DE406149C - Process for the preparation of amines by reducing unsaturated organic compounds with an aliphatically bonded nitro group - Google Patents

Description

Process for the preparation of amines by reducing unsaturated organic compounds with an aliphatically bonded nitro group. While being aromatic To convert nitro compounds smoothly into anilines, previously unsaturated ones behaved organic compounds with aliphatically bonded nitro group, such as. B. the nitrostyrenes, completely different from this. For example, P r i e b s (Annalen 225, p. 339) that the (.) - nitrostyrene completely changes the nitrogen as ammonia during the reduction splits off.

According to R o s e n m u n d (B. ¢ 2, p. ¢ 782 [r 9091) the reduction of p-methoxy-w-nitrostyrene to p-methoxyphenylethylamine carried out in two phases, first to the p-methoxyphenylaldoxime, which then by a further reduction is converted into the desired amine.

According to the same author (B.: 13, p. 3413 [191 o1), methylenedioxy-c.) - nitrostyrene is advantageously reduced in two phases to homopiperonylamine, first with zinc and glacial acetic acid to form the oxime and this with amalgam to form the amine is reduced.

It has now been found that the reduction in Nitrosty role can be conducted using metals as a catalyst so that you can desired amine in a single reduction process or easier and better Yields as before can be obtained.

Thus, the w-1 \ titrostyrene yields in the reduction with colloidal platinum in acidic alcoholic solution at room temperature contrary to the information of P r i e b s nitrogenous. Reduction products, among which an essential one Part is detectable as phenylethylamine.

Similarly, the p-methoxy-w-nitrostyrene can be used in good Convert the yield into the p.Methoxyphenyläthylamin, and also the methylene-dioxy-w-nitrostyrene the catalytic reduction gives the homopiperonylamine in a very satisfactory manner Yield.

In the patent specification 254861 is the representation of homopiperonalamine by electrolytic reduction of methylenedioxy-conitrostyrene described that they can be carried out in the much simpler way of catalytic reduction was not to be foreseen.

In addition to the amines mentioned, other amines are also used in this reaction basic products are obtained, among which the dicyclic amines, e.g. B. the di (methylenedioxyphenylethylene) amine in the reduction of methylenedioxy-w-nitrostyrene and di (phenylethyl) amine a more or less quantitatively significant role in the c.) - nitrostyrene reduction to play.

Examples. i. 6.8 g of w-nitrostyrene are dissolved in a mixture of 75 cc of glacial acetic acid and 75 cc of ethyl alcohol; 5 cc of an aqueous solution of platinum hydrochloric acid (containing 0.5 g of platinum) and 10 cc of colloidal platinum solution (containing 0.5 g of platinum and 0.3 g of gum arabic as protective colloid) and 5 cc of concentrated hydrochloric acid (D = 1.56) are added. .

This solution is with hydrogen under 2 atm. Treated overpressure, the theoretically required amount of q., 3.1 for the phenylethylamine is absorbed within an hour, and no further absorption takes place. The reaction liquid is filtered from the platinum and evaporated to dryness in vacuo. When heating with water, a considerable part of the residue goes into solution, which is taken up with alcohol after evaporation. After precipitation with ether, first a hydrochloride, apparently of the di (phenylethyl) amine, and then of the phenylethylamine are obtained, the latter having the SmP after recrystallization from ethyl alcohol. Showed 217 °. (Cf. F i 1 eti and P iccini, B. 12, p. 17 0 0 [18791).

2. 20 g of p-methoxy- (a-nitrostyrene are dissolved in 96 percent alcohol, to which 6 cc of concentrated hydrochloric acid with a density of D = 1.16 and 10 cc of palladium chloride solution (containing 0.3 g of palladium) are added the hydrogen absorption, which takes place under 3 atm. overpressure at normal temperature, the palladium is filtered off and a solution of 10 cc of platinum hydrochloric acid (corresponding to platinum solution (as in example i)) is added, whereupon the amount of hydrogen calculated for homopiperonylamine is absorbed very quickly the platinum is filtered off, the alcohol is distilled off, the reaction liquid is made alkaline, the basic reaction products are taken up in ether and, after the dried ethereal solution has evaporated, it is distilled under 18 mm pressure. After the second distillation, the p- Methoxyphenylethylamine obtained in a very satisfactory yield.

3. 15 g (-methylenedioxy-3, q.-phenyl) -3-nitroethylene (methylenedioxy-ca-nitrostyrene) are suspended in 150 g of methyl alcohol and 150 g of glacial acetic acid ), 10 ccm of platinum hydrochloric acid (ig platinum) and 2o ccm of colloidal germ solution (containing 0.1 g platinum and 0.6 g gum arabic as protective colloid), on which solution hydrogen under a pressure of 2 atm. acts. The amount of hydrogen required for the homopiperonylamine is absorbed within 30 minutes, whereupon no further absorption takes place after the absorption of 7.5 liters of hydrogen.

The reaction liquid is filtered from the platinum and in a vacuum to Evaporated to dryness. When heated with water, the majority goes into solution, while the smaller amount of crystals of acetic acid, mp 181-182 °, apparently the acetate of di (methylenedioxyphenylethylene) amine remains undissolved. the aqueous solution is evaporated to dryness and the residue from a mixture crystallized from methyl alcohol and ether, with the homopiperonylamine chlorohydrate is obtained pure in good yield.

Claims (1)

PATENT CLAIM: Process for the preparation of amines by reducing unsaturated organic compounds with an aliphatically bound nitro group, characterized in that these nitro compounds are subjected to catalytic reduction.