JPH04128252A - Production of carboxybiphenyls - Google Patents

Abstract

PURPOSE:To advantageously obtain the title substance by oxidizing an acylated biphenyl with molecular oxygen in the presence of a specific amount of an alkyl-substituted benzene in 2-10C aliphatic monocarboxylic acid as a solvent by using a mixed catalyst of a specific heavy metal/bromide. CONSTITUTION:In oxidizing a compound shown by formula I (R<1> is 1-10C alkyl; X and X<1> are F, Cl, Br, NO2, CN or SO3H; (l) is 0-3 integer) to give a corresponding carboxybiphenyl useful as a raw material for liquid crystal compound, 100 pts.wt. compound shown by formula I is oxidized with molecular oxygen in the presence of >=1 pt.wt. compound shown by formula II (R<2> is 1-2C alkyl; Y is each of groups in X and X'; (m) is 1 or 2; (n) is 0-3 integer) by using 2-10C aliphatic monocarboxylic acid as a solvent and a mixed catalyst containing one or more heavy metals selected from Co, Nm and Ce and a bromine compound to readily give the objective compound from an industrially easily obtainable raw material by using the inexpensive oxidizing agent in high yield.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing carboxybiphenyls useful as raw materials for liquid crystal compounds used in various display elements such as displays. More specifically, the present invention relates to a method for producing the corresponding carboxybiphenyls by converting acylated biphenyls with molecular oxygen.

(Prior art and 8 points) Conventionally, the following methods are known as methods for producing carboxybiphenyls. That is, (1) a method of oxidizing alkyl biphenyl or formyl biphenyl with molecular oxygen in the presence of a heavy metal catalyst and a bromine compound (European Patent No. 3009)
No. 22).

(2) A method of oxidizing alkylbiphenyl or acetylbiphenyl with permanganic acid or chromic acid (Unexamined Japanese Patent Publication No. 1983-
No. 83046).

(3) A method of reacting halogenated biphenyl and carbon monoxide in the presence of a noble metal catalyst (Japanese Patent Application Laid-Open No. 62-185055
issue).

However, although method (1) allows the use of inexpensive air as an oxidizing agent, the production of raw materials such as alkyl biphenyl and formyl biphenyl has poor regioselectivity, making purification and separation difficult, and furthermore requires the use of extremely corrosive catalysts. Method 2 (2) has disadvantages, such as requiring special equipment materials and being dangerous to handle.Method 2 (2) not only increases the cost of the oxidizing agent, but also uses highly toxic heavy metals such as manganese and chromium. This is not a preferable method from the viewpoint of preventing environmental pollution as a large amount is emitted.

Method (3) requires the use of a large amount of expensive catalyst and has a low yield, which is economically disadvantageous.

Therefore, none of these known methods is necessarily a satisfactory method for industrially producing carboxybiphenyls at low cost.

(8 points while the invention is being solved) Acylated biphenyls are i11! It is a compound that can be easily obtained by applying acylation such as anhydride or acid chloride. However, oxidation of this substance with molecular oxygen such as air is difficult compared to alkylbiphenyl and formyl biphenyl, and the known method (
For example, in European Patent No. 300,922), the reaction did not proceed at all, or side reactions occurred due to the extremely severe conditions required, resulting in poor yield and quality and was not a practical method.

The present inventors have thought that a method using acylated biphenyls, which are easy to produce and inexpensive, as a raw material, and inexpensive air as an oxidizing agent is advantageous, and has been conducting intensive studies. As a result, by using a specific solvent system and mixed catalyst system and reacting in the presence of a specific alkyl-substituted benzene, acylated biphenyls, which were previously considered difficult, can be air-oxidized extremely easily, and the desired purpose can be achieved. The inventors have discovered that carboxybiphenyls can be obtained with good selectivity and in high yields, and have completed the present invention based on this knowledge.

That is, an object of the present invention is to provide a new and useful method for producing carboxybiphenyls, which is characterized by an oxidation reaction method.

