those in the bicyclic acids (90) and... 

The versatility of TOT in clathrate formation is further illustrated by the discovery of several other clathrate types belonging to various space groups PT (/raw-stilbene, cw-stilbene a-bromobutyric acid benzene ) Pl(PT) (methyl tran -cinnamate, methyl cw-cinnamate) P2 (weso-2,3-butanediol carbonate) P2j/c (weTO-2,3-di-bromobutane) C2jc (3-bromooctane ethyl a-bromobuty-rate ° ) Pbca (l,l,l-trifluoro-2-chloro-2-bromoethane) Pbcn (dl-2,3-dibromobu-tane) hexagonal R (a-chlorotetrahydropyran) The clathrates for which X-ray crystal structure determinations have been completed are indicated in Table 1. 

Kong YH, Jo YO, Cho CW et at (2008) Inhibitoiy effects of cinnamic acid on melanin biosynthesis in skin. Biol Pharm Bull 31(5) 946-948... 

Other oxymercuration studies include those on the monoepoxide of cw,c/5-cyclo-octa-l, 5-diene, with neighbouring group participation of the oxiran oxygen, bicyclo[2,2,2]octene, cis- and rranj -cyclo-octenes and cyclononenes, 1,3-diphenylpropenones, and the bicyclic systems (492) and (493). The kinetics of methoxymercuration of substituted cinnamic acids and many aliphatic olefins have been measured. 

It should be noted that the NMR spectroscopy criteria detailed above are not the only available methods applicable for the determination of configuration. U. SchOllkopf and coworkers (360) have correlated the configuration of isomeric p-substituted formylaminoacrylic acid esters with the chemical shifts of the alkoxy groups. UV data have been used to assign configurations to the isomeric dehydrophenylalanine derivatives (325), an approach based on the -values for cinnamic acid, which are higher for /ra 5-cinnamic acid than for the cw-isomer. 

Figure 2 GC/MS chromatograms of fruit juice beverage by (A) DCM extraction and (B) SPME (PDMS) liquid sampling. Peak identification is as follows (1) dichloromethane (2) ethyl butyrate (3) ethyl isovalerate (4) limonene (5) ethyl hexanoate (6) isoamyl butyrate (7) hexanyl acetate (8) cA-3-hexenyl acetate (9) hexanol (10) di -3-hexenol (11) cA-3-hexenyl butyrate (12) furfural (13) benzaldehyde (14) linalool (15) P-terpin-eol (16) butyric acid (17) 2-methyl butyric acid (18) a-terpineol (19) hexanoic acid (20) cw-methyl cinnamate (21)l-(2-furyl)-2-hydroxyethanone (22) furaneol (23) trans-methyl cinnamate (24) y-decalactone (25) dodecanoic acid (26) (hydroxymethyl)fur-fural.

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