JPS6345661B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a reduction catalyst used in a method for producing a secondary amine by reductively alkylating an aromatic amine or aromatic nitro compound with an aldehyde or ketone in the presence of hydrogen and a reduction catalyst. Many reduction catalysts for reductive alkylation have been announced so far, including platinum sulfide catalysts (Japanese Patent Publication No. 42-26196, Japanese Patent Publications No. 24881-1987), platinum selenization or telluride catalysts (Japanese Patent Publications No. 47-592). , rhodium sulfide catalyst (Japanese Patent Publication No. 42-26197), copper chromium oxide catalyst containing barium chloride (Japanese Patent Publication No. 49-17954), copper-chromium-manganese oxide catalyst treated with acetic acid (Japanese Patent Publication No. 49-17954)
43-15601, Special Publication No. 49-17955). Among these, copper-chromium catalysts are inexpensive, but require relatively high reaction temperatures, and reduce aldehydes or ketones as a side reaction, producing a large amount of alcohol, making them industrially disadvantageous. Become. platinum sulfide,
Rhodium sulfide and platinum selenide or telluride catalysts have been shown to have low activity in reducing aldehydes or ketones and good selectivity, but there are difficulties in the method for producing the catalysts. On the other hand, platinum-based catalysts have been used as reductive alkylation catalysts, but they are said to have low selectivity and are often used in combination with various additives. In fact, this drawback was recognized in experiments conducted by the present inventors, but after conducting numerous experiments with various catalysts, surprisingly, when using a platinum catalyst supported on a specific activated carbon, To the extent possible, the above-mentioned shortcomings will be rectified;
The inventors have discovered that the selectivity is good, the catalyst has a large activity, and exhibits extremely advantageous effects industrially, leading to the present invention. That is, the present invention provides a method for producing a secondary amine by reductively alkylating an aromatic amine compound or an aromatic nitro compound and an aldehyde or ketone in the presence of hydrogen and a reduction catalyst. This is a method for producing a secondary amine, which is characterized by using a platinum catalyst supported on activated carbon produced from coconut shell as a reduction catalyst. In general, the raw materials for activated carbon are wood, sawdust,
Wood carbonized products, charcoal, fruit shells including coconut shells, lignin, pulp waste liquid, peat, grass charcoal, charcoal-free,
There are coal and pitch tar, and activation methods include chemical activation method and gas activation method, and the activated carbon obtained has ash content, content of elements other than carbon, surface complex compounds, etc. depending on the raw material and activation method.
Solid acid-base properties, specific surface area, pore distribution, pore volume, etc. differ. In the present invention, platinum was supported on various activated carbons under the same conditions according to a known method, platinum catalysts were adjusted, and as a result of numerous experiments, specific surface area, ash content, pore distribution, solid acid base Even if the properties and the reducing activities of the nitro compounds are almost the same, lignite and bituminous coal are By using a platinum catalyst supported on activated carbon made from coal or coconut shell with a low degree of coalification with a fuel ratio of 0.5 or more and 4.5 or less as a reduction catalyst, aldehydes or ketones are reduced and alcohol is produced as a by-product. The activity, hydrogenation activity of aromatic nucleus, and hydrolysis activity were small, while the reductive alkylation activity was large, and it exhibited extremely advantageous effects from an industrial perspective. The fuel ratio is (fixed carbon) / (volatile content),
It is an indicator of the degree of coalization. fixed carbon in coal,
The volatile content is as described in JIS M8812-1972. Activated carbon is a commercially available product with at least a specific surface area of
Powdered activated carbon having an ash content of 700 m ² /g is preferred, and activated carbon with an ash content of less than 7.5% by weight is preferred, as activated carbon as such contains a large amount of ash and is therefore suitable for use in the present invention. Washed thoroughly. Activated carbon produced from coal with a low degree of coalification, such as lignite and bituminous coal, or coconut shells exhibits the effects of the present invention, and activated carbon produced from brown coal or coconut shells preferably exhibits the effects of the present invention. The platinum catalyst used is activated carbon supported with platinum in an amount of 0.5 to 10% by weight, preferably 0.5 to 5% by weight, particularly preferably 1 to 3% by weight. For aromatic amine compounds or aromatic nitro compounds
It is used in an amount of 0.1 to 5% by weight, preferably 0.5 to 2% by weight. Aromatic amine compounds or aromatic nitro compounds include aniline, alkylaniline, alkoxyaniline, aryloxyaniline, arylene diamine, N-alkylnitroaniline, N
-Arylnitroaniline, nitrobenzene, alkylnitrobenzene, alkoxynitrobenzene, aryloxynitrobenzene, and dinitrobenzene are exemplified, but p-phenylenediamine, o-phenylenediamine, 4-aminodiphenylamine, p-nitroaniline, Particularly preferred are o-nitroaniline and 4-nitrodiphenylamine. Examples of aldehydes or ketones include aliphatic aldehydes, alicyclic aldehydes, aromatic aldehydes, dialkyl ketones, arylalkyl ketones, diaryl ketones, and alicyclic ketones, but include acetone, methyl ethyl ketone, methyl isobutyl ketone, and mesityl oxide. and cyclohexanone are particularly preferred. The amount used is 1.0 for aromatic amine compounds or aromatic nitro compounds.
-10 molar ratio, preferably 1.1-5.0 molar ratio, particularly preferably 1.5-3.0 molar ratio. Ten
Although there is no adverse effect on the reaction even if the molar ratio is exceeded,
Productivity decreases and becomes economically disadvantageous. The reaction is carried out at a temperature ranging from 50 to 220°C. The higher the temperature, the shorter the reaction time, but side reactions will occur and the selectivity will decrease somewhat, so it is preferable to carry out the reaction at a temperature of 80 to 190°C. Regarding the hydrogen pressure, although the reaction proceeds at normal pressure, the reaction time is long and it is economically disadvantageous, so the hydrogen pressure is in the range of 5 to 70 kg/ ^cm2 , preferably 10 to 70 kg/cm2.
Shorten the reaction time by setting the range to 40Kg/cm ² . Next, the effects of the present invention will be explained in detail with reference to Examples. Examples 1 to 5 85.7 g of p-nitrodiphenylamine and methyl isobutyl ketone were placed in a 500 ml stirred autoclave.
After charging 120 g and 2.1 g of a platinum catalyst in which % by weight of platinum was supported on activated carbon and purging with hydrogen, the reactor was pressurized to 30 Kg/cm ² with hydrogen, heated, and the reaction temperature was maintained at 150°C. During the reaction, absorbed hydrogen was constantly replenished to maintain the reaction pressure at 30 Kg/cm ² . At the time when no hydrogen absorption was observed or for 8 hours, the autoclave was cooled to room temperature and the catalyst was separated by filtration. The liquid was analyzed by gas chromatography to calculate the yield of N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD) and the by-product rate of methylisobutylcarbinol (MIBC).

