JPH05331113A - Production of high-purity m-phenylenediamine - Google Patents

Abstract

PURPOSE:To obtain high-purity m-phenylenediamine with hardly any change with time, simultaneously remarkably reduce the amount of an alcohol used and improve the productivity at the same time. CONSTITUTION:The method for producing m-phenylenediamine is characterized by reacting crude dinitrobenzene containing o- and p-dinitrobenzenes with a lower alcohol in the presence of a basic compound and a phase-transfer catalyst to provide a reactional mixture, directly subjecting the resultant reactional mixture to hydrogenating reaction without separating the m-dinitrobenzene therefrom and then separating the obtained m-phenylenediamine by distillation.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing m-phenylenediamine (hereinafter abbreviated as m-PDA). More specifically, crude m-dinitrobenzene (hereinafter referred to as m-DN
Abbreviated as B), m-PDA of higher purity than
To a method of manufacturing. m-PDA is an important compound as an intermediate for chemicals and dyes or as a heat resistant resin raw material.

[0002]

PRIOR ART AND PROBLEM TO BE SOLVED BY THE INVENTION m-P
DA is usually obtained by subjecting m-DNB to a catalytic hydrogenation reaction in the presence of a catalyst. Further, m-DNB can be obtained by nitrating benzene or nitrobenzene with a strong mixed acid, and o-dinitrobenzene (hereinafter abbreviated as o-DNB) and p-dinitrobenzene (hereinafter abbreviated as isomers) at that time. (Hereinafter abbreviated as p-DNB) as a by-product, and usually has a purity of about 90% as m-DNB. As a method for separating these isomers, a method utilizing a solubility difference in alcohol or benzene, a method of heat treatment with an aqueous caustic alkali solution, a method of heat treatment with sodium sulfite and sodium hydrogen sulfite, etc. are known, but both are known. The product purity of the obtained m-DNB is 99%.
To a limited extent, complete separation of o-DNB and p-DNB was not possible.

Therefore, since m-PDA obtained by hydrogenation of m-DNB contains impurities such as o- and p-isomers, it is necessary to purify it by rectification. Since the difference in boiling points of isomers is small, a severe rectification using a rectification column with several tens of stages and a post-treatment step such as recrystallization thereof are required. If impurities such as o- and p-isomers are contained in m-PDA even in a small amount, m-PDA
In addition to causing coloration over time, particularly when m-PDA is used as a heat-resistant resin raw material, only poor quality resin can be obtained, and its improvement is required.

[0004]

Means for Solving the Problems As a result of intensive studies for solving these problems, the present inventors have found that crude m-DNB and a lower alcohol are used in the presence of a basic compound in o- and p-
Only DNB is selectively reacted to convert it to the corresponding alkoxynitrobenzene, and m-D
If the reaction mixture is hydrogenated by a conventional method without separating NB, and a separation operation by a conventional distillation is performed, it is compared with the usually practiced separation of m-PDA and o- and p-isomers. M-PD of high purity and much easier
We found that we could obtain A and filed an application first (Japanese Patent Laid-Open No. 59-59-
141542).

As a result of further investigations by the present inventors, it was found that the addition of a phase transfer catalyst during the alkoxylation reaction improves the rate of the alkoxylation reaction and requires less alcohol. completed. That is, the present invention is characterized by adding a phase transfer catalyst when carrying out an alkoxylation reaction of an isomer in m-DNB with a lower alcohol in the presence of a base. It is intended to provide a method for producing highly pure m-PDA which is industrially highly economical and which can obtain highly purified pure m-PDA by a chemical reaction.

The type of alcohol used in the present invention includes lower aliphatic monohydric alcohols such as methanol, ethanol and isopropanol, alicyclic alcohols such as cyclohexanol, aromatic alcohols such as benzyl alcohol, and ethylene glycol. Although lower polyhydric alcohols and the like can also be used, lower aliphatic monohydric alcohols are preferable, and more preferable when the alkoxylation reaction rate and the separation efficiency of the obtained o- and p-alkoxynitrobenzenes and m-DNB are taken into consideration. Is preferably an aliphatic monohydric alcohol having 3 or less carbon atoms.

The amount of alcohol used is crude m-DNB.
There is no particular limitation as long as it is at least equimolar to the total amount of o-DNB and p-DNB contained therein. When it is small, there is a possibility that o- and p-DNB may remain, when it is large, the volumetric efficiency of the reactor is deteriorated, and it is not a convenient measure for alcohol recovery, and preferably the sum of o- and p-DNB is used. It is preferable to carry out the reaction in an amount of 2 to 15 times mol, more preferably 3 to 10 times mol, based on the amount.

The reaction temperature in the present invention is selected so as to give an appropriate reaction rate below the boiling point of the reaction system. The boiling point of the alcohol used is preferably around room temperature. It can be carried out under pressure at a temperature higher than this, but it is not economical, and the yield of m-DNB is lowered due to tar-forming or alkoxylation of m-DNB. The yield is reduced.

