Cinnamaldehyde, 1,2-additions oxidation

Physical and Chemical Properties. The (F)- and (Z)-isomers of cinnamaldehyde are both known. (F)-Cinnamaldehyde [14371-10-9] is generally produced commercially and its properties are given in Table 2. Cinnamaldehyde undergoes reactions that are typical of an a,P-unsaturated aromatic aldehyde. Slow oxidation to cinnamic acid is observed upon exposure to air. This process can be accelerated in the presence of transition-metal catalysts such as cobalt acetate (28). Under more vigorous conditions with either nitric or chromic acid, cleavage at the double bond occurs to afford benzoic acid. Epoxidation of cinnamaldehyde via a conjugate addition mechanism is observed upon treatment with a salt of /-butyl hydroperoxide (29). 

CHROMIUM TRIOXIDE-PYRIDINE COMPLEX, preparation in situ, 55, 84 Chrysene, 58,15, 16 fzans-Cinnamaldehyde, 57, 85 Cinnamaldehyde dimethylacetal, 57, 84 Cinnamyl alcohol, 56,105 58, 9 2-Cinnamylthio-2-thiazoline, 56, 82 Citric acid, 58,43 Citronellal, 58, 107, 112 Cleavage of methyl ethers with iodotri-methylsilane, 59, 35 Cobalt(II) acetylacetonate, 57, 13 Conjugate addition of aryl aldehydes, 59, 53 Copper (I) bromide, 58, 52, 54, 56 59,123 COPPER CATALYZED ARYLATION OF /3-DlCARBONYL COMPOUNDS, 58, 52 Copper (I) chloride, 57, 34 Copper (II) chloride, 56, 10 Copper(I) iodide, 55, 105, 123, 124 Copper(I) oxide, 59, 206 Copper(ll) oxide, 56, 10 Copper salts of carboxylic acids, 59, 127 Copper(l) thiophenoxide, 55, 123 59, 210 Copper(l) trifluoromethanesulfonate, 59, 202... 

Hydrogenation of cinnamaldehyde to 3-phenylpropionaldehyde over palladium catalyst may be accompanied by the formation of 3-phenyl-1-propanol and propyl-benzene,218 although the formation of 3-phenylpropionaldehyde usually predominates.219,220 The composition of the products are widely affected by the nature of palladium catalysts, solvents, supports, and additives.216,221 The hydrogenation over Pd-Al203 in ethanol or over Pd-kieselguhr in acetic acid gave 3-phenylpropionalde-hyde quantitatively at room temperature and atmospheric pressure. The addition of a 1 1 ratio of ferrous chloride to palladium also resulted in quantitative formation of 3-phenylpropionaldehyde in the hydrogenation over 5% Pd-C in methanol.221 This result was contrasted with those obtained with platinum oxide where iron additives led... 

The partial oxidation of cinnamyl alcohol (Ph-CH—CH-CH2OH) to cinnamalde-hyde was conducted in the presence of a surfactant (sodium dodecylbenzene sulfonate) because reactant and product were insoluble in water [45,50]. Oxidation on Bi-Pt/AljOj catalysts was performed at basic pH obtained by addition of Li2C03, and by controlling the air supply to avoid over-oxidation of the metal. The maximum selectivity for cinnamaldehyde, 98.5 % at 95.5 % conversion, was obtained for a Bi/Pts ratio of 0.5. The high selectivity for cinnamyl aldehyde was attributed to the negligible hydration of the aldehyde because of the conjugation of C—O, C=C, and aromatic nucleus (see Section 9.2.2.1). Under similar conditions the selectivity for oxidation of 1-dodecanol [50] to dodecanal was poor. 

Harada et al. [42] prepared nanosized palladium particles supported on activated carbons using a simple liquid-phase reduction of aqueous Pd complexes with KBH4. They found that the addition of appropriate amounts of NaOH into aqueous solutions of Na2PdCLt, followed by reduction with KBH4, produced highly dispersed Pd particles (less of 5 nm in diameter), irrespective of the carbon support used. The prepared catalysts were used efficiently in the liquid-phase oxidation of benzyl alcohol to benzaldehyde and in the liquid-phase hydrogenation of cinnamaldehyde to obtain the saturated aldehyde. 

Yadav et al. have developed the first example of ionic liquid-promoted one-pot oxidative conjugate hydrocyanation of MBH adducts with trimethylsilyl cyanide (TMSCN) (Scheme 3.210). This reaction involves an efficient regio-selective addition of TMSCN to p-keto-a-methylenes and ( )-cinnamaldehydes, obtained from oxidation of MBH adducts with IBX/[bmim]Br or isomerization-oxidation with NaN03/[Hmim]HS04, respectively, to afford the corresponding thermodynamically more stable p-cyanated products 468 and 469. ... 

In addition to the enamine 369 described in Scheme 2.69, the other four enamines 372-375 obtained from nitroanilines 359 and diphenylacetaldehyde 253o, cyclohexanecarboxaldehyde 253p, fran -cinnamaldehyde 253q, and 1,3-cyclohexanedione 376 were examined (Scheme 2.70) (Wallace et al. 2008). The condensation of aldehydes 253o-q and 1,3-cyclohexanedione 376 with nitroanilines 359 resulted in enamines 372-375 in 91, 88, 85, and 70 % isolated yields, respectively. The A-heteroannulation of 372-375 similarly gave the quinoxaline derivatives 377, 378, 379, 380, 382 in 69, 70, 13, 25, and 26 % isolated yields. In addition to fully aromatic quinoxaline 195, the corresponding A-oxide 381 was obtained, albeit in lower yields in the case of mono-phenyl substituted enamine 374. 

Smith et al. (1996) investigated the products of the OH-initated oxidation of cinnamaldehyde, generating OH by photolysis of CH3ONO. The yield of benzaldehyde formed in the presence of NO and air was 0.90 0.39, after corrections were made for photolysis of cinnamaldehyde and for reaction of benzaldehyde with OH. There are two probable channels, involving abstraction of the aldehydic H and addition to the double bond in the substituent group. In the former route, the initially formed acyl radical, CeHsCHCHCO, reacts with O2 to form the peroxy radical, and then NO to form benzaldehyde, at least in part. The two y3-hydroxy alkyl radicals formed by OH addition to the olefinic double bond react with O2 followed by NO to form -hydroxy alkoxy radicals, which will then dissociate to form benzaldehyde formaldehyde. Thus, the formation of benzaldehyde is compatible with both channels of reaction, but it was not feasible to assign channel yields. 

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