JPS6132295B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing β-chlorostyrenes.

β-Chlorstyrenes are compounds useful as intermediates for organic synthesis products, but the conventional synthesis method is to synthesize α,β-dichloroethylbenzene or styrene chlorohydrin over alumina or metaphosphoric acid at 350 to 400°C. A method in which α,β-dichloroethylbenzenes are heated in pyridine is known. However, these methods are not suitable for industrial production because they require high temperatures or have poor yields.

The present inventors have studied a method for synthesizing β-chlorostyrenes in an industrially advantageous manner and in good yield, and have arrived at the present invention. That is, the present invention is a method for producing β-chlorostyrenes, which is characterized by heating α,β-dichloroethylbenzenes to a temperature of 100 to 250°C in the presence of a transition metal compound.

α, β used as starting materials in the present invention
-Dichloroethylbenzenes include α,β-dichloroethylbenzene or its homologues. The general formula (1) for α,β-dichlorobenzenes is (wherein, X is H, an alkyl group, a halogen group, or a nitro group, and n is an integer of 1 to 3). The above alkyl groups include methyl group, ethyl group, isopropyl group,
Examples include alkyl groups having a straight chain or side chain having 1 to 6 carbon atoms. Preferred are methyl group and ethyl group. Examples of halogens include chlorine and fluorine.

Specific examples of compounds represented by general formula (1) include:
α,β-dichloroethylbenzene; homologues of α,β-dichloroethylbenzene, such as alkyl-substituted α,β-dichloroethylbenzene (P-methyl-α,β-dichloroethylbenzene, m-methyl-α,β- dichloroethylbenzene, P-ethyl-α,β-dichloroethylbenzene, etc.), halogen-substituted α,β-dichloroethylbenzene (P-ethyl-α,β-dichloroethylbenzene, etc.),
Chlor-α,β-dichloroethylbenzene, m-
Bromo-α,β-dichloroethylbenzene, etc.), nitro-substituted α,β-dichloroethylbenzene (P-nitro-α,β-dichloroethylbenzene, etc.), and two or more thereof.

In the transition metal compound used in the present invention, the transition metals include Sc with atomic number 21 to Ni with 28, Y with 39 to Cd with 48, and La with atomic number 57 to Hg with 80.
Up to 89 Ac and above elements are listed.
Among these, in consideration of practicality, elements of Group B, Group B, and Group B are preferred, and Cr, Mn, Fe, Co, Ni, and Pd are particularly preferred. Transition metal compounds include inorganic acids or organic acid salts of transition metals (inorganic acid salts such as chloride, bromide, sulfate, nitrate, phosphate, acetate, octanoate, stearate, oleate, naphthenic acid) Examples include organic acid salts such as salts and phenolates, hydroxides, oxides, organic complexes (acetylacetonate complexes, etc.), and two or more thereof. Among these, preferred are inorganic acids or organic acid salts of transition metals (especially chlorides, bromides, acetates),
and transition metal organic complexes (especially acetylacetonate complexes), particularly preferred are transition metal chlorides.

Specific examples of transition metal compounds include chromium chloride, chromic chloride, manganese chloride, ferrous chloride, ferric chloride, cobalt chloride, nickel chloride,
Palladium chloride, cobalt bromide, nickel bromide,
Palladium bromide, nickel acetate, cobalt acetate,
manganese acetate, nickel acetylacetonate,
Examples include compounds such as cobalt acetylacetonate.

In carrying out the present invention, the amount of transition metal compound used is usually 1 to 20% based on the weight of the starting material, α,β-dichloroethylbenzene.
The reaction rate increases as the amount of the transition metal compound used increases, but from the viewpoint of actual industrial use, it is preferably 3 to 10%. When the amount of the transition metal compound used is less than 1%, the reaction requires a long time, resulting in a decrease in yield. Although there is no particular problem if the content exceeds 20%, it is industrially undesirable to use more than necessary. When adding the transition metal compound to the reaction system, the transition metal compound can be added as a powder, in the form of an aqueous solution, or in the form of adsorption on a carrier (diatomaceous earth, activated carbon alumina, etc.).

In the present invention, the production of β-chlorostyrenes from α,β-dichloroethylbenzenes can be represented by the following reaction formula.

The reaction temperature is usually 100 to 250°C, but preferably 150 to 200°C in consideration of industrial implementation. If the reaction temperature is less than 100°C, the reaction rate is too slow to be practical; if it is higher than 250°C, side reactions such as dimerization and trimerization occur, resulting in a decrease in yield.

In carrying out the present invention, starting materials α,
When a transition metal compound is added to β-dichloroethylbenzenes and heated to a temperature of 100 to 250°C, hydrogen chloride is generated. Once the generation of hydrogen chloride is complete, β can be removed by distilling the reaction solution as it is or by removing the transition metal compound used by washing with water or other operations.
- Chlorstyrenes can be obtained. Further, in carrying out the present invention, it is possible to use a solvent or the like. Examples of solvents used include aromatic hydrocarbons (xylene, butylbenzene, diphenyl, etc.) and aliphatic hydrocarbons (liquid paraffin, kerosene, etc.). The amount of the solvent used is usually about 1 to 3 times the weight of the starting material α,β-dichloroethylbenzene. The present invention can also be carried out under an atmosphere of inert gas (nitrogen, acid gas, etc.) or under reduced pressure (for example, 100 mmHg or less). In addition, polymerization inhibitors (hydroquinone, hydroquinone monomethyl ether, 2,6
-di-t-butyl-P-cresol, etc.).

