JPS6153247A - Preparation of aminophenol derivative - Google Patents

Abstract

PURPOSE:To produce an N-mono(sec-alkyl)-substituted m-aminophenol useful as a synthetic intermediate of a color-developing agent for heat-sensitive or pressure-sensitive recording paper, in high yield and purity, by alkylating m-aminophenol with a specific ketone compound by catalytic reduction. CONSTITUTION:The objective compound of formula II (R<1> and R<2> are 1-11C alkyl or together form a 4-5C polymethylene) can be prepared by reacting m- aminophenol with a ketone compound of formula I (R<3> and R<4> are 1-11C alkyl or a group which forms 1-11C alkyl during the reaction), in the presence of platinum- or palladium-based catalyst (preferably platinum slightly poisoned with a sulfur compound and supported on a carrier), under hydrogen pressure of 5-60kg/cm<2>, preferably 10-40kg/cm<2>, at 80-230 deg.C, preferably 110-200 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a new method for producing N-monosubstituted m-aminophenol compounds.

General formula (1) of the present invention (wherein R1 and RM are linear chains having 1 to 11 carbon atoms or "
represents a branched alkyl group, or R1 and R8 together represent a polymethylene group having 4 to 5 carbon atoms;
The N-monosubstituted m-aminophenol compound represented by ) is a compound useful as an intermediate for synthesizing a color forming agent used in the production of thermal recording paper or pressure-sensitive recording paper.

More specifically, the present invention provides m-aminophenol with the general formula (U)C, where R' and R' are R'', R''t and L*R1 is also L.
< represents a group that can change during the reaction to R@, and R1゜R3
represents the above-mentioned window taste, and is characterized by catalytic reduction alkylation with a ketone compound represented by
) The present invention relates to a method for producing an N-monosubstituted m-aminophenol compound.

(b) Conventional technology Regarding N-monosubstituted m-aminophenols.

Some compounds are already known in which the substituent is a primary alkyl group, and compounds in which the substituent is a cyclohexyl group are also known.

Therefore, the compounds of the present invention are N-cyclohexyl-m-
It is a new compound except for aminophenol.

General methods for synthesizing N-monosubstituted m-aminophenol compounds include the following A and B.

Method C is known.

Here, R represents an alkyl group or a residue of an alkylating agent.

Method A is a method in which resorcinol and amine R-NH2 are reacted at 1150 to 200°C in the presence of an acidic catalyst, and method B is a method in which resorcinol and amine R-NH2 are reacted at 1150 to 200 °C.
This is a method in which either aminophenol or amine R-NH2L is used as a hydrochloride and the reaction is carried out at 160 to 200°C, but in both methods, in addition to unreacted compounds, N,N''-dialkyl- Due to the presence of by-products such as m-phenyl diamine compounds, a complicated separation step is required to separate the N-monosubstituted m-aminophenol compound, and the yield is also not high.

Method C is a method in which m-aminophenol is reacted with an alkylating agent R-X, but at the end of one reaction, in addition to unreacted compounds, byproducts such as N,N-dialkyl-m-7 minophenol compounds are produced. A complicated purification process is required to produce it, and the yield is quite low. Also, when method C is applied when R is a secondary alkyl group, a large amount of olefin is produced, and the yield may be even worse. .

(c) Problems to be solved by the invention General formula (N
Attempts to produce -monosubstituted m-aminophenol compounds generally have low yields and produce various by-products, requiring complicated purification steps to extract the target product.

In addition, when synthesizing the N-monosubstituted m-aminophenol represented by the general formula (1,,) of the present invention, depending on the type of secondary alkylamine and secondary alkylating agent as reaction raw materials, it is difficult to obtain There are restrictions.

The present invention is a method for producing 9N-monosecondary alkyl-substituted m-aminophenol, which could not be synthesized satisfactorily using conventional techniques, with high purity and high yield by catalytic reduction alkylation of m-aminophenol with a ketone. .

(d) Means for solving the problem In the ketone compound represented by the general formula (II) used in the reductive alkylation method of the present invention, R3°R4 is Rx,
When R1=, R'' and R'' represent a linear or branched alkyl group having 1 to 11 carbon atoms, or R'' and R2 together represent a polymethylene group having 4 to 5 carbon atoms. Examples of @R1,R'' include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, n-pentyl, l-pentyl, neopentyl, 2-
Methylbutyl, n-hexyl, 2-ethylbutyl, 4-
Methylpentyl, n-hebutyl, 2-methylhexyl,
Examples include n-octyl, n-nonyl, n-decyl, n-undecyl groups, and when R1 and R8 are combined, a tetramethylene group and a pentamethylene group.

R'' in general formula (II), R4 is R1 or R2
Examples of such a group include a vinyl group, a 2-propenyl group, and a 2-methyl-2-hydroxypropyl group.

2-methyl-2-methoxypropyl group, 4-methyl-3
-pentenyl group, etc.

Specific examples of the ketone compound of general formula (II) include the following.

