Phenylacetic acid, oxidation

This is a way to do this procedure without having to use one of those crazy tube furnaces stuffed with thorium oxide or manganous oxide catalyst [21]. The key here is to use an excess of acetic anhydride. Using even more than the amount specified will insure that the reaction proceeds in the right direction and the bad side reaction formation of dibenzylketone will be minimalized (don t ask). 18g piperonylic acid or 13.6g phenylacetic acid, 50mL acetic anhydride and 50mU pyridine are refluxed for 6 hours and the solvent removed by vacuum distillation. The remaining residue is taken up in benzene or ether, washed with 10% NaOH solution (discard the water layer), and vacuum distilled to get 8g P2P (56%). 

Diphenylbutadiene has been obtained from phenylacetic acid and cinnamaldehyde with lead oxide, by the dehydrogenation of l,4-diphenyl-2-butene with butyllithium, and by the coupling reaction of benzenediazonium chloride and cinnamyl-ideneacetic acid." The present method gives better yields than those previously reported, is adaptable to the preparation of a variety of substituted bistyryls, and is relatively easy to carry out. 

Carbocations can also be generated during the electrolysis, and they give rise to alcohols and alkenes. The carbocations are presumably formed by an oxidation of the radical at the electrode before it reacts or diffuses into solution. For example, an investigation of the electrolysis of phenylacetic acid in methanol has led to the identification of benzyl methyl ether (30%), toluene (1%), benzaldehyde dimethylacetal (1%), methyl phenylacetate (6%), and benzyl alcohol (5%), in addition to the coupling product bibenzyl (26%). ... 

Substituted phenylacetic acids form Kolbe dimers when the phenyl substituents are hydrogen or are electron attracting (Table 2, Nos. 20-23) they yield methyl ethers (non-Kolbe products), when the substituents are electron donating (see also chap. 8). Benzoic acid does not decarboxylate to diphenyl. Here the aromatic nucleus is rather oxidized to a radical cation, that undergoes aromatic substitution with the solvent [145]. 

Lithium enolates of carboxylic acids such as phenylacetic acid or of amides such as N-methyl-N-phenylvaleric acid amide 1974 are oxidized by BTSP 1949 to a-hydroxy acids, which are isolated after esterification, e.g., to 1973, or to a-hydroxyamides such as 1975 [155] (Scheme 12.43) (cf. also the formation of 3-hydroxybutyrolactam 1962). 

Similar kinetics are given by phenylacetic acid, but with isobutyric and pivalic acids the rates are given by the simple expression k2[Co(IIl)][RC02H]/[H ]. The oxidation of C6H5CD2CO2H proceeds at 80% of the rate of the protio compound. The relative rates of oxidation of a series of acids of formula RCO2H at 10 C° are... 

Long MT, BA Bartholomew, Ml Smith, PW Trudgill, DJ Hopper (1997) Enzymology of oxidation of tropic acid to phenylacetic acid in metabolism of atropine by Pseudomonas sp. strain AT3. J Bacteriol 179 1044-1050. 

Toniolo reported the carbonylation of aromatic aldehydes containing electron-donating substituents with a Pd/PPh3 catalyst system in the presence of HC1 to give phenylacetic acid derivatives [64]. No activity was observed in the absence of PPI13 or HC1, and high yields could be achieved with alkanols as solvent (e.g., EtOH). It is believed that the mechanism involves HC1 addition to the aldehyde, with the resultant chlorohydrin being subject to oxidative addition to Pd, CO insertion, and alcoholysis. Upon Cl -o- OR substitution with the formed mandelic acid derivative, a second carbonylation takes place,... 

Such stability is only relative, however, given the possibility of the acid-catalyzed 1,2-shift of a proton observed in some olefin epoxides of general structure 10.10 (Fig. 10.3) [12], Such a reaction occurs in the in vivo metabolism of styrene to phenylacetic acid the first metabolite formed is styrene oxide (10.10, R = Ph, Fig. 10.3, also 10.6), whose isomerization to phenyl-acetaldehyde (10.11, R = Ph, Fig. 10.3) and further dehydrogenation to phenylacetic acid has been demonstrated by deuterium-labeling studies. A com-... 

Hill reaction org chem Production of substituted phenylacetic acids by the oxidation of the corresponding alkylbenzene by potassium permanganate in the presence of acetic acid. hil re,ak-shon ... 

To screen a microorganism which has an ability to decarboxylate a-aryl-a-methylmalonic acids, a medium was used in which phenylmalonic acid was the sole source of carbon, because we assumed that the first step of the metabolic path would be decarboxylation of the acid to give phenylacetic acid, which would be further metabolized via oxidation at the a-position. Thus, a... 

Organic aerosols formed by gas-phase photochemical reactions of hydrocarbons, ozone, and nitrogen oxides have been identified recently in both urban and rural atmospheres. Aliphatic organic nitrates, such dicarboxylic acids as adipic and glutaric acids, carboxylic acids derived from aromatic hydrocarbons (benzoic and phenylacetic acids) and from terpenes emitted by vegetation, such as pinonic acid from a pinene, have been identified. The most important contribution in this held has been that of Schuetzle et al., who used computer-controlled... 

