JPS5835977B2 - Production method of pivalic acid chloride and aromatic carboxylic acid chloride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing pivalic acid chloride and aromatic carboxylic acid chloride from pivalic acid and a trichloromethylbenzene compound.

Pivalic acid chloride and aromatic carboxylic acid chloride are useful as intermediate raw materials for pharmaceuticals, agricultural chemicals, dyes, and other industrial chemicals.

A common method for producing pivalic acid chloride is to react pivalic acid with phosphorus pentoxide, phosphorus trichloride, thionyl chloride, phosgene, or the like.

Other methods include reacting pivalic acid with benzoyl chloride, and reacting t-butyl chloride and carbon monoxide with BF3.
A method for synthesizing pivalic acid chloride by reacting in the presence of is also known.

However, all of these methods have problems and are not necessarily preferred as industrial production methods.

For example, in a method of reacting pivalic acid with phosphorus pentoxide, phosphorus oxychloride is produced by the reaction, but the boiling point of phosphorus oxychloride is very close to that of pivalic acid chloride and cannot be separated by distillation.

In the method of reacting pivalic acid and phosphorus trichloride, the reaction can be carried out without producing phosphorus oxychloride, but in this case, the phosphorus compound remains as an impurity, and (1)
It is not easy to remove IJ.

Furthermore, the presence of phosphorus as an impurity has the disadvantage of interfering with the utilization of the reaction product.

The method of reacting pivalic acid with thionyl chloride yields pivalic acid chloride in a relatively good yield and is useful as a laboratory method, but in this case, sulfur is likely to be mixed in and expensive thionyl chloride is used. This method cannot be said to be industrially advantageous.

Furthermore, the method of reacting t-butyl chloride with carbon monoxide involves carrying out the reaction at 700 atmospheres in the presence of BF3, and since the yield is not high, this method cannot be said to be economically advantageous either.

The present inventors, as a method for producing pivalic acid chloride,
In order to improve the shortcomings of the known methods as described above, we investigated a method for simultaneously producing pivalic acid chloride and aromatic carboxylic acid chloride by directly reacting a trichloromethylbenzene compound with pivalic acid as a chlorine source.

As a result, it has been found that it has been difficult to synthesize carboxylic acid chlorides by the reaction of a carboxylic acid having a carboxyl group on a tertiary carbon with a trichloromethylbenzene compound, and although this has never been done, it has been found that synthesis of carboxylic acid chlorides under specific conditions is difficult. It was discovered that pivalic acid chloride can be obtained in good yield by reacting pensitrichloride with pivalic acid.

However, in this case, the yield of benzoyl chloride was rather low, and there was still room for improvement.

Furthermore, when 1,3-bis(trichloromethyl)benzene or the like is used as a trichloromethylbenzene compound and pivalic acid is reacted with it, the reaction does not proceed smoothly and the yield of pivalic acid chloride is extremely low. Not only,
Almost no aromatic dicarboxylic acid dichloride was obtained.

As a result of intensive research to improve these drawbacks, the present inventors discovered that the first step of reacting aromatic carboxylic acid chloride with pivalic acid and then distilling off all or part of the pivalic acid chloride from the reaction product. The residue obtained by distilling off pivalic acid chloride in the first step is reacted with a trichloromethylbenzene compound corresponding to the aromatic carboxylic acid chloride initially used in the presence of a Friedel-Crafts catalyst to synthesize aromatic carboxylic acid chloride. By combining the second step, it is possible to substantially produce pivalic acid chloride and aromatic carboxylic acid chloride from the trichloromethylbenzene compound and pivalic acid, and this method facilitates the direct reaction with pivalic acid. It is also possible to use 1,3-bis(trichloromethyl)benzene, which does not proceed as a chlorine source, and that both pivalic acid chloride and aromatic carboxylic acid chloride can be obtained in high yield by this method. The present invention has been completed.

The aromatic carboxylic acid chloride used as a raw material in the present invention is a compound represented by the general formula: where R represents a hydrogen atom, a chlorine atom, or a -COCl group, and an aromatic carboxylic acid chloride represented by the above general formula. The trichloromethylbenzene compound corresponding to chloride is a compound represented by the general formula (when R is -coct group).

In the present invention, aromatic carboxylic acid chloride and pivalic acid are reacted in the first step, and part or all of the pivalic acid chloride produced by the reaction is distilled out of the reaction system.

