JP2764325B2 - 1,3-diamino-2,4-diisopropylbenzene and method for producing the same - Google Patents

Description

The present invention relates to 1,3-diamino-2,4-diisopropylbenzene and a method for producing the same.

This aromatic diamine can be used as a raw material for isocyanate, epoxy resin, bismaleimide and the like. In addition, there are various uses as various curing agents. For example, in addition to being used as a curing agent for isocyanates, it can also be used as a curing agent for epoxy resins and bismaleimides.

[Conventional technology]

The present inventors have newly found 1,3-diamino-2,4-diisopropylbenzene and a method for producing the same.

As the above-mentioned curing agents for isocyanates, particularly aromatic diamines used for urethane RIM (Reaction Injection Molding), 4,4'-diaminodiphenylmethane (MDA), 2,4 (or 2,6) ) -Diamino-3,5-diethyltoluene (DETDA) or 2,4 (or 2,6) -diamino-3 (or 5) -tert-butyltoluene (t-BuTDA).

Conventionally, aromatic diamines are generally synthesized by a nitration-reduction reaction of a benzene derivative. However,
According to this method, it is difficult to introduce a nitro group only at a target position due to the orientation and steric effects of substituents on benzene during the first nitration reaction, and in many cases, a mixture of several isomers is used. Becomes For example, 1,3-diamino-2,4-diisopropylbenzene synthesized in the present invention is also
It is hardly formed by the nitration-reduction reaction of m-diisopropylbenzene, and isomer 1,3-diamino-4,6
-Diisopropylbenzene is obtained as the main product (A. Newton; Journal of the American Chemical Society 65: 2434 (1973)).

[Problems to be solved by the invention]

When an aromatic diamine is used as various curing agents, particularly when used for urethane RIM, it is necessary to control the reactivity of the diamine by the steric effect of the substituent. For this purpose, a method of introducing an alkyl group into an aromatic diamine and controlling the reactivity by its substitution position or steric effect has been used. However, it is hard to say that the aromatic diamine currently used satisfies the above problems. For example, when a methyl group or an ethyl group (DETDA) is introduced into an aromatic diamine, the reactivity is high and the moldability is hindered. Bulk t-butyl group (t-BuTD
When A) or the like is introduced, curing is insufficient due to low reactivity, and the heat resistance and the like of the molded product are reduced. Thus, the present inventors have selected an isopropyl group as the alkyl group, and considered controlling the reactivity by the steric effect. When the reactivity is controlled by introducing an alkyl group into the aromatic diamine, it is necessary to substitute the alkyl group at the ortho position of the amine in order to suppress the reactivity of the amine. However, as described above, it is difficult to selectively introduce an amino group into a position where the alkyl group undergoes steric action by a usual nitration-reduction reaction of alkylbenzene.

[Means for solving the problem]

The present inventors have conducted intensive studies to solve the above problems, and as a result, completed the present invention.

That is, the present invention relates to a reaction of ortho-dihalogenobenzene with isopropyl halide and the like.
1,3-dihalogenated diisopropyl-1,2-dihalogenobenzene, reduction-dehalogenation, 1,3-
The present invention relates to diamino-2,4-diisopropylbenzene and a method for producing the same.

The feature of the 1,3-diamino-2,4-diisopropylbenzene of the present invention is that when used as a curing agent, particularly as a curing agent for urethane RIM, it has a moderate degree of properties as compared with known diamines used in RIM formulations. Shows reactivity (see use examples).

The feature in the production of the diamine derivative of the present invention is 1,3-
In order to selectively perform a nitration reaction at the 2,4-position of diisopropylbenzene, a halogen group which can be removed by a reduction reaction is introduced at the 5,6-position in advance.

Hereinafter, a specific method for producing 1,3-diamino-2,4-diisopropylbenzene of the present invention will be described.