Method C2 (typical catalytic procedure).A 5% solution of NaBH4 in 5% aqueous NaOH is added dropwise under N2 to a solution of a-bromophenylacetic acid (1.50 g, 7.0 mmol) and bis(2-thienyl) ditelluride (0.30 g, 0.71 mmol) in EtOH (40 mL) until the red colour of the ditelluride just disappears. At this point air is infioduced in the system to oxidize the catalyst back to the ditelluride. The mixture is then partitioned in ether/5% aqueous NaOH. The aqueous phase is separated, acidified with 2 M HCl and extracted with ether. The extract is dried (CaCl2) and evaporated to give phenylacetic acid (0.93 g (98%) m.p. 77°C). 

It had been known for a long time that benzaldehyde and benzoic acid were formed by the oxidation of animal proteins, and that phenyl-propionic and phenylacetic acids were products of putrefaction (Sal-kowski) phenylalanine was therefore regarded, as suggested by Tie-mann, as the constituent from which these substances arose, but the actual presence of phenylalanine in the proteins was only proved when E. Fischer commenced his investigations upon the proteins. He then found that in some proteins it exceeded in amount that of tyrosine, and that it was in fact the principal aromatic constituent. Those proteins, such as gelatin, in which its presence was demonstrated by Spiro, and which contains no tyrosine, was found to contain phenylalanine as its aromatic constituent. 

Phenol, from irradiated benzene, 3 181-182 Phenolic macrocycle, 39 140-141 Phenomenological modeling density-functional theory, 38 465 oxidized (-t3) and reduced (-H) clusters, four-iron clusters, 38 462 64 Phenylacetic acid, irradiation of, 5 201 Phenylalanine... 

Silver(I) catalyzed oxidative decarboxylation using peroxydisulfate is well studied . Decarboxylated carbon radicals can form a C—C bond with 1,4-benzoquinone or 1,4-naphthoquinone (equation 17) . In the case of 1,4-benzoquinone and phenylacetic acid the yield is 87%, whereas in the case of 2-methyl-l,4-naphthoquinone and cyclopropanecar-boxylic acid the yield is as low as 37%. 

Kennedy and Stock reported the first use of Oxone for many common oxidation reactions such as formation of benzoic acid from toluene and of benzaldehyde, of ben-zophenone from diphenyhnethane, of frawi-cyclohexanediol Ifom cyclohexene, of acetone from 2-propanol, of hydroquinone from phenol, of e-caprolactone from cyclohexanone, of pyrocatechol from salicylaldehyde, of p-dinitrosobenzene from p-phenylenediamine, of phenylacetic acid from 2-phenethylamine, of dodecylsulfonic acid from dodecyl mercaptan, of diphenyl sulfone from diphenyl sulfide, of triphenylphosphine oxide from triphenylphosphine, of iodoxy benzene from iodobenzene, of benzyl chloride from toluene using NaCl and Oxone and bromination of 2-octene using KBr and Oxone . Thus, they... 

In order to confirm the radical character of 51 and to extend its utility, oxidations of ary-lacetic acids to the corresponding ketones, aldehydes or alcohols have been conducted. Competitive decarboxylation reactions of phenylacetic acid and p-substituted phenylacetic acids were carried out. The ratio of the rate constants for the decarboxylation of various substituted phenylacetic acids relative to that of phenylacetic acid was found to decrease on decreasing the electron density at the benzylic carbon. Consequently, compound 51 shows an electrophilic oxidation ability towards arylacetic acids, giving a Hammett p value of —0.408. 

Properties. Phenethyl alcohol is a colorless liquid with a mild rose odor. It can be dehydrogenated catalytically to phenylacetaldehyde and oxidized to phenylacetic acid (e.g., with chromic acid). Its lower molecular mass fatty acid esters as well as some alkyl ethers, are valuable fragrance and flavor substances. 

The known pyruvic acid 87 [Fig. (25)] [54] was oxidatively decarboxylated [55] to afford the phenylacetic acid 88, which was reductively cyclized to give the required oxindole 89 in nearly quantitative yield. 

In the original patent published by Merck in 1995, rofecoxib (2) was synthesized in three steps from the known 4-(methylthio)acetophenone (10), prepared from the Friedel-Crafts acylation of thioanisole. As depicted in Scheme 2, oxidation of sulfide 10 using an excess of magnesium monoperoxyphthalate hexahydrate (MMPP, an inexpensive, safe and commercially available surrogate for w-CPBA) gave rise to sulfone 11, which was subsequently brominated with bromine and AICI3 to afford 2-bromo-l-(4-(methylsulfonyl)phenyl)ethanone (12). After recrystallization from 1 1 EtOAc/hexane, the pure phenylacyl bromide 12 was then cyclo-condensed with phenylacetic acid under the influence of l,8-diazabicyclo[5.4.0]undec-7-ene (DBU) to deliver rofecoxib (2) in... 

Unsubstituted aliphatic carboxylic acids are only very slowly further oxidized to the lower homologous acid in the oxidation of primary alkanols less than 2% of this acid are found. However, with substituted carboxylic acids the cleavage can become the main reaction. Thus anodic oxidation of phenylacetic acid at the nickel hydroxide electrode leads to 87% benzoic acid . Cleavages of similar to a lesser extent are observed with amino acids (Chapter 3.1) or P-alkoxy substituted acids (Chapter 2.4). 

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