CH180687A - Process for the preparation of secondary or tertiary amines. - Google Patents

Description

  

  Process for the preparation of secondary or tertiary amines. It is known, secondary and tertiary amines by j'msetzung of nitrogen bases, which have at least one reactive hydrogen atom bonded to nitrogen, with aldehydes or concretes in the presence of formic acid, which act as a reducing agent for the nitrogen bases and aldehydes respectively. Ketones primarily formed condensation products acts by breaking them down into hydrogen and CO ;, to produce.



  It has been found that secondary or tertiary amines can be obtained in a smoother and more unambiguous manner if one uses nitrogen bases which contain at least one reactive hydrogen atom bonded in the nitrogen atom, for example aliphatic, cycloaliphatic or aromatic amines or heterocyclic amines Bases, the aldehydes or ketones in the presence of hydrogen, which is made up of formic esters in the reaction chamber itself,

      in particular methyl formate was obtained as a reducing agent, allowed to act at elevated temperature. The reaction obviously proceeds according to the following equation:
EMI0001.0017
    in which R is an aliphatic, cycloaliphatic, aromatic or heterocyclic radical, R 'and R "are any alkyl, cyeloalkyl, aryl or aralkyl radical,

      R "may also mean a hydrogen atom. The secondary and tertiary amines obtainable by the process described are very advantageously suitable as intermediates for the production of textile auxiliaries, dyes, etc. They have already been described in the literature. <I> Example < / I> j: 143 parts by weight of a-naphthylamine, 60 parts by weight of methyl formate and 58 parts by weight of acetone are heated to about 210 ° C. in an autoclave for 2 hours.

    After cooling, the carbonic acid formed is blown off and the contents of the autoclave are distilled. Under a pressure of 22 mm, N-monoisopropyl-a-naphthylamine changes between 185 and 188 C; it is obtained in a yield of 90%. The reaction of β-naphthylamine with acetone and methyl formate to give N-monoisopropyl-, B-naphthylamine proceeds in a similar manner.

    Example 2: 143 parts by weight of α-naphthylamine, 120 parts by weight of acetophenone and 60 parts by weight of i4Zethylformate are heated to about 210 ° C. for 2 hours. When the reaction mixture is distilled, 1-a-naphthylamino-1-phenylethane (kp2o: 233 to 235 ° C.) is obtained in a yield of 70%.



  Aniline, acetophenone and methyl formate also give rise to 1-anilino-1-phenylethane, aniline and acetone produce monoisopropylaniline, aniline and paraldehyde produce mono- and diethylaniline, and methylaniline and acetone produce methylisopropylaniline.



  The process can also be carried out in such a way that the formic acid ester is produced during the reaction of the amines with the aldehydes or ketones. In this case, methanol, for example, in which a small amount of sodium is dissolved, is introduced into an autoclave together with the reaction components and carbon oxide is then pressed into the autoclave. In this way, the desired amines are likewise obtained in good yield.



  <I> Example 3: </I> 278 parts by weight of dodecylamine, 94.5 parts by weight of methyl formate and 174 parts by weight of cyclohexanone are heated to 240 in an autoclave for 3 to 4 hours while the carbon dioxide formed is released. After the reaction has ended, pure N-cyclohexy-1-dodecylamine is obtained by fractional distillation of the contents of the autoclave and boils at 171 to 174 ° C. under a pressure of 4.4 mm.



  <I> Example </I> 170 parts by weight of piperidine, 126 parts by weight of methyl formate and 200 parts by weight of cyclohexanone are heated to <B> 9-30 '</B> C for 4 hours while releasing the carbonic acid formed. The contents of the autoclave are then fractionally distilled. Under a pressure of 22 mm, N-cyclohexylpiperidine passes over at a temperature of 122 to 123 ° C.



  <I> Example s: </I> 297 parts by weight of monocyclohexylamine, 294 parts by weight of cyclohexanone and 189 parts by weight of methyl formate are heated to 240 ° C. for 5 hours, the carbonic acid formed being released. After the reaction has ended, the contents of the autoclave are fractionally distilled. Dicyclohexylamine transfers between 130 and 132 ° C under a pressure of 16 mm.

      Example 6: 684 parts by weight of N-ethyl-a-napb.thylamine, 264 parts by weight of methyl formate and 440 parts by weight of cyclohexanone are heated to 270 ° C. for 4 hours in an autoclave. The carbon dioxide formed during the reaction is continuously removed through a reflux condenser while maintaining a pressure of about 50 atm.

    After the reaction has ended, the reaction product is fractionally distilled in vacuo; At 168 "C and 2.8 mm pressure, pure N-ethyl-N-cy = clohexS = l-a-naphthylamine distilled over.



  <I> Example 7: </I> 484 parts by weight of N-ethyl aniline, 420 parts by weight of cyclohexanone and 260 parts by weight of methyl formate are heated to 280 ° C for 4 hours in an autoclave. The carbon dioxide formed during the reaction is continuously removed through a reflux condenser while maintaining a pressure of 50 to 60 at.

    After the reaction has ended, the reaction product is distilled in vacuo; at 152.5 and 11 mm pressure, pure N-ethyl-N-cyclohexylaniline passes over in a yield of 75%.

 

Claims (1)

PATENT CLAIM: Process for the production of secondary or tertiary amines by the action of nitrogen bases, which contain at least one reactive hydrogen atom bound to a nitrogen atom, on aldehydes or ketones at elevated temperature in the presence of hydrogen, characterized in that hydrogen is used det, which was obtained in the reaction space itself from formic acid esters.