JPH04178338A - Method for producing biphenyls ethylated at the 4-position - Google Patents

Abstract

PURPOSE:To obtain the objective substances by reacting raw material biphenyl or ethylbipenyl with polyethylbenzene at a specific molar ratio of C2H5 groups/ benzene rings in a specific proportion of the raw material in the presence of a solid acid catalyst at a temperature within a specific range. CONSTITUTION:(A) Raw material biphenyls selected from biphenyl and ethylbiphenyl are reacted with (B) a polyethylbenzene at >=3.5 molar ratio of ethyl groups/benzene rings as an alkylating agent in the presence of a solid acid catalyst (e.g. silica alumina or zeolite) at >=1 (preferably >=1.5) weight ratio of the components [(A)/(B)] at 50-240 deg.C (preferably 70-200 deg.C) to produce 4-ethylbiphenyl, 4,4'-diethylbiphenyl, etc., in high selectivity and yield. The rate of reaction is regulated so as to provide a conversion rate/hr expressed by the formula (Co is the conversion rate of the raw materials; Et is the number of mol of ethyl groups in a reactor; Bz is the number of mol of benzene rings; Bp is the number of mol of biphenyl rings).

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides 4-ethylbiphenyl, 4,4- The present invention relates to a method for producing ethyl biphenyls such as diethylbiphenyl.

[Conventional technology]

Ethylbiphenyls are useful as heat carriers, pressure-sensitive paper solvents, etc., and are also useful as raw materials for biphenylcarboxylic acid and vinylbiphenyl. Among them, 4= such as 4-biphenylcarboxylic acid and 4.4'-biphenyldicarboxylic acid
Substituted products and 4,4'-substituted products are highly useful due to their symmetry.

As a method of alkylating biphenyl and producing biphenyls substituted with an alkyl group at the 4-position, a method of alkylating with an olefin using mordenite-type zeolite as a catalyst is known (Japanese Patent Laid-Open No. 63-227.529). ,
JP-A No. 63-122.635).

However, using mordenite-type zeolite as a catalyst, the selectivity at the 4-position can be increased by alkylation with olefins having 3 or more carbon atoms such as propylene and butene, and the ethylation of biphenyl with ethylene can be achieved using mordenite-type zeolite. Even if it is carried out using a catalyst, the 4-position is not selectively ethylated, and the product is the 3- or 3-position.
It is a mixture of various ethyl biphenyls mainly 3'-substituted, and especially 4,4'- in diethylbiphenyl.
The selectivity of diethylbiphenyl (selectivity among isomers) is
The yield of 4,4°-diethylbiphenyl in the ethylated product (% by weight in the compound having a biphenyl ring) was as low as about 1 to 4%.

In addition, JP-A-63-162.632 describes the transethylation reaction of biphenyl with polyethylbenzene using a solid acid catalyst, but details of the reaction conditions to increase the selectivity to the 4-position are described. was not specifically stated.

[Problem to be solved by the invention]

In view of this situation, an object of the present invention is to provide a method for producing ethyl biphenyls with increased selectivity and yield of 4-ethylbiphenyl and 4,4°-diethylbiphenyl.

[Means to solve the problem]

The present inventors conducted intensive research to establish the above method, and surprisingly found that a solid acid catalyst was used as the catalyst, and a polyester having an ethyl group/benzene ring molar ratio of 3.5 or more was used as the alkylating agent. By using ethylhensen and selecting reaction conditions such as reaction temperature, biphenyls ethylated at the 4-position such as 4-ethylbiphenyl and 4,4°-diethylbiphenyl (hereinafter referred to as 4 The present invention was completed based on the discovery that the selectivity and yield of (-ethylated biphenyls) can be increased.

That is, the present invention provides polyethylbenzene used at a reaction temperature of 50 to 240° C. in reacting at least one raw material biphenyls selected from biphenyl and ethyl biphenyl with polyethylbenzene in the presence of a solid acid catalyst. This is a method for producing biphenyls in which the reaction is carried out at an ethyl group/benzene ring molar ratio of 3.5 or more and a polyethylbenzene/raw material biphenyls weight ratio of 1 or more.

The method of the present invention will be explained in detail below.

The solid acid catalyst used in the present invention may be any catalyst commonly known as a solid acid catalyst such as silica alumina, zeolite, composite metal oxide, solid phosphoric acid, heteropolyacid, and ion exchange resin. , silica alumina or zeolite is preferred from the viewpoint of industrial availability.

