Phenylcinnamic acid

Submitted by Robert E. Buckles and Keith Breher.1 Checked by T. L. Cairns and J. C. Lorenz. 

Benzaldehyde, suitable for this synthesis, is purified in the following way. A 60-g. (58-ml.) sample is washed with two 20-ml. portions of 10% sodium carbonate and then with water. It is then dried over 5-10 g. of anhydrous magnesium sulfate. A few small crystals of hydroquinone or catechol are added with the drying agent. The dry benzaldehyde is decanted through a cotton plug into a Claisen flask it is distilled under reduced pressure, preferably below 30 mm. 

Sharpies anhydrous grade triethylamine was used without further purification. 

The acetic anhydride is carefully fractionated the 137-139° fraction is collected. 

A simple steam-distillation apparatus such as that given by Fieser 4 is entirely satisfactory. It is usually necessary to heat the distillation flask with a steam bath or a small flame in order to minimize the accumulation of excess water in the flask. 

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The production of a-phenylcinnamic acid by heating benzaldehyde with acetic anhydride and sodium phenylacetate ... 

Here the phenylacetic anhydride, possessing more reactive a-hydrogen atoms, condenses with benzaldehyde to give a-phenylcinnamic acid. The preparation of the latter is an example of the Oglialoro modiflcation of the Perkin reaction. 

This procedure is an adaption of one described by Hauser and Chambers. Previous preparations include the benzylation of diethyl phenylmalonate followed by hydrolysis, the benzylation of phenylacetonitrile followed by hydrolysis, the benzylation of phenylacetic acid through the Ivanov reagent, and the reduction of oi-phenylcinnamic acid using sodium amalgam. ... 

The Pschorr reaction, originally applied to the synthesis of phen-anthrene and its derivatives,has been adapted to the formation of new heterocyclic systems.In its original form, it consisted of treating a diazonium salt with copper powder in acid solution in this way, rans-o-amino-a-phenylcinnamic acid was converted into phen-anthrene-9-carboxylic acid, Eq. (20). Variants of the reaction include cyclizations such as that in Eq. (21). The reaction may be horaolytic... 

The preparation of a-phenylcinnamic acid from benzaldehyde, phaiyl-acetic acid, acetic anhydride and triethylamine is described. Presumably equilibria are set up between phenylacetic acid and acetic anhydride to form phenylacetic anhydride, a mixed anhydride or both ... 

The a-carbon atom of the phenylacetyl group is more susceptible to attack by the basic catalyst (triethylamine) than the acetyl group hence a-phenylcinnamic acid, but no cinnamic acid, is obtained. 

A 500-ml. three-necked flask is fitted with a reflux condenser and a thermometer, the bulb of which reaches far enough into the flask to be covered by the liquid. A solution of 46.0 g. (0.205 mole) of a-phenylcinnamic acid (p. 70) (Note 1) in 280 ml. (307 g., 2.38 moles) of quinoline (Note 2) is added to the flask along with 4.0 g. of copper chromite.2 The reaction flask is heated by means of a mantle or an oil bath until the temperature of the reaction mixture reaches 210-220°. The mixture is kept within this temperature range for 1.25 hours. The solution is then cooled immediately and added to 960 ml. of 10% hydrochloric acid in order to dissolve the quinoline (Note 3). The product is extracted from this mixture with two 200-ml. portions of ether followed by a 100-ml. portion. The combined ether extracts are filtered to remove particles of catalyst, washed with 200 ml. of 10% sodium carbonate, and dried over anhydrous sodium sulfate. The dry solution is removed from the drying agent by filtration and heated on a steam bath to distil the ether. The residue is dissolved in a hexane fraction, b.p. 60-72° (Skellysolve B) the solution is cooled to 0° and filtered to remove /raws-stilbene, if any. The hydrocarbon solvent is removed by distillation, and the czs-stilbene is distilled. The yield is 23-24 g. (62-65%), b.p. 133-136°/10 nun., 95-97°/l mm. tig 1.6183-1.6193, 1.6212-... 

Neither tritium or deuterium gas, with zero dipole moments, can be expected to interact positively with microwave radiation. Their low solubilities are seen as a further disadvantage. Our thoughts therefore turned towards an alternative procedure, of using solid tritium donors and the one that has found most favor with us is formate, usually as the potassium, sodium or ammonium salt. Catalytic hydrogen transfer of this kind is remarkably efficient as the results for a-methylcinnamic acid show [50]. The thermal reaction, when performed at a temperature of 50 °C, takes over 2 h to come to equilibrium whereas the microwave-enhanced reaction is complete within 5 min. A further advantage is that more sterically hindered al-kenes such as a-phenylcinnamic acid which are reduced with extreme difficulty when using H2 gas and Wilkinson s catalyst are easily reduced under microwave-enhanced conditions. 

Nitrophenyl)-4-chloro-2-butene, 31,80 [Pg.52]

Phenylcinnamic acid has been prepared previously by a variety of methods, the best of which appear to be the dehydration of ethyl j3-hydroxy-/3,(3-diphenylpropionate by treatment with sodium acetate in acetic acid6 and the reaction of 1,1-diphenylethylene with oxalyl chloride.7... 

Phenyl /-butyl ether, 46, 89 /3-Phenylcinnamic acid, from benzo-phenone and triethyl phosphono-acetate, 48, 75... 

A. j6-Phenylcinnamic acid. A suspension of 8.8 g. (0.20 mole) of a 55.1% sodium hydride dispersion in mineral oil (Note 1) and 300 ml. of 1,2-dimethoxyethane (Note 2) are added to a dry, 1-1., three-necked flask equipped with a stirrer, a condenser with drying tube, and a pressure-equalizing dropping funnel. The... 

Protonated amides and carboxylic acids have also been shown to activate adjacent electrophilic centers. Although protonated carboxylic acids and amides are not typically considered stable cationic groups, in superacidic media they can be readily generated and many have been observed by spectroscopic studies.16 As an example of electrophilic activation by a protonated carboxylic acid, P-phenylcinnamic acid (35) is diprotonated in super- acid to give the dication (36, observable by NMR) which then reacts with benzene and gives the indanone (37) in good yield (eq 12).17 It is known that the 1,1-diphenylethyl... 

Pschorr s synthesis of phenanthrene (1893) in five steps with the essential dediazoniation and ring closure of 2-diazonio-a-phenylcinnamic acid giving, on addition of copper powder, phenanthrene-9-carboxylic acid, is today still the highest yielding one of all the reactions discussed in this section, Pschorr was able to get 93% yield, and today electrochemically induced Pschorr and related reactions141 give almost quantitative yields in several cases. 

E-ct-phenylcinnamic acid, 6 edges, 281 EDX, 168 EDX analyses, 315 EELS, 223 eggshell, 277 eggshell repartition, 257 electrical conductivity, 8 electro-optical properties and quantum confinement,... 

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