First, the intermediate 3,5-diisopropyl-1,2-dihalogenobenzene can be synthesized by reacting ortho-dihalogenobenzene with isopropyl halide, isopropyl alcohol or propylene in the presence of an acid catalyst. In this reaction, when a 2 mol ratio isopropylating agent is used, a monoisopropyl form, a diisopropyl form,
A mixture of triisopropyl forms is obtained. When these mixtures are subjected to a rearrangement reaction in the presence of aluminum halide, 3,5-diisopropyl-ortho-dihalogenobenzene, which is a dialkyl compound, becomes a main product. in this way,
We have newly found that 3,5-diisopropyl-1,2-dihalogenobenzene is selectively produced by the diisopropylation reaction of ortho-dihalogenobenzene.

The ortho-dihalogenobenzene used includes ortho-difluorobenzene, ortho-dichlorobenzene,
Ortho-dibromobenzene and ortho-diiodobenzene can be used, but ortho-dichlorobenzene is industrially used.

The isopropyl halide used as the isopropylating agent includes isopropyl chloride, isopropyl bromide, and isopropyl fluoride. Other isopropylating agents include isopropyl alcohol and propylene.

The amount of these isopropylating agents to be used may be from 1.8 to 3 mol ratio, preferably from 2 to 2.5 mol ratio, based on the raw material ortho-dihalogenobenzene.

Acid catalysts in this alkylation-transfer reaction include:
Most preferably, aluminum chloride or aluminum bromide is used. The amount of the catalyst to be used is 0.5 to 50% by weight, preferably 0.5 to 10% by weight, based on the starting material dihalogenobenzene.

Further, if the alkylation reaction and the transfer reaction proceed in a stepwise manner, the catalyst may be used in combination without any problem.

As the alkylation catalyst, when isopropyl halide is used as the alkylating agent, in addition to aluminum chloride and aluminum bromide, ordinary Fridel-Crafts catalysts such as iron chloride, zinc chloride, stannic chloride, and titanium tetrachloride are used. it can. The amounts of these catalysts used are the same as described above.

Also, isopropyl alcohol as an alkylating agent,
When propylene is used, a protonic acid or a mixed catalyst of a protonic acid and a Lewis acid can be used as the catalyst.
At this time, as the protonic acid, hydrogen fluoride, sulfuric acid, phosphoric acid or an inorganic acid such as used in ordinary alkylation,
Organic acids can be used. The amount of these catalysts used is 0.5 to 5 equivalents, preferably 1 to 3 equivalents, based on the starting material dihalogenobenzene.

As the transfer reaction catalyst, it is desirable to use aluminum chloride or aluminum bromide. The amount of the catalyst used is 0.5 to 50% by weight, preferably 0.5 to 10% by weight based on the amount of the raw material.

The reaction temperature for carrying out the alkylation is from -10 to 100 ° C, preferably from 0 to 40 ° C.

A specific reaction method is that, when using an alkyl halide as an alkyl halide or isopropyl alcohol, a catalyst is added to ortho-dihalogenobenzene,
The catalyst may be added dropwise to the alkylating agent or added to a mixture of ortho-dihalogenobenzene and the alkylating agent. When propylene is used as the alkylating agent, a closed reactor is used, a catalyst is added to ortho-dihalogenobenzene, and then propylene is injected to carry out the reaction. In each case, the reaction proceeds rapidly and is completed in about one hour.

The temperature of the transfer reaction is 0 to 100 ° C, preferably 10 to 60 ° C.
Is good. If the reaction temperature is too low, the transition is slow, and if it is too high, halogen atoms are transferred and by-products are produced.
The time required for the transfer is about 1 to 20 hours.

After completion of the reaction, the reaction solution is neutralized, washed with water, and distilled to obtain an intermediate 3,5-diisopropyl-1,2-dihalogenobenzene. Further, the crude mixture after the reaction may be used as it is for nitration without any problem.