That is, in this case, when the aromatic carboxylic acid chloride used as a raw material is benzoyl chloride or chlorinated benzoyl chloride, the pivalic acid chloride produced in the first step does not necessarily have to be completely distilled off and is converted into pencitrichloride or A second step of reacting with chlorinated pencitrichloride may be performed.

However, when the aromatic carboxylic acid chloride used as a raw material is phthalic acid chloride, the pivalic acid chloride produced in the first step is completely distilled off, and a small amount of the excess phthalic acid chloride initially used is further distilled off. It is then necessary to carry out a second step by adding bis(trichloromethyl)benzene.

The reactions in the first and second steps of the present invention will be described below, taking as an example the case where benzoyl chloride, pivalic acid and pensitrichloride are used as raw materials.

That is, when these reactions are taken together, pivalic acid chloride and benzoyl chloride can be obtained from pivalic acid and pencitrichloride.

What is the first step of this invention? This is carried out by mixing aromatic carboxylic acid chloride and pivalic acid and heating the mixture to react while stirring.

The mixing ratio of pivalic acid and aromatic carboxylic acid chloride is 1.8 to 6.0 mol, preferably 2.2 mol to 1 mol of pivalic acid, depending on the type of aromatic carboxylic acid chloride.
-4.2 mol.

If the ratio of aromatic carboxylic acid chloride is less than this, it may be difficult to complete the reaction, and a large amount of solidified material may be generated during the reaction, making the reaction operation difficult.

Increasing the ratio of aromatic carboxylic acid chloride
Although there is no particular problem in terms of reaction, it is economically disadvantageous.

The reaction in the first step is carried out at 90 to 180°C with stirring.

When a mixture of pivalic acid and aromatic carboxylic acid chloride is heated and heated while stirring, a reaction occurs while generating HCI gas.

Depending on the type of aromatic carboxylic acid, solid matter may be formed in the reaction system, resulting in a slurry-like state.

When the temperature is further increased by 1°, the pivalic acid chloride produced by the reaction becomes refluxed.This temperature varies depending on the type of aromatic carboxylic acid chloride to be reacted and the charging ratio, but is usually 110 to 130°C.

The reaction is carried out while the generated HCI is taken out of the system.

Although the reaction can be carried out while the pivalic acid chloride produced by the reaction is refluxed, it is advantageous to proceed with the reaction while distilling the pivalic acid chloride out of the system in order to speed up the progress of the reaction.

In order to obtain highly pure pivalic acid chloride, it is preferable to distill the pivalic acid chloride through a fractionating column.

In this way, the reaction is carried out with stirring and heating while HCI and pivalic acid chloride are taken out of the system, but the reaction temperature can be gradually raised depending on the state of HCI generation and the distillation state of pivalic acid chloride. It is effective in shortening the reaction time and completing the reaction.

When the temperature of the reaction mixture reaches 150-180°C, HCI
The reaction in the first step is completed when no more is generated, and the reaction time up to this stage is usually 1 to 4 hours.

Next, when the aromatic carboxylic acid chloride used as a raw material is phthalic acid chloride, the pivalic acid chloride remaining in the reaction system is completely distilled off by distillation under reduced pressure.

In this case, it is more effective to carry out the distillation operation until a small amount of aromatic carboxylic acid chloride is distilled out in order to smoothly proceed with the reaction in the second step.

Complete distillation of pivalic acid chloride is not necessarily essential and can be omitted when the raw aromatic carboxylic acid chloride is benzoyl chloride or chlorinated benzoyl chloride.

After the first step is completed, a trichloromethylbenzene compound corresponding to the aromatic carboxylic acid chloride used as a raw material and a Friedel-Crafts catalyst are added and heated with stirring to carry out the second step reaction.

Free chill craft catalysts include FeCl3, ZnC
l2.5bC15, AlCl3.5nC14, TiCl
Among them, F e Cl
3. ZnCl2 is the preferred catalyst.

The trichloromethylbenzene compound is added in an amount that provides substantially equimolar CCl3 groups to the pivalic acid used in the first step.

That is, 1/2 mole is added in the case of pivalis.

The amount of the catalyst added is 0.0001 to 0.02 parts by weight per 1 part by weight of the trichloromethylbenzene compound.

The reaction temperature in the second step is 50 to 150°C.

