P Nitrophenylacetic acid

The acid is conveniently prepared by the reduction of p-nitrophenylacetic acid with ammonium sulphide (hydrogen sulphide in ammoniacal solution). 

This product is satisfactory for most purposes, and incidentally for the preparation of p-nitrophenylacetic acid. Occa-... 

Sterically demanding benzilic acid was used to optimize the reaction conditions in respect to reagent excess and reaction time. Complete conversion (98%) of benzilic acid to the corresponding methyl ester was obtained with two equivalents of the methyl triazene resin 10 after 6 h 96% conversion was obtained when using the n-butyl triazene resin 10. The reaction between p-nitrophenylacetic acid (1 equiv., 2 mg/ml) and the polymer-supported triazene (2 equiv.) in DCM was monitored by HPLC. A 53% conversion from the acid to the ester product was observed after 5 min data analysis indicated a second-order reaction as observed in homogeneous solution. 

To a stirred solution of 1,2,3,4-tetrahydro 6,7-dimethoxy-l-methyl-isoquinoline (35.2 g, 0.17 m) in methylene chloride (50 ml) under nitrogen at ambient temperature was added p-nitrophenylacetic acid (31.4 g,0.17 m) and then portionwise dicyclohexylcarbodiimide (37.0 g, 0.18 m) and the mixture stirred for 3 hr. The precipitated solid was removed by filtration and the filtrate evaporated to an oily residue. The residue was treated with 500 ml methanol and the solid precipitate collected by filtration to give, after drying, N-(4 nitro-phenylacetyl)-l,2,3,4-tetrahydro-6,7-dimethoxy-l-methylisoquinoline as a yellow solid, 66.0 g (100% yield). The product contains a small amount of dicyclohexylurea. 

Nitro acids such as m- and p-nitrophenylacetic acids are prepared in 62% and 95% yields, respectively, by acid hydrolysis of the corresponding nitrobenzyl cyanides. ... 

Alternatively, borane in tetrahydrofuran (BH/THF) is a useful reagent for reducing carboxylic acids to primary alcohols. Reaction of an acid with BH3/THF occurs rapidly at room temperature, and the procedure is often preferred to reduction with LiAlH because of its relative ease, safety, and specificity. Borane reacts with carboxylic acids faster than with any other functional group, thereby allowing selective transformations such as that shown below on p-nitrophenylacetic acid. If the reduction of p-nitrophenyl-acetic acid were done with LiAlH4, both nitro and carboxyl groups would be reduced. 

Use Intermediate for dyestuffs and pharmaceuticals preparation of p-nitrophenylacetic acid. 

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