JP3270571B2 - Method for producing allyl bromide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing allyl bromides which is useful in the field of synthetic organic chemistry, especially as an intermediate in the production of fine chemical products such as agrochemicals and dyes. More particularly, the present invention relates to an improved method for producing allyl bromide by a halogen exchange reaction using allyl chloride as a raw material.

[0002]

[Prior art]

 Formula (2)

[0003]

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(Where R, R₁And R_TwoAre independent
Represents a hydrogen atom or a lower alkyl group. )
Various methods have been developed for the production of allyl bromides.
It is shown. Allyl is a basic compound of formula (2)
Lomid ｛In the formula (2), R = R ₁= R_Two= H｝
Looking at the production method, generally, allyl alcohol is converted to sulfuric acid.
It is produced by reacting with hydrobromic acid in the presence.

[0005] For example, organic synthesis @ Or
ganic Synthesis, Coll. , One volume,
According to page 27 (1976), 5.9 mol of 48% hydrobromic acid and 4 mol of allyl alcohol are mixed, and 300 g of sulfuric acid is gradually added to this aqueous solution with stirring, followed by distillation. By doing so, allyl bromide can be obtained. According to this method, the objective allyl bromide is 92
Although it can be produced in a quantitatively close yield of up to 96%, a large amount of acid wastewater is industrially produced due to the use of a large amount of sulfuric acid, and an operation such as a neutralization treatment is required, which increases the cost. It has disadvantages such as.

Also known is a method for producing allyl bromide by bromination with hydrogen bromide at a high temperature (350-450 ° C.) using propylene as a raw material under a perlite catalyst (US Pat. No. 753,841 (1980)). However, this method not only has a low selectivity to allyl bromide as a by-product of 1-bromopropene, but also has a problem in separation from by-products.

On the other hand, a method for producing allyl bromide by halogen exchange reaction of allyl chloride is also known. Journal of the Organic Chemistry @J
o-urnal of the Organic Ce
mystery USSR 10, 1122 (197
According to (4 years)｝, allyl chloride or methallyl chloride is subjected to a halogen exchange reaction with excess hydrobromic acid in the presence of cuprous chloride to produce allyl bromide or methallyl bromide.

[0008] Also, Journal of the American Chemical Society @ Jo-urnal of
the American Chemical Soc
e-ity, Vol. 72, p. 4316 (1950)}, a method in which methallyl chloride is subjected to a halogen exchange reaction with sodium bromide in methanol to give methallyl bromide,
Also disclosed is a method of converting methallyl bromide with lithium bromide in acetone.

However, the former method requires not only a low conversion rate of methallyl chloride of 70% or less, but also requires special attention to measures for wastewater because a heavy metal compound subject to industrial regulations is used as a catalyst. And must be. Even in the latter method, the yield of methallyl bromide is at most only 54%.

Conventionally, regarding the halogen exchange reaction of an alkyl chloride to an alkyl bromide with a metal bromide using a phase transfer catalyst and water, Synthesis @ SYNT
H-ESIS 1: 34-5 (1984)} and Journal of the Chemical Society
Chemical Communications @Journalof
the Chemical Society Che
medical Co-communications, 125
0 (1986)}, the method of the present invention relates to an allyl halide wherein the reaction of the allyl chloride with the metal bromide is carried out in the presence of a small amount of water and a phase transfer catalyst. The production method of bromides is not known.

There are several known methods for producing allyl bromides other than the above-mentioned methods, but none of them is satisfactory in terms of raw materials or yield. The present applicant has previously proposed a method for producing the corresponding allyl bromide in good yield by reacting an allyl chloride with a metal bromide in an aprotic polar solvent (Japanese Patent Laid-Open No. 3-1).
69830). However, the method proposed by the present applicants is not necessarily a sufficient method from an industrial point of view, and has the following problems.

That is, it is necessary to use an aprotic polar solvent as a reaction solvent, and it is necessary to collect and reuse this reaction solvent industrially. In addition, there is a problem that it is difficult to apply to the production of allyl bromides having the same boiling point as the aprotic polar reaction solvent. Therefore, improvement of these problems is demanded.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems of the prior art, and has been made in the field of synthetic organic chemistry, particularly in the production of agricultural medicines and dyes. Formula (2) useful as an intermediate

[0014]

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(Wherein, R, R ₁ and R ₂ each independently represent a hydrogen atom or a lower alkyl group.) An object of the present invention is to provide an improved and more industrial production method of allyl bromides. I have.

