JPS59190927A - Dimerization of alpha-methylstyrene - Google Patents

Abstract

PURPOSE:In dimerizing the titled compound using activated clay or acid clay as a catalyst, to obtain an unsaturated linear dimer of the titled compound useful as a raw material for a lubricating oil of traction drive in high yield, by making Cellosolve exist in the reaction system. CONSTITUTION:In dimerizing alpha-methylstyrene using activated clay or acid clay as a catalyst, 2-40times, preferably 5-20times as much Cellosolve, preferably <=6C Cellosolve as the catalyst by weight is added to the reaction system, to prevent the catalyst from blocking, formation of high-boiling substances is suppressed, to give an unsaturated linear dimer of alpha-methylstyrene, especially 2,4- diphenyl-4-methylpentene-1 useful as a polymerization adjustor in high yield. This process has merits wherein amounts of the catalyst and the coexisting substance used are small. The reaction temperature is 40-150 deg.C, preferably 50- 120 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION In particular, 2,/l-diphenyl-4-methylpentene-
1 in high yield.

When α-methylstyrene is dimerized, it produces unsaturated linear dimers 2,4-diphenyl-4-methylbentene-1 and 2,4-diphenyl-4-methylpentene-2, and a saturated dimer 1, 1,3-trimethyl-3-
Phenylindane, a trimer or higher boiling point product can be obtained.

Among these products, the unsaturated linear dimers are used as raw materials for traction drive lubricating oils and also as % iC 2
．． 4-C7-1-=-4-methylbeny
N-1 is important as a polymerization regulator. Therefore, α−
Various methods have been proposed for obtaining highly pure 4-diphenyl-4-methylpentene-1 by dimerizing methylstyrene.

For example, JP-A-48-44240 proposes a method in which a solid acid such as acid clay or activated clay or a cation exchange resin is used as a catalyst, and water or a polyhydric alcohol is allowed to coexist. It is.

However, in this method, since acid clay or activated clay has a strong adsorption effect on water or polyhydric alcohol, when mixed with acid clay, etc., a blocking phenomenon of these catalysts occurs. The thus blocked catalyst adheres to the wall of the reaction vessel or, in the case of internal coil heating, to the vicinity of the coil, resulting in a decrease in catalytic efficiency. Furthermore, in this case, heat conduction becomes insufficient, and the difference between the temperature of the surface of the jacket or internal coil, which is a heating source, and the temperature of the reaction liquid increases, making it difficult to control the reaction, which is undesirable.

Furthermore, in JP-A-57-62228, α-methylstyrene is dimerized by using acid clay or activated clay as a catalyst and coexisting an aliphatic single ether, aliphatic hybrid ether, or cyclic ether in the reaction system. A method has been proposed. Although this method is unlikely to cause the aforementioned blocking phenomenon of the catalyst, for example,
The amount of high-boiling substances higher than the dimer is as large as 5% or more, and the yield of unsaturated dimer is not necessarily good. Further, the amount of catalyst used is large at 4 to 6% based on α-methylstyrene, and the amount of ether coexisting is also large at 10 to 50% based on α-methylstyrene, which is uneconomical.

The present inventors conducted intensive research in view of the above circumstances, and found that if cellosolve is coexisting in the presence of white earth as a catalyst, blocking of the catalyst can be prevented, and unsaturated dimers can be produced in high yield. The inventors have completed the present invention by discovering that the present invention can be obtained with less predominance of coexisting substances.

That is, in the present invention, in the presence of acid clay or activated clay,
α is characterized by the coexistence of cellosolve in the reaction system.
- A method for producing an unsaturated linear dimer of methylstyrene.

The amount of white earth used as a catalyst is not particularly limited, but is 0.1 to 20 parts by weight, more preferably 0.5 to 5 parts by weight, based on α-methylstyrene. If the amount of catalyst used is increased, the amount of cellosolve that must be present must also be increased, which is economically disadvantageous.

The cellosolve of the present invention is a monoether of ethylene glycol, and has an ether-bonded alcoholic hydroxyl group in the same molecule.