Depending on the compounds to be reacted, lowering the initial reaction temperature may produce solids in the reaction system, so the reaction temperature is selected depending on the compounds to be reacted.

The reaction is an exothermic reaction, and it is advantageous in controlling the reaction temperature to lower the initial reaction temperature within a range that does not generate solids as described above.

The reaction temperature, type of catalyst, and amount added are determined depending on the compound to be reacted, taking into consideration the generation of solids in the reaction system, control of the reaction temperature, etc., and the reaction temperature will vary accordingly. However, the reaction time of the second step is usually 20 minutes to 2
It's time.

After the reaction is completed, treatment is carried out by conventional vacuum distillation.
High purity aromatic carboxylic acid chloride can be obtained in good yield.

The obtained aromatic carboxylic acid chloride can be recycled to the first step.

According to the present invention, by using an inexpensive trichloromethylbenzene compound as a chlorine source, high purity pivalic acid chloride and high purity aromatic carboxylic acid chloride, which are free of impurities such as phosphorus compounds that interfere with the utilization of the reaction products, can be obtained. It can be manufactured at a high rate.

Example 1 Stirrer, thermometer and 15m1φ x 150mm
527P (3.75 moles) of benzoyl chloride and 1
53? (4.5 mol) of pivalic acid is taken and heated while stirring to raise the temperature.

Generation of HCl gas was observed around the time when the temperature of the contents reached 100°C, and distillation of pivalic acid chloride was observed around 124°C.

The heating was gradually increased depending on the state of distillation of pivalic acid chloride, and the internal temperature reached 150° C. in about 1.5 hours, and no HCI gas was generated.

Next, under a reduced pressure of 80 miHg, the remaining pi-
<Phosphoric acid chloride was distilled out, and 172P phosphoric acid chloride was obtained by combining it with that previously distilled.

The yield of pivalic acid chloride based on pivalic acid is 95%.

When this product was analyzed by gas chromatography, the purity was 98.2.
%Met.

(B) Pencitrichloride 293s' (1,50
mol) = o, tsy of FeCl3 was added.

Heat this mixture while stirring, and heat it at around 60℃ for 2 hours.
React for 0 minutes, then raise the temperature to 100°C in 30 minutes,
The reaction was completed at 100°C for an additional 10 minutes.

The crude product from the reaction was subjected to simple distillation under reduced pressure of 34 to 38 mmHg to distill off as much of the distillable material as possible.

In this way, 727 g of distillate was obtained, which was confirmed to be benzoyl chloride as a result of IR analysis.

When the yield of benzoyl chloride based on pensitrichloride is calculated assuming that the amount of benzoyl chloride initially charged in (A) is subtracted and the remainder is newly generated benzoyl chloride, it corresponds to 948%.

Gas chromatography analysis of the distilled benzoyl chloride revealed a purity of 98.7%.

Comparative Example 1 Pivalic acid 255'f? (2,5 mol), pensitrichloride 48M' (2,5 mol) and FeCl30.
75? was placed in a flask of 11 and heated while stirring.

When the internal temperature reached 65°C, HCI gas began to be generated.

The reaction was carried out at 70°C for about 30 minutes, then the temperature was raised to 100°C in about 30 minutes, and the reaction was completed after stirring at 100°C for an additional 30 minutes.

Next, this reaction solution was distilled under reduced pressure by a conventional method to distill as much of the distillable product as possible.

Distillate is 591? Met.

Gas chromatography analysis of this distillate revealed that the concentrations were 48.0 wt% pivalic acid chloride, 51.1 wt% benzoyl chloride, and 0.9 wt% others.

This result corresponds to a yield of pivalic acid chloride of 94% and a yield of benzoyl chloride of 86%.

Example 2 (A) In the same reactor used in Example 1, 609
1 (3,00 mol) of isophthalic acid chloride and 15:
1' (1.5 mol) of pivalic acid is heated and heated while stirring.

When the temperature of the contents reached 90-95°C, a white substance formed, the contents became a slurry, and HCI gas evolution occurred.

Distillation of pivalic acid chloride was observed when the internal temperature reached around 115°C.

The temperature was gradually raised while adjusting the distillation amount of pivalic acid chloride, and the temperature was raised to 170°C in 5 hours. The white solid substance that had once formed disappeared, and the reaction system became a homogeneous liquid, and HCI was generated. is gone.

