Nitro Nitrocinnamic acid

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... 

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. 

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

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... 

From or via o-substituted cinnamoyl derivatives. or/ -Substituted benzenes of type 93 (Z = 0, S, NH) can undergo ring closure (Scheme 61). Amines of type 93 (Z = NH), which usually cyclize spontaneously, are often prepared in situ by reduction of nitro compounds, e.g., o-nitrocinnamic acid with (NH4)2S gives 2-quinolone. 

The reduction is effected by adding to the substance to be reduced, in tire presence of an alkali (potassium-, sodium-, or barium-hydroxide), a weighed quantity of ferrous sulphate. By this reaction, o-nitro-benzaldehyde is reduced to o-amidobenzaldehyde o-nitrocinnamic acid to o-amidocinnainic acid. 

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