Nitrophthalic acids

Hydrogen 3-nitrophthalates. 3-Nitrophthalic anhydride, a yellow crystaUine powder of m.p. 163-164°, reacts with alcohols to yield esters of 3-nitrophthalic acid ... 

For alcohols of b.p. below 150°, mix 0- 5 g. of 3-nitrophthalic anhydride (Section VII,19) and 0-5 ml. (0-4 g.) of the dry alcohol in a test-tube fitted with a short condenser, and heat under reflux for 10 minutes after the mixture liquefies. For alcohols boiling above 150°, use the same quantities of reactants, add 5 ml. of dry toluene, heat under reflux until all the anhydride has dissolved and then for 20 minutes more remove the toluene under reduced pressure (suction with water pump). The reaction product usually solidifies upon cooling, particularly upon rubbing with a glass rod and standing. If it does not crystallise, extract it with dilute sodium bicarbonate solution, wash the extract with ether, and acidify. Recrystallise from hot water, or from 30 to 40 per cent, ethanol or from toluene. It may be noted that the m.p. of 3-nitrophthalic acid is 218°. 

Nitrophthalic acid. Equip a 1500 ml. three-necked flask, supported on a water or steam bath, with a dropping funnel, a mechanical stirrer and a thermometer the neck through which the stirrer passes should be open and the stirrer should be cormected by means of a belt to the motor (nitrous fumes are evolved in the subsequent reaction and these would damage the motor if supported directly over the reaction... 

The electrochemical reduction of 3-nitrophthalic acid at controlled potentials gave 2,1-benzisoxazole-3-carboxylic acid. Cyclization is presumed to proceed via an intermediate oxime (67AHC(8)277). Treating 5-iodoanthranilic acid with acetic anhydride gave 3-acetoxy-5-iodo-2,l-benzisoxazole (596) (65JMC550). 

Nitrophthalic Acid Azide [3-Nitrophthalsaure azid (1), in Ger]. H02C.C6H3(N02).C0.N3, mw 236.16, N 23.73%. Scales from eth petr eth, mp explds on heating. Can be prepd by treating the hydrazide of 3-nitrophthalic acid, with nitrous acid under cooling conditions Refs 1) Beil 9,(370) 2) T. Curtius A. 

Nitrophthalic acid, 2906 Nitroterephthalic acid, 2907 9,12,15-Octadecatrienoic acid, 3771 c/s-9-Octadecenoic acid, 3774 Octatetrayne-l,8-dicarboxylic acid, 3235 Oxalic acid, 0725 Pentanesulfonic acid, 2020 Perfluorosuccinic acid, 1391... 

Problem 10.24 Oxidation of 1-nitronaphthalene yields 3-nitrophthalic acid. However, if 1-nitronaphthalene is reduced to a-naphthylamine and if this amine is oxidized, the product is phthalic acid. 

The electron-attracting —NO, stabilizes ring A of 1-nitronaphthalene to oxidation, and ring B is oxidized to form 3-nitrophthalic acid. By orbital overlap, —NHj releases electron density, making ring A more susceptible to oxidation, and a-naphthylamine is oxidized to phthalic acid. The NO, labels one ring and establishes the presence of two fused benzene rings in naphthalene. 

N 18.77%. Yel crysts, mp 249-50°. Can be prepd by the interaction of 2,4-dinicro-phenyl-hydrazide with 3-nitrophthalic acid Refs l)Beil — not found 2)J.Cerezo E. Olay,AnalesSocEspanQuim 32,1090(1934) ... 

The nitration of phthalic anhydride with a mixture of concentrated sulphuric and nitric acids yields a mixture of 3-nitro- and 4-nitro-phthalic acids these are readily separated by taking advantage of tile greater solubility of the 4-nitro acid in water. Treatment of 3-nitrophthalic acid with acetic anhydride gives 3-nitrophthalic anhydride. 

Alcohols, prior to the separation by means of paper or thin layer chromatography, must be converted into suitable derivatives, mostly into 3,5-dinitrobenzoic acid esters or into the acid semiesters of 3-nitrophthalic acid or diphenic acid. The direct re-esterification of ester plasticizers with 3,5-dinitrobenzoic acid is applicable to plasticizer analysis (7). 

Nitrophthalic acid melting above 200° (sealed tube) is pure enough for this preparation. 

The mercury can be replaced by iodine in a similar manner. An iodine solution is made by dissolving 166 g. (1 mole) of potassium iodide and 255 g. (1 mole) of iodine in 250 cc. of water. This is used instead of the bromine solution. The mixture is filtered from the mercuric iodide and the filtrate acidified with 200 cc. of concentrated hydrochloric acid. The precipitate is filtered and then stirred with a solution of 10 g. of potassium iodide in 250 cc. of water to remove mercuric iodide. The mixture is filtered with suction and the precipitate crystallized from 1 liter of 50 per cent alcohol. The yield is 180 g. of 2-iodo-3-nitrobenzoic acid melting at 204-205.50 (61 per cent of the theoretical amount, based on the 3-nitrophthalic acid used). 

By various refinements the yields may be increased, but the cost of the 3-nitrophLhalic acid obtained is also increased. Because of the extreme cheapness of phthalic anhydride, it is inadvisable to increase the labor cost unduly in order to improve the yield. If a purer product is desired, crystallization from acetic acid will give 3-nitrophthalic acid melting at about 2170 (closed tube). 

Nitrophthalic acid has been prepared by the oxidation of nitronaphthalene,1 and by the nitration of phthalic acid in a variety of ways by many different workers.2 The present method is based on those of Bogert and Boroschek3 and of Lawrance.4... 

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