JPH0333153B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides 3,3'-diallyl-4, which is used as a color developer for thermal recording paper that prevents background fogging.
The present invention relates to a method for producing a 4'-dihydroxyphenyl sulfone color developer. Generally, heat-sensitive recording materials are prepared by preparing a coating liquid by mixing in advance a fine dispersion of a colorless or light-colored leuco dye and a fine dispersion of a color developer, which is a phenolic compound, and applying this coating liquid to paper, etc. Manufactured by coating and drying. If the coating liquid and heat-sensitive recording material develop color before use, they will not be able to achieve their purpose, and even if the color development is light, the commercial value as a heat-sensitive recording material will decrease. It is preferable that it be as colorless as possible. Generally, if the color developer contains many impurities, the coating liquid or heat-sensitive recording material will develop color, resulting in so-called fog. Even when 3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone is used as a color developer, the above-mentioned color development occurs if the reaction product is used as it is, making it completely impractical. The present invention provides a production method that includes a rearrangement method and a subsequent purification method to obtain a color developer made of 3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone that exhibits extremely little color development or fog. It is about the method.

[Conventional technology]

Various allyl aryl ethers (allyl aryl
It has been reported that ortho-rearrangement occurs in yields ranging from a few percent to more than 85% when reacted at 160 to 280°C for several minutes to over ten hours without a solvent or in the presence of a solvent such as kerosene or dialkylaniline. There is (ORGANIC REACTIONS, Volume, pp.1~
48). There are also reports that use catalysts to cause rearrangements at low temperatures (CHEMISTRY LETTERS,
pp.1041-1044, 1975 Published by the
Chemical Society of Japan).

4,4′-diallyloxydiphenyl sulfone
When reacted at 190 to 230°C for 4 to 8 hours, it became soluble in aqueous caustic soda solution, and it was easily observed that Claisen rearrangement occurred to form phenolic OH. The reaction mixture of Claisen rearrangement of 4,4'-diallyloxydiphenylsulfone contains unreacted 4,4'-diallyloxydiphenylsulfone and 3-allyl-4-hydroxy-4'-allyl rearranged on only one side. Oxydiphenyl sulfone and the target product 3,3'-diallyl-4,4'-
In addition to dihydroxy-diphenyl sulfone, etc., cyclization occurs between the OH group of the rearranged product and the allyl group at the ortho position, resulting in furan compounds such as five-membered coumaran type and six-membered ring chroman type. There are also by-products and other by-products that are considered highly polar substances.
Confirmed by HPLC (liquid chromatography) analysis. As an example, 4,4'-diallyloxydiphenyl sulfone was prepared in a solvent-free manner under a _N2 atmosphere at 200 to
As a result of HPLC analysis, the product rearranged at 210℃ for 6 hours contained approximately 0.05% of unreacted raw material and 3, which is a mono-rearranged product.
-allyl-4-hydroxy-4'-allyloxydiphenyl sulfone, about 5%, di-rearranged 3,
Several types of peaks were observed in addition to approximately 90% of 3'-diallyl-4,4'-dihydroxydiphenyl sulfone, including bisphenol S and substances even more polar than bisphenol S. This was recognized. As described above, the rearrangement product as it is contains many by-products, and the aforementioned coating liquid itself develops a strong color, making it impractical as a color developer for heat-sensitive recording paper.

[Problem that the invention seeks to solve]

As a result of various studies to eliminate this coloring of the coating liquid, it was found that there is a possibility of eliminating this coloration by using a recrystallization method. However, lower alcohols such as methanol and ethanol, which are usually used as recrystallization solutions, as well as dioxane, tetrahydrofuran,
Dimethylformamide, dimethyl sulfoxide, and various ketones have too high a solubility, resulting in extremely low crystal yields and cannot be put to practical use as they are. In addition, water was added to these solvents in order to lower the solubility, but the oil separated only and required several hours for crystallization or did not crystallize at all.

