JPS6019283B2 - Method for side chain chlorination of aromatic hydrocarbons having side chains - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for side chain chlorination of aromatic hydrocarbons having side chains.

Conventionally, as a side chain chlorination method for aromatic hydrocarbons having side chains, aromatic hydrocarbons having alkyl groups such as methyl groups as side chains are dissolved in a solvent such as carbon tetrachloride, and then ultraviolet rays are irradiated. A method of introducing chlorine during irradiation is known, but this method requires a high reaction temperature due to the high melting point of the product and has the disadvantage of requiring a long time to complete the reaction.

Moreover, when the chlorination reaction is carried out in this manner, chlorination occurs not only in the side chains but also in the nucleus of the aromatic hydrocarbon, and a considerable amount of resinous substances are produced as by-products, resulting in a low yield of the desired product. ,
Moreover, since the reaction mixture becomes black due to by-products, there is a disadvantage that purification is difficult. On the other hand, in order to solve the above-mentioned drawbacks, methods using catalysts such as alkylene polyamine, benzamide, urea, acetamide, triaryl phosphate, and sorbitol have been proposed in carrying out the chlorination reaction. In this case as well, there are inconveniences such as the production of synthetic polymers as the reaction progresses, and the results are not necessarily satisfactory in terms of yield, purity, etc. of the desired product.

The present invention aims to provide a method for lateral chlorination of aromatic hydrocarbons having side chains that does not have such drawbacks. A hydrocarbon solution contains one or more amiso compounds selected from alkyl amines, nitrogen-containing enocyclic amines, and alkanol amiso compounds, and then is brought into contact with chlorine under ultraviolet irradiation. According to this method, the chlorination reaction of side chains proceeds selectively and easily at a relatively low reaction temperature (approximately 80 to 15,000 ℃), and created substances such as resinous substances are Almost no product is produced, and the 0 reaction mixture does not have any drawbacks such as turning black as the reaction progresses.
The target product can be obtained in high yield and purity. Furthermore, in such a chlorination reaction, if ferric chloride or the like is present as an impurity, there is a risk that the nucleus will be chlorinated along with the side chain chlorination reaction, but according to the method of the present invention, the reaction can be prevented. Even if such impurities are present in the system, the chlorination reaction proceeds selectively with respect to side chains, giving the advantage that the creation of nuclear chlorinated products is extremely small.

To explain this, examples of the aromatic hydrocarbon having a side chain used as a starting material in the present invention include aromatic hydrocarbons having a lower alkyl group as a side chain such as toluene, xylene, and trimethylbenzene.

The method of the present invention can also effectively chlorinate side chains of aromatic compounds having side chains in which atoms or groups such as halogen atoms, carboxyl groups, halogenated acyl groups, hydroxyl groups, and sulfone groups have been introduced. It can be performed. The aliphatic polyhalogenated hydrocarbon used as a solvent in the chlorination reaction is preferably one that is stable against the chlorination reaction, particularly carbon tetrachloride.

Note that the concentration of the solution in this case may be within the range of 10 to 7% by weight. Catalysts used in the method of the present invention include alkyl amines such as triethylamine and diisopropylamine, piperidine, N-methylpiveridine, pyrrolidine, piperazine, pyridine, N-methylpyrrole,
- Nitrogen-containing heterocyclic amines such as pyrrolidone and morpholine, and alkanolamines such as monoethanolamine and inpropanolamine.

2 The preferable amount of the above-mentioned catalyst to be used varies depending on the type thereof, but is generally 0.01 to 5% by weight based on the aromatic hydrocarbon raw material. Moreover, the reaction temperature when performing the chlorination reaction under ultraviolet irradiation may be approximately 80 to 150 qo. As the ultraviolet light source 3, a xenon lamp, a low-pressure or high-pressure mercury lamp, or the like can be used. The reaction may be carried out by method 3, in which a raw material aromatic compound, a catalyst, and a solvent are placed in a reaction vessel that transmits ultraviolet rays, and chlorine is blown into the bottom of the reaction vessel while irradiating ultraviolet rays.

Next, the present invention will be explained in more detail by giving examples.

In addition, in the following examples, ferric chloride was added in the presence of iron compounds, which are considered to be the most harmful impurities to this chlorination reaction. This is to show that this can be achieved satisfactorily, and it goes without saying that much better results can be obtained in the absence of such iron compounds. Example A quartz glass reactor equipped with a chlorine gas blowing nozzle at the bottom was charged with 35 m of paraxylene, 25 m of carbon tetrachloride, 0.1 m of the catalyst shown below, and 6 M of ferric chloride as an impurity. Ultraviolet rays were irradiated from one side of the reactor using a high-pressure mercury lamp, and the reactor was reacted for 6 hours while blowing chlorine gas into the bottom of the reactor at a rate of 1 hour.

The reaction temperature was 90'0 at the start of the reaction and was gradually raised to 13,000. After the reaction was completed, carbon tetrachloride was completely removed, and in each case a product was obtained that was solid at room temperature, and the yield relative to the theoretical value was 95% or more in each case.

On the other hand, when the products were analyzed by gas chromatography, the purity of the target product, 1,4-bis(trichloromethyl)benzene, was 99% by weight or higher in all cases, and it was found that the purity of the target product, 1,4-bis(trichloromethyl)benzene, was 99% by weight or more, and ) were as shown below.

The results of examining the appearance (color tone) and light transmittance (purple, green) of one skin thickness for a 10% carbon tetrachloride solution of the above reaction product are also shown below.

However, experiment no. 1 shows a comparative example.

Claims (1)

[Claims] 1. One or more amine compounds selected from alkylamines, nitrogen-containing heterocyclic amines, and alkanolamines are added to a solution of an aromatic hydrocarbon having a side chain using an aliphatic polyhalogenated hydrocarbon as a solvent. to contain,
A method for chlorinating an aromatic hydrocarbon having a side chain, the method comprising: then contacting the aromatic hydrocarbon with chlorine under irradiation with ultraviolet rays.