(Means for solving the problems) The method for producing carboxybiphenyls according to the present invention includes:
When oxidizing the acylated biphenyls represented by the general formula 1 to produce the corresponding carboxybiphenyls, an aliphatic monocarboxylic acid having 2 to 10 carbon atoms is used as a solvent, and one or two selected from cobalt, manganese, and cerium are used.
Using a mixed catalyst containing a heavy metal and a bromine compound, in the presence of 1 part by weight of alkyl-substituted benzenes represented by Formula 2 per 100 parts by weight of acylated biphenyls, the reaction is carried out with molecular oxygen. Characterized by oxidation.

[In the formula, R1 represents an alkyl group having 1 to 10 carbon atoms, x, x
' are the same or different, F, CI, Br, N O2, CN
Or represents a 5OsH group,! represents an integer of 0 to 3, [wherein R2 is a linear or branched alkyl group having 1 to 20 carbon atoms, Y is F, CI, Br, NOx, CN or S○, H group, m represents an integer of 1 or 2, and n represents an integer of 0 to 3.] The acylated biphenyls used as raw materials in the present invention have a structure represented by -maximum 1 above. The biphenyl skeleton is F, CI, Br, NO
2, including those substituted with a substituent that is stable against oxidation such as CN or SOs H group, and the substitution value 1 does not matter; among these, 4-acetylbiphenyl and 4-acetyl-4° -Cyanobiphenyl, 4-acetyl-4°-chlorobiphenyl, ethyl-4-biphenylketone, and the like are preferred as raw materials because they are easy to produce and are easily oxidized in the method of the present invention.

The catalyst according to the method of the present invention is a mixed catalyst containing one or more heavy metals selected from cobalt, manganese, and cerium and a bromine compound.

At this time, a part of the bromine compound may be replaced with a chlorine compound.

Heavy metals such as cobalt, manganese, and cerium are
It may be added to the reaction system in any form such as oxide, hydroxide, organic salt, inorganic salt, complex, etc., but it is necessary that it be at least partially dissolved in the reaction system. Among these, organic acid salts having 2 to 20 carbon atoms and salts of bromine and chlorine are particularly preferred, and specifically, cobalt acetate, cobalt propionate, cobalt octylate, cobalt naphthenate, cobalt bromide, cobalt chloride; acetic acid Manganese, manganese naphthenate, manganese bromide, manganese chloride: cerium acetate, cerium naphthenate, cerium bromide, cerium chloride; cobalt acetylacetonate, manganese acetylacetonate, etc. are exemplified.

The bromine compound can be any bromine molecule, its acid, salt, oxyacid or organic bromide, and in particular, hydrogen bromide, ammonium bromide, sodium bromide, potassium bromide, calcium bromide, magnesium bromide, The same applies to chlorine compounds, preferably cobalt bromide, manganese bromide, cerium bromide, tetrabromoethane, tribromoethane, and the like.

As the mixed catalyst according to the present invention, for example, the following catalyst systems can be advantageously used. namely, cobalt bromide, cobalt acetate and ammonium bromide, cobalt acetate and sodium bromide, cobalt acetate and hydrogen bromide, cobalt acetate and tetrabromoethane, manganese bromide, manganese acetate and hydrogen bromide, manganese acetate and bromide. These include ammonium, manganese acetate and sodium bromide, manganese acetate and tetrabromoethane, etc. Furthermore, the combination of two or more of the heavy metals and a bromine compound is advantageous because it eliminates the induction period and has a high reaction rate. Such combinations include, for example, cobalt bromide and manganese bromide, cobalt bromide and manganese acetate, cobalt acetate and manganese bromide, cobalt acetate and manganese acetate and ammonium bromide, cobalt acetate and manganese acetate and hydrogen bromide, Cobalt bromide and cerium acetate, cobalt acetate and cerium bromide, manganese bromide and cerium acetate, cobalt acetate and manganese acetate and cerium acetate and ammonium bromide, cobalt naphthenate and manganese naphthenate and tetrabromoethane, cobalt acetylacetonate and manganese acetylacetonate and hydrogen bromide.

The appropriate amount of the heavy metal to be used is about 0.05 to 10 g/no in terms of metal concentration in the reaction system.

0.05g/! A sufficient reaction rate cannot be obtained at an unresolved concentration, and if it is used in excess of 10 g/J, there are disadvantages such as increased catalyst costs and a tendency for side reactants to increase.

