JPH0489449A - Production of 4,4'-octafluorobibenzonitrile, 4,4'-octafluorobibenzamide and 4,4'-octafluorobibenzoic acid and 4,4'-octafluorobibenzamide - Google Patents

Abstract

PURPOSE:To obtain the subject benzoic acid by reacting a 4- halogenotetrafluorobenzonitrile with copper in an organic polar solvent, then hydrolyzing the resultant subject nitrile using a conc. acid and subsequently hydrolyzing the resultant subject new amide using a relatively dilute acid. CONSTITUTION:A 4-halogenotetrafluorobenzonitrile of the formula (X is F, Cl, Br or I) is subjected to a coupling reaction in the presence of copper powder in a polar solvent to obtain 4,4'-octafluorobibenzonitrile. Hydrolysis thereof is then carried out in an >=95wt.% aqueous solution of an acid to obtain a new 4,4'-octafluorobibenzamide. The above-mentioned benzonitrile is hydrolyzed in an <=90wt.% aqueous solution of an acid to obtain 4,4'-octafluorbibenzoic acid which is useful as an intermediate of an engineering plastic such as a polyimide resin and an aramid resin, an intermediate a crosslinking agent, etc.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to intermediate raw materials for highly functional materials having excellent heat resistance, weather resistance, various stability properties, water repellency, etc., such as polyimide resins, aramid resins, etc. 4,4°-octafluorobibenzonitrile, 4,4°-octafluorobibenzamide, and 4. The present invention relates to a method for synthesizing 4°-octafluorobibenzoic acid, and to a new compound, 4,4°-octafluorobibenzamide.

[Conventional technology]

4. For 4°-octafluorobibenzonitrile, "J, Chem, Soc, (C) (Org, )"
(1971), pp. 1343-1348, according to which pentafluorobenzonitrile is
, 4,4°-octafluorobibenzonitrile is obtained by reaction with sodium iodide in N-dimethylformamide at reflux temperature.

However, in this reaction, in addition to 26% of the raw materials remaining, 4-hydrotetrafluorobenzonitrile and 4-hydrotetrafluorobenzonitrile
-Iodothydrafluorobenzonitrile is also produced, and separation of these raw materials and by-products is complicated, and the desired F
However, there is a problem that the yield of BBN is only 33% at most.

Regarding 4.4°-octafluorobibenzamide, there is no description of it in "Chemical Abstract" and, as far as the present inventors know, there is no description of it in other documents, so the compound is Considered to be a new compound.

Furthermore, 4,4'-octafluorobibenzoic acid is described in British Patent No. 1241653, in which 4-hydrotetrafluorobenzonitrile is first dissolved in copper bronze and dimethylformamide. 44'-dihydrooctafluorobiphenyl was obtained by heating to reflux temperature,
Next, this 4,4'-dihydrooctafluorobiphenyl was reacted with butyl lithium (hexane solution) in tetrahydrofuran at -70°C, then dry carbon dioxide gas was introduced, the temperature was raised to room temperature, acid treatment was carried out, and petroleum ether FyuBBA is obtained by extraction.

However, this synthesis method has an insufficient total yield due to the long reaction route, and also has low N and B at -70°C.
However, this method is not satisfactory as an industrial production method because of the high cost due to the reaction and the use of expensive reagents such as butyllithium.

[Problems to be solved by the invention]

In recent years, engineering plastics such as polyimide resins and aramid resins have been attracting attention in the field of plastics industry, and they are even more heat resistant than these materials.
There is a strong need for the development of highly functional materials with excellent weather resistance and various stability.

The present inventors conducted intensive research to obtain the above-mentioned compound, which is extremely promising as an intermediate raw material for such highly functional materials. 4,4°-octaturolobibenzonitrile (hereinafter sometimes abbreviated as F, BBN) can be synthesized by coupling reaction using copper powder in an organic solvent, and then 97% by weight of this It has been discovered that 4,4°-octafluorobibenzamide (hereinafter sometimes abbreviated as F, BBAm) can be obtained by hydrolysis in a concentrated aqueous solution of an acid such as F, BBN
We have discovered that 4°4°-octafluorobibenzoic acid (hereinafter sometimes abbreviated as F, BBA) can be obtained by hydrolyzing it in an aqueous solution of an acid at a concentration of 70% by weight, and further The present invention was completed through further research.

[Means for solving problems]

The present invention is a method for synthesizing 4,4'-octafluorobibenzonitrile, which first involves reacting 4-halogenotetrafluorobenzonitrile represented by the following general formula [1] with steel in a polar organic solvent.

(However, X represents F, C1, Br or Engineering).

The present invention also provides a method for synthesizing 4,4゛-octafluorobipenzamide, which comprises hydrolyzing 4.4゛-octafluorobibenzonitrile in an aqueous solution of an acid having a concentration of 95% by weight or more; , 4,4'-octafluorobibenzonitrile is hydrolyzed in an aqueous solution of an acid having a concentration of 90% by weight or less. It is something.

A further object of the present invention is to provide a novel compound, 4,4°-octafluorobibenzamide.

