JPS58219144A - Preparation of o-toluic acid chloride - Google Patents

Abstract

PURPOSE:To prepare the titled compound from an economically available raw materials, with a relatively simple operation, by reacting o-chlorotoluene with less than equivalent amount of metallic Mg, converting the product to o-toluic acid by carbonation and hydrolysis, and chlorinating the acid. CONSTITUTION:0-Chlorotoluene which is produced in a large amount as a by- product in the preparation of p-chlorotoluene, is used as a starting raw material, and is made to react with less than equivalent amount of metallic Mg to obtain o-tolylmagnesium chloride dissolved in the unreacted raw material. Carbon dioxide gas is blown into the reacton liquid under cooling at -7-+7 deg.C to effect the carbonation, and the product is hydrolyzed with a mineral acid to produce o- toluic acid in the reaction liquid. The liquid is left to stand for a while to separate into two layers. The water-containing layer separated as the lower layer is removed, and the organic layer is heated (at about 140 deg.C), and mixed slowly with benzotrichloride as a chlorination agent to obtain the objective compound, which is recovered from the unreacted raw materials by vacuum distillation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing orthotoluyl acid chloride using orthochlorotoluene as a raw material.

Conventional 1 orthotoluylic acid chloride is generally (1)
and ψ), the ortho-toluyl compound obtained by t-oxidation of ortho-xylene is used as an intermediate raw material, and a chlorinating agent such as thionyl chloride or phosgene is applied to it. In the conventional method using xylene as a starting material, xylene as a starting material is relatively expensive. To.

Before the chlorination reaction of orthotoluic acid in formula 0), it is necessary to separate 7-talic acid from orthotoluic acid in advance, and the chlorination reaction tis(.

The powdered 'orthotoluic acid obtained by the reaction of Eq. However, it has the drawback that the handling and reaction operations are complicated.

In the production of lavala chlortoluene, the present inventor used orthochlorotoluene, which is produced in large quantities as a by-product and is currently of little use value, and which can be obtained at low cost, as a starting material. The result of repeated research on how to efficiently obtain orthotoluylic acid chloride! This method succeeded in obtaining orthotoluylic acid chloride at low cost through relatively easy operations.

That is, the present invention involves the first step of reacting excess orthochlorotoluene with less than an equivalent amount of metallic magnesium to convert a portion of it into orthotolylmagnesium chloride, and the step of blowing charcoal gas into the reaction solution of the first root. After carbonating orthotolylmagnesium chloride, orthotolyl magnesium chloride is added and hydrolyzed to produce orthotoluic acid in the reaction solution.A second step'', and water is separated from the reaction solution obtained in the second step. This is a method for producing orthotoluic acid chloride using orthochlorotoluene as a raw material, which comprises a third step of chlorinating orthotoluic acid in the solution by applying bensitrichloride to the reaction solution.

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

The first step of the present invention is a step of reacting metal magnesium to orthochlorotoluene as a raw material to form orthotolylmagnesium chloride as shown in equation (3).

0, H4(OH,) 0/+Mr→0. H, (OH,
) (MrOz )...-(3) The reaction of formula (3) above is a reaction that produces an alkylmagnesium halide, which is generally known as a Grignard reagent, by reacting metallic magnesium with an alkyl halide. It is equivalent.

However, conventional Grignard reagents are generally prepared by reacting an alkyl halide with #1 equivalent of metallic magnesium in a sufficiently large amount of a solvent such as an ether.

In the m1 step of the present invention, an excess of orthochlorotoluene is used as a raw material, and an equivalent amount or less of metallic magnesium is reacted with it. The reaction is started by placing a part of the raw material orthochlorotoluene to be used and metal magnesium chips in a container, heating the contents to about 70 to 14017, and while maintaining the temperature, the raw material orthochlorotoluene is added. Gradually add the rest of the mixture.

In this reaction! The reaction can be carried out more smoothly by adding a small amount of a low boiling point compound such as tetrahydrofuran to the raw material orthochlorotoluene. Further, it is necessary to use the raw material orthochlorotoluene in excess of the amount of metal magnesium. Due to this.

