CN102603451A - Method for preparing diphenylethane catalyzed by mixed liquid of concentrated sulfuric acid and ion liquid - Google Patents

Abstract

The invention provides a method for preparing diaryl ethane, which relates to the field of acid-catalyzed preparation of diaryl ethane. Aiming at the shortcomings of traditional acid catalysts, the invention provides a mixed solution of concentrated sulfuric acid and ionic liquid as an acid catalyst to catalyze the Friedel-Crafts alkylation reaction of xylene (or ethane) and styrene. Compared with the prior art, the invention has mild reaction, less side reactions, simple post-treatment, recyclable catalyst, less acid consumption, low cost and is more suitable for industrial production.

Description

A kind of concentrated sulfuric acid and ionic liquid mixed solution catalyzes the method for preparing diaryl ethane

technical field

The invention relates to the field of diaryl ethane production, in particular to the field of acid-catalyzed Friedel-Crafts reaction for preparing diaryl ethane.

Background technique

Power capacitor insulating oil is the main material for the production of power capacitors, and its performance directly affects the performance of power capacitors. As high-performance full-film capacitors gradually replace film-paper composite capacitors, alkylbenzene-type insulating oils suitable for impregnating film-paper composite capacitors are also fully replaced by diarylethanes (including PXE and PXE) that are suitable for impregnating full-film capacitors. PEPE) and benzyl toluene type insulating oil. At present, the total national output of diarylethan (including PXE and PEPE) and benzyltoluene (MBT/DBT) insulating oil used as insulating oil for power capacitors is about 55,000 tons per year. Among them, diarylethane used as insulating oil for power capacitors is prepared by Friedel-Crafts reaction of xylene (or ethylbenzene) and styrene under acid catalysis.

Traditionally, the reaction between xylene (or ethylbenzene) and styrene directly uses concentrated sulfuric acid as an acid catalyst. The advantage of using concentrated sulfuric acid is that it is cheap and easy to get, and has strong acidity. The disadvantage of concentrated sulfuric acid catalysis lies in its strong corrosiveness and oxidative properties, large dosage and cannot be recycled to produce a large amount of waste acid, which is difficult to handle and corrodes equipment.

Although the environmentally friendly solid acid catalysis method developed in recent years has been used to catalyze the synthesis of diaryl ethane (chemical reagents, 10 (2), 85-86, 1988), the preparation process of solid acid catalyst is complicated and expensive And it needs frequent regeneration in the production process, which hinders its further industrialization.

More and more studies have shown that ionic liquids with Lewis acidity can be used instead of traditional liquid protic acid catalysts to catalyze Friedel-Crafts reactions (Chemical Industry and Engineering Technology, 27(3), 1-3, 2006). However, although the chloroaluminate-type ionic liquids with high catalytic activity that have been studied more have been used in catalytic reactions in the laboratory, this ionic liquid is very sensitive to water vapor in the air and needs to be processed under absolutely anhydrous conditions. Therefore, it is also unfavorable for industrialized production.

Contents of the invention

Purpose of the present invention is exactly to provide a kind of method that takes the mixed solution of the vitriol oil and ionic liquid as catalyzer to synthesize diaryl ethane at the deficiency of above acid catalyst.

The steps of the method for synthesizing the insulating oil diarylethane for power capacitors provided by the invention are: mixing concentrated sulfuric acid and ionic liquid according to a certain ratio to make an acidic ionic liquid mixed liquid, using the acidic ionic liquid mixed liquid as a catalyst, and using xylene (or ethylbenzene) and styrene as raw materials, carry out alkylation reaction at a certain temperature, stand still after the reaction, separate layers, separate the catalyst, and obtain the product through vacuum distillation, the catalyst can be used directly for next catalytic reaction.

咪唑盐类

吡啶盐类

(其中R1可以为C1～C4烷基；R2可以为H或C1～C16烷基；R3可以为C1～C4烷基；R4可以为C1～C16烷基；R5可以为C1～C4烷基；R6可以为C1～C4烷基；R7可以为C1～C4烷基)等中的一种或两种及以上混合物，阴离子可以为Cl^-、HSO₄ ^-、PF₆ ^-、BF₄ ^-等中的一种或两种及以上混合物，而且阴阳离子均不限于以上几类。Said ionic liquid cations can be quaternary ammonium salts Quaternary phosphonium salts

Imidazolium salts

Pyridinium salts

(R1 can be C1～C4 alkyl; R2 can be H or C1～C16 alkyl; R3 can be C1～C4 alkyl; R4 can be C1～C16 alkyl; R5 can be C1～C4 alkyl; R6 It can be C1~C4 alkyl; R7 can be C1~C4 alkyl) or a mixture of two or more, and the anion can be one of Cl ^- , HSO ₄ ^- , PF ₆ ^- , BF ₄ ^-, etc. One or two or more mixtures, and the anions and cations are not limited to the above categories.