The present invention will be explained in detail below.

The synthesis method of the present invention includes a coupling reaction step (A) in which 4-halogenotetrafluorobenzonitrile (hereinafter sometimes abbreviated as F4XBN) is reacted with copper in a polar organic solvent to generate F and BBN; F is obtained by hydrolyzing the F and BBN in an aqueous solution of an acid having a concentration of 95% by weight or more.

Hydrolysis step (B) for producing BBAm, and
Hydrolysis step (B2) in which F, BBN is hydrolyzed in an aqueous solution of acid with a concentration of 90% by weight or less to generate F, BBA
It becomes more.

Coupling Process (A) In this process, as mentioned above, F4XBN is reacted with copper in a polar organic solvent to generate new compounds F and BBN, and the reaction formula follows the following formula it is conceivable that.

(However, X represents F, C1, Br, or ■) In the above F4XBN, which is the starting material for this step, X is a halogen such as F, C1, Br, or I, for example. Examples of such F, ) and 4-iodotetrafluorobenzonitrile (hereinafter sometimes abbreviated as F4IBN).

Among these, from the viewpoint of good coupling reactivity,
Preference is given to using F, BrBN or F, IBM as starting material.

Preferred starting material of the present invention is F4B, as described above.
As a method for synthesizing rBN and FjBN, F4XBN is produced by reacting F and BN with a metal halide such as lithium bromide, potassium bromide, potassium iodide, etc. in an organic solvent.
A method for obtaining the following can be suitably employed.

As the polar organic solvent used in the reaction step (A),
It is inert to the starting materials F and IXBN and the products F and BBN, and since the reaction in this step requires a relatively high temperature, it has a high boiling point (preferably 120 to 300
℃, particularly preferably 150 to 250℃) can be suitably used.

Examples of such polar organic solvents include dimethylsulfoxide, dimethylsulfone, tetramethylsulfone, sulfolane, diphenylsulfone, diphenylsulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, hexamethylphosphoric triamide, quinoline, and benzonitrile. , nitrobenzene, dialkyl ethers of glycols, monoalkyl ether acetates of glycols, and other aprotic polar organic solvents can be suitably used.

Among these polar organic solvents, these F
Good solubility in both 4XBN and F, BBN,
In addition, from the viewpoint of water solubility, which is convenient for isolation of reaction products F and BBN, as will be described later, it is particularly preferable to use sulfolane.

The copper used in this step is preferably in the form of flakes or powder, which has a large surface area from the viewpoint of reactivity, and commonly commercially available copper powders can be used. Also, as is clear from the above formula (■), the required amount of copper is the starting material F
, 0.5 mol per 1 mol of XBN, but since this reaction is a solid/liquid two-layer reaction, copper is
, a large excess amount relative to 1 mole of XBN, i.e., 1 to 2
It is preferable to use 0 mol, preferably 2 to 10 mol.

The reaction temperature in this step is usually 100 to 300°C,
Preferably it is 180-240°C. At a temperature above the lower limit, a sufficient reaction rate is obtained, while at a temperature below the upper limit, side reactions hardly occur, so it is preferable to appropriately determine one reaction temperature within the temperature range.

The reaction time of this step is usually 0.5 to 20 hours, preferably about 1 to 5 hours.

Since F and BBN obtained in this process have poor water solubility,
After the reaction is complete, residual copper and by-products of copper halide (copper bromide,
F, B obtained by filtering solids such as iodized steel, etc.
A BN solution is poured into a large amount of water to precipitate the F1BBN crystals, and the crystals are separated and dried to obtain F, BBN.
Isolate N and proceed to the next hydrolysis step (B,) or (B2)
I do.

Process B In this process, F and BBN obtained in the above process (A) are
It is hydrolyzed in an aqueous acid solution having a concentration of 5% by weight or more to produce a new compound, F, BBAm.

The reaction formula is thought to follow the following formula (2).

(However, HY represents an acid.) Examples of the aqueous acid solution having a concentration of 95% by weight or higher include concentrated sulfuric acid, concentrated phosphoric acid, etc., but from the viewpoint of reactivity, operability, economic efficiency, etc. It is preferable to use concentrated sulfuric acid having a concentration of about 97% by weight or more.

If the concentration of the acid is less than the above lower limit, the production of F and BBAm tends to decrease and the production of F and BBA tends to increase, which is not preferable.

The reaction temperature in this step (B) is 80 to 120°C
The reaction time is usually 0.5 to 5 hours.

Since F and BBAm obtained in this step have poor water solubility, after the reaction is completed, the reaction mixture is poured into a large amount of water to
BBAOI crystals are precipitated, isolated by a known method such as filtration, and dried to obtain the desired product F, BBAm.

This step also converts the F and BBN obtained in step (A) to 9
F by hydrolysis in an aqueous solution of acid with a concentration of 0% by weight or less,
It produces BBA, and its reaction formula is the following formula ■
It is considered that this is in accordance with the following.

