JPS5848588B2 - Method for producing fluoran compounds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a fluoran compound [represented by general formula (4)] useful as a coloring agent for pressure-sensitive copying paper and heat-sensitive recording paper, and more specifically relates to a method for producing a fluoran compound [represented by general formula (4)]. 1] and a phthalide compound, which is an intermediate product obtained from a compound represented by the general formula [odor]; a method for producing a fluoran compound, which is characterized by once taking out a phthalide compound [represented by the general formula] and then subjecting it to intramolecular ring closure. It is.

(Here, R1 and R2 represent a hydrogen atom, a lower alkyl group, a hydroxyethyl group, a β-chloroethyl group, an aralkyl group, a cycloalkyl group, a phenyl group which may have a substituent, and R1 and R2 are mutually Even if they are connected to form a heterocycle!

R3 and R4 represent a hydrogen atom or a lower alkyl group or an aralkyl group, R5 and Hiki represent a hydrogen atom or a methyl group or an ethyl group, R7 represents a hydrogen atom or a lower alkyl group, an aralkyl group, or an acyl group; R8 represents a hydrogen atom or a lower alkyl group, an aralkyl group, or an acyl group; It represents a hydrogen atom or a lower alkyl group, and n represents an integer value of 1 to 5.

) If it is attempted to directly obtain the fluoran compound represented by the general formula 20 by the conventionally used method shown by the following formula, the following problems arise.

(Here, Rl, R2, R4, R5, R6, R7, R6n
is the same as in general formula (■) or general force (1).

)1) If the reaction is heated to complete the reaction in a short time, a large amount of impurities will be produced, causing a decrease in yield, and the treated water will become highly concentrated colored water, posing a major problem in wastewater treatment.

i1) If the reaction is carried out at a low temperature to suppress the formation of impurities, it will take a long time to produce fluorane.

111) In particular, when R8 is a hydrogen atom, a bislactone type compound is produced in the conventional method, which causes a decrease in the yield of the fluoran compound.

This is clear from the following experimental facts.

Compound (I) and compound (II) (R=H, CH3
) in sulfuric acid at 90'C for 4 hours and at room temperature (approximately 2
The product compound, i.e., the phthalide compound (IID1, fluoran compound (5), bislactone compound (V)) produced when the reaction was carried out at 5°C for 48 hours was developed on a thin layer of silica gel (developing solvent benzene: ethyl acetate 3:1). However, since a clear difference was observed, the results determined based on this are shown in Table 1.

As can be seen from Table 1, bislactone compounds are produced under all reaction conditions, and it can be seen that it takes a long time to ring-close all the phthalide compounds at room temperature at R=CH3 where less bislactone compounds are produced.

The structural formula of the bislactone type compound was determined as a result of isolation analysis.

As a result of research to solve these problems, the manufacturing method of the present invention has been developed.

Next, a typical manufacturing method of the present invention will be described.

Equimolar moles of a benzophenone derivative represented by the general formula (2a) and a diphenylamine derivative represented by the general formula (2) are mixed in 70% or more acidic acid at 200 to 50°C, optionally under water cooling (20°C or less) for 3 to 24 hours. A phthalide compound represented by the general formula can be obtained by reacting for a period of time, pouring the reaction solution into a large amount of ice water, and neutralizing with an aqueous alkaline solution.

At this time, the treated water is only lightly colored.

After recrystallization and purification, intramolecular closure is performed by dissolving it in 80% or more acidic acid at room temperature or by heating.

At this time, since there is no unreacted penzophenone, no bislactone compound can be produced even if heated.

A fluoran compound is obtained by pouring this reaction solution into ice water and neutralizing it with alkaline water.

In addition, if either R3 or R4 of the phthalide compound is a hydrogen atom, intramolecular ring closure occurs simply by heating the phthalide compound to a temperature higher than its melting point, which is an excellent method as there is no need to use a condensing agent such as sulfuric acid. It is.

Next, the manufacturing method of the present invention will be explained in detail using Examples, but the present invention is not limited unless the gist of the present invention is exceeded.