Next, pivalic acid chloride remaining in the reaction system was distilled out under reduced pressure of 70 mmHg, and a total of 171 g of pivalic acid chloride was obtained, including that distilled out earlier.

This is pivalic acid chloride yield 94 based on pivalic acid.
, corresponding to 5%.

Glass chromatography analysis revealed that the purity of this product was 9.
It was 8.4%.

(B) In (A), pivalic acid chloride was distilled off at 0.degree. C., and 121 isophthalic acid chloride was distilled off from the residue under reduced pressure of 8 TIL mHg.

This distillation residue contains 235P (0.75 mol) of 1,3-bis(trichloromethyl)benzene and 0.11' of FeC.
13 was added and the reaction was carried out at 130 to 140°C for about 45 minutes with stirring to complete the reaction.

The crude product was then subjected to simple distillation under conditions of 126-130'c/8 mmHg to distill off as much of the distillable material as possible.

In this way, 739.4? isophthalic acid chloride was obtained.

When combined with the first distilled isophthalic acid chloride, the recovered amount of isophthalic acid chloride becomes 751.4 f.

In (A), after subtracting the amount of isophthalic acid chloride initially charged, the remainder is newly generated isophthalic acid chloride, and 1,3-bis(trichloromethyl)
The yield of isophthaloyl chloride based on benzene is calculated to be 93.5%.

Further, when this was analyzed by gas chromatography, the purity of the obtained isophthalic acid chloride was 98.9%.

Example 3 <A) In the same reactor as used in Example 1, 609 t
? (3.0 mol) of isophthalic acid chloride and 153f
(1.5 mol) of pivalic acid was taken, Example 2-(A)
React in the same manner as 170. OS' pivalic acid chloride was obtained.

(B) The residue from which pivalic acid chloride was distilled off in (A) was distilled under reduced pressure of 8 mmHg, and 141 isophthalic acid chloride was distilled out.

This distillation residue contains 23Fl (0.75 mol) of 1,3-bis(trichloromethyl)benzene and 0.25? ZnC
12 was added, and the mixture was reacted at 130 to 145°C for about 1 hour with stirring.

The crude product was then distilled to 126-b to obtain 733.9 f of isophthalic acid chloride.

When combined with the first distilled isophthalic acid chloride,
The recovered isophthalic acid chloride is 747.9P.

In (A), assuming that the amount of isophthalic acid chloride initially charged is subtracted and the remainder is newly generated isophthalic acid chloride, 1,3-bis(trichloromethyl)
The yield of isophthaloyl chloride based on benzene is calculated to be 91.2%.

Further, the purity of isophthalic acid chloride obtained by gas chromatographic analysis was 98.7%.

Comparative Example 2 306.4f (3.0 mol) of pivalic acid and 469.31 (1.5 mol) of 1.3- bis(trichloromethyl)benzene and 3. Ot's Fe
Take Cl3, heat it while stirring, and raise the temperature to 100~
The reaction was carried out at 145°C for 1 hour.

Generation of HCI gas was observed during the reaction.

This gas was absorbed into an aqueous solution of caustic soda, and the amount of HCI generated was determined by neutralization titration.

The reaction rate calculated from the amount of HCI generated was 63%.

The reaction mixture was distilled to obtain 335 g of a low boiling distillate and 325 g of a high boiling distillate.

As a result of gas chromatography analysis of the distillate, the low boiling distillate contained 62.6 wt% pivalic acid chloride and 28.4 wt% pivalic acid.
wt%, other 9. It was Owt%.

The yield of pivalic acid chloride based on pivalic acid was 58%.

No isophthaloyl chloride was observed in the high-boiling distillate.

Claims (1)

[Claims] 1 In the general formula S, R represents a hydrogen atom, a chlorine atom, or a -coct group. A first step of reacting the aromatic carboxylic acid chloride represented by pivalic acid with pivalic acid, and then distilling off part or all of the pivalic acid chloride from the reaction product; A pivalic acid chloride characterized by comprising a second step of reacting the aromatic carboxylic acid chloride represented by the above general formula with a trichloromethylbenzene compound corresponding to the aromatic carboxylic acid chloride in the presence of a free chill craft catalyst to synthesize an aromatic carboxylic acid chloride. A method for producing aromatic carboxylic acid chloride.