A-CHLOROPHENYLACETIC ACID

Chloro-2-nitropropane, 37, 25 5-Chloro-2-pentanone, 31, 74 a-CHLOROPHENYLACETIC ACID, 36, 3... 

DKR of esters bearing an electron-withdrawing group at the a-carbon can be performed easily under mild reaction conditions because of the low pKa of the a-proton. Tsai et al. have reported an efficient DKR of rac-2,2,2-trifluoroethyl a-chorophenyl acetate in water-saturated isooctane [15]. They used lipase MY from Candida rugosa for the KR and trioctylamine as the base for racemization. (R)-a-chlorophenylacetic acid was obtained in 93% yield and 89.5% ee (Scheme 5.2). 

The ring-closure of 3-methoxyphenyl thioacetate in concentrated sulphuric acid gives 3-methyl-6-methoxybenzo[6]thiophen in good yield. 2-Phenylbenzo[6]thiophen-3-carboxylic acids have been synthesized by the reaction of thianaphthenquinones (340) with a-chlorophenylacetic acid, followed by cyclization of the o-(carboxybenzylthio)phenylglyoxylic acid (341) isolated as an intermediate. - These benzo[f>]thiophencarboxylic... 

Chlorophenylacetic acid has been prepared from mandeloni-trile and hydrochloric acid in a sealed tube, from mandelic acid and hydrochloric acid in a sealed tube/ from a-nitrostyrene and hydrochloric acid in a sealed tube, from phenylglycine, hydrochloric acid, and sodium nitrite, from mandelic acid and phosphorus pentachloride (to give the acid chloride which is then hydrolyzed), and, in poor yield, from mandelic acid and thionyl chloride. In the method described, ethyl mandelate is prepared according to Fischer and Speier. The conversion to the chloroester and the acid hydrolysis step are modifications of a preparation described by McKenzie and Barrow. ... 

The Hammett equation is the best-known and most widely studied of the various linear free energy relations for correlating reaction rate and equilibrium constant data. It was first proposed to correlate the rate constants and equilibrium constants for the side chain reactions of para and meta substituted benzene derivatives. Hammett (37-39) noted that for a large number of reactions of these compounds plots of log k (or log K) for one reaction versus log k (or log K) for a second reaction of the corresponding member of a series of such derivatives was reasonably linear. Figure 7.5 is a plot of this type involving the ionization constants for phenylacetic acid derivatives and for benzoic acid derivatives. The point labeled p-Cl has for its ordinate log Ka for p-chlorophenylacetic acid and for its abscissa log Ka for p-chloroben-zoic acid. The points approximate a straight line, which can be expressed as... 

In an in vitro fermentation study, rumen microorganisms metabolized both isomers of [ C]DDT o,p- and p,p-) to the corresponding DDD isomers at a rate of 12%/h. With p,//-DDT, 11% of the C detected was an unidentified polar product associated with microbial and substrate residues (Fries et al., 1969). In another in vitro study, extracts of Hydrogenomonas sp. cultures degraded DDT to DDD, l-chloro-2,2-bis(/5-chlorophenyl)ethane (DDMS), DBF, and several other products under anaerobic conditions. Under aerobic conditions containing whole cells, one of the rings is cleaved and p-chlorophenylacetic acid is formed (Pfaender and Alexander, 1972). 

Biological. Reported degradation products by the microorganism Alcaligenes BM-2 for a mixture of polychlorinated biphenyls include monohydroxychlorobiphenyl, 2-hydroxy-6-oxochlorophenylhexa-2,4-dieonic acid, chlorobenzoic acid, chlorobenzoylpropionic acid, chlorophenylacetic acid, and 3-chlorophenyl-2-chloropropenic acid (Yagi and Sudo, 1980). When PCB-1016 was statically incubated in the dark at 25 °C with yeast extract and settled domestic wastewater inoculum, no significant biodegradation was observed. At a concentration of 5 mg/L, percent losses after 7, 14, 21, and 28-d incubation periods were 44, 47, 46, and 48, respectively. At a concentration of 10 mg/L, only 22, 46, 20, and 13% losses were observed after the 7, 14, 21, and 28-d incubation periods, respectively (Tabak et al., 1981). 