In the method for producing an intermediate dinitro compound by nitrating 3,5-diisopropyl-1,2-dihalogenobenzene, a usual nitrating agent can be used. As the nitrating agent, mixed acids, fuming nitric acid, nitric acid-acetic acid, and other known nitrating agents can be used. Using these nitrating agents, the reaction is carried out as follows.

That is, when nitrating with fuming nitric acid, it is used 3 to 12 times the molar amount of the raw material. When nitrating with a mixed acid, a mixed acid composed of a combination of nitric acid or nitrate such as sodium nitrate or potassium nitrate and concentrated sulfuric acid is used. At this time, nitric acid or nitrate: concentrated sulfuric acid is 2.2 to 5: 6
Used in a molar ratio range of 10.

The reaction temperature at the time of performing dinitration is desirably 50 to 120 ° C, preferably 50 to 80 ° C. If the reaction temperature is too low, the progress of dinitration is slow and dinitration is difficult to complete. Conversely, if the reaction temperature is too high, side reactions such as ipsonitration and oxidation of the isopropyl group occur simultaneously.

The reaction procedure may be either dropwise addition of the raw material into the nitrating agent or dropwise addition of the nitrating agent to the raw material. When using a mixed acid as the nitrating agent, use a mixed acid prepared in advance or mix the raw material and one acid,
Either method of dropping the other acid may be used.

After completion of the reaction, the reaction solution is diluted with ice water to precipitate crystals. If this is filtered and washed with water, an intermediate dinitro compound is obtained.

The method for reducing and dehalogenating the obtained dinitro compound is a method for reducing a normal nitro group to an amino group (for example, New Experimental Chemistry, Vol. 15, Oxidation and Reduction [II], Maruzen (1
977)) can be applied, but catalytic reduction is preferred industrially.

As a catalyst used for the catalytic reduction, generally used metal catalysts such as nickel, palladium, platinum, rhodium, ruthenium, cobalt and copper can be used, but palladium is industrially useful. These catalysts can be used in a metal state, but usually, carbon,
Barium sulfate, silica gel, alumina or the like is used by adhering to the surface of a carrier, and nickel, cobalt, copper or the like is also used as a Raney catalyst. The amount of the catalyst to be used is in the range of 0.01 to 10% by weight as a metal with respect to the raw material dinitro compound, usually 2 to 8% by weight when used in a metal state, and 0.1 to 0.1% when supported on a carrier. -5% by weight.

In the method of the present invention, dehalogenation is performed as a hydrogen halide, and the dehydrohalogenating agent used for the dehalogenation is an oxide, hydroxide, carbonate, bicarbonate of an alkali metal or alkaline earth metal. Salts, or ammonia or organic amines. For example, sodium hydroxide,
Examples include potassium hydroxide, calcium hydroxide, magnesium oxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, ammonia and triethylamine. The amount of the dehydrohalogenating agent to be used is usually 1 to 2 equivalents to the halogen atom.

The reaction solvent is not particularly limited as long as it is inert to the reaction, and includes alcohols such as methanol, ethanol, and isopropyl alcohol, glycols such as ethylene glycol and propylene glycol, diethyl ether, dioxane, tetrahydrofuran, and methyl cellosolve. Ethers are used. In some cases, hexane, aliphatic hydrocarbons such as cyclohexane, benzene,
Aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate and butyl acetate, and aprotic polar solvents such as N, N-dimethylformamide and N-methylpyrrolidone can also be used.

When the reaction progresses slowly when a reaction solvent immiscible with water is used, the reaction can be promoted by adding a phase transfer catalyst such as a quaternary ammonium salt or a quaternary phosphonium salt.

The amount of the solvent used is sufficient to suspend or completely dissolve the raw material, and is not particularly limited. Usually, the solvent is used in an amount of 0.5 to 10 times the weight of the raw material.

The reaction temperature is not particularly limited. Generally 20 ~ 200 ℃
And particularly preferably in the range of 20 to 100 ° C.