Said certain ratio is concentrated sulfuric acid:ionic liquid=2:1～10:1 (molar ratio), preferably the ratio is 3:1～6:1.

The molar ratio of the added styrene to the concentrated sulfuric acid in the catalyst is 1:1-20:1, preferably 2:1-10:1.

The raw material ratio of said xylene (or ethylbenzene) to styrene is 3:1-30:1, preferably 8:1-20:1.

Said alkylation reaction temperature is 50-140°C, preferably 70-100°C.

The alkylation reaction time is 3-15 hours, preferably 5-8 hours.

Compared with the existing concentrated sulfuric acid catalyst, solid acid catalyst and chloroaluminic acid type ionic liquid catalyst technology, the method for catalyzing and synthesizing diaryl ethane with concentrated sulfuric acid and ionic liquid mixed solution as a catalyst provided by the present invention, after the present invention The treatment is simple, and the catalyst can be separated and recycled from the product only by liquid separation, which reduces the cost; the reaction process of the present invention is mild, produces less side reaction products, less acid consumption, low pollution, and is stable to water vapor and air, and is easy to operate, thus It is more suitable for industrialized production.

Detailed ways

The following examples can enable those skilled in the art to understand the present invention more comprehensively, but do not limit the present invention in any way.

Example 1

Add 3.4 grams of tributyltetradecylphosphonium chloride into a 250 mL round bottom flask, slowly add 2.4 grams of 96-98% concentrated sulfuric acid dropwise under stirring, and mix evenly to obtain an acid catalyst. 90 grams of xylene was added to the catalyst, and a mixed solution of 37.2 grams of xylene and 6.2 grams of styrene was added dropwise at 80° C. with stirring, and the reaction was continued for 4 hours. Stand still, separate layers, remove the ionic liquid catalyst in the lower layer (recovery), first evaporate the xylene under normal pressure, and then evaporate the product under reduced pressure to obtain 11.6 g of diarylethane with a yield of 92.8%.

Example 2

Add the above recovered acid catalyst to a 250mL round bottom flask, then add 90g of xylene, add dropwise a mixture of 37.2g of xylene and 9.4g of styrene under stirring at 80°C, drop it in two hours, and continue the reaction for 4 hours. Stand still, separate layers, remove the ionic liquid catalyst (recovery) in the lower layer, first evaporate the xylene under normal pressure, and then evaporate the product under reduced pressure to obtain 16.3 g of diarylethane with a yield of 85.8%.

Example 3

Add the above recovered acid catalyst to a 250mL round bottom flask, then add 90g of xylene, add dropwise a mixture of 37.2g of xylene and 12.4g of styrene under stirring at 80°C, drop it in two hours, and continue the reaction for 3 hours. Stand still, separate layers, separate and remove the ionic liquid catalyst (recovery) in the lower layer, first evaporate the xylene under normal pressure, and then evaporate the product under reduced pressure to obtain 20.9 g of diarylethane with a yield of 83.6%.

Example 4

Add the above recovered acid catalyst to a 250mL round bottom flask, then add 90g of xylene, add dropwise a mixture of 37.2g of xylene and 6.2g of styrene under stirring at 70°C, drop it in two hours, and continue the reaction for 5 hours. Stand still, separate layers, remove the ionic liquid catalyst in the lower layer (recovery), first evaporate the xylene under normal pressure, and then evaporate the product under reduced pressure to obtain 11.1 g of diarylethane with a yield of 88.8%.

Example 5

Add the above recovered acid catalyst to a 250mL round bottom flask, then add 90g of xylene, add dropwise a mixture of 37.2g of xylene and 6.2g of styrene under stirring at 100°C, drop it in two hours, and continue the reaction for 4 hours. Stand still, separate layers, remove the ionic liquid catalyst (recovery) in the lower layer, first evaporate the xylene under normal pressure, and then evaporate the product under reduced pressure to obtain 10.9 g of diarylethane with a yield of 87.2%.

Example 6

Add the above recovered acid catalyst to a 250mL round bottom flask, then add 90g of ethylbenzene, add dropwise a mixture of 37.2g of ethylbenzene and 6.2g of styrene under stirring at 80°C, drop it in two hours, and continue the reaction for 4 hours. Stand still, separate layers, remove the ionic liquid catalyst (recovery) in the lower layer, evaporate ethylbenzene under normal pressure first, and then evaporate the product under reduced pressure to obtain 10.3 g of diarylethane with a yield of 82.4%.

Example 7

Add 4.4 grams of tributyltetradecylphosphonium hexafluorophosphate into a 250 mL round bottom flask, slowly add 4.0 grams of 96-98% concentrated sulfuric acid dropwise under stirring, and mix evenly to obtain an acid catalyst. 90 grams of xylene was added to the catalyst, and a mixed solution of 37.2 grams of xylene and 6.2 grams of styrene was added dropwise at 80° C. with stirring, and the reaction was continued for 4 hours. Stand still, separate layers, separate and remove the ionic liquid catalyst (recovery) in the lower layer, first evaporate the xylene under normal pressure, and then evaporate the product under reduced pressure to obtain 11.3 g of diarylethane with a yield of 90.4%.

