JPH0219358A - Production of 4,4'-methylenedianiline - Google Patents

Abstract

PURPOSE:To obtain the title compound useful as an intermediate for producing polyurethane while improving reaction rate and selectivity by making water content of a dehydrated condensate obtained from aniline and a methylenating agent into <=a specific weight and heating the condensate in the presence of a specific zeolite catalyst. CONSTITUTION:Aniline is condensed with a methylenating agent (e.g. aqueous solution of formalin or paraformaldehyde) through dehydration, then water content in the dehydrated condensate is made into <=0.1wt.% and the condensate is heated in the presence of a zeolite catalyst such as dealuminated Y type zeolite or fluorinated dealuminated Y type zeolite to give 4,4'-methylenedianiline. In the reaction the molar ratio of aniline/the methylenating agent is 2-50, preferably 4-20. A crude dehydrated condensate is obtained by an ordinary dehydration method, further dehydrated with a drying agent or by distillation with an azeotropic agent of water such as benzene into <=0.1, preferably <=0.05wt.% water content and used.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for producing 4,4'-methylene dianiline from aniline and a methylenating agent. The present invention relates to a method for producing 4,4'-methylene dianiline by reducing the moisture content of a dehydrated condensate obtained from a methylenating agent and a methylenating agent to 0.1% by weight or less.

[Conventional technology]

4.4'-Methylene dianiline is most useful as an intermediate in the production of high purity methylene diisocyanate as a raw material for polyurethane. As one method for its production, a method has been disclosed in which aniline and formaldehyde are dehydrated and condensed, and this dehydrated condensate is heated in the presence of a zeolite catalyst (
(Japanese Patent Publication No. 55-34138, Japanese Patent Publication No. 56-14104, Japanese Patent Publication No. 58-27261).

In these production methods using zeolite catalysts, in addition to 4,4'-methylene dianiline, 2,4'-
Four types are produced: methylene dianiline, polymethylene polyphenylaniline, and an intermediate.

However, since the selectivity for these four types of products is low, there are problems in that the yield of the target 4,4'-methylene dianiline is poor and the reaction rate is slow.

[Problem to be solved by the invention]

The purpose of the present invention is to solve the above problems.

The object of the present invention is to propose a method for producing 4,4'-methylene dianiline that improves the selectivity and reaction rate of 4,4'-methylene dianiline as the target product.

[Means to solve the problem]

In the present invention, aniline and a methylenating agent are dehydrated and condensed, and this dehydrated condensate is heated in the presence of a zeolite catalyst to produce 4,4'
- A method for producing methylene dianiline, characterized in that a dealuminated Y-type zeolite or a fluorinated dealuminated Y-type zeolite is used as a zeolite catalyst, and the water content in the dehydrated condensate is 0.1% by weight or less. This is a method for producing 4,4'-methylene dianiline.

In the method for producing 4,4'-methylene dianiline of the present invention, as a first step, aniline and a methylenating agent are subjected to dehydration condensation to obtain a dehydrated condensate.

As the methylenating agent to be reacted with aniline, a methylenating agent containing formaldehyde can be used, and examples thereof include an aqueous formalin solution, paraformaldehyde, trioxane, and dialkoxymethane such as dimethoxymethane. Among these, it is particularly preferable to use formalin aqueous solution, paraformaldehyde and trioxane. The molar ratio of aniline and methylenating agent used in this reaction is 2 to 50,
The number is preferably 4 to 20.

The reaction is preferably carried out in a liquid phase, in which case the reaction may be carried out without a solvent, but it is also possible to carry out the reaction using a solvent. Examples of solvents include aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as pentane, hexane, heptane, octane, nonane, decane, cyclohexane, and decalin; and carbon halides such as dichloromethane, chloroform, and carbon tetrachloride. Examples include hydrogen.

The reaction method is to mix aniline and a methylenating agent without a catalyst to form a condensate, and then separate the aqueous phase.

At this time, the reaction is carried out at a humidity of usually lO to 200°C, preferably 20 to ioo°C, a pressure of usually normal pressure to 30 kg/d, preferably normal pressure to 5 kg/cd, usually 0.1 to 100 hours, preferably 0. React for 5 to 40 hours. The aqueous phase is separated from the condensate thus produced by a general dehydration method such as vacuum suction using a rotary evaporator or other dehydration equipment to obtain a crude dehydrated condensate. Furthermore, the crude dehydrated metal product is dehydrated by an advanced drying method such as adding a desiccant such as Molecular Sieve 3A or an azeotrope of water such as benzene and distilling it off to remove water by 0.1 weight. % or less, preferably 0.05% by weight or less.

The dehydrated condensate contains C, H5N=CH.

C, H, NHCH, NHCGH.

C, H, NHCH, C, H, NH2 C, H, NH (CH, CGH4NHhCH, C, H4N
H.

(x: 1 or more), and the position of each substituent on the benzene ring is not fixed.