Acetone, 2-butanone, 3-pentanone, 2-pentanone, 3-methyl-2-butanone, 2-hexanone, 4
-Methyl-2-pentanone, 4-heptanone, 2-methyl-3-hexanone, 3-heptanone, 2-hebutanone, 5-methyl-2-hexanone, 4,4-dimethyl-2
-Pentanone, 4-methyl-2-hexanone, 5-methyl-3-hexanone, 2-octanone.

3-octanone, 5-methyl-3-heptanone, 6-methyl-2-heptanone, 4-ethyl-2-hexanone,
6-methyl-3-heptanone, 4-octanone.

6-Methyl-4-heptanone, 2-nonanone, 5-nonanone, 2,6-dimethyl-4-heptanone, 4-methyl-2-octanone, 3-nonanone, 5-ethyl-3-heptanone, 7-methyl-5 -Octanone, 2-decanone, 3-decanone, 4-decanone, 2-undecanone, 6
-undecanone, 2-dodecanone, 2-tridecanone,
7-tridecanone, methyl vinyl ketone, diacetone alcohol, 4-methoxy-4-methyl-2-pentanone, 6-methyl-5-hepten-2-one, cyclopentanone, cyclohexanone, etc.

To carry out the reductive alkylation reaction of the present invention, m-aminophenol, the ketone compound 1 of general formula (11), a reaction solvent, and a catalyst are placed in an autoclave, and the mixture is reduced with hydrogen under pressure and heat.

The ketone compound is used in an amount of 1 mol or more, preferably 1 to 2 mol, relative to m-aminophenol.

Reaction solvents include alcohols such as methanol, ethanol, isopropanol, 2-methoxyethanol, and 2-ethoxyethanol, ethers of polyhydric alcohols such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether, dioxane, dimethylformamide, and toluene. etc. can be used. It is also possible to use the ketone compound used as a solvent.

The catalyst is platinum or palladium-based, especially platinum on a carrier is effective, and a platinum catalyst slightly poisoned with a sulfur compound is preferred.

The reaction is carried out using 5 to 60 kg/llj of hydrogen, preferably 10
It is carried out at a temperature of 80-230°C, preferably 110-200°C, under a pressure of ~40 kg/at. When the theoretical amount of hydrogen is absorbed and consumed, a state is reached where hydrogen is no longer absorbed and unreacted m-aminophenol also disappears.

To isolate the N-monosubstituted m-aminophenol compound, the contents of the autoclave are filtered to remove the catalyst, the solvent and excess ketone are removed by distillation or steam distillation, and then treated with water or boiling water. to remove soluble substances. For further purification as required, methods such as recrystallization from toluene, n-hexane, etc. or vacuum distillation can be employed.

(e) Actions and effects Since this reductive alkylation reaction proceeds quantitatively, the yield and purity of the N-monosubstituted m-aminophenol compound are extremely high, and therefore this product is not removed from the reaction system. Alternatively, it is possible to proceed to the next step without purification, which is an industrially advantageous method.

Further, by this reductive alkylation method, it is possible to quantitatively obtain an N-monosubstituted m-aminophenol compound in which the α-position carbon of the alkyl group bonded to nitrogen is a tertiary carbon.

(f) Example Next, the present invention will be explained in more detail with reference to Examples.

Example 1 100% ethanol was added to a 500ee stirring autoclave.
g, acetone 48.8 g, m-aminophenol 76,
After charging 4 g and 2 g of 5% platinum/carbon catalyst and replacing with hydrogen, the temperature was raised to 120°C and reductive alkylation was performed at a hydrogen pressure of 20 kg/e-. By injecting hydrogen several times in response to hydrogen consumption, a 1 molar ratio of hydrogen to m-aminophenol was consumed. After cooling to 60° C., the contents were filtered to remove the catalyst, and after washing with a small amount of ethanol, most of the ethanol was recovered from the filtrate by distillation. After adding 800 cc of water to the distillation residue and stirring, the crystals were filtered, washed with water, and dried.

N-1-methylethyl-m-aminophenol xo4.
8 g (melting point 99-100°C, LC purity 98.5%) was obtained as white crystals. This was recrystallized from toluene to obtain white crystals with a melting point of 100.5 to 101.5° C. The single element analysis value and mass spectrum value agreed with the calculated value.

Example 2゜ 40g of ethanol, 25.6g of diacetone alcohol.

21.8 g m-aminophenol, 1 g glacial acetic acid and 5%
Using 0.8 g of platinum/carbon catalyst, reductive alkylation, post-treatment and recrystallization were carried out in the same manner as in Example 1 to obtain 25 g of N-1-methylethyl-m-aminophenol.

The melting point was 100.5-101.5°C.

The structure of this compound was confirmed from FD mass spectrum and NMR spectrum.

Example 3 The reaction was carried out in exactly the same manner as in Example 2 except that 28.6 diacetone alcohol methyl ether was used instead of diacetone alcohol.

26 g of N-1-methylethyl-m-aminophenol, which was exactly the same as in Example 2, was obtained. The melting point was 100.5-101.5°C.

