Title of Invention

AN IMPROVED PROCESS FOR THE PREPARATION OF ALKYLATED AROMATIC AMINES.

Abstract

The invention relates to an an improved process for the preparation of alkylated aromatic amine for the selective preparation of ortho and N-alkylated aromatic amines such as 2,6-dialkylamines, 2,6-diethylaniline or dimethylaniline ,N-ethyl or N-methyl anilines. The process involves the reaction of an aromatic amine and a primary or a secondary alcohol in the presence of a new catalyst containing attapulgite impregnated with a combination of iron oxide and the oxides selected from transition metals of the periodic table. The reaction is effected under moderate conditions of atmospheric pressure and low temperatures.

Full Text

The present invention relates to an improved process for the preparation of alkylated aromatic amines. This invention particularly relates to an improved process for the selective preparation of ortho and N-alkylated aromatic amines. The present invention more particularly relates to an improved process for the preparation of 2,6-Dialkylamines such as 2,6-Diethylaniline or dimethylaniline and N-alkylated amines such as N-ethyl or N-methyl anilines. The process of the present invention involves the reaction of an aromatic amine and a primary or a secondary alcohol in the presence of a new catalyst containing attapulgite impregnated with a combination of iron oxide and the oxides selected from transition metals of the periodic table. The reaction is effected under moderate conditions of atmospheric pressure and low temperatures. Attapulgite used in the catalyst. is a fibrous clay. The chemical analysis of attapulgite clay shows the presence of oxides such as SiO , Al O , MgO, Na O, Fe O and water along with traces of nickel,chromium, zinc, copper, lead, tin, vanadium and silver. We have carried out extensive research in respect of the use of attapulgite for catalysing chemical reactions. Some of the other uses of attapulgite are listed here:- It is used as a polymerisation catalyst, in refining vegetable oils and fats, as a carrier for granular and powered agricultural chemicals (insecticides and herbicides), in petroleum refining, decolourising, neutralising, brightening and for desulphurisation. It is also used as an oil base and water base foundry sand binders, latex paint thickener, gelling agent, polishing-suspend-ing agent for abrasives and as a wax emulsion stabilizer. We have observed during our research that attapulgite can be used as catalyst for alkylation reaction, on our continued work developing attapulgite as a catalyst, for selective alkylation of aromatic amines we have observed that when attapulgite is impregnated with a combination of iron oxide and oxides selected from transition metals of the periodic table, the effect of alkylation is greatly enhanced. The catalysing activity of the resultant catalyst for the alkylation reaction, in particular for ortho and N-alkylation is found to be enhanced. Alkylated aromatic amines are useful in a broad range of applications. Particularly ortho-alkylated aromatic amines are used as intermediates for producing dyes, insecticides, resin stabilisers, rubber compounding ingredients and the like. In the Japanese patent publication No.47-24014/72 a method has been described Ln which aromatic amines such as aniline and the like are reacted with alkyl aluminium halide, followed by reaction of the resultant mixture with olefins. In Japanese Patent No-50-137934/75 a method has been described in which aromatic amines are reacted with lower olefins in the presence of a catalyst consisting of aluminium anilide and halogenated hydrocarbons. The above mentioned processes have advantages that the reaction activity and selectivity are high, but due to the involvement of. very high temperatures and pressures there is a disadvantage that the reaction apparatus suitable for the conditions has to be used, and since a substantial amount of the catalyst is used, post treatment for removing the catalyst from the reaction mixture is troublesome. Other prior art processes for producing ortho alkylated aromatic amines include methods like that proposed in a,s patent No. 2814646 in which an aromatic amine is reacted with olefins under heating in the presence of an aluminium anilide catalyst. The disadvantage of this process is that the reaction activity is low. although the selectivity in the product is high. In (J . S patent No. 4, 351, 958 a process for producing orfcho-alkylated aromatic amines in which, an aromatic amine is reacted with olefins, has been described at a temperature in the range of o 2 200-500 C with reaction pressure from 1-30 kg/cm and a catalyst comprising of iron oxide as a main constituent. A variety of catalysts have been tried by this method and the maximum selectivity of 2,6-dialkyianiline is reported as 51.6% under optimum conditions. N-Alkylated aromatic amines are useful in a broad range of applications. They