(However, H2 represents an acid.) Examples of the aqueous acid solution having a concentration of 90% by weight or less include sulfuric acid, hydrohalic acid (hydrochloric acid, hydrobromic acid, etc.),
Examples include phosphoric acid, p-toluenesulfonic acid, etc., and although not particularly limited, sulfuric acid is preferably used from the viewpoint of reactivity, operability, economical efficiency, etc. The concentration of the acid is usually The amount is 30 to 90% by weight, preferably 50 to 90% by weight in an aqueous sulfuric acid solution.

The reaction temperature in this step (B2) is 100 to 180
The temperature is preferably about 0.degree. C., and the reaction time is usually 0.5 to 5 hours.

Since F and BBA obtained in this process have poor water solubility,
After the reaction was completed, one reaction mixture was poured into a large amount of water and F and B were added.
BA crystals are precipitated, separated by a known method such as filtration, and dried to obtain the target product F, BBA.

In addition, as a method for synthesizing F, BBA, in addition to this, in the hydrolysis step (B-, instead of using F, BBN, F,
A similar method of hydrolysis using BBAm can also be adopted.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 25.9 g of 4-bromotetrafluorobenzonitrile (F4BrBN) (purity of about 98% by weight, about 0.10 mol) and copper powder were placed in a 200 ml three-tube flask equipped with a stirrer, a thermometer, and a reflux condenser. 13.1g (approximately 0.2
0 mol) and 100 g of anhydrous sulfolane were added, and the mixture was heated at 210°C.
1 after the completion of the reaction.
When the reaction solution was analyzed by gas chromatography (GC), the reaction rate of F and BrBN was 100%, and
4.4°-octafluorobibenzonitrile (F, BB
The production rate of N) was 80%. The reaction solution was cooled to room temperature, and the solids (mainly copper powder) were removed by suction filtration. The resulting filtrate was dispersed in distilled water at about 10,100 O, and precipitated. The crystals were filtered and dried to obtain 13.9 g of F, BBN crystals (purity of about 95% by weight, about 37.9 mmol).
I got it. The yield from raw material F and BrBN was about 75.9%.

The obtained F, BBN crystals were recrystallized using petroleum ether and had a melting point of 129 to 131°C.

Example 2 F, BBN crystals 5 obtained in Example 1 were placed in a 50 ml Mitsuro flask equipped with a stirrer, a thermometer, and a reflux condenser.
(purity of about 95% by weight, about 13.6 mmol) and 50g of concentrated sulfuric acid of about 97% by weight were added, and about 1
After the reaction was completed with heating and stirring for 0 hours, the reaction solution was
00ml of cooled distilled water, the precipitated crystals were separated by filtration, and then an aqueous sodium hydroxide solution with a concentration of about 5% by weight was added to the crystals, and the remaining crystals were separated by filtration and washed with distilled water. After drying, 4.8 g of crystals of 4,4°-octafluorobibezamide (F,BBAm) (purity about 9
8% by weight, approximately 12.3 mmol). The yield from F and BBN was 89.7%, and the yield from the raw material F4BrBN was about 68.4%.

The physical property values of F and BBAm obtained here were as follows.

Melting point = 287-289℃"F-NMR:
('H-/ force y)') :/ri) (internal standard: CF, COOH, solvent: acetone-d6) δ=-
62.3 to -62.5 ppm (m, 4F).

65,7~-65.9ppm (m, 4F)=H-NM
R: (internal standard, TMS, solvent: acetone-d,) δ=7
．． 60ppm(s, 2)1).

δ = 7.80 ppm (s, 2H) Infrared absorption spectrum (IR): KBr method (see Figure 1) Example 3 The reaction was carried out in the same manner except that 50 g of about 70% by weight sulfuric acid was used instead. , about 500ml of reaction solution
The precipitated crystals were filtered and dried to give 4,4'-octafluorobibenzoic acid (F,B
5.24 g of crystals of BA) (purity about 95% by weight, about 12.
9 mmol) was obtained. The yield from F, BBN is 94.5
%, the yield from the raw material F4BrBN was about 71.7%.

The obtained F, BBA crystals were recrystallized using petroleum ether and had a melting point of 316 to 318°C.

[Brief explanation of the drawing]

FIG. 1 is an infrared absorption spectrum of 2,2°, 3,3°, 5.5°, 6.6′-octafluoro4.4°-bibenzamide.

Claims (1)

[Scope of Claims] (1) 4,4'-octafluorobibenzonitrile produced by reacting 4-halogenotetrafluorobenzonitrile represented by the following general formula [1] with copper in a polar organic solvent. Synthesis method. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [1] (However, X represents F, Cl, Br, or I) (2) 4
, 95% by weight of 4'-octafluorobibenzonitrile
1. A method for synthesizing 4,4'-octafluorobibenzamide, which comprises hydrolyzing it in an aqueous solution of acid at a concentration higher than that of the acid. (3) 4,4'-octafluorobibenzonitrile 9
A method for synthesizing 4,4'-octafluorobibenzoic acid, which comprises hydrolyzing it in an aqueous solution of an acid having a concentration of 0% by weight or less. (4) 4,4'-octafluorobibenzamide.