Cinnamaldehyde Hydrocinnamaldehyde

A more general reaction between kojic acid and aldehydes is a trimolecu-lar condensation discovered by Barham and Reed." By a process of elimination, they arrived at the conclusion that C6 of kojic acid was most probably the point of attack two molecules of kojic acid reacted with one molecule of the aldehyde, with the elimination of one molecule of water, giving a product of structure LXXV. Such compounds were prepared from kojic acid and the following aldehydes the normal alkanals from formaldehyde to heptanal, benzaldehyde, cinnamaldehyde, hydrocinnamaldehyde, 2-furaldehyde, and acrolein. The compound derived from kojic acid and benzaldehyde (LXXV, R = phenyl) was also obtained by treating LXXII (R = phenyl) with hot, aqueous sodium carbonate.92... 

A typical probe reaction for estimating catalytic properties in selective hydrogenations is the hydrogenation of cinnamaldehyde. This molecule contains both a C=C and a C=0 double bond, thus the formation of hydrocinnamaldehyde and/or cinnamyl alcohol by reduction of the one or the other, or the formation of phenyl propanol in the case of complete reduction may indicate the potential of the catalyst for other fine chemical transformations. Indeed, this reaction was one of the first to be tested by CNT-supported catalysts [120]. Noble metals show a high activity in this reaction and... 

Reduction of the double bond only was achieved by catalytic hydrogenation over palladium prepared by reduction with sodium borohydride. This catalyst does not catalyze hydrogenation of the aldehyde group [31]. Also sodium borohydride-reduced nickel was used for conversion of cinnamaldehyde to hydrocinnamaldehyde [31]. Homogeneous hydrogenation over tris(triphenylphosphine)rhodium chloride gave 60% of hydrocinnamaldehyde and 40% of ethylbenzene [5(5]. Raney nickel, by contrast, catalyzes total reduction to hydrocinnamyl alcohol [4S. Total reduction of both the double... 

Yamamoto has recently described a novel catalytic, asymmetric aldol addition reaction of enol stannanes 19 and 21 with aldehydes (Eqs. 8B2.6 and 8B2.7) [14]. The stannyl ketones are prepared solvent-free by treatment of the corresponding enol acetates with tributyltin methoxide. Although, in general, these enolates are known to exist as mixtures of C- and 0-bound tautomers, it is reported that the mixture may be utilized in the catalytic process. The complexes Yamamoto utilized in this unprecedented process are noteworthy in their novelty as catalysts for catalytic C-C bond-forming reactions. The active complex is generated upon treatment of Ag(OTf) with (R)-BINAP in THF. Under optimal conditions, 10 mol % catalyst 20 effects the addition of enol stannanes with benzaldehyde, hydrocinnamaldehyde, or cinnamaldehyde to give the adducts of acetone, rerf-butyl methyl ketone (pinacolone), and acetophenone in good yields and 41-95% ee (Table 8B2.3). 

Aromatic unsaturated aldehydes behave differently, since they are vinylogues of benzaldehydes. In cinnamaldehydes, reduction of the C=0 group and C=C bond are almost equally competitive. However, the selective hydrogenation to hydrocinnamalde-hydes or cynnamyl alcohols is controlled depending on the metal, on the support, on additives and on solvent. Hydrocinnamaldehydes form selectively over Pd catalysts modified with potassium salts of weak acids or FeSO/. Cobalt carbonyl catalysts under 0X0 conditions, or CojfCOlg in the presence of amines, efficiently (96.4% yield) catalyze selective reduction " ... 

The cinnamaldehyde C=C bond is also preferentially reduced under 0x0 conditions using RhCl(PPh3)3 or RhCl(CO)(PPh3)2 to produce hydrocinnamaldehyde quantitatively. Cinnamyl alcohols are obtained in >90% yields over appropriate catalysts. Platinum catalysts modified by FeSOa and zinc acetate -, 5% iridium-on-carbon or 5% osmium-on-carbon smoothly afford cinnamyl alcohol. 

In this paper we will report on the selective hydrogenation of o /3 unsaturated aldehydes using a supported palladium catalyst in a range of ionic liquids. We will also compare their reactivity and selectivity to conventionally used organic solvents. Two systems have been investigated, cinnamaldehyde to form hydrocinnamaldehyde and citral... 

Figure 2 Time variation of cinnamaldehyde conversion (closed symbols) and selectivity (open symbols) towards hydrocinnamaldehyde in [bmim][BF4] (circles) and [C8Py][Bp4] (squares) at 60 °C and 40 bar and in [emim][NTf2] (triangles) at 30 °C and 5 bar...

For the hydrogenation of octine, cinnamaldehyde, and naphthalene, the Kjj values are given in Chapter 12 (Tables 14.3 and 14.4), indicating that the intermediates octene, hydrocinnamaldehyde, and tetrahn should be favored for SCILL catalysts ( N,intermediate/ N,feed < 1)> whetcas for the intermediate cinnamyl alcohol this should be the reverse = %... 

For intermediates with a lower solubility in the IL than the feed (octene compared to octine, hydrocinnamaldehyde to cinnamaldehyde, and tetrahn compared to naphthalene) the maximum yield of the intermediate increases compared to the uncoated case (Table 14.4). For the intermediate ciimamyl alcohol, which has a higher solubility than the feedstock cinnamaldehyde, this is reverse, and the yield decreases, if the SCILL catalyst is used. 

Tessonnier J-P, Pesant L, Ehret G, Ledoux MJ, Pham-Huu C. Pd nanoparticles introduced inside multi-walled carbon nanotubes for selective hydrogenation of cinnamaldehyde into hydrocinnamaldehyde. Appl Catal A 2005 288 203-10. 

Monotetpene, linalool, limonene, a-pinene, dtronellal, dtral, geranial Pyruvic acid, acetaldehyde, ethanol Isopropanal, isopropanol, a-keto-isobutyric add 3-Methylbutanal, 3-methylbutanol, a-keto-isocaproic add 2-Methylbutanal, 2-methylbutanol Benzaldehyde, phenylacetaldehyde, dnnamaldehyde Hydrocinnamaldehyde, p-hydroxybenzaldehyde p-Hydroxy phenylacetaldehyde, p-hydroxy dnnamaldehyde, p-hydroxy cinnamaldehyde... 

A soln. of cinnamaldehyde ethylene glycol cyclic acetal (prepared from the aldehyde and ethylene glycol) in ethyl acetate hydrogenated with 5%-Pd-on-carbon until uptake of 1 equivalent Hg ceases after 10 min., and the intermediate acetal refluxed 1 hr. with 5%-HCl soln. in benzene-dioxane hydrocinnamaldehyde. Y 89%. F. e. s. J. H. Billman, J. I. Stiles, and J. Tonnis, Synth. Commun. 1, 127 (1971). 

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