JPS5843379B2 - Production method of benzoyl chloride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method for producing benzoyl chloride by hydrolysis of pencitrichloride, in which benzoyl chloride in which benzoic acid is dissolved is used as a reaction medium, and pencitrichloride and water are mixed in the reaction medium. The present invention relates to a method for producing benzoyl chloride by adding and hydrolyzing it by a Friedel-Crafts reaction.

Conventionally, as a method for producing benzoyl chloride, a method is known in which benzoic acid is reacted with pensitrichloride in the presence of a Friedel-Crafts catalyst, as shown in formula (1).

When using the reaction of formula (1) above, the reaction is relatively rapid and benzoyl chloride can be obtained as a product in good yield without producing by-products, but benzoyl chloride is expensive. had to be used as raw material.

As another method for producing benzoyl chloride, F e Cla -Z n C12 is added to heated pensitrichloride.
A method is known in which pencitrichloride is directly hydrolyzed as shown in equation (2) by dropping water or inhaling water vapor in the presence of a Friedel-Crafts catalyst such as.

When using the reaction of formula (2), pensitrichloride can be directly hydrolyzed to obtain benzoyl chloride without using expensive benzoic acid as a raw material, but the reaction between pencitrichloride and water is slow. A part of the water added for this purpose escapes as unreacted water vapor, along with reaction products and unreacted pensitrichloride, and hydrogen chloride produced by the reaction, and is transferred to conduits outside the container, condensation pipes, etc. In addition to causing troubles such as condensation and clogging of pensitrichloride, when water is dropped into a large amount of pensitrichloride in the presence of Friedel-Crafts catalyst, the main reaction product In addition to certain benzoyl chloride, a condensate such as a residue is produced as a by-product in the subsequent distillation, which has the disadvantage that the yield of benzoyl chloride based on the raw material pensitrichloride is reduced.

As a result of repeated research on preventing side reactions in the production of benzoyl chloride by direct hydrolysis of pensitrichloride and obtaining benzoyl chloride in good yield, the present inventor discovered that using heated benzoyl chloride as a reaction medium, , in the presence of a Friedel-Crafts catalyst, by simultaneously and continuously adding pencitrichloride and an equivalent amount of water in small portions, without forming the above-mentioned by-products in the medium. discovered that benzoyl chloride can be produced in good yield by hydrolyzing pensitrichloride.

However, even when using this method, it is necessary to add pencitrichloride and water while strictly controlling the addition so that they are always maintained in equivalent amounts in the medium, and the ratio of the two varies. It has been found that the yield of benzoyl chloride tends to decrease when an imbalance occurs, especially when pensitrichloride is added in excess, even temporarily.

As a result of further research in order to improve the above-mentioned drawbacks, the inventors of the present invention found that by using a liquid in which an appropriate amount of benzoic acid was dissolved in benzoyl chloride in advance as a medium liquid,
It has been found that even if there is some imbalance in the addition ratio of pencitrichloride and water, the production of by-products is suppressed and benzoyl chloride can always be obtained in good yield.

The present invention has been made based on the above findings.

That is, in the present invention, benzoyl chloride in which benzoic acid is dissolved is used as a reaction medium liquid, this reaction medium liquid is heated, and pensitrichloride and an equivalent amount of water are added to this in the presence of a Friedel-Crafts catalyst. This is a method for producing benzoyl chloride, in which pensitrichloride is hydrolyzed by adding it.

When using the method of the present invention, benzoyl chloride can be obtained with a much higher yield than the conventional method of directly adding water to bensito'J chloride and hydrolyzing it.

The method of the present invention will be described in more detail below.

In the method of the present invention, benzoyl chloride in which benzoic acid is dissolved is used as a reaction medium liquid, and this reaction medium liquid is heated.
This is a method in which pensitrichloride and water are added to this in the presence of a Friedel-Crafts catalyst to cause a hydrolysis reaction of pencitrichloride in the medium liquid.
In this case, the benzoic acid dissolved in the medium has the effect of preventing the formation of by-products in the reaction between pensitrichloride and water.

However, when the amount of benzoic acid in the medium is small, the effect of preventing side reactions is insufficient.

The experimental results show that desirable results can be obtained by always having benzoic acid present in the medium liquid in an amount of 10% or more, more preferably 20φ or more, based on the total amount of the medium liquid throughout the reaction process. showed that.

Additionally, there is no problem even if a larger amount of benzoic acid is dissolved in the medium liquid, but if it is too much, it will be difficult to dissolve and it will be difficult to operate, so it is better to avoid it. good.

Therefore, it is desirable to keep the diameter to 70φ or less, more preferably about 60% of the medium liquid.

The medium liquid used in the above method of the present invention can be prepared by dissolving a predetermined amount of benzoic acid in heated benzoyl chloride.

A part of the product can be used as the benzoyl chloride used as the medium liquid.

Another method for preparing a liquid medium is to add water to heated benzoyl chloride in the presence of a Friedel-Crafts catalyst to hydrolyze a portion of the benzoyl chloride to form benzoyl as shown in formula (3). It can be obtained by converting it into an acid.

C6H,, C0C6+H2O=C6H5COOH+HC
(3) In the method of the present invention, pencitrichloride and water are added to the medium solution prepared as described above and reacted. The reaction can be carried out by simultaneously adding a small amount of both water and water to the medium liquid.

In this case, there is no risk that variations in the addition ratio of both during the addition process will affect the yield, so the addition of pencitrichloride and water must be strictly controlled so that both are always maintained in equivalent amounts. Even if there is some variation in the rate of addition of both, it is sufficient to add them in an equivalent amount in the end.

Therefore, the reaction operation is extremely easy.

