JPS62129229A - Production of ethylbiphenyl compound - Google Patents

Abstract

PURPOSE:To obtain the titled compound suppressing the formation of byproducts, by carrying out trans-alkylation reaction of biphenyl with an ethylbenzene compound in an inert gas atmosphere free from oxygen, washing the reaction product with water and separating the objective compound by distillation. CONSTITUTION:1mol of biphenyl and 1.3-4mol of ethylbenzene compound (in terms of ethyl group) are subjected to trans-alkylation reaction in the presence of a Friedel-Crafts catalyst at 80-150 deg.C under a condition to give a product having a m-ethylbiphenyl/p-ethylbiphenyl ratio of 0.3-1.6. The reaction product is washed with water and separated by distillation to obtain ethylbiphenyl in high yield. The product is useful as a thermal medium, solvent, insulation oil, lubrication oil, etc., as well as a raw material of ethylbicyclohexyl compound. It has excellent heat stability and extremely low corrosiveness at high temperature.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for producing ethyl biphenyls, and more particularly to a method for producing ethyl biphenyls by transalkylating biphenyl and ethylbenzenes. .

[Prior Art] Ethyl biphenyls are useful as heat carriers, solvents for pressure-sensitive copying paper, insulating oils, lubricating oils for working fluids, etc., and are also useful as vinyl biphenyls obtained by dehydrogenating them or vinyl biphenyls obtained by dehydrogenating them. It is also useful as a raw material for ethylbicyclohexyl, etc., which can be obtained by hydrogenation. These applications require thermal stability, low odor, and low corrosion.

It is known that when biphenyl and ethylbenzenes are transalkylated to produce ethylbiphenyls, in addition to monoethylphenyl, by-products such as diebulbiphenyl, triethylphenyl, and 9-methylfluorene are produced. There is. It is also known that monoethyl biphenyl has three isomers: 〇-isomer, m-isomer, and p-isomer.

By the way, 9-methylfluorene is not only an impurity with a boiling point close to that of monoethyl phenyl, but also has poor thermal stability and easily forms hydroperoxide. In addition, 〇-ethylbiphenyl has poor thermal stability, and a product containing a large amount of it is unsatisfactory as a heat medium. p-ethylbiphenyl has good thermal stability, but Materials with a high solidification point and present in extremely large quantities are not suitable as heat carriers, insulators, solvents, or lubricating oils.

U.S. Patent No. 3,636.179 proposes a method for producing ethyl biphenyls that reduces the production of 0-ethyl biphenyl to a small amount of about 1@50% or less and limits the production of 9-methylfluorene to a few percent. are doing.

This method can provide ethyl and phenyl compounds suitable for heat carriers and other uses, but if the amount of 9-methylfluorene produced is kept sufficiently low to a satisfactory value of 9, the reaction rate will be reduced. There is a problem in that we have no choice but to lower the value. Furthermore, according to the research of the present inventors, reaction products containing ethylphenyls obtained by a 1- to 1-lance alkylation reaction of biphenyl and ethylbenzenes using a free-sol Tarafluoro catalyst using a known method include: In addition to 9-methylfluorene, it has been discovered that undesirable compounds are produced during product quality and usage processes, particularly substances that promote corrosion of reaction equipment, piping, etc. (hereinafter referred to as corrosion-promoting substances).
It was recognized that this may be mixed into the ethyl biphenyls fraction.

[Problem to be Solved by the Invention 1] An object of the present invention is to provide a method for producing ethyl biphenyls that have excellent thermal stability and produce less corrosion-promoting substances, and to provide a method for producing ethyl biphenyls that have excellent thermal stability, a heat medium, a solvent, an insulating oil, a lubricating oil. The purpose of the present invention is to produce ethyl phenyl compounds suitable for such uses, and to provide a method for producing ethyl biphenyls with good yield.

[Means for Solving the Problems] The present invention provides a transalkylation reaction between biphenyl and ethylbenzenes in the presence of a Friedelkraff catalyst under an inert gas atmosphere that does not substantially contain oxygen gas. This is a method for producing ethyl phenyl compounds, in which the reaction product obtained by the reaction is washed with water and then separated by distillation. In particular, ethylbenzenes are used in an amount of 1.3 to 3.6 moles in terms of ethyl group per mole of biphenyl. Atmosphere of inert gas that does not substantially contain oxygen gas Non-reactive humidity 80-1
The reaction product obtained by reacting at 50°C and such that the ratio of m-ethyl biphenyl to ethyl biphenyl in the product is in the range of 0.3 to 1.6 is washed with water and then decomposed by distillation. This is achieved by

In the present invention, ethyl biphenyls are produced by a transalkylation reaction between biphenyl and ethylbenzenes.

Here, as the ethylbenzenes used, one or more ethyl substituted products such as ethylbengin, diethylbenzene, 1-diethylbenzene, ethyltoluene, or diethyltoluene can be used. Industrially, polyethylbenzenes, which are produced by-product when producing ethylbenzene from benzene and ethylene, are desirable, and this polyethylbenzene is mainly composed of diethylbenzene and contains small amounts of ethylbenzene, triethylbenzene, and tetraethylbenzene.

