Reduction of cinnamic acid

When reduction is complete (Note 7) the cathode liquor is decanted or siphoned from the mercury, filtered from traces of solid matter-and acidified with an excess of sulfuric acid (sp. gr. 1.1). The hydrocinnamic acid separates as an oil and solidifies on thorough cooling. The yield of crude product, which contains water and other impurities is 180-200 g. It is purified by distillation under reduced pressure. The product boiling at 194-197775 mm. (145-147718 mm.) is colorless and melts at 47.5-48°. The yield of distilled acid is 160-180 g. (80-90 per cent of the theoretical amount) depending upon the quality of the cinnamic acid used (Note 4). 

This is a commercial size. Any sturdy glass vessel of similar dimensions may be used. 

The lead anode should have about the same surface area a-the cathode. The porous cup used was 8 x 21 cm., but similar sizes will do. A three-legged desiccator plate makes a convenient support for the cup. 

3 Any dilute solution of sodium sulfate may be used. If several runs are to be made, the solution recovered from the filtration of the 

The quality of the cinnamic acid used is important. The yield from a commercial C. P. acid melting at 132.5-133° was 86-90 per cent. From a lot melting at 131.5-133° obtained by recrystallizing a crude acid with the use of boneblack the yield was 81-83 per cent. With a technical grade of material the yield fell, in some runs, below 60 per cent, the reduction mixture foamed considerably and much high-boiling residue was left on distillation. 

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Hydrocinnamic acid may also be prepared by the reduction of cinnamic acid with sodium and alcohol or with sodium amalgam or with hydrogen in the presence of Adams platinum oxide catalyst (Section 111,150) ... 

The add is obtained by the reduction of cinnamic acid by means of sodium amalgam. The acid is then esterified by the condensing action of a mineral acid in methyl alcohol solution. The ester is an oil of very sweet odour, and is very useful for flower bouquets. 

This acid, CgH. CH. CH COOH, has a sweet and powerful odour, and can be used to advantage in many rose odours. It is recommended especially for perfuming powders and sachets. It is a crystalline compound, melting at 47° and boiling at 280°. It can be obtained by the reduction of cinnamic acid by means of sodium. 

Hydrocinnamic Acid or 3-Phenylpropionic Acid, C6HsCH2CH2COOH mw 150.17, crystals, mp 46° si sol in w sol in ale or eth. Prepd by the reduction of cinnamic acid with Na-amalgam... 

Reduction of cinnamic acid to 3-phenylpropanoic acid (hydrocinnamic acid). Method A. Carry out the hydrogenation of 14.8 g (0.1 mol) of pure cinnamic acid dissolved in 100 ml of ethanol using 0.1 g of Adams catalyst (Section 4.2.61, p. 459) according to the procedure detailed in Section 2.17.1, p. 89... 

Illustrations of the application of LSV for studies of reactions under purely kinetic conditions include the oxidation of 9-substituted fluorenide ions [99] and the reduction of 2,6-diphenylpyrylium ions [100], in both cases leading to the neutral radical, which dimerizes in an RR-type reaction, the oxidation of 1,4-dithiafulvenes into tetrathiafulva-lenes [101], the oxidative ring opening of arylcyclopropanes [102], the reduction of fluoro-alkoxyarenes in liquid ammonia [103], and the competition between protonation and dimerization during the reduction of cinnamic acid esters in MeOH [104]. 

Hydrocinnamic acid has been prepared by the reduction of cinnamic acid with sodium amalgam, (1) with hydriodic acid at 100°, (2) and with phosphorus and hydriodic acid (3) by the action of potassium... 

Marie prepared this acid by the electrolytic reduction of cinnamic acid. He used a mercury cathode, which presented some difficulties. 

Reduction of allylic andpropargylic alcohols. Although lithium aluminum hydride does not reduce ethylenie or acetylenic hydrocarbons, it reduces allylic alcohols and their acetylenic counterparts. The reaction was first encountered by Nystrom and W. G. Brown in the reduction of cinnamic acid to dihydrocinnamyl alcohol. Investigation showed that the anomaly is not in the reduction of the carboxyl group. 

Derivation Reduction of cinnamic acid with sodium amalgam. 

I.2.5. Phenylcyclopropanes by Metal Hydride Reduction of Cinnamic Acids, Esters,... 

L-Phenylalanine,which is derived via the shikimic acid pathway,is an important precursor for aromatic aroma components. This amino acid can be transformed into phe-nylpyruvate by transamination and by subsequent decarboxylation to 2-phenylacetyl-CoA in an analogous reaction as discussed for leucine and valine. 2-Phenylacetyl-CoA is converted into esters of a variety of alcohols or reduced to 2-phenylethanol and transformed into 2-phenyl-ethyl esters. The end products of phenylalanine catabolism are fumaric acid and acetoacetate which are further metabolized by the TCA-cycle. Phenylalanine ammonia lyase converts the amino acid into cinnamic acid, the key intermediate of phenylpropanoid metabolism. By a series of enzymes (cinnamate-4-hydroxylase, p-coumarate 3-hydroxylase, catechol O-methyltransferase and ferulate 5-hydroxylase) cinnamic acid is transformed into p-couma-ric-, caffeic-, ferulic-, 5-hydroxyferulic- and sinapic acids,which act as precursors for flavor components and are important intermediates in the biosynthesis of fla-vonoides, lignins, etc. Reduction of cinnamic acids to aldehydes and alcohols by cinnamoyl-CoA NADPH-oxido-reductase and cinnamoyl-alcohol-dehydrogenase form important flavor compounds such as cinnamic aldehyde, cin-namyl alcohol and esters. Further reduction of cinnamyl alcohols lead to propenyl- and allylphenols such as... 

Hydrocirinamic acid has been prepared by the reduction of cinnamic acid with sodium amalgam,1 with hydriodic acid at 100°,2 and with phosphorus and hydriodic acid 3 by the action of potassium cyanide on /3-phenylethyl chloride followed by hydrolysis 4 by the add hydrolysis of benzyl-acetoacetic ester 5 and by several other methods of no preparative value. It has also been prepared electrolytically by the reduction of cinnamic add in alkaline solution on cathodes of lead 8 and mercury.9... 

Hydrociniuunic Acid. Benzenepropanoic acid 3-phenylpropionic acid <3-phenylpropionic acid benzylaceiic acid. C H 0Oj mol wl 150.18. C 71.98%. H 6.71%, O 21.31%. CgHjCHjCHjCOOH. Prepn by reduction of cinnamic acid lngersoll, Org. Syn. 9, 42 (1929) from propjo -phenone Schwenk, Papa, J. Org. Chem. 11, 798 (1946) by Mauer oxidation of 1-phenyl-3-propanol Langenbeck,... 

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