Example 1 Preparation of 3-pyrrolidino-6-methyl-7-aniIJ/fluoran 2-(4'-pyrrolidino-27-hydroxybenzoyl)benzoic acid 24.88S' and 4-methoxy2-methyldiphenylamine 17 ．． 0 4? Concentrated sulfuric acid 24
Dissolve in OS' and stir at 20°C for 5.5 hours.

Pour the reaction solution into a large amount of ice water, collect the crystals, and wash with water.

The precipitated crystals are again dispersed in water and neutralized with a 3% aqueous sodium carbonate solution.

After collecting and washing the precipitated crystals with water, the precipitated crystals are extracted with 500 ml of chloroform, washed with 100 M of a 3% aqueous sodium carbonate solution, then washed with water, and after drying with sodium sulfate, the chloroform is distilled off under reduced pressure.

The obtained red crystals were mixed with 20rrt of isopropyl alcohol.
3(47-pyrrolidino-2'-hydroxyphenyl)-3-(5'-anily47-
32.58S' of pale reddish-purple crystals of methyl-27-methoxyphenyl)phthalide are obtained.

Crude yield 80. 30.4 g of white crystals, melting point 184°C after recrystallization in 5% 0 acetonitrile.

The obtained crystals are dissolved in an oil bath while maintaining the internal temperature at 185±2° C. and stirring gently.

Foaming is observed along with dissolution.

After the foaming stops, the temperature is kept at the same temperature for another 10 minutes, allowed to cool to room temperature, and then recrystallized with acetonitrile to obtain pale ocher crystals of 2762, melting point 222-223°C.

Total yield 72.8% Example 2 Process for producing 3-diethylamino-6-methyl-7-anilifluorane 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid 15.65f and 4-methoxy-2 -Methyl diphenylamine 10.65P was dissolved in concentrated sulfuric acid 1501 and reacted at 20°C for 13.5 hours.

The rest was treated in the same manner as in Example 1 to obtain 20.66f of white crystals of 3-(4-diethylamino-2'-hydroxyphenyl)3-(5-anilino-4'-methyl-27-methoxyphenyl)phthalide. obtain.

Melting point: 192-3°C Yield: 81.3% The obtained crystals were foamed and dissolved in an oil bath at an internal temperature of 195-200°C, kept at the same temperature for 10 minutes after foaming was completed, and then recrystallized with toluene. A white crystal of 18.4S' was obtained.

Melting point 194-196°C Total yield -77.3%
Example 3 3-diethylamino-7-(N-methylanilino)fluoran 2-(4'-diethylamino-2'hydroxybenzoyl)benzoic acid 6.26P and 4-methoxyN-methyldiphenylamine 4.26? was dissolved in concentrated sulfuric acid 40P and reacted at room temperature (approximately 25°C) for 16 hours, followed by treatment in the same manner as in Example 1 to obtain 3-(4'-diethylamino-2'-hydroxyphenyl) 3-3(5' -N-methylanilino 27-
Off-white crystals of methoxyphenyl) phthalide7. 2 4
Obtain fI.

Melting point: 175-17, 58C Yield: 71.3% Next, the obtained crystals were foamed and dissolved in an oil bath at an internal temperature of 180±2°C, kept at the same temperature for 10 minutes, and then allowed to cool.

Recrystallize from ethyl alcohol to obtain white crystals 6.461.

Melting point 161-163°C Total yield 67.9%
Example 4 The compound of Example 3 was synthesized using a different method.

2 (4/-diethylamino-2'-methoxybenzoyl)benzoic acid3. 2 7 P and 4-ethoxy N-methyldiphenylamine2. 2 7 f to 95%
Plate in 3M sulfuric acid and react at room temperature (approximately 25°C) for 8 hours.

The reaction solution was treated in the same manner as in Example 1 to give 3-(4'-diethylamino-2'-methoxyphenyl)-3-(5'-N
-Methylanilino 27-ethoxyphenyl)phthalide 4.13S' white crystals are obtained.

Yield: 77.1%; melting point: 159-160°C when recrystallized from a 3:1 mixed solvent of inpropanol and acetonitrile.