The amount of bromine used is 0 in terms of bromine atom per heavy metal atom.
．． 1 to 10 equivalents are suitable. If the amount is less than 0.1 equivalent, a sufficient reaction rate cannot be obtained, and if more than 10 equivalents are used, the product will be contaminated by bromine and the catalyst cost will be high, which is undesirable. Using a bromine compound and a chlorine compound together In this case, the ratio of chlorine to bromine is 0. 7
The following are appropriate.

Among the alkyl-substituted benzenes represented by general formula 2, toluene, ethylbenzene, n-
Examples include propylbenzene, isopropylbenzene, chlorotoluene, chloroethylbenzene, chloroisopropylbenzene, xylene, methylethylbenzene, etc. Among them, when toluene, ethylbenzene, n-propylbenzene, chlorotoluene, and chlorotoluene are used, is preferable because oxidation can proceed smoothly with a small amount added.

The amount of alkyl-substituted benzene used must be 1 part by weight or more per 100 parts by weight of the acylated biphenyls as raw materials, and is usually about 1 to 100 parts by weight, preferably 1 part by weight.
It is about 0 to 50 parts by weight.

If the amount of the alkyl-substituted benzene added is less than 1 part by weight, the reaction will hardly proceed, whereas if the amount exceeds 100 parts by weight, there will be no reaction advantage and it will only be economically disadvantageous.

This method of addition can be carried out even if the entire amount is added together with the raw materials, catalyst and solvent at the start of the reaction, but it is preferable not only to make them coexist at the start of the reaction but also to feed them continuously or intermittently during the reaction. , it is possible to obtain the desired effect with a smaller amount of use. In this case, the feed rate of the alkyl-substituted benzenes is as follows:
A range of 0.5 to 50 parts by weight/h can be employed, more preferably a range of 1 to 20 parts by weight/h.

As the reaction solvent, an aliphatic monocarboxylic acid having 2 to 10 carbon atoms is used, and acetic acid is particularly preferred.
It is preferable to use it in a range of about 2000 parts by weight.

As the molecular oxygen used as the oxidizing agent, pure oxygen or industrial exhaust gas can be used, but from an industrial perspective, air is most suitable.

The reaction temperature is about 100 to 250°C, more preferably 1
The temperature is about 50 to 220°C. If the temperature is lower than 100°C, the reaction rate is slow, and if the temperature exceeds 250°C, the oxidation of the solvent to carbon dioxide and the decomposition of the product become significant, which is not preferable.

The reaction pressure is such that the total pressure is about 1 to 50 kQ/c4G, especially about 3 to 30 kO/cjG, and the oxygen partial pressure is about 8
It is preferable that the value be about Ω/cl# or less.

The reaction time varies depending on the type and amount of raw materials, alkyl-substituted benzenes and catalysts, reaction temperature, oxygen partial pressure, etc., but is generally within the range of 10 minutes to 10 hours.
! selected.

The invention is generally practiced as follows.

That is, a predetermined amount of raw materials, a catalyst, alkyl-substituted benzenes, and a reaction solvent are charged into a pressure-resistant reaction 8 equipped with a stirrer and equipped with a gas inlet and a gas outlet, and the inside of the system is replaced or pressurized with nitrogen or oxygen-containing gas. Heat to the specified temperature. In this temperature raising process, it is preferable to perform some kind of stirring for the purpose of raising the temperature uniformly, but blowing gas is not necessarily required.

Oxygen absorption begins at around 100°C during boat fishing. After the absorption starts, oxygen or an oxygen-containing gas is introduced and the reaction is carried out while maintaining the reaction pressure and oxygen partial pressure within a predetermined range. The exhaust gas is cooled and the condensate is returned to the reactor.

After a predetermined reaction time, the reactor is cooled, the reactants are taken out, and the! A part of the solvent or solvent is removed by distillation, or another solvent such as water is added to crystallize the desired carboxybiphenyls, or after the solvent is removed by distillation, recrystallization is performed.

In the above reaction operation, when the reaction is carried out while supplying alkyl-substituted benzenes, it is preferable to connect a pressurizing feed pump to the reaction group and continuously feed a predetermined amount of alkyl-substituted benzenes. It is also possible to use an intermittent preparation method, such as preparing the ingredients at once and then restarting the preparation.