Examples of the basic compound used in the present invention include hydroxides of alkali metals such as caustic soda, caustic potash and calcium hydroxide, and alkaline earth metals or their carbonates, bicarbonates, sulfites and bisulfites. Examples include salt. It is particularly preferable to use caustic soda which is inexpensive and has a strong basicity. The amount of these basic compounds used is roughly m
-It is sufficient that the total amount of o- and p-DNB contained in DNB is stoichiometrically equivalent or more. M-D when used in large quantities
As a result, NB is tarred and the yield and quality are deteriorated. Therefore, 1.0 to 2.0 equivalents are preferable. When these are added, there is no problem whether they are used as a solid or as an aqueous solution, but depending on the separation and purification method, it is advantageous to use them as an aqueous solution to remove residual base compounds and the like. The phase transfer catalyst used in the present invention is represented by the general formulas (1) and (2)

[0010]

[Chemical 1]

[In the formula, each R represents an alkyl group, a phenyl group, a benzyl group or an alkoxy group, and X represents a halogen atom, a hydroxyl group, a sulfate group or an acetate group. ] Quaternary alkyl ammonium salts represented by, and amine oxides, for example, tetramethyl ammonium chloride, tetramethyl ammonium acetate, tetraethyl ammonium chloride, tetrabutyl ammonium bromide, tetraethyl ammonium iodide, tetraethyl ammonium bromide,
Tetrabutylammonium hydroxide, tetrabutylammonium iodide, trioctylmethylammonium chloride, tridodecylmethylammonium chloride, phenyltrimethylammonium chloride, benzyltrimethylammonium chloride, benzyltrimethylammonium bromide, benzyltriethylammonium chloride, benzyltributylammonium chloride, benzyl Examples thereof include tributylammonium bromide, cetyltrimethylammonium chloride, dimethyldodecylamine oxide, dimethyltetradecylamine oxide, dimethylhexadecylamine oxide, and dimethyloctadecylamine oxide.

There is no problem even if this phase transfer catalyst is used alone or in combination of several kinds, and the amount used is not particularly limited as long as it is 0.1% by weight or more based on the crude m-DNB. When it is small, o- and p-DNB may remain, and when it is large, it is economically disadvantageous. It is preferably 0.1 to 10% by weight, more preferably 0.5 to
It is 5% by weight.

To carry out the present invention, the crude m-DNB containing o- and p-alkoxynitrobenzene obtained by the alkoxylation reaction is used as it is in a known method, for example, in the presence of a noble metal catalyst under normal pressure or pressure. After hydrogenation using an organic solvent such as alcohol or toluene under pressure to convert the reaction product into a mixture of the corresponding amine mixture, the alkoxyanilines and m-PDA may be subsequently separated by distillation.

When ethanol or propanol or the like is used as alcohol for separation into ethoxyaniline, propoxyaniline or the like, these alkoxyanilines are extracted with a non-aqueous solvent during the hydrogenation reaction or after completion of the reaction. Then, if these are distilled, the separation efficiency can be improved.

[0015]

EXAMPLES Hereinafter, the present invention will be described with reference to Examples and Comparative Examples.
This will be specifically described. The raw material m-
The composition of DNB is m-DNB 88.6%, o-DNB
It was 9.0% and p-DNB 2.4%, and the analysis was carried out by gas chromatography.

Example 1 200.0 g of crude m-DNB, 20.0 g of methanol, 2
32.0 g of 0% caustic soda water and 2.0 g of trioctylmethylammonium chloride were charged into a reactor equipped with a stirrer and reacted under reflux (75 to 78 ° C.) for 3 hours. When this reaction mass was analyzed, o- and p-DNB were not detected, and the reaction with methanol was completed. Furthermore, 176.7 g of m-DNB (recovery rate 99.7%), o
-Nitroanisole 16.0 g (yield 97.6%), p
-4.1 g (yield 93.2%) of nitroanisole was quantified, and it was confirmed that m-DNB can be recovered almost quantitatively without loss.

Subsequently, in order to remove the remaining basic compound after distilling off the remaining methanol,
After rinsing with hot water of about 100 g and separating from oil and water, the oil layer was used as it was as a raw material for the following hydrogenation step.

195.1 g of the above oil layer (m-DN in this)
B was 173.2 g), methanol 97.5 g and 5% Pd-carbon 0.25 g were charged into a stainless steel autoclave, reaction temperature 100 ° C., hydrogen pressure 40 kg / c.
Hydrogenated at m ² G. The reaction was completed in 55 minutes. After cooling, residual hydrogen was released and the reaction solution was filtered to separate it from the catalyst.