The zeolite is preferably Y-type zeolite, L-type zeolite, or those subjected to chemical treatment such as ion exchange or fluorination treatment. The acid strength of these solid acid catalysts is as follows:
It is preferable to have 0.1 to 3 mol/kg of acid sites with a heat of adsorption of ammonia of 85 K joules or more. When the number of acid sites is less than 0.1 mol/kg, it is difficult to obtain an industrially sufficient conversion rate, and when it is more than 3 mol/kg, the rate of carbonaceous precipitation increases and the catalyst life is shortened.

Note that a metal oxide solid acid catalyst that has lost its activity can be easily regenerated by firing it at about 500'C with air diluted with nitrogen to remove carbonaceous matter.

The raw material biphenyls used in the present invention are biphenyl and/or ethyl biphenyl. Ethylbiphenyl includes 2-ethyl biphenyl, 3-ethyl biphenyl, 4
- One type or a mixture of two or more types selected from ethyl biphenyl, but the one containing more 4-ethyl biphenyl,
This is advantageous because the selectivity and yield of 4,4°-diethylbiphenyl are increased. These raw material biphenyls preferably have a basic nitrogen content of 50 ppm or less, preferably 20 ppm or less.

In addition, the remaining biphenyl, monoethyl biphenyl, diethylbiphenyl, triethyl biphenyl, etc. after separating 4-ethylbiphenyl and/or 4,4°-diethylbiphenyl from the product of the ethylation reaction may be recycled to the reaction system. .

Polyethylbenzene used as an ethylating agent has an ethyl group/benzene ring=3. 5 (molar ratio) or more, preferably 3.8 (molar ratio) or more. Compounds include tetraethylbenzene, pentaethylbenzene, and hexaethylbenzene, and mixtures include mixtures of these compounds, or one or more of these compounds and one of other polyethylbenzenes such as ethylbenzene, diethylbenzene, and triethylbenzene. Alternatively, a mixture of two or more types may be mentioned, but they are mixed at the above molar ratio. In addition, polyethylbenzene as used in the present invention includes ethylbenzene, 1.2-diethylbenzene, 1.3-diethylbenzene, 1.4-diethylbenzene, 1.2.3-triethylbenzene, l.
, 2.4-) diethylbenzene, 1.3.5-)
Diethylbenzene, 1,2.3.4-tetraethylbenzene, l.

2,3.5-tetraethylbenzene, 1.2.4.5-
Refers to compounds such as tetraethylbenzene, pentaethylbenzene, and hexaethylbenzene. If the molar ratio of ethyl group/benzene ring is small, the selectivity or yield of the 4-position ethylated biphenyls will be poor.

The amount of polyethylbenzene used is 1 or more, preferably 1.5 or more in weight ratio to the raw material biphenyls. If the amount of polyethylbenzene used is small, the reaction progresses slowly.

The reaction temperature of the present invention is 50°C to 240°C, preferably 50°C to 240°C.
0°C to 220°C, more preferably 706°C to 200°C
It is. When the reaction temperature is below the melting point of the reaction raw materials, a solvent that does not participate in the reaction, such as decalin or n-paraffin, can be used. If the reaction temperature is lower than 50°C, the reaction rate will be too slow to be industrially practical, and if the reaction temperature is higher than 240°C, the selectivity of the 4-position ethylated biphenyls will be low.

Usually, the lower the reaction temperature, the better the selectivity for 4-position ethylated biphenyls, and when a high reaction temperature is selected, a high selectivity for 4-position ethylated biphenyls can be obtained by shortening the reaction time.

The reaction pressure is normal pressure to 50 kg/ctl, preferably normal pressure to 30 kg/crl. Considering the catalyst life, it is appropriate to select the reaction pressure so that the reaction raw materials and reaction products become liquid in the reactor. Even if the reaction pressure is higher than necessary, it will not adversely affect the reaction, but there is no need to make it particularly high.

The production method can be carried out in a flow reaction format or a batch reaction format. A fixed-bed flow reaction format is suitable for large-scale production at an industrial level, and a batch reaction format is suitable for small-scale production.

In the case of a batch reaction type, the amount of catalyst in the present invention is catalyst/(raw material biphenyls + polyethylbenzene) = 0.05 to 0.
50 (weight ratio), preferably 0°10 to 0.30 (weight ratio), and in the case of flow reaction type, WH8V = 0.1 to
5h-1, preferably 0.2 to 3h-1.