For esters such as ethyl formate and methyl acetate,
Although crystallization occurred, it was still difficult to obtain a good yield. Although dicarboxylic acid esters such as ethyl oxalate and ethyl malonate are relatively good solvents, they have a drawback of high boiling points, which is industrially disadvantageous. Although dichloroethane (1,2-dichloroethane) is a good solvent, there is still considerable fog after one recrystallization, and it was necessary to repeat recrystallization several times to eliminate the fog. In the case of the second and third recrystallization, the solubility decreases considerably, and 10
It was necessary to use ~30 times the amount of dichloroethane. Even if the amount of ethane dichloride used is increased to about 10 times the amount of ethane dichloride used, and a portion of lower alcohol such as methanol or propanol is used in combination with 1 to 2% of ethane dichloride, it will dissolve, but the yield will decrease. In addition, aromatic solvents have extremely low solubility and are not practical. In addition, in the case of aromatic solvents with high boiling points, such as dichlorobenzene, the reaction product can be melted and dissolved in the solvent at high temperatures, but it separates into an oil upon cooling and solidifies as it is, resulting in purification. No effect will be obtained.

[Means for solving problems]

The Claisen rearrangement reaction can be carried out in either a solvent-free or solvent-based manner, but avoid solvent-free rearrangement reactions in which temperature control is difficult and the reaction is treated as a solid when cold, and reactions in which ethylene glycol is used as a solvent, which produce highly polar substances, as much as possible. It is preferable to perform the rearrangement reaction in the presence of a mineral oil-based solvent whose boiling point is adjusted to 180-270°C, suppress the formation of di-rearranged products to 90% or less, and prevent an increase in fog components as much as possible during the reaction process. In addition, the present inventors have determined that the reaction product obtained thereby is
The yield is also improved by a purification method in which recrystallization is performed using a three-way mixed solvent containing a small amount of a dichloroalkane such as 1,2-dichloroethane, an aromatic solvent such as toluene, and a solvent with extremely high solubility such as isopropanol. The present inventors have discovered that 3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone with little or no fog can be obtained, and have arrived at the present invention.

According to the present invention, there is provided a method for producing a color developer for thermal recording paper comprising 3,3'-diallyl-4,4'-diphenyl by subjecting 4,4'-diallyloxydiphenyl sulfone to Claisen rearrangement. 3-allyl-4-hydroxy-4'- which is a mono-rearranged product in which only one side of 4,4'-diallyloxydiphenyl sulfone is rearranged, is provided.
The amount of allyloxydiphenyl sulfone is 5 to 20% based on the weight of the raw material 4,4'-diallyloxydiphenyl sulfone, and the di-rearranged 3,
The reaction is terminated by suppressing the formation of 3'-diallyl-4,4'-dihydroxydiphenyl sulfone to 90% or less, and the resulting 3,3'-diallyl-
A reaction product containing 4,4'-dihydroxydiphenyl sulfone as a main component is recrystallized using (A) at least one dichloroalkane solvent, (B) at least one aromatic solvent, and ( C) Using a solvent mixed with at least one of alcohol-based, glycol-based, and/or ether-based solvents in amounts of 10 to 90% by weight, 10 to 90% by weight, and 0.1 to 30% by weight, respectively. It is characterized by being recrystallized and purified.

In the present invention, as dichloroalkane,
In addition to 1,2-dichloroethane, 1,3-dichloropropane, 1,4-dichlorobutane, etc. can be used. In addition to toluene, aromatic solvents include benzene, xylene, monochlorobenzene, dichlorobenzene, trichlorobenzene,
Monochlorotoluene, dichlorotoluene, etc. can be used. In addition to isopropanol, solvents with high solubility include methanol, ethanol, propanol, butanol, ethylene glycol, diethylene glycol, dioxane,
Tetrahydrofuran, dimethylformamide,
Dimethyl sulfoxide, acetone, methyl ethyl ketone, diethyl ketone, etc. can be used.

In addition, in order to avoid handling the rearrangement product as a solid, first make it into an alkaline aqueous solution, add a solvent such as ethane dichloride, which is a component of the recrystallization solvent, and then make it acidic by adding an aqueous solution of hydrochloric acid, etc. Alternatively, after dissolution, the solution may be allowed to stand still and separated into layers, and after removing the saline solution, the remaining recrystallization solvents such as toluene and alcohol may be added to recrystallize. Furthermore, for alcohols and ketones that are hardly soluble in an aqueous inorganic salt solution when ethane dichloride and toluene coexist, ethane dichloride and toluene should be prepared before separating and removing the aqueous inorganic salt solution. Even if alcohol is added together with the aqueous solution, there is no problem since the alcohol will not be removed together with the aqueous solution.

