JPS5910329B2 - Method for producing unsaturated dimers of styrenes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing unsaturated dimers of styrenes by dimerizing or co-dimerizing styrenes.

It is known that when styrenes are dimerized or co-dimerized, saturated dimers and unsaturated dimers are generally produced.

For example, in the case of dimerization of styrene, 1-phenyl-3-methylindane is obtained as a saturated dimer, and 1,3-diphenyl-1-butene is obtained as an unsaturated dimer. Unsaturated dimers of styrenes are useful compounds in themselves and as raw materials for various reactions, but it has not been possible to obtain unsaturated dimers with good selectivity when dimerizing styrenes. When sulfuric acid is used as a catalyst, the production of saturated dimers, trimers and higher oligomers is unavoidable. In addition, in order to improve the selectivity of unsaturated dimers, it is necessary to lower the sulfuric acid concentration or raise the temperature, which tends to cause corrosion of the equipment. When solid acids or acid clay are used, saturated dimers are mainly produced.

The present invention solves these drawbacks and provides a method for obtaining unsaturated dimers of styrenes with good selectivity and high yield through dimerization or co-dimerization of styrenes.

The styrene used in the present invention may be any styrene as long as it is represented by formula (I), but in particular industrially,
Styrene, m- or p-vinyltoluene, etc. can be used advantageously.

In the present invention, two or more types of styrenes can also be used for co-dimerization. The present invention involves dimerizing styrenes represented by formula (I) in the presence of perchlorate anions.

Specifically, a compound that produces a perchlorine anion is added to the reaction system to perform a dimerization reaction of styrenes.

Although any compound that produces a perchlorate anion can be used, typical ones are: Perchloric acid (HClO4), perchloracetyl (CH3COClO
4), butyryl perchlorate (C, H, COClO4), valeryl perchlorate (C4H, COClO4), penzoyl perchlorate (《 》-COClO4), naphthyl perchlorate ([W゛Co1000”0゛),etc;
Metal salts of perchloric acid, such as lithium, sodium, potassium, magnesium, calcium and barium salts; oxonium salts of perchloric acid, such as dioxorhenium perchlorate, trimethylpyrylium perchlorate, triphenylpyrylium Perchlorate, etc.; triphenyl methyl perchlorate of perchloric acid, i.e., triphenyl methyl perchlorate (Ph, C + ClO4); tropylinium salt of perchloric acid, i.e., tropi-1 nonium perchlorate (C, H, + ClO4-); perchloric acid Ammonium salts of ammonium perchlorate, n-butylammonium perchlorate, its N-alkyl substituted product, pyridinium perchlorate and its alkylated product, and aniline perchlorate, its aromatic substituted product, and These alkyl-substituted products include methylaniline perchlorate and dimethylaniline perchlorate.

In the case of stable perchlorates such as metal salts such as sodium perchlorate and N-alkyl substituted ammonium salts of perchlorate, protic acids such as sulfuric acid or BF, FeC
By mixing with Lewis acids such as I, I, etc.,
A sufficient amount of perchlorate anion is produced for the reaction, and the dimerization reaction of styrenes can easily proceed to a satisfactory degree.

Cationic polymerization of styrenes starts when a catalyst compound acts on a styrene monomer to generate a counter ion between the monomer cation and an anion generated from the catalyst.
Further monomer is added to this counterion, and the polymerization reaction proceeds. On the other hand, the termination reaction of polymerization is caused by a proton elimination reaction between the generated polymer ion pairs. In this case, depending on the type of anion, there are differences in monomer addition reactivity, proton elimination reactivity, and reactivity in which the anion itself is added to the polymer terminal and stabilized. for example,
In the case of sulfuric acid and metal halide anions, the addition reaction of styrene monomers is the main reaction, forming one or more oligomers.
However, in the case of an α-alkylstyrene monomer in which an alkyl group is substituted at the α-position of styrene, it is difficult to grow beyond a dimer due to steric hindrance of the α-alkyl group, and a dimer is easily obtained.

On the other hand, for styrene monomers that do not have α-alkyl groups, no method has been provided for dimerizing them with good yield, and only oligomers or mixtures of oligomers and high polymers have been obtained.

As the reaction temperature increases, the proton elimination reaction is promoted, and the reaction tends to stop at the dimer level. mass increases. As a result of research on the cationic polymerization of styrenes, the present inventors found that it has proton elimination properties to the extent that polymerization is terminated by dimerization, and that saturated dimers are generated by intramolecular addition upon proton elimination. The present invention was completed by discovering unique anions and temperature conditions.