The above filtrate (in which m-PDA 102.0
g) was desolvated and then batch-distilled at a reflux ratio of 10 to 20 in a rectification column having a reduced pressure of 15 mmHg and a theoretical plate number of 10 plates,
O- and p-methoxyaniline up to a boiling point of 121 ° C (boiling point at atmospheric pressure of literature value is o-methoxyaniline at 225 ° C,
p-methoxyaniline 240-242 ° C) fraction 15.2
g, and m-PDA having a boiling point of 162 ° C. (boiling point at normal pressure in the literature is 282-284 ° C.), and 88.1 g of a fraction (removal yield in the distillation step was 86.4%). This m-PDA fraction showed a light transmittance of 98% at 450 nm with methanol as a control, and a purity of 99.99%.

Comparative Example 1 Hydrogenation was carried out under the same conditions as in Example 1 as it was without the step of reacting the crude m-DNB described in Example 1 with methanol. The reaction was completed in 60 minutes. After cooling, residual hydrogen was released and the reaction solution was filtered to separate the catalyst.

The above-mentioned filtrate was subjected to the same rectification column and the same distillation conditions as in Example 1 to obtain m-PDA and o- and p-isomers (both of these literature values have normal pressure boiling points of o-isomer 256 to 258 ° C.). , P
-Isomer (267 ° C) was batch-distilled to obtain m-PDA with a purity of 99.98%.
It was only%. The light transmittance of this m-PDA at 450 nm with methanol as a control was 86%. Further, in order to bring the extraction yield during distillation to about 85%, it was necessary to use a rectification column having 50 theoretical plates and a reflux ratio of 20 to 30.

Example 2 As in Example 1, except that 28.7 g of ethanol was used instead of methanol and 2.0 g of dodecyldimethylamine oxide was used instead of trioctylmethylammonium chloride, at the boiling point of the solvent (about 80 ° C.). Ethoxylation was carried out for 6 hours. When the reaction mass was analyzed, o- and p-DNB were not detected, and 176.9 g of m-DNB (recovery rate 99.8%), 17.4 g of o-nitrophenetol
(Yield 97.0%), p-nitrophenetol 4.4 g
(Yield 93.2%) was present. Subsequently, after removing the remaining methanol by distillation, in order to remove the remaining basic compounds and the like, the molten oil was washed with about 100 g of hot water, the oil was separated, and the oil layer was directly used as a raw material for the hydrogenation step described below.

194.7 g of the above oil layer (m-DN in this)
B was 172.7 g), toluene 170 g and 5
% Pd-carbon (0.25 g) was charged into a stainless steel autoclave, the reaction temperature was 100 ° C., and the hydrogen pressure was 40 kg / cm ^2.
Hydrogenated at G. The reaction was completed in 60 minutes. After cooling, residual hydrogen was released and the reaction solution was filtered to separate it from the catalyst.

The above filtrate (in which m-PDA 103.2
g) was separated and 170 g of toluene was newly added to extract o- and p-ethoxyaniline. After concentrating the aqueous layer, batch distillation was carried out at a reflux ratio of 5 to 10 using a rectification column with a reduced pressure of 15 mmHg and a theoretical plate number of 10 to obtain a purified m-PDA.
Fraction 93.9 g (removal yield in the distillation step 91.0
%) Was obtained. This m-PDA fraction showed a light transmittance of 96% at 450 nm with methanol as a control, and its purity was 99.99%.

[0025]

Industrial Applicability According to the present invention, highly pure m-PDA with little change over time, which has not been achieved by the prior art, can be obtained in a high yield, and an industrial production which is advantageous in terms of quality and economy is achieved. To be done. That is, according to the prior art which is outside the scope of the present invention, when obtaining a pure m-PDA, for example, as shown in Comparative Examples,
Although m-DNB containing an isomer is directly hydrogenated and rigorous rectification is carried out, it is an industrially disadvantageous production method because it is not a satisfactory technique in terms of quality and yield.

On the other hand, according to the present invention, as shown in Examples,
In the presence of a basic compound and a phase transfer catalyst, only the isomer in m-DNB is subjected to an alkoxylation reaction with a lower alcohol to convert it into a corresponding alkoxynitrobenzene, and then, after hydrogenation, fractional distillation is carried out, and it is compared with the conventional technique. It is much easier to obtain a high-yield and high-purity m-PDA, and by adding a phase transfer catalyst during the alkoxylation, it is possible to significantly reduce the amount of alcohol used. It is an industrially extremely advantageous invention compared to the prior art,
Its significance is great.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Teruyuki Nagata 30 Asmuta-cho, Omuta-shi, Fukuoka Mitsui Toatsu Chemical Co., Ltd.

Claims (2)

[Claims] 1. A crude m-dinitrobenzene containing o- and p-dinitrobenzene is reacted with a lower alcohol in the presence of a basic compound and a phase transfer catalyst to obtain substantially o.
Only the-, and p-isomers were selectively converted to the corresponding alkoxy nitrobenzenes and m- from the resulting reaction mixture.
A method for producing m-phenylenediamine, which comprises performing a hydrogenation reaction as it is without separating dinitrobenzene, and then separating the obtained m-phenylenediamine by distillation. 2. The method according to claim 1, wherein the lower alcohol is an aliphatic monohydric alcohol having 3 or less carbon atoms.