 Further, the reaction is carried out in a range from normal pressure to 50 atm.

The procedure for performing the reduction-dehalogenation reaction includes a method in which a reaction is performed by adding a dehydrohalogenation agent in advance, and a method in which a nitro group is reduced and then a dehydrohalogenation agent is added to perform a dehalogenation reaction. . In each case, the reaction proceeds smoothly, and the desired 1,3-diamino-2,4-diisopropylbenzene can be produced. However, in the former method, depending on the dehydrohalogenating agent to be used, the latter method may react with the dinitro compound as a raw material, so the latter method is preferable. The progress of the reaction can be monitored by the amount of hydrogen absorption or liquid chromatography analysis.

The reaction solution obtained by the above method is filtered or extracted to remove the catalyst and the inorganic salt. After concentration of the obtained solution, distillation or crystallization as an amine hydrochloride gives the desired 1,3-diamino-2,4-diisopropylbenzene.

[Action]

The 1,3-diamino-2,4-diisopropylbenzene of the present invention is an aromatic diamine that can be industrially used for various purposes. This compound is an aromatic diamine that has not been known so far and can be easily provided by the method of the present invention.

 Hereinafter, the present invention will be described in detail with reference to examples.

〔Example〕

A reaction flask equipped with a stirrer, thermometer and condenser was charged with 44.1 g (0.3 mol) of o-dichlorobenzene and charged at 5 ° C.
And 0.5 g of aluminum chloride was added. to this,
48 g (0.611 mol) of isopropyl chloride was added dropwise over 30 minutes. When the dropping of isopropyl chloride is started, hydrogen chloride gas starts to be generated. After the dropwise addition, the temperature was raised to room temperature, and the mixture was stirred for 15 hours. After the completion of the reaction, 30 ml of a 5% aqueous sodium hydroxide solution was added to neutralize the mixture, the aqueous layer was separated, and the organic layer was washed with 50 ml of water. The obtained organic layer was distilled under reduced pressure to obtain a colorless liquid 3,3.
5-Diisopropyl-o-dichlorobenzene was obtained.

Yield 58.9 g (74% yield, purity 87%) Boiling point 119-120 ° C (7 mmHg) 48 g (0.181 mol) of 87% pure 3,5-diisopropyl-1,2-dichlorobenzene obtained in this way was obtained. 31 g (0.462 mol) of nitric acid having a specific gravity of 1.52 previously cooled to 0 to 5 ° C.
It was dropped into a mixed acid of 215 g (2.08 mol) of 5% sulfuric acid over 10 minutes. After the dropwise addition, the cooling bath was removed, and the mixture was stirred at 50 ° C. for 3 hours. After completion of the reaction, the reaction solution was discharged into crushed ice, and the precipitated solid was collected by filtration. The obtained solid was washed with water until the washing liquid became neutral, and then sludged with 100 ml of isopropyl alcohol, dried, and light yellow crystals of 4,6-dinitro-3,5-diisopropyl-1,2- Dichlorobenzene was obtained.

Yield 41 g (71% yield, 99% purity) Melting point 82-84 ° C ¹ H-NMR (CDCl ³ , TMS) ppm δ: 1.37 (12H, t, 3-and 5-CH ( CH ₃ ) ₂ ) 2.5- 3.5 (2H, m, 3- and 5- CH (CH 3) 2) elemental analysis (%) C H N Cl calculated 44.88 4.39 8.72 22.08 analytical values 45.05 4.21 8.73 21.76 the resulting 4,6-dinitro -3 , 5-Diisopropyl-1,2
-40 g (0.125 mol) of dichlorobenzene were added to 50 ml of methanol, followed by 5 g of 5% -Pd / C2 (5 wt%).
Pressure reduction was performed under a hydrogen atmosphere at a reaction pressure of 5 to 23 kg / cm ² . When stirring was started, heat was generated, and the reaction temperature rose to 60 ° C. About one hour after the start of the reaction, the absorption of hydrogen stopped.
At this stage, 28% as a dehydrochlorinating agent-16.7 g of aqueous ammonia
(2.2eq.), And the reaction temperature was further increased by 10
A time reaction was performed. After the completion of the reaction, the mixture is filtered and Pd
/ C was removed. After adding 50 ml of toluene to the filtrate, the organic phase was separated and washed with water. The obtained solution was dried over potassium carbonate and concentrated, and the residue was distilled under reduced pressure to obtain 1,3-diamino-2,4-diisopropylbenzene as a yellow liquid.

