Hydrocinnamic 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. i.r). 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-I97°/75 mm (i45 i47°/i8 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 as 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. 

Any dilute solution of sodium sulfate may be used. If several runs are to be made, the solution recovered from the filtration of the hydrocinnamic acid should be neutralized with sodium hydroxide, diluted if necessary, and used again. Traces of hydrocinnamic acid contained in this solution are thus saved, c. p. chemicals are not necessary. 

The quality of the cinnamic acid used is important. The yield from a commercial c. p. acid melting at 132.5-1330 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 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. 

Method 1. Place 11 5 g, of clean metallic sodium (compare Section III,7, Note 1), cut into small pieces, into a dry 1 litre round-bottomed fiask fitted with a 25 cm. double surface reflux condenser. Introduce 250 ml. of absolute, but preferably super dry (see Section 11,47, 5) ethyl alcohol all at once. A vigorous reaction ensues if the condenser tends to become flooded with alcohol, cool the flask either by surrounding it with a wet towel or by directing the waste water from the condenser upon 

C6H5CH=CHC02Na + 2H (electrolytic) C6H5CH2CH2C02Na 2C6H5CH2CH2C02Na + H2S04 C6H5CH2CH2C02H + Na2S04 

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The ketones are readily prepared, for example, acetophenone from benzene, acetyl chloride (or acetic anhydride) and aluminium chloride by the Friedel and Crafts reaction ethyl benzyl ketones by passing a mixture of phenylacetic acid and propionic acid over thoria at 450° and n-propyl- p-phenylethylketone by circulating a mixture of hydrocinnamic acid and n-butyric acid over thoria (for further details, see under Aromatic Ketones, Sections IV,136, IV,137 and IV,141). 

The dibenzyl ketone has a very high b.p. (ca. 200°/21 mm.) and this remains in the flask when the unsymmetrical ketone has been removed by distillation. The dialkyl ketone has a comparatively low b.p. and is therefore easily removed by fractionation under normal pressure acetone is most simply separated by washing with water. In this way methyl benzyl ketone (R = CHj), ethyl benzyl ketone (R = CHgCH,) and n-propyl benzyl ketone (R = CHjCHjCH,) are prepared. By using hydrocinnamic acid in place of phenylacetic acid ... 

Ethyl p-phenylethyl ketone. Use 100 g. of pure hydrocinnamic acid and 200 g. (201 -5 ml.) of pure propionic acid. Fractionation of the distillate yields 70 g. of diethyl ketone (b.p. 100-102°), 72 g. of ethyl p-phenyl-ethyl ketone (b.p. 245-249° the pure ketone boils at 248°), and 18 g, of crude di-p-phenylethyl ketone (high b.p. residue). 

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) ... 

Hydrocinnamic Acid.—The preparation illustrates the use of sodium amalgam as a reducing agent It should be noted that hydiocinnamic acid may be also obtained from m.donic ester by acting upon the sodium compound nith benzyl chloride, then hydrolysing and removing carbon dioxide,... 

Hempel fractionating column, 137 Hofmann s bottles 30 Hot-water funnel, 53 Hydrazobenzene, 146 Hydriodic acid, 113 Hydrobenzamide, 196 Hydrobromic acid, 140 Hydrochloric add gas, 93 Hydrocinnamic acid, 204 Hydrogen, qualitative determination, r quantitative, ... 

It can be characterised by its phenyl-urethane, melting at 47° to 48°, or by oxidising its acetic acid solution by means of chromic acid, when it yields hydrocinnamic acid, melting at 49°. 

Methyl Phenyl-propionate,—Phenyl-propionic acid, also known as hydrocinnamic acid, forms a methyl ester of the formula... 

Hydrocinnamic acid Aliphatic acid jJ-Phenylethyl alkyl ketone... 

Hydrocinnamic acid. Reflux a mixture of 53 5 g. of propiophenone (Section IV,137), 20-6 g. of sulphur and 46 g. (46 ml.) of morpholine for 6 horns. Pour the reaction product into 400 ml. of 10 per cent, alcohohc sodium hydroxide solution and reflux for 7 hours. Distil off the alcohol, dilute with water, acidify with hydrochloric acid (to Congo red paper), and extract three times with ether. Wash the ether extracts with water, dry, remove the ether and distil. Collect the hydrocinnamic acid at 125-129°/ 6 mm. it solidifies completely on cooling, m.p. 46-47°. The yield is 39 g. 

Hydrazobenzene, d757 Hydrindene, ilO Hydrocinnamic acid, pl50 Hydroquinone, d430 Hydroquinone dimethyl ether, d495 Hydroxyacetanilides, al5 thru al7 Hydroxybenzene, p65 2-Hydroxybenzenemethanol, hl07... 

B. Dissolve 10 g (1) in 100 ml water containing 10% NaOH and add with stirring, 300 g 3% Na-Hg portionwise at intervals of one hour and stir for ten hours. Filter, concentrate to one-half volume and acidify to precipitate the hydrocinnamic acid (II) in about 50% yield. 

In an analogous way, by the action of the equivalent amount (exactly 1 mole) of benzyl chloride on diethyl sodiomalonate, diethyl benzylmalonate, and finally hydrocinnamic acid, are formed. 

If undiluted methyl alcohol is used as a solvent a secondary catalytic action of the palladium results in the production of ester.1 In this case 5 g. of potassium hydroxide are added, the solution is concentrated by heating, and hydrocinnamic acid precipitated with dilute hydrochloric acid. 

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