[0016]

The present inventors have conducted intensive studies to solve the problems of the prior art. As a result, based on the findings of the present inventors, allyl halides, especially allyl bromides, have been found. Is a compound which is susceptible to hydrolysis when heated in the presence of water and easily converted to allyl alcohols, etc., but surprisingly, the halogen exchange reaction between allyl chlorides and metal bromides. Is carried out in the presence of a small amount of water and a phase transfer catalyst, whereby a high conversion rate and high yield of the desired allyl bromide can be produced, and the metal bromide is insoluble in allyl chlorides, In a reaction system in which water and a phase transfer catalyst are not present, the halogen exchange reaction does not proceed at all.

On the other hand, even in a reaction system to which water is added, when no phase transfer catalyst is present, a small amount of the allyl bromide is formed, but the conversion of the allyl chloride is low. Also, in the presence of a phase transfer catalyst, the conversion was similarly low in a reaction system in which water was not present, and it was found that an appropriate range of water content was necessary to obtain a sufficient conversion, and the present invention was completed. I came to. That is, the present invention relates to a compound of the formula (1)

[0018]

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Wherein R, R ₁ and R ₂ each independently represent a hydrogen atom or a lower alkyl group. The allyl chloride represented by the formula is reacted with water and a metal bromide in the presence of a phase transfer catalyst. Formula (2) characterized by the following:

[0020]

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(Wherein, R, R ₁ and R ₂ each independently represent a hydrogen atom or a lower alkyl group).

The method of the present invention is an excellent production method which can be used industrially. According to the method of the present invention, allyl chlorides can be reacted with high volumetric efficiency under relatively mild conditions. Allyl bromide can be produced at a high conversion rate and a high yield. In addition, isolation of the target product after the reaction is also necessary after dissolving the inorganic salt by adding water to the reaction mixture after completion of the reaction, whereby relatively high-purity allyl bromides can be obtained only by liquid separation operation. By performing distillation purification according to the above, a highly pure product of allyl bromide can be obtained.

The allyl bromides obtained according to the present invention have a high quality that can be sufficiently used as a useful intermediate in the field of synthetic organic chemistry, especially for agrochemicals and dyes.
Hereinafter, the method of the present invention will be described.

In the present invention, allyl chlorides of the formula (1) are used as a raw material. Specifically, allyl chloride, methallyl chloride, γ-methylallyl chloride,
γ, γ-dimethylallyl chloride, β-methyl-γ, γ
-Dimethylallyl chloride, γ-ethylallyl chloride, γ-n-propylallyl chloride, γ-isopropylallyl chloride, γ-n-butylallyl chloride, γ
-Sec-butyl allyl chloride, γ-iso-butyl allyl chloride, γ-tertiary butyl allyl chloride and the like.

The metal bromide used as a halogen exchange agent for the allyl chlorides of the formula (1) is not particularly limited as long as it is a metal bromide. Specifically, lithium bromide, sodium bromide, potassium bromide, bromide Calcium, ferrous bromide,
Ferric bromide, cupric bromide, rubidium bromide and the like can be mentioned, but sodium bromide is industrially preferable.

Although the amount of the metal bromide used is of course smaller than the stoichiometric amount, the metal bromide is usually used in an amount exceeding the stoichiometric amount in consideration of the conversion ratio of the allyl chloride as the raw material and the yield of the allyl bromide as the target product. It is appropriate to do. The upper limit of the amount used is preferably not more than twice as much as the allyl chloride as the raw material from the viewpoint of stirring efficiency and economical viewpoint.

The process of the present invention is characterized in that the reaction of an allyl chloride with a metal bromide is carried out in the presence of a small amount of water and a phase transfer catalyst. If the amount of water added to the reaction system is too small, the progress of the reaction is extremely slow,
If the amount is too large, the yield will decrease. The amount of water used is in the range of 0.1 to 30% by weight, preferably 0.5 to 20% by weight, particularly preferably 2 to 30% by weight, based on the raw material allyl chlorides.
-15% by weight.