The reactor is not limited to the above-mentioned device equipped with a stirrer, but may also be of a bubble column type, for example.

The reaction method is not limited to batch reaction, but continuous and semi-continuous methods are also possible. Specifically, raw materials, catalysts, alkyl-substituted benzenes, and solvents are continuously supplied to the reactor, and reaction products are continuously extracted. For example, a method in which a part of the compound is charged and then only the raw material is charged, and a method in which the raw material and the alkyl-substituted benzene and/or the solvent are charged and reacted together are exemplified.

(Example) The present invention will be described in detail below with reference to Examples.

Example 1 200 g of 4-acetylbiphenyl and cobalt bromide hexahydrate were placed in a titanium autoclave with a capacity of 1.5 mm equipped with a gas inlet, a gas outlet with a reflux condenser, a thermometer, and an electromagnetic stirrer. a catalyst consisting of 6.70 g and 0.55 g of manganese acetate tetrahydrate, 45 g of toluene and 80 g of acetic acid.
Prepare 0g.

The pressure was increased to 18 ko/cjG with nitrogen, and the mixture was heated with stirring. Start introducing air at 120°C, cool and reflux the evaporating W# acid, and raise the system to 170°C while extracting exhaust gas.
It was maintained at ~180°C and a pressure of 20 kQ/dG. After about 1 hour of reaction, almost no oxygen absorption was observed. At this point, the introduction of air was stopped and the reactor was cooled. The contents were taken out and the crystals were separated, and the obtained solid was washed with water and hot water, and then dried. As a result of analysis, 4-carboxydiphenyl crystals with a purity of 99.1% (by gas chromatography) were obtained. 175.2g of was obtained (yield 86.0%).

Moreover, 25.2 g of 4-carboxybiphenyl was contained in the r liquid. This amount corresponded to 12.5% based on the starting material 4·-acetylbiphenyl.

As a result, the total yield of the target product was 98.5%.
2 In the same reactor as in Example 1, add 200 4-acetylbiphenyl
g, catalyst consisting of cobalt bromide hexahydrate*6.70g and manganese acetate tetrahydrate 0.55g, toluene 15g
and 111,800 g of vinegar and 18 ko/c with nitrogen.
The mixture was pressurized to JG and heated while stirring. Air was introduced from 120°C, and when the temperature reached 150°C, toluene was started to be introduced at a rate of 15 g/h. The evaporating acetic acid is cooled and refluxed, and the temperature is further raised while extracting the exhaust gas until the reaction temperature reaches 1.
The temperature was maintained at 70°C to 180°C and the pressure was 20 Jl/ajG. About 1 hour after the start of toluene charging, the introduction of toluene and air was stopped, and the reactor was cooled.The toluene used in one or more reactions was 30 g in total. As a result of similar analysis,
4-Carboxybiphenyl with a purity of 99.3% was obtained from the solid in a yield of 86.2%. Similarly, 4- contained in r liquid
The overall yield with addition of carboxybiphenyl was 98.7%.

Example 3 Ethylbenzene was used as the alkyl-substituted benzene, 5.1 g of cobalt acetate tetrahydrate, 0.55 g of manganese acetate tetrahydrate and hydrobromic acid (47% hydrogen bromide) were used as catalysts.
4-carboxybiphenyl was prepared according to Example 1 except that >13.0g was used, and the result was 5.
Obtained with a yield of 7.5%.

Example 4 In-10-pyrubenzene was used as the alkyl-substituted benzene, and cobalt naphthenate (C) was used as the catalyst.

Milo%>21.0g, manganese naphthenate (MnMi10
%) and 8.3 g of sodium bromine were used.
41+shita. As a result, the target product was obtained with a yield of 95.3%.

Example 5 m-chlorotoluene as alkyl-substituted benzenes,
As a catalyst, 5.5 g of cobalt acetate tetrahydrate, 0.6 g of manganese acetate tetrahydrate, and 12.5 g of ammonium bromide.
4-carboxybiphenyl was prepared according to Example 1 except that g was used.

As a result, the target product was obtained with a yield of 98.3%.