The amount of perchlorate anion to be used in the reaction system is preferably 0.02 to 100 mmole equivalent per mole of styrene.

Although it can be used outside this range, if it is used in a small amount, a satisfactory reaction rate cannot be obtained and the reaction time is required, while if it is used in a large amount, it requires extra effort to remove the catalyst, which is economically disadvantageous. In this case, it must be noted that there is a risk of harmful effects associated with oxidation. The reaction temperature is O℃
The temperature can be selected as appropriate within a temperature range of over 150°C, but more preferably within a temperature range of 20°C to 80°C. 0
If the reaction temperature is below ℃, oligomers of styrene trimers or higher or polymers with a higher degree of polymerization will be produced, while if the reaction temperature is high, the reaction rate will increase, but radical polymerization of styrene may occur. Since saturated dimers are produced and the selectivity of unsaturated dimers decreases, the dimerization reaction must be carried out at an appropriate temperature range of 150° C. or lower.

The reaction of the present invention is preferably carried out in the presence of a solvent.

Any solvent may be used as long as it does not stop the cationic polymerization of styrenes. Preferred examples of the solvent include aromatic compounds such as benzene, chlorobenzene, dichlorobenzene, trichlorobenzene, and nitrobenzene; saturated aliphatic hydrocarbons having 5 to 18 carbon atoms, such as n-hexane; cyclohexane, methylcyclohexane,
Saturated alicyclic hydrocarbons such as ethylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, methylethylcyclohexane and decalin; or halides thereof such as methylene chloride, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, etc. Of course, the solvents that can be used in the present invention are not limited to the compounds specifically exemplified here. In addition, two or more types of solvents can also be used in combination. The reaction of the present invention is carried out under liquid phase reaction conditions, and pressure can be applied as necessary to maintain the liquid phase.

The unsaturated dimer can be isolated from the reaction mixture by vacuum distillation.

According to the present invention, all of the styrene dimers produced are unsaturated dimers, and the yield thereof is extremely high.

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

Example 1 A benzene solution of acetyl perchlorate (CH3COCl4) was added to a benzene solution of styrene in dry nitrogen. Allowed to react for minutes.

After stopping the reaction with ammoniacal methanol, under reduced pressure 4
Solvent and unreacted styrene were removed at 0°C. The conversion rate was determined by quantifying unreacted styrene using gas chromatography.

The yield of dimer in the product was determined from the molecular weight distribution of the product obtained by gel permeation chromatography. The produced dimer was confirmed to be almost a single component by gas chromatography, and its structure was confirmed to be 1,3-diphenyl-1-butene by chromatography and IR. Table 1 shows the results. Examples 2 to 8 Table 1 shows the results of styrene dimerization reactions performed according to Example 1 by changing the catalyst, solvent, and temperature.

In this case as well, the dimer produced was 1,3-diphenyl-1-butene.

Example 9 Example 1 was performed using acetyl perchlorate (CH, COClO4) as a catalyst, replacing styrene with a mixture of m-vinyltoluene (65%) and p-vinyltoluene (35%).
The dimerization reaction of vinyltoluene was carried out according to the method.

The products are 1,3-bis(4-methylphenyl)-1-butene; 1,3-bis(3-methylphenyl)-1-butene; 1-(4-methylphenyl)-3-(3-methylphenyl)-1 -Butene; 1-(3-methylphenyl)-
It was a mixture of 3-(4-methylphenyl)-1-butene, the conversion rate was 100 wt%, and the dimer yield was 85 wt%. Comparative Examples 1-2 Table 2 shows the results of reacting styrene with the same catalyst as used in the Examples at a temperature of 0° C. or lower according to the method of the Examples.

As is clear from Table 2, the formation of dimers was hardly observed or was slight, and the conversion rate was also low.

Comparative Examples 3 to 5 Table 3 shows the results of reacting styrene with conventionally known sulfuric acid, boron trifluoride (ethyl ether solution) (BF3O(C2H5)2), and solid acid (Galleon Earth 036 manufactured by Mizusawa Chemical). Shown below.

Claims (1)

[Scope of Claims] 1. An unsaturated dimer of styrene, which is characterized by dimerizing styrene, etc. represented by the following formula in the presence of perchlorate anions in a temperature range of more than 0°C and less than 150°C. manufacturing method. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (R is hydrogen or a lower alkyl group with 1 to 3 carbon atoms, n is the number of alkyl groups when R is an alkyl group, and is 1 or 2, when n is 2 R may be the same or different alkyl groups).