Not only in the first step but throughout all the steps of the present invention, the reaction product can be used in excess and dissolved in 9-orthochlorotoluene and maintained in a good condition, so that the 9-reaction can be carried out smoothly. However, it is better to avoid using an excessive amount of orthochlorotoluene, as this means that a large amount of processing liquid will be handled through the metalwork 1.4 tons. What is the preferred amount of orthochlorotoluene used?

It is about 1.5 to 5 i11 relative to metal magnesium.

During the reaction, a small amount of ■2 is 0. It is preferable to add a halogen element such as H or Br or a compound thereof as a catalyst in order to promote one reaction. Also, when adding an appropriate amount of a low boiling point compound such as tetrahydrofuran to JIK orthochlorotoluene, the reaction can be made to proceed more smoothly. The boiling point of the reaction solution in the third step decreases to 1
Since it is difficult to maintain an appropriate level of reaction source, the amount added is 70% relative to the raw material orthochlorotoluene used.
It is desirable to limit the amount to about % IL.

After completing the first step, the reaction solution is obtained in a state in which the reaction product orthotolylmagnesium chloride is dissolved in unreacted orthochlorotoluene used in an excess of 9%.

In the second step of the present invention, carbon dioxide gas is blown into the reaction solution after the first step, and orthotolylmagnesium chloride in the solution is carbonated by the reaction shown in equation (4). By Mine I! 11! is added to hydrolyze it, and orthotoluyl i! is added to the solution. 11t-This is the step of generating.

0, H, (OH,) (MfO/)+OO□→06H4
(OH3) (000MfO/)...(4) e1 0s H4(OHs) (000MfO/)H;
OO* H4(CH3)(000H)+MfO/,...
...(5) That is, in the 9th 2nd factory, the 9th 11th.
! After completing step 4, carbon dioxide gas is first blown into the reaction solution to carbonate the orthotolylmagnesium chloride in the solution. Since this reaction is exothermic, the reaction solution should be heated at 17~+7υ to suppress the formation of by-products.
It is desirable to do this while cooling to a certain degree. 9.Also used as a substitute for blowing carbon dioxide into the reaction solution.

Isomorphic carbonic acid may be added to the solution. Next, when a mineral acid and water are added to one reaction solution and stirred, the orthotolyl magnesium carbonate in the first solution undergoes hydrolysis and becomes orthotoluic acid as shown in formula (5).

If you leave the reaction solution after the above hydrolysis for a while! Since the reaction mixture is separated into two layers, an organic reaction liquid layer and a water layer containing magnesium chloride, after the lower water layer is separated and removed, only the upper organic layer is transferred to the sixth step.

In the third step, pencitrichloride is applied to the organic reaction solution obtained in the second step to remove orthotoluyl i in the solution.
This is a step of chlorinating by the reaction of formula (4i).

06H, (OHs) (ouoii) + O,H, (0
0/, )-+0, H4(0)1. ) (000/) +
0. ) l, (000/) - (63 That is, the 9 reaction solution obtained by the 2nd process is! The raw material orthochlorotoluene used in excess in the first step exists in an unreacted state, and 9 reacts as a tube solvent. Since the product, orthotoluic acid, is in a dissolved state, heat this reaction solution and gradually add pensitrichloride as a chlorinating agent to it to dissolve it in the solution. The orthotoluic acid that is present! easily reacts with pencitrichloride to produce the desired product, orthotoluic acid chloride.In this case, 9 metal chloride such as ferric chloride is added as a catalyst to the reaction solution. The 9 reaction can be accelerated by adding .

This reaction is a liquid-liquid reaction, so compared to the conventional chlorination of orthotoluic acid as shown in equation 0),
Much easier to operate. Also.

The reaction is carried out at a relatively high temperature of about 140 υ, but orthochlorotoluene, which is the main solvent in one reaction solution, has a boiling point of about 1700 υ, so it is relatively easy to raise the temperature of the reaction solution above the above level during one reaction. This allows the reaction temperature to be maintained. However, if the reaction solution after the second step contains a large amount of a low boiling point compound such as tetrahydrofuran added in the first step reaction.

In the 6th step, the boiling point of the 9 reaction solution was lowered.