Yield: 16.8 g (70% yield, 95% purity) Boiling point: 143 to 145 ° C (4 mmHg) ¹ H-NMR (CDCl ³ , TMS) PPm δ: 1.23 (6H, d, 2- or 4-CH ( CH ₃ )) _{2) 1.42 (6H, d,} 2- or 4-CH (CH 3) 2) 2.5~3.5 (2H, m, 2- and 4- CH (CH 3) 2) 3.53 (4H, br S, NH 2 × 2) 6.15 (1H, d, 6-H, J 6-5 = 8.0Hz) 6.80 (1H, d, 5-H, J 5-6 = 8.0Hz) elemental analysis (%) C H N calculated 74.95 10.48 14.57 Analytical value 74.16 10.24 14.46 Use Example Using the diamine obtained in the example and commercially available MDA, DETDA and t-BuTDA, the reactivity as a urethane curing agent was compared. The reaction was performed by dissolving 0.025 mol of various diamine compounds in dioxypropylene glycol to 100 parts,
To this solution was added 0.01 g of dibutyltin laurate as a catalyst, and to this was added an isocyanate (NCO group content 2 obtained by reacting a mixture of diphenylmethane diisocyanate and its modified carbodiimide with tripropylene glycol).
12.1 g of 6% prepolymer) is added and mixed with stirring.

As a method of expressing the reactivity, after performing the mixing and stirring for 5 seconds, the viscosity was measured with a rheometer (manufactured by Toyo Seiki).

 The results are shown in FIG.

〔effect〕

As described above, it has been found that 3,5-diisopropyl-1,2-dihalogenobenzene is selectively produced by the diisopropylation reaction of ortho-dihalogenobenzene. If this is used as a starting material, 1,3-diamino-2,4-diisopropylbenzene, which is difficult to be produced by ordinary dinitration-reduction reaction of m-diisopropylbenzene, can be efficiently synthesized. The obtained diamine has low reactivity due to the steric effect of the isopropyl group, and exhibits an appropriate curing rate when used as a curing agent, particularly as a curing agent for urethane RIM.

As a result, when the present diamine is used for urethane RIM, a film having good moldability and high physical properties can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a thickening curve of urethane using a diamine as a curing agent. In FIG. 1, reference numerals are as follows. 1. Diamine of the present invention MDA: 4,4'-diaminodiphenylmethane DETDA: 2,4 / 2,6-diamino-3,5-diethyltoluene t-BuTDA: 2,4 / 2,6-diamino −3 / 5-tret-butyltoluene

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-169569 (JP, A) JP-A-54-52036 (JP, A) JP-A-53-23936 (JP, A) JP-A-51-239 34119 (JP, A) JP-A-62-221657 (JP, A) JP-A-54-55526 (JP, A) JP-A-53-90228 (JP, A) (58) Fields investigated (Int. ⁶ , DB name) C07C 211/49 C07C 209/32 C07C 209/68 CA

Claims (2)

(57) [Claims] 1. A 1,3-diamino-2,4-diisopropylbenzene. 2. The method according to claim 1, wherein 3,5-diisopropyl-1,2-dihalogenobenzene obtained by reacting ortho-dihalogenobenzene with isopropyl, propylene or isopropanol is subjected to dinitration and reduction-dehalogenation. A method for producing 1,3-diamino-2,4-diisopropylbenzene.