Example 4゜100g of methanol, 60.6g of 2-butanone, 1m-aminophenol? 6.4. After reductive alkylation was performed at 120° C. in the same manner as in Example 1 using 2 g of a 5% platinum/carbon catalyst, the catalyst was filtered off, methanol was distilled off, and the mixture was dehydrated and dried. 114 g of N-1-methylpropyl-m-aminophenol was obtained as a pale yellow viscous liquid. This was distilled under reduced pressure to a boiling point of 154-156℃, 79℃, 5mmHg.
110 g of pale yellow viscous liquid was obtained.

Example 5゜Methanol 50g, 3-pentanone 69.3g, m-
Reductive alkylation was carried out with hydrogen at 120°C using 76.4 g of aminophenol and 1 g of 5% platinum/carbon catalyst. After completion of the reaction, the catalyst was filtered, methanol was distilled off, and the mixture was stirred with 800 cc of water. The oil was separated and dried. 125 g of pale yellow viscous liquid was distilled under reduced pressure to obtain 117 g of N-1-ethylpropyl-rfl-aminophenol with a boiling point of 164-166°C/10.5 mdg.

When left to stand, it solidified into white crystals with a melting point of 40-41°C, and an LC purity of 99.3%.

Example 6゜Methanol 100g, 2-pentanone 72.4g, m
Reductive alkylation was carried out with hydrogen at 120° C. using 76.4 g of -aminophenol and 1 g of 5% platinum/carbon catalyst. After removing catalyst and methanol.

After stirring with 800 cc of water, the oil was separated and dehydrated.

Distilled 123.2g of oil under reduced pressure to obtain a boiling point of 162-16
117 g of N-1-methylbutyl-m-aminophenol (110 mdg at 4°C) was obtained as a pale yellow viscous liquid. L.C.
Purity was 98.9%.

Example 7 In place of 2-pentanone in Example 6, 72.4 g of 3-methyl-2-butanone was used to carry out reductive alkylation in the same manner. After removing the catalyst and methanol, washing with water and drying, 120.2 g of N-1,2-dimethylpropyl-
m-aminophenol as white crystals (m point 65.5-67
℃, LC purity 98.5%). White crystals obtained by recrystallizing this from a mixed solvent of toluene and n-hexane had a melting point of 67 to 68°C.

Example 8゜100g of methanol, 8% of 4-methyl-2-pentanone
4.1 g, m-aminophenol 76.4 g and 5%
The reaction was carried out in the same manner as in Example 6 using 1 g of platinum/carbon catalyst and post-treated. The obtained 126 g of oil was distilled under reduced pressure to obtain 121s tt of N-Ll, 3-dimethylbutyl-m-aminophenol, which is a pale yellow viscous liquid with a boiling point of 143 to 147° C. and 74 mmHg.

Example 9゜100g of methanol, 68.5g of 4-heptanone, m
Reductive alkylation with hydrogen was carried out at 180° C. using 54.6 g of -aminophenol and 1 g of a 5% platinum/carbon catalyst, the catalyst was filtered off, methanol was distilled off, and steam distillation was further carried out. The oil was separated, washed with water, dried, and then distilled under reduced pressure to a boiling point of 14"l to 151"C/4mtn.
N-1-propyl butyl, a pale yellow viscous liquid of Hg
95 g of nl-aminophenol was obtained.

Example 10゜Reacted in the same manner as in Example 9 using 100 g of methanol, 85.4 g of 2,6-dimethyl-4-hebutanone, 54.6 g of m-aminophenol and 1 g of 5% platinum/carbon catalyst, and post-treated. did. After dehydration and drying, N is distilled under reduced pressure to form a pale yellow viscous liquid with a boiling point of 155-158°C/4 mdg.
110 g of -1-isobutyl-3-methylbutyl-m-aminophenol was obtained.

Example 11゜100g of methanol, 56.5g of cyclohexanone,
Reductive alkylation with hydrogen was carried out at 130°C using m-aminophenol 54.6E and 1 g of 5% platinum/carbon catalyst, and! After filtering off the soot, methanol was distilled off, and steam distillation was further performed. The contents were cooled, and the crystals were filtered and dried. 92.7 g of crystals were recrystallized from a mixed solvent of toluene and hexane to obtain N-
88 g of cyclohexyl-m-aminophenol was obtained as white crystals.

Example 12 The same procedure as in Example 11 was carried out except that 50.5 g of cyclopentanone was used instead of cyclohexanone. The obtained oil was distilled under reduced pressure to a boiling point of 152-156'C/6.
115 g of N-cyclopentyl-m-aminophenol was obtained as a pale yellow viscous liquid of N+sHH. The melting point is about -
The temperature was 15°C.

Claims (1)

[Claims] m-aminophenol is represented by the general formula (II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, R^3, R^4 are R^1, R^2 or R^1
Alternatively, R^2 represents a group that can change during the reaction. R^
1. R^2 represents a linear or branched alkyl group having 1 to 11 carbon atoms, or R^1 and R^2 together represent a polymethylene group having 4 to 5 carbon atoms. ) General formula (I) ▲Mathematical formulas, chemical formulas, tables, etc. are available▼(I) Process for producing an N-monosubstituted m-aminophenol compound characterized by catalytic reductive alkylation with a ketone compound represented by .