The type of the phase transfer catalyst to be used may be any compound having a property of transferring bromoanion to the organic phase, such as quaternary ammonium salts, phosphonium salts, macrocyclic polyethers, and chain polyethers. Although there is no particular limitation on the compound of formula (I), quaternary ammonium salts are preferred from an economic viewpoint. Examples of quaternary ammonium salts include tetrabutylammonium bromide, tetrabutylammonium chloride, tetrahexylammonium bromide, tetrahexylammonium chloride, benzyltributylammonium bromide, benzyltributylammonium chloride, and the like. There is no restriction. The upper limit of the amount of the phase transfer catalyst is not particularly limited, but is preferably small from an economic viewpoint, and is preferably 0.1 to 0.1% based on allyl chlorides.
Is suitably in the range of ~ 20% by weight, and 0.5 ~ 10% by weight.
Is more preferable.

The specific embodiments of the present invention are as follows. A predetermined amount of a metal bromide and a predetermined amount of a phase transfer catalyst are charged into 1 mol of allyl chloride, a predetermined amount of water is added, and the mixture is heated and reacted under stirring. The reaction temperature is not particularly limited as long as allyl chlorides or allyl bromides are not deteriorated, but preferably in the range of 20 to 100 ° C. The order of charging the raw material, the catalyst and the water is not limited to the above-described method. After charging the metal bromide to the allyl chlorides, add water with stirring, and then charge the phase transfer catalyst. Alternatively, after adding water to the mixture of the metal bromide and the phase transfer catalyst, the allyl chlorides may be charged. In addition, the method of the reaction may be a method in which the raw material, the phase transfer catalyst, and water are charged in the entire amount to perform the reaction, a method in which the metal bromide is charged in a divided manner, and a method in which the reaction is performed while dropping allyl chlorides. Various methods are available.

In the present invention, the progress of the reaction can be known using means such as gas chromatography. As a method for isolating the allyl bromide produced by the above-mentioned halogen exchange reaction, the reaction mixture is cooled, if necessary, after the reaction, in an amount to dissolve the by-produced metal chloride, residual metal bromide and the phase transfer catalyst. Water is added, and allyl bromides produced by a liquid separation operation are isolated by a very simple method. When a higher purity allyl bromide is obtained, after liquid separation, an amount of metal bromide, a phase transfer catalyst and water corresponding to the remaining methallyl chloride is added, and the mixture is subjected to a halogen exchange reaction again, or the above isolation method. Purification by distillation of the allyl bromide obtained in the above, or a method of removing the mixture of allyl chlorides and allyl bromide obtained as the first distillation at the time of distillation to obtain the remaining allyl bromide, purification method. . In addition, the mixture of the allyl chlorides and allyl bromides, which are the raw materials obtained as the initial distillation, can be subjected again to a halogen exchange reaction, if necessary. As the method of distillation, any method of distillation under normal pressure or distillation under reduced pressure is possible.

[0031]

The present invention will be described in more detail with reference to the following examples.

Example 1 In a 500 ml round bottom flask equipped with a cooling condenser, 122.4 g (1.2 mol) of sodium bromide, 76.5 g (1.0 mol) of allyl chloride, 3.2 g of tetrabutylammonium bromide ( (10 mmol) and 3 g of water, and the mixture was reacted at 65 ° C. for 6 hours with stirring. After cooling the reaction solution to 16 ° C., 300 g of water was added to the reaction solution, and the mixture was separated to obtain 117.1 g of crude allyl bromide as an oil. As a result of analyzing the crude allyl bromide by gas chromatography, the production rate of allyl bromide was 93.3% (vs. allyl chloride), and the raw material allyl chloride remained at 6.4% (vs. allyl chloride used). Met. There were almost no by-products other than allyl bromide, and allyl bromide was selectively produced. The obtained crude allyl bromide was distilled by a distillation apparatus equipped with a rectification column to obtain 105.5 g (purity of 98% or more) of allyl bromide having a boiling point of 69.5 to 71.0 ° C.
Yield 87.2% (vs. allyl chloride). In addition, 10.3 g of a mixture of allyl chloride and allyl bromide was obtained as the first distillation.