Example 8

Add 2.9 grams of tributyltetradecylphosphonium tetrafluoroborate into a 500 mL round bottom flask, slowly add 2.4 grams of 96-98% concentrated sulfuric acid dropwise under stirring, and mix evenly to obtain an acid catalyst. 180 grams of xylene was added to the catalyst, and a mixed solution of 74.4 grams of xylene and 12.4 grams of styrene was added dropwise under stirring at 80° C., and the reaction was continued for 6 hours after two hours of dripping. Stand still, separate layers, separate and remove the ionic liquid catalyst (recovery) in the lower layer, first evaporate the xylene under normal pressure, and then evaporate the product under reduced pressure to obtain 21.2 g of diarylethane with a yield of 84.8%.

Example 9

Add 1.6 grams of triethylamine sulfate into a 250 mL round bottom flask, slowly add 2.4 grams of 96-98% concentrated sulfuric acid dropwise under stirring, and mix evenly to obtain an acid catalyst. 90 grams of xylene was added to the catalyst, and a mixed solution of 37.2 grams of xylene and 6.2 grams of styrene was added dropwise at 80° C. with stirring, and the reaction was continued for 4 hours. Stand still, separate layers, remove the ionic liquid catalyst (recovery) in the lower layer, first evaporate the xylene under normal pressure, and then evaporate the product under reduced pressure to obtain 10.9 g of diarylethane with a yield of 87.2%.

Example 10

Add 1.3 g of 1-methyl-3-butylimidazole chloride into a 250 mL round bottom flask, slowly add 2.4 g of 96-98% concentrated sulfuric acid dropwise under stirring, and mix evenly to obtain an acid catalyst. 90 grams of xylene was added to the catalyst, and a mixed solution of 37.2 grams of xylene and 6.2 grams of styrene was added dropwise under stirring at 100° C., and the dripping was completed in two hours, and the reaction was continued for 4 hours. Stand still, separate layers, remove the ionic liquid catalyst in the lower layer (recovery), first evaporate the xylene under normal pressure, and then evaporate the product under reduced pressure to obtain 11.04 g of diarylethane with a yield of 88.3%.

Example 11

Add 1.3 g of 1-butylpyridine chloride into a 250 mL round bottom flask, slowly add 2.4 g of 96-98% concentrated sulfuric acid dropwise under stirring, and mix evenly to obtain an acid catalyst. 90 grams of xylene was added to the catalyst, and a mixed solution of 37.2 grams of xylene and 6.2 grams of styrene was added dropwise under stirring at 100° C., and the dripping was completed in two hours, and the reaction was continued for 4 hours. Stand still, separate layers, separate and remove the ionic liquid catalyst (recovery) in the lower layer, first evaporate the xylene under normal pressure, and then evaporate the product under reduced pressure to obtain 11.2 g of diarylethane with a yield of 89.6%.

Claims (7)

1. a method for preparing diaryl ethane is characterized in that taking the vitriol oil and ionic liquid mixed solution as acidic catalyst, with dimethylbenzene (or ethylbenzene) and styrene as raw material to carry out alkylation reaction, after reaction finishes The catalyst is separated, and the product can be obtained by distillation under reduced pressure, and the catalyst can be reused. 2. according to the method for claim 1, it is characterized in that said ionic liquid cation can be quaternary ammonium salt

Quaternary phosphonium salts

Imidazolium salts

Pyridinium salts

(R1 can be C1～C4 alkyl; R2 can be H or C1～C16 alkyl; R3 can be C1～C4 alkyl; R4 can be C1～C16 alkyl; R5 can be C1～C4 alkyl; R6 It can be C1~C4 alkyl; R7 can be C1~C4 alkyl) or a mixture of two or more, and the anion can be one of Cl ^- , HSO ₄ ^- , PF ₆ ^- , BF ₄ ^-, etc. One or two or more mixtures, and the anions and cations are not limited to the above categories. 3. according to the method for claim 1, it is characterized in that said certain ratio is concentrated sulfuric acid: ionic liquid=2: 1～10: 1 (molar ratio). 4. according to the method for claim 1, it is characterized in that the mol ratio of the vitriol oil in the said added styrene and the catalyzer is 1: 1～20: 1. 5. according to the method for claim 1, the raw material ratio that it is characterized in that said xylene (or ethylbenzene) and styrene is 3: 1～30: 1. 6. The method according to claim 1, characterized in that said alkylation reaction temperature is 50-140°C. 7. The method according to claim 1, characterized in that said alkylation reaction time is 3 to 15 hours.