CS270153B1 - Method of 2,6-dialkyl-n-/l-methoxy-2-propyl-aniline preparation - Google Patents

Abstract

The solution relates to the method of preparation 2,6-dialkyl-N- (1'-methoxy-2-propyl) aniline . of formula (I) by hydrogenation 2,6-dialkyl-N / l-methoxy-2-propylidene / of the formula II on hydrogenation catalyst. The reaction is carried out in an anhydrous organic solvent from the group including ethanol, methanol, 1-methoxy-2 -propanol, xylene, toluene at 150 ° C \ t to 190 ° C. and a pressure of 6 to 13 MPa. How hydro- | The catalytic converter shall be used \ t a small catalyst. The solution can be used in the chemical industry.

Description

The present invention relates to a process for the preparation of 2,6-dialkyl-N- (1'-methoxy-2'-propyl) aniline by hydrogenation of 2,6-dialkyl-N- (1'-methoxy-2'-propylldene) aniline in the presence of hydrogenation. I, i> I y I Λ lorn.

It is known that the appropriate N-substituted amines can be prepared from the hydroxy base of Schlff bases. The hydrogenation is carried out according to the nature of the compounds on various hydrogenation ketal leachates such as platinum on activated carbon, platinum dioxide, palladium, Raney nickel, nickel on alumina, cobalt, copper-based resin catalysts / Moller, Fi'Houben-weyl, Melhudon durlschen 11/1, II, p. 602.-648, Georg Thime Verlag, Stuttgart, 4th edition o, 1957 /.

The committee of catalysts depends on the solubility of the hydrogenation of the C »N bond in order to suppress the hydrogenation of other parts of the molecule, such as hydrogenation of the aromatic ring, hydrogenolysis of the bonds, rearrangements and the like.

The hydrogenation of the imine group of 2,6-dialkyl-N- [1'-methoxy-2'-propylldene] aniline does not proceed satisfactorily on nickel-based catalysts, is carried out non-selectively in low yield and with the formation of a number of compounds from which the desired product is difficult to obtain. separate '. Suitable hydrogenation catalysts are precious metals which, even under mild conditions, give 2-methyl-6-ethyl-N- [1'-methoxy-2'-propyl] aniline in high yield. The Adkins copper-based catalyst, where the support is chromium oxide, is a highly active catalyst. Its advantage is that it does not attack the aromatic nucleus. However, its selectivity is limited as it easily reduces carbonyl compounds. ·

It has now been found that the 2,6-dialkyl-N- [1'-methoxy-2'-propyl] aniline of the formula I.

wherein R 1 and R 2 are methyl or ethyl, can be prepared by hydrogenation of 2,6-dialkyl

-N- (1'-methoxy-2'-propylldene) aniline of formula II

R ¹

2 in which R and R have the meanings already given on the hydrogenation catalyst according to the invention. The invention is based on the use of a methanochrome catalyst as the hydrogenation catalyst and the reaction is carried out in an anhydrous organic solvent from the group consisting of ethanol, methanol, 1-methoxy-2-propanol, xylene, toluene at a pressure of 6 to 13 MPa at room temperature. 150-190 ° C. The amount of hydrogenation catalyst is 2 to 10% by weight, per reduced imine.

Isolation of the product is carried out by distillation after filtering off the catalyst and distilling off the solvent. Water in the reaction medium acts hydrolytically on the Schiff base, which reduces the purity and yield of the product.

The preparation of 2,6-dialkyl-N- (1'-methoxy-2'-propyl) aniline according to the invention gives the product in substantially higher yields than in the previous processes.

CS 270153 Bl

The following examples illustrate but do not limit the scope of the invention.

Example 1

2-methyl-6-ethyl-N- [1'-methoxy-2'-propyl] aniline

5.0 g of 2-methyl-6-ethyl-N- [1'-methoxy-2'-propylidene] aniline, 15 ml of 1-methoxy-2-propanol and 0.5 g of propellant with a propeller stirrer were placed in a 100 ml hydrogenation autoclave equipped with a propeller stirrer. g of monochlorochromide catalyst. The hydrogenation was carried out at a temperature of 170 ° C and a pressure of 12.5 MPa. After 6 h, the reaction mixture was filtered off from the catalyst and the catalyst was applied to the filter! ptuinyl 1-mutuxy-2-prupunulum. The filtrate was concentrated and finally distilled in vacuo.

4.6 g of 2-methyl-6-ethyl-N- [1'-methoxy-2'-propyl] aniline are obtained, m.p. in. 81 DEG C.72.66 Pa, containing 1.8% by weight. 2-methyl-6-ethylaniline. .

Example 2. '

2,6-dimethyl-N- [1-methoxy-2-propyl] aniline

5.0 g of 2,6-dimethyl'-N- [1'-methoxy-2'-propylidene] aniline in 25 ml of 1-methoxy-2-propanol were hydrogenated in the presence of 0.5 g of meanatochromic catalyst as in Example 1. , at a temperature of 180 ° C and a pressure of 13 MPa of hydrogen for 5 hours.

G 5.0 g of a mixture of 94.2% 2,6-dimethyl-N- (1'-methoxy-2'-propyl) aniline and 5.8% 2,6-dimethylaniline were obtained.

Rectification on a column gave a product with a purity of 98.5% with m.p. in. 84 ° C /4.2 Pa.

Example 3

2,6-diethyl-N- [1'-methoxy-2'-propyl] aniline '

5.0 g of 2,6-diethyl-N- [1'-methoxy-2-propylidine] aniline in 25 ml of 1-methoxy-2-propanol were hydrogenated in the presence of 0.5 g of copper-chromium catalyst at 170-180 ° C and pressure of hydrogen 13 MPa for 7 h as in Example 1.

A mixture containing 93.6% of 2,6-diethyl-N - [1'-methoxy-2'-propyl] aniline and 6.3% of 2,6-diethylaniline was obtained. Rectification on a column gave a product with a purity of 97% with a temperature of 92 ° C / 2.6 Pa, n _g ° = 1.5124.

Claims (1)

OBJECT OF THE INVENTION Process for the preparation of 2,6-dialkyl-N- [1-methoxy-2-propyl] aniline of general formula I 12. wherein R and R are methyl or ethyl hydrogenation of 2,6-dialkyl-N- [1'-methoxy-2'-propylidene] aniline of formula II CS 270153 Bl Wherein R 1 and R 2 are as defined above, characterized in that a copper-chromium catalyst is used as the hydrogenation catalyst and the reaction is carried out in an anhydrous organic solvent selected from the group consisting of ethanol, methanol, 1-methoxy-2-propanol, xylene, toluene at a pressure of · 6 to 13 MPa and at a temperature of 150 to 190 ° C. ·