3-nitrocinnamic acid

In a 200-cc. round-bottom flask, fitted with a reflux condenser, are placed 50 g. (0.33 mole) of m-nitrobenzaldehyde (Note 1), 40 g. (0.48 mole) of freshly fused sodium acetate, and 70 g. (0.68 mole) of acetic anhydride. The contents of the flask are well mixed and the mixture heated in an oil bath held at 1800 for about thirteen hours. After the reaction product has been allowed to cool slightly, it is poured into 200-300 cc. of water and then filtered by suction (Note 2). After the solid has been washed several times with water, it is dissolved in a solution of 20 cc. of ammonium hydroxide (sp. gr. 0.9) in about 200 cc. of water. The solution of the ammonium salt, after filtering, is poured into a solution of 15 cc. of sulfuric acid (sp. gr. 1.84) in about 200 cc. of water (Note 3). The precipitated m-nitro-cinnamic acid is filtered, redissolved in ammonium hydroxide, and again precipitated by pouring the solution into dilute sulfuric acid (Note 4). 

After the last precipitation, the fra-nitrocinnamic acid is washed with a little water and then sucked as dry as possible (Note 5). The product, which still contains considerable water, is dissolved in 250-300 cc. of boiling 95 per cent alcohol from which the nitrocinnamic acid crystallizes on cooling. The yield amounts to 47-49 g. (74—77 per cent of the theoretical amount). 

The product is pale yellow and melts at 192-194°. If a purer product is desired, it may be recrystallized from benzene or alcohol (Note 6). 

In one run, the product was extracted from the reaction mixture with benzene, removed from the benzene by a sodium carbonate solution, and this solution in turn acidified to obtain the w-nitrocinnamic acid. Neither the product nor the yield was as satisfactory by this method. 

If acid is added to the solution of the ammonium salt, the precipitated w-nitrocinnamic acid carries down a considerable quantity of ammonium salts. 

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A Preparation of a-Ethyl-m-Nitrocinnamic Acid This acid is prepared from 100 g of m-nitrobenzaldehyde, 210 g of butyric anhydride and 73 g of sodium butyrate. The crude a-ethyl-m-nitrocinnamic acid is crystallized from ethanol giving about 105 g, MP 140° to 142°C. From the filtrates there may be isolated a small amount of a stereoisomer, which when pure melts at 105° to 106°C. 

Nitrobenzaldehyde has been prepared from />-nitrotoluene by treatment with isoamyl nitrite in the presence of sodium methylate,1 by oxidation with chromyl chloride,2 cerium dioxide,3 or chromium trioxide in the presence of acetic anhydride.4 It can also be prepared by the oxidation of -nitrobenzyl chloride,5 7>-nitrobenzyl alcohol,6 or the esters of -nitrocinnamic acid.7... 

A. tn-NUrocinnamic acid. In a 1-1. round-bottomed flask fitted with a reflux condenser are placed 151 g. (1 mole) of tw-nitro-benzaldehyde (Note 1), 115 g. (1.1 moles) of malonic acid, 250 ml. of 95% ethanol, and 25 ml. of pyridine. The mixture is heated on a steam bath under gentle reflux for 6-8 hours and cooled. The large masses of crystals are broken up with a spatula, and the reaction mixture is cooled in an ice bath. The solid is collected on a Buchner funnel, and the residue is washed with 100 ml. of cold ethanol and then with two 100-ml. portions of diethyl ether. The crude w-nitrocinnamic acid is suspended in 300 ml. of ethanol and digested on a steam plate for 2-3 hours. The mixture is cooled and filtered, and the solid is air-dried. The product, 144 155 g. (75-80%), is a light-yellow solid and melts at 200-201° (Note 2). 

B. m-Nitrostyrene. In a 250-ml. two-necked flask equipped with a 250° thermometer and an air condenser are placed 30 g. (0.155 mole) of m-nitrocinnamic acid, 2 g. of copper powder, and 60 ml. of dry quinoline (Note 3). The flask is heated with a Bunsen burner to 185-195°, during which time a steady stream of carbon dioxide is evolved. After 2-3 hours (Note 4), the reaction mixture is cooled and poured into a mixture of 75 ml. of concentrated hydrochloric acid and 175 g. of ice. The m-nitro-styrene is isolated by steam distillation, approximately 1 1. of... 

This procedure has been used by the submitters and others to prepare the following cinnamic acids from substituted benzal-dehydes o-nitrocinnamic acid (70%),2 -nitrocinnamic acid (77%),2 w-cyanocinnamic acid (71%),3 o-chlorocinnamic acid (82%),4 m-chlorocinnamic acid (53%),4 -chlorocinnamic acid (73%),4 2,4-dichlorocinnamic acid (70%),4 3,4-dichlorocinnamic acid (81%),4 w-bromocinnamic acid (31%),4 -methoxycinnamic acid (60%),4 and 3,4-dimethoxycinnamic acid (77%).4... 

For the reduction of nitro-compounds containing a group which may be attacked by nascent hydrogen, as, for example, an aldehyde group, an unsaturated side chain, and so on, special methods must he applied. In such cases ferrous hydroxide or iron powder (cf. Chap. VII. 5, arsanilic acid) are often used. The reduction is carried out thus a weighed amount of ferrous sulphate is caused to act, in the presence of alkali (potassium or sodium hydroxide, baryta), on the substance to he reduced. In this way it is possible to reduce, for example, o-nitro-benzaldehyde to aminobenzaldehyde, and o-nitrocinnamic acid to amino-cinnamic acid. 

Hartman, I., and P. W. Robertson The Kinetics of Halogen Addition to Unsaturated Compounds. Part XX. Nitrocinnamic Acids. J. chem. Soc. (London) 1945, 891-... 

Perfluoro(3-isothiocyanato-2-methyl-2-pentene) reacts with N-nucleophiles to produce a series of fluoroalkyl-substituted 6/f-l,3-thiazines <1997RJO720>. The acid-catalyzed cyclization of thioureas immobilized on Wang (X = O) or Rink resin (X = NH) provides a convenient route to a wide range of 2-amino-4/7-benzothiazine derivatives 212 (Scheme 23) <20000L3667>. The thioureas are obtained in four steps from 2-nitrocinnamic acids. A general synthesis of 2-alkylidene-4-imino-l,4-dihydrobenzo-l,3-thiazines 213-215 involves treatment of 2-isothiocyanato-benzonitrile with acidic methylene compounds under basic conditions <2003SL1503>. The ( )-isomers are the predominant isomers formed. 

Nitrocinnamic acid [555-68-0] M 193.2, m 200-201 . Crystd from benzene or EtOH. 

Nitro-n-butane, 302, 307 m-Nitrocinnamic acid, 719 Nitrogen, detection of, 1040, 1045 ... 

Nitrocinnamic Acid Azides or Nitrocinnamoyl Azides, C9H6N403, mw 218-17, N 25-68%. The following isomers are described in the literature O Nitrocinnamoyl Azide, 02N.CgH4.CH CH.CO. Ng... 

A number of interesting photocyclizations have been reported in aromatic nitro compounds. The first authenticated example is probably that of Tanasescu392 who showed that photolysis of 2-nitrocinnamic acid (370) led to the formation of 3-hydroxy-3/7-indole-2-carboxylic acid 1-oxide (371). Although the mechanism of... 

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