Dinitrophenylacetic acid

Place 25 g. of phenylacetic acid (Section IV,160) in a 500 ml. roimd-bottomed flask, cool the latter in running water and add 250 ml. of fuming nitric acid, rather slowly at first and then more rapidly. The addition occupies about 15 minutes. Attach a condenser to the flask, reflux the solution for 1 hour, and pour into about 500 ml. of cold water. When cold, filter the crude 2 4-dinitrophenylacetic acid at the pump and wash it with cold water the resulting acid, after drying at 100 , is almost pure (m.p. 181 ) and weighs 31 g. Recrystallise it from 300 ml. of 20 per cent, alcohol. Collect the first main crop (25 g.), and allow the mother liquor to stand overnight when a further 2 g. of pure acid is obtained dry at 100 . The yield of pure 2 4-dinitrophenylacetic acid, m.p. 183 , is 27 g. 

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In 1912, Borsche found out that the esters and amides of 6-nitro-l,2-benzisox-azole-3-carboxylic acid could be obtained in high yield in the reaction of isoamyl-nitrite with 2,4-dinitrophenylacetic acid derivatives in the presence of sodium methoxide [426],... 

Dinitrophenylacetic acid reacts in a similar way and involves partial decarboxylation to form a mixture of 6-nitroanthranil-3-carboxylic acid and 6-nitroan-thranil [431-433]. The reaction mechanism is a nucleophilic attack of the methylene carbon by the nitro group oxygen atom, as shown in Scheme 2.64. The formed cyclic product undergoes dehydration or dehydration with simultaneous decarboxylation. 

Substituted o-nitrophenylacetic acids have been reported to give anthroxanic acids on heating with aqueous sodium hydroxide177 or with phosphorus pentachloride in benzene.178 Amides react similarly.178 6-Nitroanthranils are produced by the action of hot concentrated sulfuric acid on 2,4-dinitrophenylacetic acid (97, R = OH)179 and 2,4-dinitrophenylacetones (e.g., 97, R = CH3) 180-182 the carbonyl substituent is lost in the reaction. 

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