There is no known example of dimerizing α-methylstyrene by coexisting cellosolve with white earth metals as in the present invention. Furthermore, compared to alcohol as a coexisting substance, the blocking phenomenon of the catalyst as described above hardly occurs. Also,
Compared to the monoethers mentioned above, there are fewer high-boiling products, less unsaturated dimer, % 2.4-diphenyl-4-
This method has the advantage that the yield of methylpentene-1 is high and the amount of catalyst and coexisting substances used can be small.

The types of cellosolves that should coexist are not particularly limited, but include methyl, ethyl, n-propyl, 1so-propyl, n-butyl, 1so-butyl, tert-
Cellosolve having 6 or less carbon atoms, such as butyl cellosolve, is preferred. Cellosolve having more than 6 carbon atoms can also be used, but since the properties as a hydrocarbon are stronger than as a cellosolve, the amount of cellosolve used must be increased, which is not preferred. Furthermore, as the number of carbon atoms increases and the boiling point becomes higher, the amount of heat required for recovery becomes large, and since the boiling point approaches the dimer, it is difficult to separate the dimer after one reaction by distillation. This is disadvantageous because it becomes difficult.

The amount of cellosolve to be used can be appropriately determined depending on the type of material, but in the case of cellosolve having 6 or less carbon atoms, the amount is 2 to 40 times, more preferably 5 to 20 times the amount of the catalyst.

If cellosolve is less than this amount, the selectivity of 2,4-diphenyl-4-methylpentene-1 will decrease, and if a larger amount of cellosolve is present, the activity of the catalyst will decrease. Both are unfavorable because they reduce the conversion rate.

The reaction temperature is usually 40 to 150°C, more preferably 50°C.
~120°C. A reaction temperature lower than 40° C. is not preferred because the dimerization rate of α-methylstyrene is slow and the reaction time is too long. Also, if the temperature exceeds 150℃, 2,4-
The selectivity of diphenyl-4-methylpentene-1 decreases, and the production of high boiling point products such as trimer or higher increases.

Although the present invention can be carried out without a solvent, it can also be carried out using a solvent inert to the reaction, such as n-paraffin. When it is difficult to control the reaction temperature, it is preferable to use one solvent.

The reaction may be carried out either batchwise or in a flow manner; however, since activated clay or acid clay is usually obtained as a fine powder, a batchwise manner is usually appropriate.

After the reaction is completed, unreacted α-methylstyrene, cellosolve, etc. are separated by distillation, for example, to obtain the desired unsaturated linear dimer.

Next, the present invention will be explained with reference to examples.

Example 1 20 g of n-butyl cellosolve was placed in a reaction vessel equipped with a stirrer.
Add 2 g of activated clay (Ga I/Onite 236, manufactured by Mizusawa Chemical Co., Ltd.) and stir for 15 minutes. Next, α-methylstyrene 200
g was added thereto and gradually heated while stirring, and stirring was continued at 110°C (this is referred to as reaction temperature) for 60 minutes (this is referred to as reaction time). Liquid composition after cooling: Table 1 based on total analysis
It was as shown in

Examples 2 to 6 α-methylstyrene was polymerized in the same manner as in Example 1 under the conditions shown in Table 1. Composition 1 of the reaction solution was as shown in Table 1.

Comparative Examples 1 and 2 In Comparative Example 1, activated clay 2. Op, a mixture of 200 g of α-methylstyrene and 20 g of n-butanol was heated at 90°C.
The reaction was allowed to proceed for 3 hours.

In Comparative Example 2, a mixture of 6 g of activated clay, 200 g of α-methylstyrene, and 25 g of diisopropyl ether was reacted at 90° C. for 3 hours.

Results 1 are shown in the following table, and in all cases there were many high-boiling substances of trimer or higher.

Claims (1)

[Claims] (1) A method for producing an unsaturated linear dimer of α-methylstyrene, which comprises allowing cellosolve to coexist in the reaction system in the presence of active white clay or acid clay.