For convenience of operation, the recrystallization solvents may be added separately in stages. It is sufficient that the entire amount is added by the time of cooling recrystallization.

〔Effect of the invention〕

Claisen rearrangement of 4,4'-diallyloxydiphenyl sulfone gives 3,3'-diallyl-4,
When producing a color developer for heat-sensitive recording materials containing 4'-dihydroxydiphenyl sulfone as a main component, by carrying out the production method of the present invention, a fine dispersion of leuco dye and a fine dispersion of color developer can be mixed. It becomes possible to produce a color developer that causes very little or no color development in the coating liquid as a mixed liquid and fog in the heat-sensitive recording material at a high yield and through simple operations. Furthermore, depending on the quality of the rearrangement product and the purpose of the product, it is possible to further increase the yield by sacrificing fog to some extent by adjusting the amount of lower alcohols such as isopropanol used. On the other hand, it is possible to obtain a color developer completely free from fog at a slight sacrifice in yield. Furthermore, by carrying out the present invention, it becomes possible to arbitrarily adjust the manufacturing cost and performance as required.

〔Example〕

The invention will be further explained below by way of examples. Performance test method (color development of paint liquid, fog test) In order to evaluate the purification effect, a paint liquid was prepared and evaluated as follows.

Put 0.05g of each purified product in a mortar and add 5% PVA to it.
1.0 g of an aqueous solution was added and thoroughly ground with a pestle, and 3.0 g of water was added and further ground. Apply this liquid to a length with an inner diameter of 10 mm.
Place in a 120 mm test tube, add 3 drops (approximately 0.19 g) of a fine dispersion of leuco dye with the following composition, stir with a spatula, and warm in a hot bath at 50 to 55 °C for 5 minutes. The brightness of the paint liquid was determined by allowing it to stand at room temperature for more than a minute and visually checking it against a brightness scale (manufactured by Japan Sensei Research Institute). In addition,
The brightness of the blank (without developer) was N=8. If N=7.5 or more, it can be considered that there is almost no fog.

Leuco dye fine dispersion composition 3-N-Methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane...1.5g 10% PVA aqueous solution...2.0 Water...0.5 (Stock solution sufficiently finely dispersed in a sand mill 4.0) 4.0 g of the above finely dispersed stock solution was diluted with 8.0 g of water to obtain a finely dispersed leuco dye liquid.

Example 1 In a 1000 ml four-necked flask, 4,4'-diallyloxydiphenyl sulfone (purity as determined by HPLC analysis) was added.
99.0%) 330g (1.0 mol), 220g of MC Oil W-8 (manufactured by Idemitsu Kosan), and 220g of white kerosene (manufactured by Daikyo Sekiyu) were added, and after replacing with _N2 , the mixture was heated at 200-210℃ under a _N2 stream for 5 minutes. Transposed in time. This was left to stand for a while, and about 3 g of the reaction product separated in the lower layer was pipetted out.
It was used as a separate sample for analysis. The HPLC analysis results showed that the unreacted raw material was 1.20%, the mono-translocated product was 19.8%, and the di-transposed product was 77.4%.
It was %. For the remaining sampled product,
Add 16.5 g of ethylene glycol at 150℃ with stirring, and add 82.5g (2.0 mol) of caustic soda and water at 125℃.
An aqueous solution consisting of 495 g was gradually added to form an alkaline aqueous solution of the reaction product, and after the mixture was allowed to stand still, the alkali aqueous solution in the lower layer was extracted leaving the paraffin oil in the upper layer. The amount of this alkaline aqueous solution was 905g.

A portion of this alkaline aqueous solution (225 g (0.25 mol))
Pour into a 500 ml four-necked flask, add 80 g of dichloroethane (1,2-dichloroethane), and while stirring, gradually add 97 g (0.53 mol) of 20% aqueous hydrochloric acid solution to make it acidic. After stirring for a while at about 75°C. Let stand and separate into layers,
Remove the upper layer of inorganic salt aqueous solution and add toluene to the remainder.
After adding 80 g and 8.4 g of isopropanol and stirring and dissolving at 80 to 85° C. for a while, the mixture was cooled and recrystallized. 25℃
The crystals were mixed with 40g of dichloroethane and toluene.
It was washed with 40 g of the mixed solution, and then washed with 100 g of water, and then dried.