are used as raw materials for synthesis of organic chemicals, and as intermediates for producing dyes, in agrochemical industries like fertilizers, as resin stabilisers, rubber compounding ingredients and the like. The vapour phase catalytic reaction of aniline and ethanol is the method of choice for the industrial production of N-ethylaniline. In European patent KP 39,06] a method has been described wherein aromatic amines are prepared treating olefins with ammonia, and a primary or a secondary amine in presence of Ruthenium or ferric compound dissolved in liguid phase solvent. o The temperatures and pressures employed being 100-250 C and 1-12000 psiq. In Japanese patent 58,146,534 a method has been described in which N-alkylated anilines are prepared by alkylation of H NC H X with alcohols/ethers in gas phase in presence of S ion, Ti and Zr catalysts. Other prior arts for producing N-ethylaniline include both liquid phase methods and vapour phase methods. These processes differ mostly in the type of catalyst used. The liquid phase processes produce N-ethylaniline with equal quantities of the diethylated products, and are still in vogue. Several combinations of the catalyst have been reported , in particular alumina promoted with different metal oxides appears to have been widely employed. Zeolites have been used extensively as catalysts for the production of N-alkylated aniliness. Bauxite is also proved to be a good catalyst for this reaction. The main object of the present invention is to provide an improved process for the preparation of alkylated aromatic amines. Another object of the present invention is to provide an improved process for the preparation of ortho-alkylated and N-alkylated aromatic amines. Yet another object of the present invention is to provide an improved process for the preparation of ortho-ethyl or ortho-methyl or N-ethyl or N-methyl amines. The invention is based on the finding that when attapulgite is impregnated with a combination of iron oxide and oxides selected from the transition metals of the periodic table. The Activity of the resultant catalyst is enhanced for selective alkylation of the aromatic amines. Accordingly the present invention provides An improved process for the preparation of alkylated aromatic amines which comprises, reacting an aromatic amine as herein described in the range of 1-3 moles with a primary or secondary alcohol as herein described in the range of 1-10 moles based on 1 mole of amine in the presence of attapulgite impregnated with a combination of iron oxide and oxides selected from transition metals as herein described of the periodic table as a catalyst at atmospheric pressure and at a temperature in the range of 300-400 °C, recovering the desired amine by conventional methods as herein described. The amine used may be such as aniline, o-toluidine, m-toluidine, p-toluidine, o-ethylaniline, m-ethylaniline, n-methylaniline. The alcohol used may be such as methanol, ethanol, n-propanol, n-butyl alcohol, iso-butyl alcohol, isopropyl alcohol and the like. The amount of alcohol used may be in the range of 1-10 moles of alcohol based on 1 mole of the aromatic amine used. After completion of the reaction the ortho-alkylated aromatic amine maybe separated from the reaction mixture by distillation. The recovered alcohol and aromatic amine can be recycled. As side reaction N,N-dialkylamines maybe produced in quantities of 10-20%. These byproducts maybe recycled to produce the desired alkylated amine under the same reaction conditions, thus in effect causing a quantitative conversion of the amine to the desired alkylated aromatic amines. The metal oxides used for impregnation may be such as oxides of typical metallic elements such as aluminium oxide, silicon oxide, germanium dioxide, magnesium oxide, and oxides of the transition metals such copper oxide, titanium oxide, zirconium oxide, cromium oxide and the like. In our corresponding application on NF-220/95 we have described and claimed a process for the preparation of the catalyst which is employed in the process of the present invention. The details of the invention is described in the following examples which are presented by way of illustration only and should not be construed to limit the scope of the present invention. Example 1: 50 gms of attapulgite containing iron oxide and tin oxide as catalyst is packed into a reactor and heated o to 350 C. A liquid mixture of aniline and ethanol having a mole ratio of 1:5 is fed at a rate of 60 ml/hr whereby the reaction is effected. The product components so obtained are separated by distillation. The conversion of the amine is 65% and the yield of the ortho-alkylated aromatic amine is 44%. Example 2: 50 gms of attapulgite containing iron oxide and tin oxide as catalyst is packed into a reactor and heated o to 370 C. A liquid mixture of aniline and ethanol having a mole ratio of 1:5 is fed at a rate of 60 ml/hr whereby the reaction is effected. The