The production method of the present invention has the following effects, that is, the reaction operation is simple and the yield is high (70 to 90
%).

The present invention will be explained below with reference to Examples.

Example 1 100 g of α,β-dichloroethylbenzene and 5 g of nickel chloride are placed in an Erlenmeyer flask and reacted at 160 to 170° C. for 3 hours while stirring with a magnetic stirrer, and the generation of hydrogen chloride is almost completed. This reaction product was then distilled under reduced pressure to a boiling point of 90-95℃/20mm.
67 g (yield: 84%) of Hg fraction was obtained. This product was confirmed to be a mixture of cis and trans β-chlorostyrene based on infrared absorption spectrum and NMR gas chromatography.

Reference Example 1 When gallium chloride was used in place of nickel chloride in the reaction of Example 1, almost no reaction occurred and almost all the raw materials were recovered.

Reference Example 2 When zinc chloride is used instead of nickel chloride in the reaction of Example 1, hydrogen chloride is generated, but 2
-The yield of chlorstyrene was less than 20%, and a large amount of high-boiling substances were produced.

Example 2 P-methyl-α,β-dichloroethylbenzene
Put 100g and 10g of cobalt acetate into an Erlenmeyer flask, and stir with a magnetic stirrer until 180~
After 5 hours of reaction at 200°C, the generation of hydrogen chloride is almost complete. This reactant is then distilled under reduced pressure to determine its boiling point.
61 g (yield: 75%) of a fraction having a temperature of 115-120°C/30 mmHg was obtained. This includes infrared absorption spectra, NMR,
Gas chromatography confirmed that it was a cis-trans mixture of P-methyl-β-chlorostyrene.

Example 3 100 g of α,β-dichloroethylbenzene and 5 g of chromic chloride (CrCl ₃ ) were placed in an Erlenmeyer flask and stirred with a magnetic stirrer.
After 10 hours of reaction at 180 to 200°C, the generation of hydrogen chloride is almost complete. This reaction product was distilled under reduced pressure to obtain 56 g (yield 70%) of β-chlorostyrene as a fraction with a boiling point of 90-95°C/20 mmHg.

Example 4 100g of α,β-dichloroethylbenzene and manganese acetate dihydrate {Mn(CH,COO) ₃・2H ₂ O}10
When the mixture is placed in an Erlenmeyer flask and stirred with a magnetic stirrer for 15 hours at 180 to 200°C, the generation of hydrogen chloride is almost complete. By distilling this reaction product under reduced pressure, the boiling point is 90-95℃/20mm.
52 g of β-chlorostyrene (yield: 65
%) was obtained.

Example 5 100 g of α,β-dichloroethylbenzene and 5 g of ferric chloride (FeCl ₃ ) were placed in an Erlenmeyer flask.
While stirring with a magnetic stirrer, heat to 180~
After 10 hours of reaction at 200°C, the generation of hydrogen chloride is almost complete. This reaction product was distilled under reduced pressure to obtain 60 g (yield 75%) of β-chlorostyrene as a fraction with a boiling point of 90-95°C/20 mmHg.

Example 6 P-methyl-α,β-dichloroethylbenzene
100 g of nickel bromide (NiBr ₂ ) are placed in an Erlenmeyer flask and reacted at 170 to 190° C. for 3 hours while stirring with a magnetic stirrer, until almost all hydrogen chloride has been generated. By distilling this reaction product under reduced pressure, a fraction with a boiling point of 115-120℃/20mmHg is produced.
-Methyl-β-chlorostyrene 69g (yield 85%)
I got it.

Example 7 100 g of α,β-dichloroethylbenzene and 10 g of nickel acetylacetonate complex {(CH ₃ COCH ₂ COCH ₃ ) ₂ Ni} were placed in an Erlenmeyer flask and heated at 180 to 200°C while stirring with a magnetic stirrer. After 10 hours of reaction, the generation of hydrogen chloride is almost complete. This reaction product was distilled under reduced pressure to obtain 60 g (yield 75%) of β-chlorostyrene as a fraction with a boiling point of 90-95°C/20 mmHg.

Claims (1)

[Claims] 1. A method for producing β-chlorostyrenes, which comprises heating α,β-dichloroethylbenzenes to a temperature of 100 to 250°C in the presence of a transition metal compound. 2 The transition metal compound is an element in group B or group B of the periodic table.
The manufacturing method according to claim 1, which is a compound of a transition metal selected from the group consisting of and. 3. The production method according to claim 1 or 2, wherein the transition metal compound is an inorganic acid or an organic acid salt of a transition metal, or an organic complex of a transition metal.