Amount obtained: 50.8g (61.6%) Brightness of paint liquid: N=8 Example 2 225g of the remaining alkaline aqueous solution obtained in Example 1
(0.25 mol) and recrystallized in the same manner as in Example 1 except that isopropanol was changed to 4.2 g.

Amount obtained: 67.4g (81.7%) Brightness of coating liquid: N=7 Example 3 The reaction was carried out in the same manner as in Example 1, except that the reaction time was changed to 6 hours, to obtain an alkaline aqueous solution. The HPLC analysis results showed that the reaction materials were 0.51%, mono-translocated products were 14.0%, and di-transposed products were 82.1%. Subsequently, recrystallization was performed in the same manner as in Example 1.

Amount obtained 53.6g (65.0%) MP 148.5~152.0℃ Brightness of paint liquid N=8~8.5 Example 4 225g of the remaining alkaline aqueous solution obtained in Example 3
Recrystallization was carried out in the same manner as in Example 1, except that 4.2 g of isopropanol was used and 4.2 g of isopropanol was used.

Amount obtained: 66.8g (81.0%) MP: 148.7~152.2℃ Brightness of paint liquid: N=7~7.5 Comparative example 1 225g of the remaining alkaline aqueous solution obtained in Example 3
Recrystallization was carried out in the same manner as in Example 1, except that (0.25 mol) was used and isopropanol was not used.

Amount obtained: 75.9 g (92%) Brightness of paint liquid: N = 4.5 to 5 (severe fog) Example 5 The reaction was carried out in the same manner as in Example 1, except that the reaction time was changed to 7 hours. An alkaline aqueous solution was obtained. The HPLC analysis results showed that the unreacted raw material was 0.44%, the mono-rearranged product was 8.2%, and the di-rearranged product was 88.1%.

Subsequently, recrystallization was performed in the same manner as in Example 1.

Amount obtained 48.7g (59.0%) Brightness of paint liquid N=8 Example 6 225g (0.25 mol) of the alkaline aqueous solution obtained in Example 5
except that 4.2g of isopropanol was used.
Recrystallization was carried out in the same manner as in Example 1.

Amount obtained: 68.5 g (83.0%) Brightness of coating liquid: N=6 Comparative Example 2 Recrystallization was carried out in the same manner as in Example 1, except that isopropanol was not used in Example 6.

Amount obtained: 74.3g (90.0%) Brightness of paint liquid: N=4.5-5 (severe fog) Example 7 The reaction was carried out in the same manner as in Example 1, except that the reaction time was changed to 8 hours. An alkaline aqueous solution was obtained. The HPLC analysis results showed that the unreacted raw material was 0.20%, the mono-translocated product was 7.0%, and the di-transposed product was 88.7%.

Subsequently, recrystallization was performed in the same manner as in Example 1.

Amount obtained: 50.2g (60.8%) Brightness of paint liquid: N=6.5 Example 8 225g of the remaining alkaline aqueous solution obtained in Example 7
(0.25 mol) and 11.0 g of isopropanol.
Recrystallization was carried out in the same manner as in Example 1 except that.

Amount obtained 42.0g (50.9%) Brightness of paint liquid N = 7 to 7.5 Comparative example 3 225g (0.25 mol) of the alkaline aqueous solution obtained in Example 3
into a 1000ml four-necked flask and add ethane dichloride.
Add 300g and while stirring, add 97g of 20% hydrochloric acid aqueous solution.
(0.54 mol) was gradually added to make the mixture acidic, and after stirring for a while at 75°C, the mixture was allowed to separate into layers, the upper aqueous layer was extracted, and the remaining lower layer was cooled and recrystallized. Filter at 25%, wash with 80g of ethane dichloride, and add 100g of water.
After washing, it was dried.

Amount obtained: 46.2g (56.0%) Brightness of paint liquid: N=4.5 (severe fog) Comparative example 4 38.0g of the crystals obtained in Comparative example 3 above were mixed with ethane dichloride.
It was dissolved in a mixed solvent of 380 g and 3.8 g of methanol, cooled, and recrystallized. Filtered crystallized ethane dichloride
It was washed with 50 g and dried.