Moreover, instead of adding pencitrichloride and water simultaneously and continuously, each can be divided into several parts and added in alternating batches.

Even with this method, side reactions are suppressed by the buffering effect of benzoic acid dissolved in the medium, so
Benzoyl chloride can be obtained in high yield.

When adding pencitrichloride and water to the medium liquid above, in order to increase the reaction rate, the medium liquid was
It is necessary to heat it to 80°C.

The preferred reaction temperature is in the range of 110-130°C.

The Friedel-Crafts catalyst used in the reaction is FeCl3. Metal chlorides commonly used in Friedel-Crafts reactions of this type can be used, such as ZnCl2.

After the reaction is completed, the product liquid can be distilled under reduced pressure to obtain benzoyl chloride as a product.

Since the benzoic acid added at the beginning is dissolved in the reaction completed solution, during distillation, a portion of the benzoyl chloride with benzoic acid dissolved is left as a residue in the pot, and this solution is added again to the medium. It can be used repeatedly as a solution in the next reaction, or by further adding pencitrichloride in an amount commensurate with the benzoic acid dissolved therein to the product solution after the completion of the reaction. The reaction can also convert the entire liquid medium into bendoyl chloride, which can then be recovered as a product by distillation.

As described above, in the method of the present invention, the hydrolysis reaction of benzo l-IJ fuculoid is carried out in benzoyl chloride in which benzoic acid is dissolved, and the action of benzoic acid dissolved in the medium is This suppresses the formation reaction of by-products that become residue during distillation, so even if there is a slight imbalance in the addition rate of pencitrichloride and water, pencitrichloride can always be produced in a stable and high yield. This is an excellent method for producing benzoyl chloride that allows hydrolysis of

Next, examples of the present invention are listed.

Example 1 4 equipped with a stirrer, a thermometer, a water dropping tube reaching the bottom of the flask, a Bensito IJ chloride dropping tube and a condenser.
203.9° benzoyl chloride 1 benzoyl chloride in a Tulo flask
769 and 30.25 g of FeCl as a catalyst,
The temperature was raised to 120°C to obtain a reaction medium liquid.

Next, 293 p of pencitrichloride and 27.0 g of water were simultaneously added to the reaction medium while stirring.
The solution was added dropwise over a period of time to effect hydrolysis of pensitrichloride.

Further, 325 g of pensitrichloride was added dropwise over 2 hours, stirring was continued for 30 minutes, and the benzoic acid in the medium was changed to benzoyl chloride to complete the reaction.

After the reaction, the product was distilled under reduced pressure to 95°C (final vacuum degree 2).
5iiHg)L, pencyyl chloride 850 as distillate
g (5 g of pot residue) was obtained.

The yield of benzoyl chloride based on the pensitrichloride used was 99.1%.

Example 2 Using the same apparatus as in Example 1, 300! of benzoyl chloride was added to a 4-ton flask. ! and FIC130 as a catalyst,
The mixture was heated to 120° C., and 29.6 g of water was added dropwise over 2 hours to convert a portion of the benzoyl chloride into benzoic acid, which was used as a reaction medium liquid.

Next, 257 g of pencitrichloride and 23.6 g of water were added to the above medium solution. ! i+ was added dropwise alternately in three separate portions to hydrolyze benzo I-IJ fuculoids.

The total time required for dropping was 3 hours.

Finally, in order to convert benzoic acid dissolved in the medium into benzoyl chloride, 321 g of pensitrichloride was added dropwise over 2 hours, and stirring was continued for 30 minutes.

After the reaction was completed, the product was distilled to obtain 7t2.9 of benzoyl chloride (residue: 5.9) as a distillate.

The yield of benzoyl chloride based on the pensitrichloride used was 99.1 yen.

Comparative Example 1 (When benzoic acid is not dissolved in the medium liquid) Using the same apparatus as in Example 1, 303 g of benzoyl chloride and FIC130,1 as a catalyst were placed in a 4-tube flask.
79 was heated to 120°C, and 583 g of pencitrichloride and 53.7 g of water were simultaneously added dropwise thereto over 6 hours to hydrolyze pencitrichloride.

After the dropwise addition, stirring was continued for 30 minutes to complete the reaction.

The product after the reaction was completed was distilled in the same manner as in Example 1 to obtain 707 g of benzoyl chloride (11 g of residue).

The yield of benzoyl chloride based on the pensitrichloride used was 96.4%.

Comparative Example 2 (When water was directly added to pensitrichloride to hydrolyze it).

Using the same apparatus as in Example 1, 813 g of pencitrichloride and F e as a catalyst were placed in a 4-ton flask.
Cls O-24 fl was added, the temperature was raised to 120°C, and 14.99 g of water was added dropwise thereto over 6 hours, and stirring was continued for an additional 30 minutes to complete the reaction.

The product after the reaction was completed was distilled in the same manner as in Example 1 to obtain 544.9 g of benzoyl chloride (38 g of residue).

The yield of benzoyl chloride based on the pensitrichloride used was 93.0%.

Claims (1)

[Claims] 1. Use benzoyl chloride in which benzoic acid is dissolved in 1 io heavy plate or more as a reaction medium liquid, heat this reaction medium liquid, add pencitrichloride and water to it, and add Friedel-Crafts catalyst. A method for producing benzoyl chloride, which comprises adding the benzoyl chloride in the presence of the benzoyl chloride. 2. The method for producing benzoyl chloride according to claim 1, wherein pensitrichloride and water are simultaneously and continuously added to the reaction medium. 3. The method for producing benzoyl chloride according to claim 1, wherein pensitrichloride and water are added in alternating batches to the reaction medium.