Example 6 p-ethyltoluene as alkyl-substituted benzenes,
As a catalyst, 10.2 g of cobalt acetate tetrahydrate, 6.0 g of manganese acetate tetrahydrate, and tetrabromoethane 8.
4-carboxybiphenyl was prepared according to Example 1 except that 6 g was used.

As a result, the target product was obtained with a yield of 95.5%.

Example 7 The reaction was carried out under the same conditions as in Example 1 except that 4-acetyl-4'-chlorobiphenyl was used as the acylated biphenyls. As a result, the desired 4-carboxy-4'-chlorobiphenyl was obtained. Obtained with a yield of 98.1%.

Example 8 The reaction was carried out under the same conditions as in Example 1 except that 4-acylated biphenyls were used as 4-acylated biphenyls. As a result, the desired 4-carboxy-4'
-Cyanobiphenyl was obtained with a yield of 98.1%.

Example 9 A reaction using ethyl-4-acetyl-biphenyl ketone as the acylated biphenyls was carried out under the same conditions as in Example 1. As a result, the desired 4-carboxy-biphenyl was obtained with a yield of 981%. obtained at a rate.

Example 10 A reaction was carried out under the same reaction conditions as in Example 1 except that the amount of toluene added was changed to 7.5 g. As a result, the objective 4
-Carboxybiphenyl was obtained with a yield of 86.2%.

Example 11 A reaction was carried out under the same reaction conditions as in Example 1 except that the amount of toluene added was changed to 75 g. As a result, the objective 4-
Carboxybiphenyl was obtained with a yield of 97.8%.

Comparative example 1 In Example 1, the reaction was carried out without adding any toluene.

That is, in the same reaction H as in Example 1, 150 g of 4-acetylbiphenyl, a catalyst consisting of 6.70 g of cobalt bromide hexahydrate and 0.55 g of manganese acetate tetrahydrate, and 80 g of acetic acid were added.
0 g was charged, pressurized to 18 kg/cdG with nitrogen, and heated while stirring. Air was introduced from 120°C and heated for 3 hours at a reaction temperature of 180°C, but the absorption of oxygen was J
2.The temperature was further raised to 250°C, but no oxygen absorption was observed.The reactor was cooled, the contents were taken out, and the same analysis as in Example 1 was performed.
The target 4-carboxybiphenyl was not detected.

Comparative Example 2 When the reaction was carried out under the same reaction conditions as in Example 1 except that the amount of toluene added was changed to Ig, the desired 4-carboxybiphenyl was obtained in a yield of only 5.3%.

(Effects of the Invention) By applying the method of the present invention, acylated biphenyls, which are industrially easily available, can be easily oxidized with an inexpensive oxidizing agent such as air, and the corresponding carboxybiphenyls can be oxidized. It can be obtained in extremely high yields.

Patent applicant: Shin Nippon Rika Co., Ltd.

Claims (1)

[Claims] (1) When oxidizing the acylated biphenyls represented by general formula 1 to produce the corresponding carboxybiphenyls, using an aliphatic monocarboxylic acid having 2 to 10 carbon atoms as a solvent,
Using a mixed catalyst containing one or more heavy metals selected from cobalt, manganese, and cerium and a bromine compound, 1 part by weight or more of alkyl-substituted benzene represented by general formula 2 per 100 parts by weight of acylated biphenyls. A method for producing carboxybiphenyls, which comprises oxidizing them with molecular oxygen in the presence of carboxybiphenyls. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1) [In the formula, R^1 is an alkyl group having 1 to 10 carbon atoms,
X' is the same or different and is F, Cl, Br, NO_2, C
Represents N or SO_3H group. l represents an integer of 0 to 3. ] ▲There are mathematical formulas, chemical formulas, tables, etc.▼(2) [In the formula, R^2 is a linear or branched alkyl group having 1 to 20 carbon atoms, and Y is F, Cl, Br, NO_2, C.N.
or SO_3H group, m is an integer of 1 or 2, and n is 0 to
Each represents an integer of 3. ](2) 0.5 parts by weight of alkyl-substituted benzenes per 100 parts by weight of acylated biphenyl
2. The method for producing carboxybiphenyls according to claim 1, wherein the reaction is carried out while being continuously or intermittently supplied at a rate of ~50 parts by weight/h.