Amount obtained: 19.0g (50.0%) (Total yield: 28.0%) Brightness of paint liquid N = 6.5 (Fog was considerably improved, but the yield decreased) Example 9 In Example 1, white kerosene was not used, and MC Oil W-
The reaction was carried out in the same manner as in Example 1, except that 440 g of 8 (Idemitsu Kosan) was used and the reaction was carried out for 4.5 hours to obtain an alkaline aqueous solution. HPLC analysis results indicate that unreacted raw materials
0.62%, mono-translocated product 12.5%, and di-transposed product 83.1%.

Subsequently, recrystallization was performed in the same manner as in Example 1.

Amount obtained: 47.7g (57.8%) Brightness of paint liquid: N=7.5 Example 10 225g of the remaining alkaline aqueous solution obtained in Example 9
(0.25 mol) and 4.2 g of isopropanol
Recrystallization was carried out in the same manner as in Example 1 except that.

Amount obtained: 67.0 g (81.2%) Lightness of coating liquid: N=6 Example 11 The reaction was carried out in the same manner as in Example 9, except that the reaction time was changed to 5.5 hours, to obtain an alkaline aqueous solution. The HPLC analysis results showed that the unreacted raw material was 0.48%, the mono-rearranged product was 10.5%, and the di-rearranged product was 85.5%.

Subsequently, recrystallization was performed in the same manner as in Example 1.

Amount obtained: 47.8g (57.9%) Brightness of paint liquid: N=7 Comparative example 5 4,4'-diallyloxydiphenyl sulfone (HPLC analysis purity 99.0%) in a 1000ml four-necked flask
Add 330g (1.0 mol) and 600g of ethylene glycol,
After _N2 substitution, reaction was carried out at 195-200°C for 5.5 hours under a _N2 stream. After the reaction, the mixture was poured into water, crushed, and washed with water. After drying, the amount obtained was 320 g, and the yield was 97.0%.
mp134.5~145.5℃.

The HPLC analysis results showed that the unreacted raw material was 0.24%, the mono-rearranged product was 8.42%, and the di-rearranged product was 81.0%.

Continuously add 80.0g of powder, 160g of 90% acetic acid, and water.
It was recrystallized from 160 g of a mixed solvent, filtered, washed with a mixed solution of 50 g of 90% acetic acid and 50 g of water, and dried.
Yield 66.0g (82.5%) (Total yield 80.0%) mp142−
147℃. Lightness of paint liquid N<4 (very much fogging) Comparative Example 6 Using 60.0 g of the crystals obtained in Comparative Example 5, recrystallize from a mixed solvent of 150 g of dichloroethane and 1.5 g of water, filter, and dichloride. It was washed with 80 g of ethane and dried.

Amount obtained: 39.0g (65.0%) (total yield: 52.0%) Brightness of paint liquid: N=5 (severe fog) Comparative example 7 Using 37.0g of crystals obtained in Comparative example 6, 400g of dichloroethane and 3.0g of methanol were added. Recrystallize from a mixed solvent, filter, and add 40 g of dichloroethane and 0.3 g of methanol.
It was washed with a mixed solution of and dried.

Amount 18.5g (50.0%) (Total yield 26.0%) mp 148−152℃ Brightness of paint liquid N=7.5 (Fog was improved, but the yield deteriorated)

Claims (1)

[Claims] 1 Claisen rearrangement of 4,4'-diallyloxydiphenyl sulfone to produce 3,3'-diallyl-4,
In producing a color developer for thermal recording paper consisting of 4'-dihydroxydiphenyl sulfone, 3-allyl-4-hydroxy, which is a mono-rearranged product in which only one side of 4,4'-diallyloxydiphenyl sulfone is rearranged, is used. The amount of -4'-allyloxydiphenyl sulfone is set to 5 to 20% based on the weight of the raw material 4,4'-diallyloxydiphenyl sulfone, and the di-rearranged 3,3'-diallyl-4 , 4'-dihydroxydiphenylsulfone production is suppressed to 90% or less to terminate the reaction, resulting in a reaction in which the main component is 3,3'-diallyl-4,4'-dihydroxyphenylsulfone. The product as a recrystallization solvent
(A) at least one dichloroalkane solvent;
(B) at least one aromatic solvent and (C) at least one alcohol-based or (and) glycol-based or (and) ether-based solvent, each containing 10 to
1. A method for producing a color developer for thermal recording paper, which comprises recrystallizing and purifying the color developer using a mixed solvent in an amount of 90% by weight, 10 to 90% by weight, and 0.1 to 30% by weight.