Diphenylacetic acid, reaction with

Tetraphenylethane (2). A solution of diphenylacetic acid 1 (2f fS g, O.f mol) In OMF was electrolyzed for 17 h and the voltage was increased from f 20 to 220 V dunng electrotysts. The reaction mixture was poured into water and extracted with EtjO. The extract was filtered, washed and the solvent evaporated. Recrystallization from CHCI3 gave 4 g of 2 (24%), mp 207-208 C. 

In a i-l. round-bottom flask are placed 250 cc. of glacial acetic acid, 15 g. of red phosphorus and 5 g. of iodine. The mixture is allowed to stand for fifteen to twenty minutes until the iodine has reacted, and then 5 cc. of water and 100 g. of benzilic acid are added. A reflux condenser is attached and the mixture is boiled continuously for at least two and a half hours. After the reaction is complete, the hot mixture is filtered with suction to remove the excess red phosphorus (Note 2). The hot filtrate is slowly poured into a cold, well-stirred, filtered solution of 20-25 g- °f sodium bisulfite in 1 1. of water (Note 3). This procedure removes the excess iodine and precipitates the diphenylacetic acid as a fine white or slightly yellow powder (Note 4). The product is filtered with suction, washed with cold water and dried thoroughly on filter paper. The yield is 88-90 g. (94-97 per cent of the theoretical amount) of a solid melting at 141-1440 (Note 5). If a crystalline product is desired, the acid is dissolved in about 500 cc. of hot 50 per cent alcohol and then cooled. The melting point after recrystallization is 144-1450. 

Decarbonylation has been reported in the reaction of a-anilino-a,a-diphenylacetic acid with p-toluenesulfonylchloride and pyridine furnishing CO and the imine of benzophenone and aniline Sheenan, J. C., Frankenfeld, J. W. J. Org. Chem. 1962, 27, 628. 

A small part of the primary product rearranges to form diphenylacetic acid. The reaction rate is proportional to the product of concentrations of substrate and H30+, and the solvent isotope effect (kH/kD ) is larger than 1 (Table 19) [220, 221]. General catalysis by chloroacetic acid has been observed [220]. The reaction rate is increased by electron-releasing substituents and decreased by electron-withdrawing substituents at the aromatic ring. The data follow Hammett s rule with a p value of —2.38 [221]. There is no doubt that the reaction takes place with ratedetermining proton transfer in the first step (A-SE2 mechanism). The same conclusion may be drawn on the basis of similar evidence for the acid catalyzed hydrolysis of 2-diazoacenaphthenone [222]. 

The carbonyl group of 3-thietanone reacts typically with nucleophiles such as hydrazine (to give 364), 2,4-dinitrophenylhydrazine, ° tosylhydrazine, semicarbazide, and phenylmagnesium bromide.It undergoes the Wittig reaction (e.g., the formation of 365) yields vary from 14 to 74%. Sodium hydroxide cleaves the presumed 2,2-bis-trifluoromethyl-4,4-diphenyl-3-thietanone to diphenylacetic acid. ... 

Vorliinder showed that benzene plays no rule in the reaction (CS also can be used hut is less satisfactory) and noted that diphcnylchluroacetic acid is not an intermodiulc, since it reacts with benzene and aluminum chloride to give triphenyi-acetic acid. He noted also thal diphenylacetic acid does not react with aluminum chloride, that diphenylcurblnul gives products other than liuorene derivatives, and... 

Decarbonylation and Decarboxylation - The photochemical reactions between carboxylic acids such as formic and trifluoroacetic acid and silica surfaces have been studied. The irradiation of diphenylacetic acid in acetonitrile with acridine results in the decarboxylation and the formation of the adduct (102). When the two achiral compounds, acridine and diphenylacetic acid, are cocrystallized a chiral two component molecular crystal is obtained in which the components are present in a 1 1 ratio. Both (—)- and (+)- crystals can be obtained. This crystalline material is photochemically reactive and irradiation brings about decarboxylation and formation of the adduct (102) with an ee of 35%. This compound is accompanied by a low yield of (103) which is formed exclusively on irradiation of the reactants in acetonitrile solution.Photochemical decarboxylation can be brought about by the irradiation of benzilate (104)/ methyl viologen pairs. ... 

Benzyl alcohol and benzene in a mixture of glacial acetic acid and sulfuric acid give diphenylmethane even at room temperature,646 and diphenyl-methanol gives an almost theoretical yield of diphenyl-p-tolylmethane when boiled with toluene and phosphoric oxide 647 diphenylacetic acid is formed in yields up to 96% on reaction of mandelic acid with benzene in the presence of aluminum chloride.648... 