It will be difficult to maintain the above reaction temperature, and side reactions may cause a decrease in the yield of orthotolyl chorolylide.In such cases, remove low-boiling seafood from the reaction solution by distillation in advance. This is desirable.

The reaction tIIi obtained in the third step is a mixed solution containing orthochlorotoluene as a solvent, orthotoluic acid chloride, which is the target product produced by the reaction of formula (6), and benzoyl chloride, which is a by-product. Orthotoluic acid chloride can be obtained as a product by distilling these by vacuum distillation.

Orthochlorotoluene recovered by fractional distillation is *@1
It can be returned to the process and used repeatedly.

As described above, the present invention is a method for producing orthotoluylic acid chloride through a series of steps using 9orthochlorotoluene as a raw material. and! In the present invention, since orthochlorotoluene, which is available at low cost, is used as the raw material, the product can be obtained at low production costs. In addition, according to the present invention, by using an excessive amount of orthochlorotoluene as a raw material in the first step, the subsequent series of chemical reactions can be carried out by reactions between liquids, making the nine-reaction operation easy. ? Furthermore, it has the advantage of having little handling loss, and furthermore, it has excellent effects such as the ability to efficiently obtain products because it generates few by-products in intermediate steps.

Next, nine examples of the present invention are listed.

Example (1st factory) In a four-bottle flask with a capacity of 11 equipped with a stirrer, a thermometer, a raw material orthochlorotoluene dropping tube, and a condenser, 1215f of precious metal My chips and I2[L2F as a catalyst were added.
Accept it! A small amount of a mixed solution of 253 g of raw material orthochlorotoluene and 60 t of tetrahydrofurane is added to this, and the contents are heated to about 70 TJ to start the reaction.Subsequently, while heating is continued, the raw material orthochlorotoluene and tetrahydrofuran are mixed. Add the rest of the mixture dropwise over about 1 hour.
To perform a Grignard reaction. After the dropwise addition, stirring was continued for about 30 minutes to complete the reaction.

(Second step) After the Grignard reaction in the M1 step was completed, the reaction solution in the flask was cooled in a permanent acetone bath, and enough violet 00□ gas was blown into it to carbonate the Grignard reagent. After that, an equivalent amount of 20XHOj was added to the metal My used in the first step, and hydrolysis was performed by stirring. During the reaction, a gel-like substance of My(OH)0/ was produced, but it eventually became Mvolt and dissolved.

(Third step) After the reaction solution from the second step was transferred to a separating flask and allowed to stand for a while to separate into two layers: a water layer and an organic liquid layer.

The lower water layer was separated from the upper organic liquid layer.

The organic liquid layer was removed and placed in a four-way flask, and excess tetrahydrofuran contained in the liquid was distilled off using a six-ball Glinski fractionator.

P/O/, α5f was added as a catalyst into the flask, and while the Shoinai Tanimo was heated to about 140'o, pencitrichloride 81F was added dropwise to it over about 1 hour.

After that, stirring was continued for 30 minutes to complete the chlorination reaction.
・Set.

After the completion of the reaction, the product liquid in the flask was distilled using a three-ball Glinski fractionator to obtain orthotoluic acid chloride 58f as an M product fraction and benzoyl chloride 5 as a by-product fraction.
4f and orthochlorotoluene 1 as recovered raw material fraction
I got qot*.

The yield of the product orthotoluic acid chloride based on the raw material orthochlorotoluene used (subtracting the recovered amount) was 75%.

Patent applicant: Nikkei Kako Co., Ltd.

Claims (1)

[Claims] The first step is to react an equivalent amount or less of metallic magnesium to excess orthochlorotoluene and convert a portion of it into orthotolylmagnesium chloride, and the first step is to blow Subanaka gas into the reaction solution of the first step to convert orthotolylmagnesium chloride into a charcoal tube. The second step is to add mineral acid and hydrolyze to produce orthotoluic acid in the reaction solution, and after separating the water from the reaction solution obtained in the second step, pensitrichloride is added to the reaction solution. A method for producing orthotoluic acid chloride, comprising a fifth step of chlorinating orthotoluic acid in the liquid.