Linear alpha-methylstyrene dimers' production process

FIELD: industrial organic synthesis.

SUBSTANCE: linear alpha-methylstyrene dimers that can be used as molecular weight regulators for various polymers, as varnish solvents, and as base material in production of synthetic oils are obtained via oligomerization of α-methylstyrene in presence of zeolite ZSM-12 in H form in amount 1 to 10% at temperature 60-120°C.

EFFECT: increased selectivity and simplified production process.

1 tbl, 8 ex

 

The invention relates to the field of petrochemical synthesis, namely the method of obtaining a linear unsaturated dimer α-methylstyrene.

Linear dimers α-methylstyrene-4-methyl-2,4-diphenylene-1,2-ENES are used as molecular weight regulators of various polymers, as solvents for lacquers, dielectric fluid, the basis for synthetic oils.

A method of obtaining linear dimers α-methylstyrene in the presence of catalytic systems based on crystalline zeolite like alumophosphates [Ajisaka, Hemminki, Vsserv etc. - Petrochemicals. 1999, t, No. 4, s-283]. The catalysts are prepared from crystalline alumophosphate VPI-5, the lattice of which includes an 18-membered rings of atoms of Al and P with a free diameter of 1.2-1.3 nm, and the Si - and Mn-modifications. During heat treatment of these materials occurs, the structure of VPI-5 AlPO4-8 with a more narrow 14-membered rings. The catalyst obtained from unmodified crystallite AlPO4-8, at atmospheric pressure, the temperature of 75-100°and flow rate 1.5 h-1conversion α-methylstyrene is 80-83%, the selectivity of the formation of linear dimers 93,6-96,3%, the content of the cyclic dimer is 3-4%. Modified with silicon and manganese contacts Si-AlPO4-8 and Mn-AlPO4-8 exhibit higher aktivnosti transformation α -methylstyrene, but their selectivity for the formation of linear unsaturated dimer below 50-90%, and in the presence of Mn-AlPO4-8 dramatically increases the yield of the cyclic dimer - up to 45%.

A significant disadvantage of this method is the inaccessibility of the used catalysts, the complexity of this method for their preparation and use of expensive synthetic reagents for the preparation of catalysts.

In [Vphase, Vporn, Theparking etc. On some methods of oligomerization α-methylstyrene. // Russian journal of applied chemistry. 2000. V.13. No. 5. S]. describes how to obtain a linear dimers α-methylstyrene, carried out by oligomerization him on the zeolite Y in the presence of a solvent of methylene chloride. Conversion α-methylstyrene is 98,4 to 99.9 wt.%, the selectivity of the formation of linear unsaturated dimer reaches 76,1-87,0%. Concentration α-methylstyrene in CH2Cl2is about 30%, the number of catalyst - 60-90 wt.% on α-methylsterol. The reaction is carried out at a temperature of 25-40°C for 1-2 hours Without solvent CH2Cl2or when using other solvents, the reaction proceeds with a low conversion α-methylstyrene.

The disadvantages of this method is the use of expensive solvent CH2Cl2and in large quantities - 70 wt.%. Conducting the reaction in a solvent is slojnee technology oligomerization, as becomes necessary stage rectification, and therefore, you receive the additional equipment and additional energy costs. When the distillation of the solvent, the reaction mass is subjected to temperatures that can cause changes in the composition of the reaction mass and deterioration of the quality of the target product. In addition, the activity of the catalyst used in the way that seems low, so it is used in large quantities (60-90 wt.% for raw materials). The selectivity of the formation of linear unsaturated dimer is low and is 76,1-87%.

Also known is a method of obtaining linear dimers α-methylstyrene, carried out by the dimerization α-methylstyrene in the presence of zeolite type Y in NaH-form with a degree of exchange of ions. Na, equal 60-95 wt.%, subjected to heat treatment in an atmosphere of air at 500-700°C. the reaction Temperature 60-140°C catalyst 5-20 wt.%. The selectivity of the formation of linear dimers α-methylstyrene is 87,0-96,1% conversion of raw materials to 96.2-100.0 wt.% [RF patent №2189964. 2001, BI No. 27, 2002].

The disadvantages of this method are: (a) is quite complicated and multistage technology of preparation of the catalyst, including several stages of ion exchange, high temperature processing; b) insufficient stability of cristalli the definition of the structure of zeolites of type I in the process of decationization and high temperature processing. With deep decationization may occur the destruction of the crystal lattice with the formation of the amorphous phase. The same processes occur in the high-temperature calcination.

Closest to the proposed invention, the technical solution chosen as a prototype, is a method for linear dimers α-methylstyrene, carried out by the dimerization α-methylstyrene in the presence of mordenite type zeolite in the H form. The reaction temperature of 80-120°C catalyst 5-20 wt.%. The selectivity of the formation of linear dimers α-methylstyrene is a 87.0-89.9 percent conversion of raw materials 94,9-of 99.7 wt.% [RF patent №2200142. 2001, BI No. 7, 2003].

The disadvantages of this method include:

1. Not a high selectivity of the formation of linear unsaturated dimer α-methylstyrene. Select linear dimers from the reaction mass clear rectification difficult and expensive. Since it is proposed to use the reaction mass without separation, the purity of the target product has a great value.

2. The use of the catalyst in fairly large quantities - up to 20 wt.%.

3. The number of the resulting trimers α-methylstyrene reaches of 10.3 wt.%.

The aim of the present invention is to increase the selectivity and simplification of the method of obtaining a linear unsaturated what's the dimers α -methylstyrene.