The direct replacement of chlorine in 2-chlorotetrahydrothiophene by means of MeSH leads to low yields of (339). However, reaction with diphenylacetic acid and EtjN gives the diphenylacetic ester which can be converted to (339) in excellent yield by MeSH. Alternatively, 2-mercaptotetra-hydrothiophene can be prepared by the thiourea method (CHEC-I) and methylated to give (339) <92CB1641>. Deprotonation of (339) with Bu"Li at —30°C gives the 2-lithio derivative this reacts with a variety of electrophiles (alkyl halides, carbonyl compounds) to form (340) (Scheme 69). 

To a solution of 0.56 gm (5.1 mole) of / -phenylenediamine and 1.0 gm (10.3 mole) of triethylamine in 1(K) ml of dry ether is added dropwise a solution of 2.37 gm (10.3 mole) of diphenylacetyl chloride in 20 ml of dry ether (diphenylacetylchloride is prepared from diphenylacetic acid and thionyl chloride) [25]. Fine, white crystals immediately appear and the reaction mixture is continuously stirred for 18 hr. The resulting solid is filtered, washed with cold water and dried to give, after recrystallization from DMF-water, 1.67 gm (66%), m.p. 333°-336°C. 

A novel formal decarboxylation of the amino acid a-anilino-a,a-diphenylacetic acid has been observed upon treatment with tosyl chloride in pyridine. It has been proposed that a mixed anhydride of p-toluenesulfonic acid has undergone an elimination viaiV-deprotonation and synchronous extrusion of carbon monoxide in this reaction. Interestingly, no A-tosylation occurs (eq 22). 

Carboxylic acids are bromodecarboxylated by reaction with (diacetoxyiodo)benzene and bromine under irradiation with a tungsten lamp, leading to respective alkyl or aryl bromides in 50-79% yield [97]. The reaction works very well with carboxylic acids having a primary, secondary or tertiary a-carbon atom, although diphenylacetic acid gives benzophenone. Benzoic acid derivatives are bromodecarboxylated in... 

In 1838, Justus von Liebig found that treating benzil (l,2-diphenylethan-l,2-dione) with hydroxide gave, after acid quench, 2-hydroxy-2,2-diphenylacetic acid, which he called benzilic acid. The mechanism of this benzilic acid rearrangement starts with attack of hydroxide on one of the carbonyl groups. The tetrahedral intermediate can collapse in a reaction reminiscent of a semipinacol rearrangement. 

Based on extensive studies of C-H transformation with Pd(ii), Yu et al. recently achieved asymmetric desymmetrization in a CDC reaction (Scheme 7.26). ° Boc-L-Isoleucine (Boc-Ile-OH) was an effective chiral ligand for the Pd(ii)-catalyzed enantioselective C-H activation of a,a-diphenylacetic acid Na salt. The resultant Pd-aryl intermediate is considered to undergo insertion into styrenes or acrylates, followed by p-hydrogen elimination to afford the coupling product with a chiral quaternary carbon center in good... 

A possible way to induce selectivity in the photodecarboxylation process could be through photosensitized reactions in the soHd state. In fact, when a two-component molecular crystal of phenanthridine and 3-indoleacetic acid is irradiated at low temperature (-70°C), 3-methyHndole is formed in high yield as the sole product by contrast, when the same reaction is carried out in acetonitrile solution, four products are obtained.Furthermore, irradiation of two-component molecular crystals of arylalkyl carboxylic acids with stoichiometric amounts of electron acceptor causes decarboxylative condensation between the two components with important selectivities. " Thus, irradiation of (S)-naproxen in a chiral crystal with 1,2,4,5-tetracyanobenzene produces a decarboxylated condensation product retaining the initial chirality." Photolysis of an enantiomorphous bimolecular crystal of acridine with the R or S enantiomer of 2-phenylpropionic acid causes stereoselective condensation to give three optically active products. An absolute asymmetric synthesis has also been achieved by the enantioselective decarboxylative condensation of a chiral molecular crystal formed from achiral diphenylacetic acid and acridine (Scheme 9). ... 

The rate of the reaction is increased by electron-releasing substituents in the benzene ring (in contrast to the mild enhancement by electron-withdrawing substituents in the pyrolysis of 1,2-diphenylacetates, (Section 2.9) and by electron-withdrawing substituents in the alkyl function, R (226). These facts are consistent with a cyclic mechanism in which N-O heterolysis is more advanced than C-H heterolysis or O-H bond formation in the transition state. The alpha isomers are more reactive than the beta isomers, but study of the latter is complicated as in the presence of traces of acid they are isomerised to the alpha form. 

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