[Table] * Comparative Examples 1 to 3 of by-product ratio relative to charged methyl isobutyl ketone The experiments were carried out under the conditions of Examples 1 to 5, except that platinum catalysts of different origin of activated carbon were used in Examples 1 to 5.

[Table] * Examples of by-product ratio relative to charged methyl isobutyl ketone 6, 7 184.2 g of 4-aminodiphenylamine, 116.2 g of acetone, and 1.8 g of a platinum catalyst with 2% by weight of platinum supported on activated carbon were placed in a 500 ml stirring autoclave. and set the reaction temperature to 120℃ and the reaction time to 3.
The procedure was the same as in Examples 1 to 5 except that the time was changed to N-
The yield of isopropyl-N'-phenyl-p-phenylenediamine (IPPD) and the by-product rate of isopropanol (IPA) were calculated.

[Table] *Comparative example of by-product rate with respect to charged acetone 4 The conditions of Examples 6 and 7 were used except that a platinum catalyst supported on activated carbon derived from sawdust was used.
The yield of IPPD was 90.4% and the by-product rate of IPA was 6.2%. Examples 8 and 9 The same procedure as in Examples 1 to 5 was carried out except that 69.1 g of p-nitroaniline, 180.3 g of methyl ethyl ketone, and 1.4 g of a platinum catalyst with /wt% platinum supported on activated carbon were charged into a 500 ml stirring autoclave. ，
The yield of N'-di-secondary butyl-p-phenylenediamine (DBPPD) and the by-product rate of secondary butyl alcohol (SBA) were calculated.

[Table] * Comparison example of by-product rate with respect to charged methyl ethyl ketone 5 Conducted under the conditions of Examples 8 and 9 except that a platinum catalyst supported on activated carbon derived from sawdust was used.
The yield of DBPPD was 75.9% and the by-product rate of SBA was 4.3%.

Claims (1)

[Claims] 1 In the method of producing a secondary amine by reductive alkylation of an aromatic amine compound or an aromatic nitro compound and an aldehyde or ketone in the presence of hydrogen and a reduction catalyst, coal or coconut shell with a fuel ratio of 0.5 or more and 4.5 or less 1. A method for producing a secondary amine, which comprises using a platinum catalyst supported on activated carbon produced from as a reduction catalyst.