This goal is achieved by the fact that the method of obtaining the unsaturated dimers α-methylstyrene by dimerization α-methylstyrene, carry out, according to the invention in the presence of zeolite ZSM-12 in the protonated form at the reaction temperature of 60 to 120°and the amount of catalyst 1-10 wt.%.

Comparative analysis of the proposed solutions with the prototype shows that the inventive method differs from the prototype in that in the process of dimerization α-methylstyrene to unsaturated linear dimers as the catalyst used, the zeolite ZSM-12 in H-form. The process of dimerization is carried out in the presence of 1-10 wt.% of the catalyst. The selectivity of the formation of linear unsaturated dimer α-methylstyrene reaches 94,8-96,6% conversion of raw materials 95-100,0 wt.%.

The resulting reaction mass contains up to 5.0 wt.% unreacted α-methylstyrene, 90,0÷to 95.5 wt.% linear dimer, 1,4÷2.8 wt.% cyclic dimer, 1,2-2.2 wt.% the trimers. Tetramera α-methylstyrene and more high-molecular compounds are absent. Particularly noteworthy is the very low yield of trimer α-methylstyrene, reached on the proposed catalyst. Reaction mass of such composition can be used without any additional processing, for example, as a modifier in the production of polymers. Therefore will not require additional capital and energy-intensive operations to remove the solvent, by distillation of the unreacted monomer, the selection of the target fractions, removal and disposal of VAT residue.

Zeolite ZSM-12 is aluminosilicate material with a typical unit cell described by the formula Na8(AlO2)8(SiO2)40·24H2O and a clear crystal structure. Refers to high zeolite family of pentelow. From other zeolites of structural type pentasil differ in the structure of the crystal lattice, which is based on the five-membered ring, and a high content of silicon (SiO2/Al2O3>25), which determines the strength and localization of the active acid sites. These features cause unusual physico-chemical, adsorption and catalytic properties of pentelow. Pentasil have high chemical and thermal stability, homogeneity of catalytically active sites inside the channels of zeolite.

The porous structure of ZSM-12 is a system of interconnected rectilinear channels formed by 12-membered rings with the diameter of the entrance window of 0.55-of 0.62 nm.

Zeolite ZSM-12 is produced on an industrial scale. Used as a component of the zeolite catalization for some petrochemical and chemical processes, such as cracking of diisopropylbenzene obtaining a mixture of benzene is, toluene and xylenes [U.S. Patent No. 4593136, 1986]. It is also known the use of ZSM-12 as a catalyst for the conversion of alcohols and ethers in aromatic hydrocarbons [U.S. Patent 4538015, 1985].

The proposed method is as follows.

The catalyst is zeolite ZSM - 12 synthesized in the protonated form in JSC "Angarsk plant of catalysts and organic synthesis" by DK 04-21303-008-2004. The molar ratio of SiO2/Al2O3100; crystallinity 96%. Before experiments on the dimerization α-methylstyrene, the catalyst was calcined in air at 540°C for 4 hours

Dimerization α-methylstyrene conduct periodic method.

Raw materials (α-methylsterol) is loaded into the reactor at the reaction temperature of 60 to 120°With portions upload the catalyst in the amount of 1-10 wt.% for raw materials. The suspension is stirred at the reaction temperature for 1-6 hours. After a certain period of time take samples and analyzed by GLC on a chromatograph brand "Chrome 5". Condition analysis: glass capillary column 0,2÷0.25 mm×20 m with a stationary liquid phase SE-30 linear programming temperature from 100 to 280°With speeds of 6°C/min carrier Gas is helium, the speed of the carrier gas 1÷2 ml/min, the ratio of the flow of carrier gas through the column and the bypass 1:100.

The proposed method for the ill is trebuetsya the following examples (table 1).

EXAMPLE 1. In a heated glass reactor with stirrer, reflux condenser and thermometer load of 100 g α-methylstyrene and start to heat up. At a temperature of 80°load portions 1 g of zeolite ZSM-12. The suspension is stirred at 80°C for 6 hours After cooling and filtering off the catalyst was prepared of 99.3 g of the reaction mixture composition, wt.%:

α-methylsterol5,0
linear dimers (4-methyl-2,4-diphenylpentane-1
and 4-methyl-2,4-diphenylpentane-2)90,0
cyclic dimer (1,1,3-trimethyl-3-phenylindane)2,8
trimers2,2

Conversion α-methylstyrene is 95,0 wt.%, the selectivity for the linear unsaturated dimer - 94,8%.

EXAMPLES 2-8. Analogously to example 1. Conditions and results of examples shown in table 1.

td align="center"> L-D
Table 1
Dimerization α-methylstyrene in the presence of ZSM-12
№ № In Kt, wt.%T °Time, h's products, %Conversion α-MS, %
C-DTrimers
1.180694,82,92,395,0
2.1120495,72,22,198,3
3.280595,92,51,696,2
4.21004for 95.32,42,397,2
5.560396,52,21,396,8
6.580296,31,91,898,1
7.1060196,61,42,0to 97.1
8.1080195,52,32,2100,0

The method of obtaining the unsaturated dimers α-methylstyrene by oligomerization α-methylstyrene in the presence of zeolite catalyst in the protonated form, characterized in that the catalyst used C is of Olite ZSM-12 in the amount of 1-10 wt.% and the reaction is carried out at a temperature of 60-120° C for 1-6 hours



 

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