The amount of ethylbenzene to be used for biphenyl is calculated based on ethyl group conversion, that is, 1 mole of diethylbenzene is 2 moles, and 1 mole of triethylbenzene is 3 L. 1.3 to 4 mol, preferably 2 to 3 mol, of the above compound is used. If the amount of ethylbenzenes is less than 1.3 moles, when the reaction rate of biphenyl is increased, the proportion of 9-methylfluorene produced tends to be relatively high, and the amount of corrosion-promoting substances tends to increase as well. Also, phenyl 1
Using more than 4 moles of ethylbenzene per mole not only increases the amount of unreacted ethylbenzene, but also increases the production rate of p-ethylbiphenyl.

The 1-lance alkylation reaction is carried out in the presence of a Friedel-Crafts catalyst. Suitable Friedelkraft catalysts include aluminum chloride, aluminum bromide, boron fluoride, and the like. The amount of Friedel Krach catalyst used is
The amount is 0.005 to 0.1 mol, preferably 0.01 to 0.05 mol, per 1 mol of phenyl.

Further, the transalkylation reaction is carried out in an inert gas atmosphere that does not substantially contain oxygen gas. Transalkylation reactions are usually carried out batchwise or continuously, but in either case, the catalyst, raw materials, and reaction products are present in a liquid phase, and the components mainly consisting of vapors of the raw materials or reaction products are vaporized. They often exist in phase. However, according to the inventors' research, when oxygen gas derived from air is mixed into the gas phase, even in a small amount of about 1% by volume, substances that deteriorate thermal stability such as 9-methylfluorene and substances that promote corrosion occur. It has been found that the formation of these is also promoted, and on the other hand, when the reaction is carried out in an atmosphere of an inert gas that does not substantially contain oxygen gas, the formation of these is significantly reduced.

Although the chemical structure of this corrosion-promoting substance has not been clarified, this corrosion-promoting substance is a by-reaction product of the Friedel-Krach reaction, especially halides and reaction products in the usage environment, such as oxidation products. It is thought that they are involved. Also,
Although the effect of these corrosion-promoting substances on corrosion of reaction equipment, piping, and detection is unknown, it appears that their corrosion-promoting function lasts for a long period of time.

Therefore, the present invention is carried out in an atmosphere of an inert gas that does not substantially contain oxygen gas, such as nitrogen gas, argon gas, hydrogen gas, methane gas, or the like. A preferred inert gas is nitrogen gas.

It is preferable to continuously flow this inert gas through the reactor during the reaction.If the inert gas is blown into the liquid phase, the reaction system can be stirred at the same time, and the inert gas can be dissolved in the liquid phase. It is also advantageous in expelling oxygen gas. The amount of inert gas flowing through varies depending on the shape of the reactor, especially the seal, but it is desirable to always maintain the oxygen gas concentration in the gas phase portion of the reactor at 0.5 volume/1% or less.

Note that such an oxygen gas concentration can sometimes be obtained by refluxing the reaction system, but this will not be effective unless refluxing is done in an inert gas atmosphere, and inert gas circulation is essential. It is. Furthermore, from the viewpoint of preventing oxygen gas from dissolving the raw material biphenyl or polyethylbenzene, it is preferable to seal it with an inert gas such as nitrogen during transportation or storage.

The transalkylation reaction is carried out at a reaction temperature of 80-150°C, preferably 100-130°C.

When the reaction temperature is lower than 80°C, the reaction rate is slow, and 1
When the temperature is higher than 40°C, the vapor pressure of ethylbenzenes becomes high, and it is necessary to pressurize to prevent them from flowing out of the reaction system.

In the present invention, the reaction rate is m-ethylbiphenyl/p
- Ethyl biphenyl ratio (hereinafter referred to as m/p ratio) is 0.
It is controlled to be in the range of 3 to 1.6. The production rate of 9-methylfluorene generally increases by increasing the reaction rate, but the rate varies depending on other reaction conditions. Therefore, controlling the production of 9-methylfluorene by controlling the reaction rate is obviously disadvantageous because it may unnecessarily limit the reaction rate to a low level depending on the reaction conditions. The present inventors found that under the reaction conditions described above,
By controlling the m/p ratio, regardless of other reaction conditions, 9
- It has been found that the production rate of methylfluorene can be kept below a certain level. That is, the mlO ratio is 1.6
If the ratio is set below, the production ratio of 9-methylfluorene can be reduced to 10% or less expressed as the selectivity to phenyl starting material, but if it is set to 1.6 or more, the production ratio of 9-methylfluorene increases rapidly. On the other hand, if m/p ratio is 0
．． When it is smaller than 3, the proportion of p-tech-1-rubiphenyls increases, the freezing point becomes high, and the production rate of ethyl biphenyls becomes low. Therefore, the m/p ratio is 0.3~
J: 1.6, preferably in the range of 0.6 to 1.2. The mlp ratio increases as the reaction rate increases under the same conditions. Ethylbenzene is 1.5 mol in terms of ethyl group per 1 mol of biphenyl, m/pi-1,0,3 is 50% biphenyl reaction rate.
and m/p ratios of 0.6, 1.2 and 1
．． 6 has a biphenyl reaction rate of around 60%, around 70% and 7
Each corresponds to 5% before in. Further, when the amount of ethylbenzene per mole of phenyl is 3 moles in terms of ethyl group, m/p ratios of 0.3 and 0.6 correspond to biphenyl reaction rates of around 70% and around 80%, respectively.

