Method for the selective production of N-methyl-para-anisidine
The invention “Method for selective synthesis of N-methyl-para-anisidine” relates to chemical technology processes, namely to catalytic alkylation of aromatic amines and nitro compounds. The invention relates to the method for synthesis of N-methyl-para-anisidine (N-methyl-para-methoxyaniline; N-methyl-para-amino anisole) from para-anisidine (para-amino anisole; para-methoxyaniline) or para-nitro anisole (1-methoxy-4-nitrobenzene) and methanol in the presence of hydrogen or without hydrogen on heterogeneous catalyst. Proposed method permits to use existing process plants used for obtaining aniline and 14-methylaniline. The invention purpose is to provide the possibility to produce N-methyl-para-anisidine with purity at least 98% and high output that allows arrangement of highly profitable industry-scale manufacturing process.
1. A process for producing N-methyl-para-anisidine, the process comprising the steps of:
a) providing para-anisidine, methanol and a copper-chromium dehydration catalyst modified with one or more of oxides of barium, oxides of zinc, oxides of aluminum, oxides of titanium, oxides of iron, oxides of calcium, oxides of magnesium, oxides of nickel and oxides of cobalt;
b) causing N-alkylation of the para-anisidine with the methanol in the vapor phase over the dehydration catalyst at a temperature of 180 to 260° C. and at atmospheric pressure; and
c) isolating the resultant N-methyl-para-anisidine by rectification.
2. The process of claim 1 , wherein the N-alkylation step is carried out in the presence of nitrogen.
3. The process of claim 1 , wherein the N-alkylation step is carried out in the presence of hydrogen.
4. The process of claim 1 , wherein the catalyst comprises 55% by weight CuO, 10.5% by weight ZnO, 13.5% by weight Cr 2 O 3 , balance Al 2 O 3 .
5. The process of claim 1 , wherein the catalyst comprises 25% by weight CuO, 25% by weight ZnO, 5% by weight CaO, balance Al 2 O 3 .
6. The process of claim 1 , wherein the catalyst comprises 25-45% by weight CuO, 2-10% by weight BaO, 15-35% by weight TiO 3 , balance Cr 2 O 3 .
7. The process of claim 1 , wherein the catalyst comprises 35-45% by weight CuO, 25-35% by weight ZnO, 3-8% by weight NiO, balance Al 2 O 3 .
8. The process of claim 1 , wherein the catalyst comprises 12-19% by weight CuO, 2-3% by weight MnO, 1.0-1.4% by weight Cr 2 O 3 , 1.0-1.4% by weight Fe 2 O 3 , 0.5-0.8% by weight Co 3 O 4 , balance Al 2 O 3 .
9. The process of claim 1 , wherein the catalyst further comprises Raney nickel.
10. The process of claim 1 , wherein the catalyst comprise 75-100% by weight copper oxide, 0.1-1% by weight chromium (3 + ) oxide.
11. The process of claim 1 , wherein the catalyst comprises 36% by weight Cu, 31% by weight Cr, and 6% by weight Ba.
12. The process of claim 1 , wherein the N-alkylation step is carried out in the presence of triethylamine and the molar ratio of triethylamine to para-anisidine is 0.05-0.1:1.