2.71 of the obtained crystals are dissolved in 20P concentrated sulfuric acid and heated to 70°C for 1 hour.

After cooling, it is poured into ice water and neutralized with an aqueous solution of caustic soda, and the precipitated crystals are collected and dried to obtain the desired product 2.31.

Total yield 74.8% Example 5 Preparation of 3-pyrrolidino-6-methyl-7-(4'-methylanilino)fluoran 2-(4'-pyrrolidino-2'-hydroxybenzoyl)benzoic acid 30.13P and 4 -Methoxy-2,4'-dimethyldiphenylamine 22P is dissolved in 400 F of concentrated sulfuric acid and reacted at 20-25°C for 4 hours.

The reaction solution was treated in the same manner as in Example 1 to obtain 3(4'-pyrrolidino-27-hydroxyphenyl)3-(5'1P-methylanilino4'-methyl-27-methoxyphenyl).
Obtain pale purple crystals of phthalide 35.881.

Recrystallization with a mixed solvent of isopropanol and acetonitrile yields 71.2% crystals with a melting point of 172-173°C.

When 181 of the obtained crystals is heated to 180° C. to 190° C. and foamed and dissolved, crystallization occurs as the foaming decreases.

After cooling, washing with 50rIL of hot acetonitrile yields 16
Obtain white crystals of f.

Acid D: 221-222.5℃ Total yield: 67.
8% Example 6 Method for producing 3-P-}luidino-7-anilinofluorane 2-(4'-P-toluidino-27-methoxybenzoyl)benzoic acid 7221 and 4-hydroxydiphenylamine 3.72 were added to 90 % sulfuric acid 60P, 15-20℃
Stir for 18 hours.

When the reaction solution was treated in the same manner as in Example 1, 3-(4'-p-
Toluidino-2'-methoxyphenyl)-3-(5'-
Anilino 2'-hydroxyphenyl)phthalide light purple crystals7. 1 8 f is obtained.

The obtained crystals were dissolved in 20y of concentrated sulfuric acid and reacted at 70'C for 1 hour, then poured into ice water, neutralized with aqueous caustic soda solution, and the precipitated crystals were collected.

Recrystallization from toluene gives 6.05f white crystals.

Claims (1)

[Claims] 1. A benzophenone derivative represented by the general formula g1) and a diphenylamine derivative represented by the general formula 1 are subjected to dehydration condensation to obtain a phthalide compound represented by the general formula (■), which is then subjected to intramolecular ring closure. General formula (
4) A method for producing a fluoran compound represented by. (Here, R1 and R2 represent a hydrogen atom, a lower alkyl group, a hydroxyethyl group, a β-chloroethyl group, an aralkyl group, a cycloalkyl group, a phenyl group which may have a substituent, and R1 and R2 are mutually They may be linked to form a heterocycle. R3 and R4 represent a hydrogen atom, a lower alkyl group or an aralkyl group, R5 and Hiki represent a hydrogen atom, a methyl group or an ethyl group, and R7 represents a hydrogen atom or a lower alkyl group. (represents an alkyl group, aralkyl group, or acyl group, R8 represents a hydrogen atom or a lower alkyl group, and n represents an integer value of 1 to 5) 2 One of R3 and Hiki is a hydrogen atom and the other is a lower alkyl group The method for producing a fluoran compound according to claim 1, characterized in that a compound represented by the general formulas 0] and (2), which is an aralkyl group or an aralkyl group, is used. 3. A method for producing a fluoran compound according to claim 2, characterized in that a diphenyl asin derivative of the general formula [2] is used, in which Rs is a hydrogen atom. 4. A phthalide compound represented by the general formula I
A method for producing a fluoran compound according to claim 1, characterized in that intramolecular ring closure is carried out in a condensing agent such as phosphoric acid, aluminum chloride, or zinc chloride, 5. Phthalide represented by the general formula A method for producing a fluoran compound according to claim 2, characterized in that intramolecular ring closure is carried out by heating the compound to a temperature above its skeleton melting point.