In the present invention, in order to change the composition of the reaction product, a fraction containing diethylbiphenyl etc. can be recycled in advance into the reaction system at a ratio of 0.3 mol or less per 1 mol of biphenyl.

Once the 1-lance alkylation reaction is complete, the reaction products are desirably removed by washing the Friedel-Craft catalyst with water, and then separated into various fractions by distillation.

In distillation, depending on the reaction conditions, a benzene fraction, an ethylbenzene fraction consisting of ethylbenzene, diethylbenzene, triethylbenzene, etc., a biphenyl fraction, an ethylbiphenyls fraction mainly composed of m-ethylbiphenyl and p-ethylbiphenyl, It can be separated into diethyl phenyl fraction, triethyl biphenyl fraction, etc.

Here, it is preferable to circulate the ethylbenzene fraction and the biphenyl fraction to the reaction system, and part or all of the diethyl and phenyl fractions can also be recycled to the reaction system.

Distillation of ethyl biphenyls thus obtained, 9
- Since the content of by-products such as methyl fluorene is low, the content of corrosion-promoting substances is also significantly low, and the freezing point is not high, it can be suitably used for applications such as heat carriers, solvents, and insulating oils. Furthermore, since there are few by-products, it can be advantageously used as a raw material for water addition or dehydrogenation reactions.

[Example] Hereinafter, the method of the present invention will be explained based on Examples and Comparative Examples.

Examples 1 to 6 Polyethylbenzene with an average number of ethyl groups of around 2.1 and aluminum chloride, which were produced as by-products in the process of producing ethylbenzene from phenyl, benzene and ethylene, were collected in a Mitsuro flask equipped with a condenser stirrer for refluxing and an inert gas blowing nozzle. The reaction solution was heated to a predetermined temperature while stirring and blowing nitrogen gas into the reaction solution, and then the transalkylation reaction was carried out under the conditions shown in Table 1 under a nitrogen gas atmosphere.

The reaction solution was collected at predetermined intervals and after the completion of the reaction, washed with water to remove ammonium chloride, and then analyzed by gas chromatography. The results are shown in Table 2.

In addition, after the reaction is completed, the reaction product is cooled and washed with water,
This is distilled to collect the mononibur biphenyl fraction at 280-295°C, and the central fraction 286-295°C.
The 90°C fraction was analyzed.

It is shown in Table 3 of the Song Dynasty.

In general, 5US304 was used as the material, and the 286-290'C fraction obtained in each of the above examples was used.
Seven corrosion strokes were carried out for one year under conditions of a temperature range of 150 to 200°C and an average temperature of 180°C. The results are shown in Table 4.

In addition, each comparative example was performed in the same manner as in each example except that the transalkylation was performed in an air atmosphere. The conditions for the transalkylation reaction are shown in Table 1, and the gas chromatography analysis results of the reaction solution are shown in Table 2.
The analysis results of the 0°C fraction are shown in Table 3, and the results of the corrosion test are shown in Table 4.

Table 1 Table 3 Table 4 [Effects of the Invention] According to the production method of the present invention, it is possible to obtain ethyl biphenyls which have excellent thermal stability and have significantly low corrosive action at high temperatures.

Patent applicant: Nippon Steel Chemical Co., Ltd. Agent: Attorney: Katsuo Naruse (2 others)

Claims (3)

[Claims] (1) When transalkylating biphenyl and ethylbenzenes in the presence of a Friedel-Crafts catalyst, the reaction product obtained by reacting in an inert gas atmosphere that does not substantially contain oxygen gas is washed with water. , a method for producing ethyl biphenyls, characterized by distillation separation. (2) 1.3 to 4 moles of ethylbenzenes are present in terms of ethyl group per mole of biphenyl, and the reaction temperature is 80 to 1 in an atmosphere of inert gas that does not substantially contain oxygen gas.
at 50°C and m-ethylbiphenyl/p in the product.
The method for producing ethyl biphenyls according to claim 1, wherein the reaction is carried out so that the -ethyl biphenyl ratio is in the range of 0.3 to 1.6. (3) Claim 1 in which the inert gas is nitrogen gas
A method for producing ethyl biphenyls according to item 1 or 2.