Example 2 In a 500 ml round bottom flask equipped with a cooling condenser, 122.4 g (1.2 mol) of sodium bromide, 90.6 g (1 mol) of methallyl chloride, and 3.2 g of tetrabutylammonium bromide ( (10 mmol) and 5 g of water, and the mixture was reacted at 65 ° C. for 6 hours with stirring. After cooling the reaction solution, 300 g of water was added to the reaction solution, and the mixture was separated to obtain 131.4 g of crude methallyl bromide as an oil. When the crude methallyl bromide was analyzed by gas chromatography, the production rate of methallyl bromide was 94.1% (vs. methallyl chloride), and the raw material methallyl chloride was 5.5% (vs. Ril chloride). There were almost no by-products other than methallyl bromide, and methallyl bromide was selectively produced. The crude methallyl bromide obtained was distilled under a reduced pressure of 200 mmHg by a distillation apparatus equipped with a rectification column to obtain 118.9 g (purity of 98% or more) of methallyl bromide having a boiling point of 52.0 to 53.0 ° C. . Yield 88.1
% (Vs. methallyl chloride).

COMPARATIVE EXAMPLE 1 (Reaction under the condition that water was not added) In a 100 ml round bottom flask equipped with a cooling condenser, 24.5 g (0.24 mol) of sodium bromide and 18.0 g (0.28 g of methallyl chloride) were added. Mol) and 0.6 g (1.9 mmol) of tetrabutylammonium bromide, and the mixture was reacted at 65 ° C. for 6 hours with stirring. After cooling the reaction solution, 60 g of water was added to the reaction solution, and the oil obtained by liquid separation was analyzed by gas chromatography to find that the production rate of methallyl bromide was 6.
4% (vs. methallyl chloride).

COMPARATIVE EXAMPLE 2 (Reaction under the condition that no phase transfer catalyst was added) In a 100 ml round bottom flask equipped with a cooling condenser, 24.5 g (0.24 mol) of sodium bromide and 18.0 g (08.0 g) of methallyl chloride were added. .2 mol) and water 1.0
After charging g, the reaction was carried out at 65 ° C. for 6 hours with stirring. After cooling the reaction solution, 60 g of water was added to the reaction solution, and the oil obtained by liquid separation was analyzed by gas chromatography. The yield of methallyl bromide was 0.68% (vs. methallyl chloride). there were.

Examples 3 to 6 In Examples 3 to 6, the amount of water added to the reaction was examined. Other reaction conditions were the same as in Example 2. The results are shown in Table 1 (Table 1).

[0037]

[Table 1]

Examples 7 to 8 The types of metal bromide added to the reactions in Examples 7 and 8 were examined. Other reaction conditions were the same as in Example 2. The results are shown in Table 2 (Table 2).

[0039]

[Table 2]

Examples 9 to 10 The types of allyl chloride used in the reactions in Examples 9 to 10 were examined. Other reaction conditions were the same as in Example 2. The results are shown in Table 3 (Table 3).

[0041]

[Table 3]

[0042]

According to the method of the present invention, allyl chlorides are used as raw materials, and the desired allyl bromides can be efficiently produced under a mild condition with a high volumetric efficiency and in a high yield without using a solvent. Can be converted to Moreover, due to the high reaction selectivity, the isolation method is performed at room temperature,
Only the operation of separating with water is sufficient. When obtaining higher purity allyl bromides, it is only necessary to remove residual allyl chlorides by distillation under mild conditions, and isolation and purification are easy. Further, there is an advantage that a mixture of residual allyl chloride and allyl bromide obtained by distillation can be directly used as a raw material for a halogen exchange reaction. Therefore, the present invention is an industrially valuable production method of allyl bromides, which are useful synthetic intermediates in the field of synthetic organic chemistry, especially agricultural chemicals and dyes.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-169830 (JP, A) JP-A-2-207037 (JP, A) JP-A-2-107336 (JP, A) JP-A 64-64 45321 (JP, A) JP-A-60-94919 (JP, A) JP-B-41-19683 (JP, B1) Translated by Iwao Tabushi, et al., "Phase transfer catalyst", published by Kagaku Dojin, September 5, 1978 Pp. 139-146 (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 21/14 C07C 17/20

Claims (2)

(57) [Claims] (1) Formula (1) (Wherein, R, R ¹ and R ² each independently represent a hydrogen atom or a lower alkyl group). Phase transfer of allyl chloride represented by the formula: A compound of the formula (2) characterized by reacting with a metal bromide in the presence of a catalyst. (Wherein, R, R ¹ and R ² each independently represent a hydrogen atom or a lower alkyl group). 2. The method according to claim 1, wherein the allyl chloride is methallyl chloride, the allyl bromide is methallyl bromide, and the metal bromide is sodium bromide.