DE523273C - Process for the preparation of m- or p-amino-substituted aromatic carboxylic acid nitriles - Google Patents

Description

In the. Work by R u ρ e and Vogler (HeIv. Chim. Acta 8 [1925], page 832 ff.) Describes the preparation of o-aminobenzonitrile by catalytic reduction of o-xitrobenzonitrile. In the corresponding hydrogenation of the m- and p-xitrocyane derivative, however, the researchers mentioned did not succeed in isolating the intermediate, namely the m- and p-aminobenzonitrile, in pure form; they attribute the positive results of the search for o-xitrobenzyl cyanide to the presence of the xitrile group adjacent to the xitro group.

It has now been found that the representation of m- and p-amino-substituted aromatic Carboxylic acid nitriles by means of catalytic reduction of the corresponding xitro derivatives Surprisingly, it succeeds if one is in the presence of nickel or nickel and others Metals of the iron group containing catalysts works under the application of pressure and the reaction temperature does not rise above 40 °.

J. ν. Braun and Blessing Cvgl. Ber. 56 [1923J, page 2156) have already p-Nitrobenzyleyanid to p-aminobenzyl cyanide reduced with Nikkei as a catalyst, but they worked with a io ° / ₀ solution in tetrahydronaphthalene at a temperature of 120 ° and reached yields of 70 "/, . the present method has the advantage that only small quantities of solvent need, at temperatures 40 ⁰ not exceed operates and obtains excellent yields.

The catalyst used in the present process is either of nickel alone or of a mixture of this with other metals of the iron group, and indeed these are metals by reducing (over 400 °) that deposited on a support at elevated temperature Metal connections made.

The products formed are important intermediate products in the construction of drugs and dyes.

Examples

i. 80 parts by weight of p-nitrobenzyl cyanide 100 parts by weight of alcohol and 2 parts by weight of nickel catalyst are added and treated with hydrogen in a stirred autoclave at a pressure of 30 atmospheres. The reduction begins at room temperature with an increase in temperature; by cooling one ensures that 40 ° is not be exceeded. After the uptake of hydrogen has ceased, the nickel is separated by suction, first the alcohol is distilled off and then the residue is added

'■' ·) The patent seeker stated that the inventors were:

Dr. Gustav Ehrhart in Frankfurt a. M.-Höchst, Dr. Walter Kross and Dr. Hans Schlichenmaier in Bad Soden, Taunus.

Claims (1)

reduced pressure. Under 19 mm pressure, the p-aminobenzyl cyanide goes over at 195 to 198 ⁰ and solidifies in the receiver to form white crystals with a melting point of 46 °. The yield is almost quantitative. ~ - 3 ° £ p-nitrobenzonitrile are mixed with 50 ecm of alcohol and 1 g of catalyst containing the metals nickel and cobalt in a ratio of 3: ι, and treated with hydrogen under the conditions given in Example ι. After distilling off the alcohol and recrystallizing the residue from toluene, the p-aminobenzonitrile is obtained in very good yield. ^X 5 3-25 g of the sodium salt of i-nitro-4-cyanobenzene-3-sulfonic acid are treated with 200 ecm of water and 2 g of nickel catalyst as in Example ι. This gives the i-amino-4-cyanobenzene-3-sulfonic acid, which does not melt up to 300 ⁰ after acidification of the nitrated solution. 4 · 3 ° ti m-nitrobenzonitrile are mixed with 1 g of alcohol and 1 g of nickel catalyst and _{reduced with hydrogen under pressure (} as in Example 1. After the alcohol has been distilled off, the purification is carried out by distillation under atmospheric pressure. The m-aminobenzonitrile is obtained in almost quantitative yield, melting at S3 to 54 °. Pat ε ν τ α ν s ρ r υ c η: M- method for displaying or P'-amino-substituted aromatic carboxylic acid nitriles, characterized in that treating the corresponding nitro derivatives with molecular hydrogen under pressure in the presence of nickel or of this or other metals of the iron group-containing catalysts at temperatures 40 ⁰ not exceed.