The reaction rate of the present invention is desirably adjusted so that the conversion rate of the starting biphenyls per hour of reaction time falls within the range defined by the following formula (%).

However, Co represents the conversion rate (X) of the raw material biphenyls, Et represents the number of moles of ethyl groups in the reactor, Bz represents the number of moles of benzene rings in the reactor, and Bp represents the number of moles of biphenyl rings in the reactor.

That is, it is preferable to conduct the reaction so that the conversion rate during any one hour during the reaction is within the range of the above formula. The reaction rate can be adjusted by selecting and combining parameters such as reaction temperature, amount of catalyst used, and reaction time from the ranges described above. Usually, the 4-position ethylated biphenyls can be obtained with high selectivity and yield by setting the reaction temperature low and adjusting the reaction rate by increasing the amount of catalyst used and/or prolonging the reaction time.

When the reaction is carried out under such conditions, a transethylation reaction occurs, and the raw material biphenyls are ethylated, and polyethylbenzene is deethylated.

Therefore, the mixture after the completion of the reaction contains ethyl biphenyls such as biphenyl, ethyl biphenyl, diethylbiphenyl, and triethyl biphenyl, polyethylbenzenes with reduced ethyl groups, benzenes, and the like.

The mixture after completion of the reaction of the present invention contains ethylbenzenes, biphenyl, monoethyl biphenyl, diethylbiphenyl, triethyl biphenyl, tetraethyl biphenyl, etc. in addition to the 4-position ethylated biphenyls as described above, but depending on the selection in the reaction. Due to its high purity, 4-ethylbiphenyl or 4゜4'-ethylbiphenyl can be produced with a purity of 80% by distillation.
% or more. Therefore, after concentrating, it is not necessarily necessary to further separate 4-ethylbiphenyl or 4,4°-diethylbiphenyl using a separation method such as cooling crystallization, pressure crystallization, or adsorption. If the purity of 4-ethylbiphenyl or 4,4'-diethylbiphenyl separated by distillation is not sufficient, increase the purity to 100% by recrystallizing it using a solvent such as methanol, ethanol, isopropanol, etc. I can do it.

The remaining biphenyl, monoethyl biphenyl, diethylbiphenyl, triethyl biphenyl, etc. after separating the 4-position ethylated biphenyls may be used as a heating medium, solvent, etc., or recycled to the reactor to produce 4-position ethylated biphenyls. It can also be used as a raw material.

〔Example〕

Hereinafter, the present invention will be specifically explained based on Examples.

Examples 1 to 9, Comparative Examples 1 to 2 In an autoclave equipped with a stirrer, biphenyl or 4-ethylbiphenyl, silica alumina or Y-type theolite as a catalyst, and a tetraethyl-Hensen isomer mixture or a diethyl-Hensen isomer mixture as an ethylating agent. was charged, and the reaction was carried out under the reaction conditions shown in Table 1. The silica alumina and Y-type theolite used in the catalyst had 0.40 mol/kg and 1.40 mol/kg of acid sites with a heat of adsorption of ammonia of 85 joules or more, respectively.

Table 2 shows the weight proportion of the compound having a biphenyl ring in the reaction product, as well as the selectivity and yield of 4-ethylbiphenyl and 4,4°-diethylbiphenyl.

〔Effect of the invention〕

According to the invention, 4-ethylbiphenyl and/or 4,
4'-diethylbiphenyl can be produced efficiently and is industrially significant.

Patent applicant: Nippon Steel Chemical Co., Ltd.

Claims (2)

[Claims] (1) In reacting at least one raw material biphenyls selected from biphenyl and ethyl biphenyl with polyethylbenzene in the presence of a solid acid catalyst, the reaction temperature is 50 to 240°C, and the ethyl group of the polyethylbenzene used is A method for producing biphenyls ethylated at the 4-position, characterized in that the reaction is carried out under conditions where the molar ratio of /benzene ring is 3.5 or more and the weight ratio of polyethylbenzene/raw material biphenyls is 1 or more. (2) The conversion rate of raw material biphenyls per hour of reaction time is determined by the following formula: Co≦15Et/(Bz+Bp) (where, in the formula, Co represents the conversion rate (X) of raw material biphenyls, and Et represents the conversion rate (X) of raw material biphenyls in the reactor. 4-position according to claim 1, in which the reaction is carried out within the range defined by the number of moles of ethyl groups in the reactor, Bz indicates the number of moles of benzene rings in the reactor, and Bp indicates the number of moles of biphenyl rings in the reactor. A method for producing ethylated biphenyls.