JPS6245559A - Production of 2-hydroxybiphenyl-3-carboxylic acid - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful as a developer for heat-sensitive paper, etc., selectively and economically in good yield, by converting 2- hydroxybiphenyl into sodium salt with NaOH, separating the resultant sodium salt and reacting the sodium salt with CO2 under specific conditions. CONSTITUTION:2-Hydroxybiphenyl expressed by formula IV and NaOH in an amount of preferably near equimolar amount are reacted in a lower alcohol, e.g. methanol, while refluxing, heating and stirring, and the resultant sodium salt of the 2-hydroxybiphenyl expressed by formula V is concentrated and separated under ordinary pressure or reduced pressure, vacuum-dried at 120-140 deg.C, pulverized to <=20 mesh particle size in a ball mill, etc., and reacted under 7-40kg/cm<2>.G gas pressure and within a range such that the upper limit P (kg/cm<2>.G) of the CO2 gas may not exceed the value of the formula P=(220-T)/1.5 [T is the reaction temperature ( deg.C)] at 140-190 deg.C for 30min-6 hr while heating to afford the compound expressed by formula I.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing 2-hydroxybiphenyl-3-carboxylic acid represented by formula (I). 2-Hydroxybiphenyl-3-carboxylic acid is a compound that has recently attracted attention as a color developer for pressure-sensitive and thermal paper (Japanese Patent Application Laid-open No. 1983
-20807 Publication).

Conventional technologyConventional,? -Hydroxybiphenyl-3-carboxylic acid L
The following method has been reported as a professional manufacturing method.

(1) A method of heating 2-hydroxybiphenyl with excess potassium carbonate to 160 to 180°C under carbon dioxide gas pressure [J, Gen, CheL+, (U, S, S,
R), 8.424 (+938)].

(2) A method of heating 2-hydroxybiphenyl L-salt to F100-220°C under carbon dioxide gas (German Patent No. 8.25).

The conventional method described above has the following problems from an industrial point of view. In other words, in method (1), '14! ! ! 'I
: 1 of potassium carbonate is required and approximately 60 atm of t? Since the reaction is carried out under +i pressure carbon dioxide gas, the cost is high in terms of raw materials and equipment.

= On the other hand, the German patent that proposed method (2) states that
Reaction conditions etc. that selectively and economically provide the target 2-hydroxybiphenyl-3-carboxylic acid have not been specified. For example, according to the recitation of Wood inventors, the reaction condition range shown in the German patent includes 2-hydroxybiphenyl-5-carboxylic acid (II) and 2-hydroxybiphenyl-3-15-dicarboxylic acid (II). It has become clear that (m) may be produced as a by-product, resulting in a decrease in the yield of the desired 2-hydroxyhyphenyl-3-carboxylic acid.

02H Problems to be Solved by the Invention In order to solve the problems of the conventional method as described above, the present inventors conducted a sex test 3.J and found that the sodium salt corresponding to 2-hydroxybiphenyl (IV) (V) is generated;
By reacting this with 'tRWJ gas to produce 2-hydroxybiphenyl-3-carboxylic acid (CI), we have completed a production method that can selectively and economically obtain the desired product. .

aO Means to Solve the Problem In the present invention, 2-hydroxybiphenyl and sodium hydroxide are first reacted using a lower alcohol such as methanol or ethanol as a solvent, and then the solvent and the produced water are heated and distilled. to separate sodium 1 of 2-hydroxybiphenyl. As the lower alcohol solvent, methanol is preferably used since it is inexpensive. In such cases, the common method is to use wood as a solvent, but as shown below, we have found some advantages in using a lower alcohol as a solvent.

That is, the sodium salt of 2-hydroxybiphenyl is hygroscopic, but if it contains wood, the concentration of the target 2-hydroxybiphenyl-3-carboxylic acid in the reaction with carbon dioxide gas is significantly lowered. For this reason, it is necessary to completely remove the wood. However, when water is used as a solvent, the heat of evaporation of PPt in water is large, and therefore a large amount of energy is consumed for heating and distilling it off. Also, is it necessary to finally perform vacuum drying at 130-160°C to completely remove water, or is it possible that the remaining water and the sodium salt of 2-hydroxybiphenyl react reversibly? -Hydroxybiphenyl is partially produced and distilled off, resulting in a decrease in the yield of 2-hydroxybiphenyl for sodium.

On the other hand, when lower alcohols, especially methanol, are used as a solvent, the latent heat of vaporization is small, so the solvent can be easily distilled off, and -1-
Almost no distillation of hydroxybiphenyl was observed.