conversion of the amine is 69% and the yield of the ortho-alkylated aromatic amine is 50%. Example 3: 50 gms of attapulgite containing iron oxide and magnesium oxide as catalyst is packed into a reactor and heated to 370 C. A liquid mixture of aniline and ethanol having a mole ratio of 1:5 is fed at a rate of 60 ml/hr whereby the reaction is effected. The product components so obtained are separated by distillation. The conversion of the amine is 52% and the yield of the ortho-alkylated aromatic amine is 5%. Example 4: 50 gms of attapulgite containing iron oxide and Zinc oxide as catalyst is packed into a reactor and heated to 370 C. A liquid mixture of aniline and ethanol having a mole ratio of 1:5 is fed at a rate of 60 ml/hr whereby the reaction is effected. The product components are separated by distillation. The conversion of the amine is 58% and the yield of the ortho- alkylated aromatic amine is 11%. Example 5: 50 qms of attapulgite containing iron oxide and Chromium oxide as catalyst is packed into a reactor and heated to 370 C. A liquid mixture of aniline and ethanol having a mole ratio of 1:5 is fed at a rate of 60 ml/hr whereby the reaction is effected. The product components are separated by distillation. The conversion of the amine is 57% and the yield of the ortho-alkylated aromatic amine is 14%. Example 6: 50 gms of attapulgite impregnated with iron oxide and germanium dioxide as catalyst is packed into a reactor and heated to 375 C . A liquid mixture of aniline and ethanol having a mole ratio of 1:5 is fed at a rate of 60 ml/hr whereby the reaction is effected. The product components are separated by distillation. The conversion of aniline obtained is 87% and the yield of N-alkylaniline is 75%. Example 7: 50 gms of attapulgite impregnated with iron oxide and germanium dioxide as catalyst is packed into a reactor and heated to 350 C . A liquid mixture of aniline and ethanol having a mole ratio of 1:5 is fed at a rate of 60 ml/hr whereby the reaction is effected. The product components are separated by distillation. The conversion of aniline obtained is 80% and the yield of N-alkylaniline is 64%. Example 8: 50 gms of attapulgite containing iron oxide and magnesium oxide as catalyst is packed into a reactor and heated to 370 C. A liquid mixture of aniline and ethanol having a mole ratio of 1:5 is fed at a rate of 60 ml/hr whereby the reaction is effected. The product components are separated by distillation. The conversion of the amine is 52% and the yield of the N-alkylated aromatic amine is 22%. Example 9: 50 gms of attapulgite impregnated with iron oxide and chromium oxide as catalyst is packed into a reactor and o heated to 375 C . A liquid mixture of aniline and ethanol having a mole ratio of 1:5 is fed at a rate of 60 ml/hr whereby the reaction is effected. The product components are separated by distillation. The conversion of aniline obtained is 57% and the yield of N-alkylaniline is 33%. Example 10: 50 gms of attapulgite impregnated with iron oxide and zino oxide as catalyst is packed into a reactor and o heated to 370 C . A liquid mixture of aniline and ethenol having a mole ratio of 1:5 is fed at a rate of 60 ml/hr whereby the reaction is effected. The product components are separated by distillation. The conversion of aniline obtained is 58% and the yield of N-alkylaniline is 38%. We claim: 1. An improved process for the preparation of alkylated aromatic amines which comprises, reacting an aromatic amine as herein described in the range of 1-3 moles with a primary or secondary alcohol as herein described in the range of 1-10 moles based on 1 mole of amine in the presence of attapulgite impregnated with a combination of iron oxide and oxides selected from transition metals as herein described of the periodic table as a catalyst at atmospheric pressure and at a temperature in the range of 300-400°C, recovering the desired amine by conventional methods as herein described. 2. An improved process as claimed in claim 1 wherein the aromatic amine used is selected from aniline, toluidine, xylidine. 3. An improved process as claimed in claim 1 wherein the alcohol used is selected from ethanol, methanol, isopropyl alcohol. 4. An improved process as claimed in claim 1 where in the alkylated aromatic amine produced is recovered by distillation. 5. An improved process as claimed in claim 1 wherein the transition metal oxide selected from magnesium oxide, chromium oxide, zinc oxide, germanium oxide. 6. An improved process for the preparation of alkylated aromatic amine substantially herein described with reference to the examples.

Documents:

2619-del-1996-abstract.pdf

2619-del-1996-claims.pdf

2619-del-1996-correspondence-others.pdf

2619-del-1996-correspondence-po.pdf

2619-del-1996-description (complete).pdf

2619-del-1996-form-1.pdf

2619-del-1996-form-19.pdf

2619-del-1996-form-2.pdf

2619-del-1996-form-3.pdf

2619-del-1996-form-4.pdf

2619-del-1996-petition 138.pdf