Next, in the second step, the dehydrated condensate obtained above is heated in the presence of a zeolite catalyst to produce the desired 4,4'-methylene dianiline.

The zeolite catalyst used in the present invention is dealuminated Y
type zeolite or fluorinated dealuminated Y type zeolite.

Y-type zeolite, which is the bone core of these zeolites, is 5
io2/A12o, (molar ratio) is 2 to 5, and it is a three-dimensional framework structure consisting of 5in4 and A104 tetrahedra that share oxygen atoms with each other, and the electrical balance of each tetrahedron containing aluminum is is balanced by the presence of cations in the aluminosilicate skeleton.

Dealuminated Y-type zeolite is a dealuminated Y-type zeolite, and is a product of dealuminated Y-type zeolite.
l,03 (molar ratio) is 5.5 to 20, and the crystal structure is almost the same as Y-type zeolite, but the size of the unit cell is generally contracted by about 1 to 2%. Examples of exchange cations include protons, alkaline earth cations, rare earth cations, and transition metal cations, with protons being preferred.

Y-type zeolite generally has higher acid strength, heat resistance, and acid/base resistance as the SiO,/A1203 (mole ratio) is higher; Because type zeolite is not produced.

After producing Y-type zeolite with a raw material composition having a SiO□/Aizoa (molar ratio) of 2 to 5, dealumination is performed.

While maintaining the basic crystal structure of Y-type zeolite, S
iO,/Al□0. (molar ratio) is being increased.

As such dealuminated Y-type zeolite, commercially available products can be used, such as TSZ-330 manufactured by Tosoh Corporation.
HUA, TSZ-350) IUA, rsz-360
Examples include HUA (both are trademarks). In addition, it can be prepared from Y-type zeolite, for example, by the following methods (1) and (2).

■The first method is to remove aluminum by EDTA in the liquid phase.
For example, proton exchange type Y zeolite was added to a solution containing 1 to 10 times the weight of distilled water and 0.1 to 1 times the weight of EDTA and left for 10 to 200 hours. After that, add 0.5 to 3 times the weight of 1 to 3 NHC1 dropwise, heat to 100°C while stirring, and after stirring for 1 to 10 hours, separate the same phase by filtration or centrifugation, and wash with the drained water. This is followed by firing at 300 to 700°C for 1 to 10 hours in air or under a nitrogen atmosphere.

■The second method is a steam treatment method under high temperature, for example, for proton exchange type Y zeolite in a fixed bed,
10-100 with nitrogen in the temperature range of 0-900℃
After treatment for 1 to 10 hours using steam diluted to Alternatively, proton exchange type Y zeolite is heated in a fluidized bed at normal pressure or pressurized conditions at 600 to 900°C.
After treatment for 1 to IO hours using steam diluted 10 to 100% with nitrogen at a temperature range of about 10 to 10
This is a method of washing with 0 times the weight of distilled water and firing in air or under a nitrogen atmosphere at 300 to 700°C for 1 to 10 hours.

Fluorine-treated dealuminated Y-type zeolite is obtained by fluorine-treating the above-mentioned dealuminated Y-type zeolite to bond fluorine within the crystal structure.
At□0. (molar ratio) is 5.5 to 20, and the fluorine content is 0.1 to 30% by weight. The exchanged cation is a proton,
Examples include alkaline earth cations, rare earth cations, and transition metal cations, but protons are preferred. Proton exchange type fluorine treated dealuminated Y-type zeolite is X in Table 1.
It has a line diffraction pattern and has a different crystal structure from dealuminated Y-type zeolite and fluorine-treated dealuminated Y-type zeolite.

Table 1 Diffraction angle (2θ°) Relative intensity 6.4±0.2
90~10010.4±0.2
60~8012.1±0.2
40~7014.8±0.2 1~3
016.0±0.2 70-9019.
1±0.2 10~4020.8±0.
2 20~5023.3±0.2
1~2024.2±0.2
20~5025.2±0.2 1~30
27.6±0.2 10-30 Note) X-ray diffraction analysis is measured using Cuka radiation.

However, the relative intensity of the diffraction line of 6.4±0.2 is assumed to be 100.

The fluorine-treated dealuminated Y-type zeolite can be obtained by contacting the above-described dealuminated Y-type zeolite with a fluorine-containing compound. Examples of fluorine-containing compounds include ammonium fluoride, tetramethylammonium fluoride, tetraethylammonium fluoride, methylammonium fluoride, dimethylammonium fluoride, and other ammonium fluoride compounds; sodium fluoride, hydrogen fluoride, boron trifluoride, and monofluoride. Acetic acid, CFCI, CF, C1
□.

CF3Cl, CF,, CHF2Cl, CHF,,
CFCI, -CFCI,,CF2C1-CF,C1,C
F2Cl-CF,, CF, -CF,, C1,-CF
, C.I.

CI+, -(JIF,, CF, Or, CF, Br-
CF, Or, HF, SF4. SF,.