Biological. Reported degradation products by the microorganism Alcaligenes BM-2 for a mixture of polychlorinated biphenyls include monohydroxychlorobiphenyl, 2-hydroxy-6-oxochlorophenyl-hexa-2,4-dieonic acid, chlorobenzoic acid, chlorobenzoylpropionic acid, chlorophenylacetic acid, and 3-chlorophenyl-2-chloropropenic acid (Yagi and Sudo, 1980). 

Chromium tetraphenyl acid r-a-chlorophenylacetate, 2(C6H5)4Cr.02C.CH(Cl).C6H5.CeH5.CH(Cl).C02H, prepared from the pentaphenyl base and two equivalents of phenylchloraeetic acid, melts at 118° C., is soluble in alcohols, less soluble in chloroform, and insoluble in ether. 

Electroreduction of benzal chloride in the presence of carbon dioxide in DMF solvent gives very low yield of phenylacetic acid (131) (equation 70). The study suggests that the monoanion adds C02 to yield intermediate a-chlorophenylacetate which forms a-lactone. The acid is obtained following hydrolysis of the a-lactone by adventitious moisture in the DMF as shown in Scheme 910. 

Benzene-1.2-diamine reacts with ethyl a-chlorophenylacetate in the presence of tri-ethylamine to give 3.4-dihydro-3-phenylquinoxalin-2(l/f)-one, which is oxidized to 3-phcnylquinoxalin-2(l//)-one with potassium permanganate or selenious acid in acetic acid. ... 

It has been claimed that a-chloroester carbanions and Grignard reagents derived from /-butyl esters of a-halocarboxylic acids are pyramidal and hard. They tend to attack the enone carbonyl. On the other hand, carbanions of a-chlorophenylacetates are planar, delocalized, and soft, and they behave as Michael donors (50). 

A one-pot two-step synthesis of hydroxystilbenes with trans selectivity was developed through a modified Perkin reaction between benzaldehydes and phenylacetic acids bearing 4- or 2-hydroxy substitution at the aromatic ring [67]. The reaction was performed under mild conditions in the presence of piperidine-methylimidazole and polyethylene glycol under microwave irradiation. As a result, 71% yield of ( )-4-chloro-4 -hydroxy-3 -methoxystilbene from 4-hydroxy-3-methoxybenzaldehyde and 4-chlorophenylacetic acid was obtained. A microwave-induced one-pot process for the preparation of arylethenes has been patented [118]. For the preparation of a series of arylethenes (I R -R = H, OH, OMe, AcO, halo, NO2 R, R, R = OH, AcO R= H, substituted aryl), reaction of 2- or 4-hydroxy substituted cinnamic adds or derivatives in the presence of a base, under reflux or microwave irradiation, has been used. For example, a mixture of a-phenyl-4-hydroxy-3-methoxycinnamic acid, NaHC03, methylimidazole, and polyethylene glycol was microwaved at 200 W and 180 °C for 10 min to give 96% 4-hydroxy-3-methoxystilbene. 

Pyrethroid Esters of Benzene Acetate. These insecticides have more extensive stmctural optimization in both acid and alcohol moieties. Fenvalerate [51630-58-17, a-cyano-(3-phenoxyphenyl)methyl (+)-(2R,5)"Ct"isoprop5i-4-chlorophenylacetate (24) d 1.17, vp 1.4 p.Pa at 25°C), a mixture of four isomers, is soluble in water to 0.3 mg/L The rat oral LD q is 450 mg/kg. Esfenvalerate [66230-04-4] is the (+)-2-(i, 5)-isomer (mp 59°C). The rat LD qS are 75, 458 (oral), and the rabbit dermal LD q is 2000 mg/kg. These pyrethroids are widely used general-purpose insecticides for field, vegetable, and fmit crops. 

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