Sodium 2-hydroxybiphenyl 1)! The solvent used during production is preferably heated before use in order to minimize the speed of use from an economical point of view.

That is, a lower alcohol solution of sodium hydroxide is stirred while being heated under reflux, and approximately equimolar amount j1 of 2-hydroxybiphenyl is added thereto. In this case, even if either 2-hydroxybiphenyl or sodium hydroxide is used in excess, the following reaction will proceed without any problem. However, excess amount interferes with the reaction! From an economic point of view, it is preferable to use both in an equimolar ratio of 17i1: since it is necessary to finally recover the compound without removing the 7i1.

2-Hydroxybiphenyl and sodium hydroxide 1 react quickly under the above conditions to produce the sodium salt of 2-hydroxybiphenyl. It is nearly saturated in this solvent system. This solution is subjected to C condensation at normal pressure or reduced pressure and finally vacuum dried at 120 to 140°C to obtain the sodium salt of 2-hydroxybiphenyl as a colorless solid. Next, the sodium salt of 2-hydroxybiphenyl is ground to 20 meshes or less, preferably 100 meshes or less, using a ball mill or the like, and subjected to reaction with carbon dioxide gas.

The reaction with carbon dioxide largely depends on the reaction temperature and the pressure of carbon dioxide. If the reaction temperature is less than 140°C or the carbon dioxide pressure is less than 7 kg/cm2.0, the reaction conversion rate will be low and it will be necessary to recover a large amount of 2-hydroxybiphenyl as a raw material, which is not economical. On the other hand, when the reaction temperature becomes high, 2=hydroxybiphenyl-3,
The by-product of 5-dicarboxylic acid gradually increases. This is because the target 2-hydroxybiphenyl-3-carphonic acid further reacts with carbon dioxide gas, and when the temperature exceeds 190°C, this side reaction causes 2-hydroxybiphenyl-3-carphonic acid to react with carbon dioxide gas.
The production yield of carboxylic acid decreases.

Also, even if the anti-15 temperature is 190°C or higher.

In the range of 160 DEG C. to 190 DEG C., when the carbon dioxide gas is at high pressure, the by-product of 2-hydroxybiphenyl-3,5-dicarboxylic acid increases. This becomes more noticeable as the anti-I5 temperature increases. The by-product 2-hydroxybiphenyl-3,5-dicarboxylic acid is poorly soluble in various solvents and is nonvolatile, so it is difficult to remove by ordinary separation and purification methods such as recrystallization and distillation. Therefore, it is desirable to carry out the reaction under reaction conditions in which 2-hydroxybiphenyl-3,5-dicarboxylic acid is hardly produced as a by-product. From this point of view, when the reaction temperature is in the range of 160°C to 190°C, the carbon dioxide pressure is calculated by the following formula: The value of P (kg/cm2·G) expressed by the formula % [in the formula, T is the reaction temperature (°C)] or less is preferable. On the other hand, when the reaction temperature is 160°C or lower, 2-hydroxybiphenyl-3,5
-The by-product of dicarboxylic acid is not so significant. Furthermore, the higher the carbon dioxide gas pressure, the higher the production yield of the target 2-hydroxybiphenyl-3-carboxylic acid. However, even if the carbon dioxide pressure is too high, 2-hydroxybiphenyl-3
- The production yield of carboxylic acid did not change much, to 40,
If it exceeds 4 QJ/cm2, the production yield will hardly improve substantially, so it is not preferable from an economic point of view to carry out the reaction under a carbon dioxide pressure exceeding 4QJ/cm2.

As described above, the reaction between the sodium salt of 2-hydroxybiphenyl and carbon dioxide gas largely depends on the reaction temperature and carbon dioxide pressure, and these are related to phase W. 2-Hydroxybiphenyl-3 selectively and economically
-The reaction temperature and carbon dioxide pressure to obtain carboxylic acid are as follows: reaction temperature is 140-190℃,)'ANA gas pressure is 7-40℃.
In the range of kHz/cm2・G and 1XWA gas pressure, the two limit P (kg/cm2・G) is as follows P= (220
-T) /1.5 [In the formula, T is the reaction temperature (° C.) within a range that does not exceed the value of K.

The reaction can be completed by stirring sodium 2-hydroxybiphenyl m at the above reaction temperature and under carbon dioxide pressure, and the reaction time is usually in the range of 30 minutes to 6 hours.