Examples include fluorine compounds such as BF2. As a fluorine treatment method, for example, dealuminated Y-type zeolite is treated with 0
．． 0.01 to 30% by weight of an aqueous solution of a fluorine-containing compound.
After immersion for 01 to 24 hours, the solid phase is separated by filtration or centrifugation and incubated in air or under a nitrogen atmosphere for 300 to 24 hours.
Fire at 800°C. Another method is to treat dealuminated Y-type zeolite with a gaseous fluorine-containing compound and
Specifically, dealuminated Y-type zeolite is charged into a reaction tube, the reaction tube is brought to a predetermined temperature, and then the gaseous fluorine-containing compound is for a predetermined time (e.g. 0.1
- 10 hours, preferably 0.5 to 2 hours) to contact the dealuminated Y-type zeolite with the gaseous fluorine-containing compound described above, after which any fluorine remaining in the reaction tube may be removed. This method removes the contained compounds by replacing them with an inert gas such as nitrogen, or by degassing them under reduced pressure.

Although the zeolite catalyst used in the present invention can be used as it is, it is preferably pretreated with heat in order to carry out the reaction efficiently. As such a heating pretreatment method, water in the zeolite is dehydrated by heating at a temperature of usually 500° C. or higher, preferably 650° C. or higher, and lower than the temperature at which the crystal structure of the zeolite used is destroyed.

The catalyst is preferably in powder or pellet form;
The catalyst concentration is between 1 and 200% by weight, preferably between 5 and 50% by weight, based on the reaction mixture.

In the second stage reaction method of the present invention, a zeolite catalyst is added to the dehydrated condensate obtained in the first stage with a water content of 0.1% by weight or less, and the temperature is usually 20 to 300°C, preferably 30 to 1.8°C.
Conditions: 0°C, more preferably 40 to 140°C, pressure usually normal pressure to 30 kg/d, preferably normal pressure to 5 kg/d, 1:t O, 1 to 20 hours, preferably 0.2 to 5 hours. 4'-methylene dianiline can be produced each month by reacting with At this time, it is desirable that the aniline added in excess in the first step coexists in the reaction system.

The reaction method according to the above production method may be a batch method using a liquid phase, a semi-batch method using a liquid phase, or a continuous method using a fixed bed.

〔Effect of the invention〕

According to the present invention, the water content of the dehydrated condensate is reduced to 0.1% by weight or less, and the reaction is carried out using a zeolite catalyst with high reaction efficiency, so that the target product 4,4'-methylene dianiline [Example J] Examples of the present invention will be described below.

Example 1 400.4 g of aniline and 69.8 g of 37% formalin
& are mixed at room temperature and stirred for 5 hours. After that, after leaving it overnight, separate the aqueous layer and use a rotary evaporator at 50℃ for 30 minutes.
N by dehydration for 4 hours under 0m5+Hg vacuum,
A N'-diphenylmethylene diamine/aniline mixture was obtained. The structure was confirmed by 13CNMH.5 As a result, it was found that 100% of formaldehyde had reacted to form N,N'-diphenylmethylenediamine.

The water content of this dehydrated composite was 0.18% by weight.

This was dehydrated using molecular sieve 3A to reduce the water content to 0.0.
It was bound at 5% by weight.

Next, in a 25" Peng Q flask equipped with a reflux condenser, 2.5 g of N,N'-diphenylmethylenediamine/aniline mixture and a proton-exchange dealuminated Y-type zeolite preheated at 600°C for 3 hours at room temperature under N2 were added. T.S.Z.
-330HUA (manufactured by Tosoh Corporation, trademark, 5i02)
/A1203 (mole ratio) = 5.5-6.5) 0.50g
was added, and the reaction was carried out at 120°C for 3 hours. After cooling to room temperature, the reaction mixture was poured into a mixed system of 100 mQ of diethyl ether and 100 mQ of a 10% sodium hydroxide aqueous solution, and the organic layer was analyzed by GC and GPC. The results are shown in Table 2.

Examples 2 to 6 Examples 2 to 6 were conducted in the same manner as in Example 1, except that the catalyst, pretreatment conditions, reaction temperature, and reaction time were changed as shown in Table 2. Table 2 shows the results.
Shown below.

Comparative Examples 1 to 2 The same procedure as in Example 1 was carried out except that the dehydrated condensate was used as it was without being dehydrated with a molecular sieve (water content was 0.18% by weight), and the temperature was changed as shown in Table 2. I went. The results are shown in Table 2.

Claims (1)

[Claims] (1) In a method for producing 4,4'-methylene dianiline by dehydrating and condensing aniline and a methylenating agent and heating the dehydrated condensate in the presence of a zeolite catalyst, dealuminated Y-type zeolite or A method for producing 4,4'-methylene dianiline, which comprises using fluorine-treated dealuminated Y-type zeolite and controlling the water content in the dehydrated condensate to 0.1% by weight or less.