After the reaction is complete, dissolve the reaction mixture in water, add mineral acids such as hydrochloric acid or sulfuric acid to cause acid precipitation, and wash with solvent if necessary.
By performing purification operations such as ff1 or .f crystals, 2-hydroxybiphenyl-3-carboxylic acid can be extracted.

The content of the present invention will be explained in more detail below using Examples and Comparative Examples.

Example 1 40 g of sodium hydroxide was heated GIW with 200 methanol in a one-cross eggplant flask equipped with a ring 1i condenser. 170 g of 2-hydroxybiphenyl was added to this and heated under reflux to obtain a homogeneous solution. This solution was concentrated under reduced pressure, and the precipitated crystals were further heated at 130°C, 15 to 10 Torr.
The mixture was dried under vacuum for 2 hours under vacuum to obtain 190 g of 2-hydroxybiphenyl sodium Am (colorless solid). During this time,
Almost no distillation of 2-hydroxybiphenyl was observed.

The obtained sodium salt of 2-hydroxybiphenyl was ground into 20 meshes or less using a ball mill.

Collect 25g of this, put it in an autoclave with an internal volume of 200 - equipped with a stirrer, replace the inside of the autoclave with carbon dioxide gas, and set the carbon dioxide gas to be introduced at a pressure of 'Okg/am2.
The mixture was heated and stirred at 170°C for 4 hours. As the reaction progressed, carbon dioxide gas was consumed and the pressure decreased, but carbon dioxide gas was supplemented from the outside to maintain the pressure at 10 kg/cm2 at all times. The reaction mixture was dissolved in 200 ml of warm water, adjusted to pH 7-8 by adding cold hydrochloric acid, and washed with diazomethane.

Concentrated hydrochloric acid was added to the aqueous layer to adjust the pH to below 1, and the precipitated crystals were collected by filtration and dried under vacuum to form a colorless solid. 8g was obtained. A part of this product was methylated with diazomethane and then analyzed by gas chromatography, and the results showed that 2-hydroxybiphenyl-3-carboxylic acid, 2-hydroxybiphenyl-5-carboxylic acid, 2-hydroxydophenyl-
It is a mixture of 3,5-dicarboxylic acids, and the mixing ratio is 8
It was found that the molar ratio was 4:3:3.

1iii Colorless solid. 4 g was collected and recrystallized from ice-methanol to obtain 8.1 g of 2-hydroxybiphenyl-3-carboxylic acid as a pure product. This one is mp,
The temperature was 188-189°C.

Comparative Example 1 In Example 1, 200 methanol was replaced with 200 methanol.
A similar operation was carried out using W& to obtain 5 g of sodium 2-hydroxybiphenyl j131. In this case, 10.5 g of 2-hydroxybiphenyl was distilled out during vacuum drying.

Examples 2 to 5 and Comparative Examples 2 to 7 The reaction temperature and carbon dioxide pressure in Example 1 were
A similar reaction was carried out by varying the temperature from 0°C to 230°C and from 5 to 50 kg/cl.2. Pour the reaction mixture into warm water 2
The solution was dissolved in 100 g of ethyl acetate, and concentrated hydrochloric acid was added to adjust the pH to below 1, followed by extraction with 200 g of ethyl acetate. After a portion of the extract was treated with Cyatumekun, quantitative analysis was performed using gas chromatography, and the results shown in Table 1 were obtained.

(Here are blank spaces) Table 10 Reaction conditions and tens of products I: 2-hydroxybiphenyl-3-carboxylic acid II
: 2-hydroxybiphenyl-5-carboxylic acid ■: 2
-Hydroxybiphenyl-3,5-dicarboxylic alcohol ■: 2
- Effects of the invention of hydroxybiphenyl Due to the uninvention, it has become possible to selectively and economically produce 2-hydroxybiphenyl-3-carboxylic acid, which is expected to be used as a color developer for thermal paper, and supply it to the relevant industry. .

Claims (1)

[Claims] 2-hydroxybiphenyl and sodium hydroxide are reacted in a lower alcohol solvent, the resulting sodium salt of 2-hydroxybiphenyl is separated, and the sodium salt of 2-hydroxybiphenyl is separated under pressure of carbon dioxide gas. , in carrying out the heating reaction, the reaction temperature is in the range of 140 to 190°C, the carbon dioxide pressure is in the range of 7 to 40 kg/cm^2・G, and the upper limit of the carbon dioxide pressure P (kg/cm^2・G) is expressed by the following formula: P=(220-T)/1.5 [In the formula, T is the reaction temperature (°C)].
-Production method of hydroxybiphenyl-3-carboxylic acid.