JPS6311340B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel method for producing p-tert.butyl-benzene derivatives. The products obtained by the production method of the invention are known substances, in particular known as intermediates for chemicals. The method of the present invention involves the use of a temperature range between about -20°C and +20°C under the action of high-energy radiation and/or in the presence of a radical former.
p at a temperature of 35°C, preferably about -10°C to +10°C.
-tert.butyltoluene and chlorine are reacted, and the resulting p-tert.butyl-benzyl chloride is purified if necessary, and then converted into p-tert.butyl-benzaldehyde by a method known per se. It is characterized by transformation. The production process of the invention is characterized by a remarkable high selectivity (the amount of benzyl derivative in the reaction product ) is obtained. It is surprising that this selectivity is obtained in a relatively low temperature range. The conventional radical chlorination method of the methyl group of p-tert.butyl-toluene was not economical. That is, the tert.butyl group was always heavily chlorinated, and a small amount of nuclear chlorination also occurred. In conventional p-tert.butyl-benzyl chloride obtained as a mixture with p-chloro-tert.butyl-toluene and/or nuclear chlorinated p-tert.butyl-toluene, on an industrial scale, It is almost impossible to remove these by-products. Therefore, a method is needed to obtain a uniform chlorination product of p-tert.butyltoluene. According to the present invention, radical chlorination can be carried out at relatively low temperatures. It has thus been found that by selecting the temperature, the desired selectivity can be obtained in an unexpected manner, as can be seen from the tables shown in the Examples below. In the method of the present invention, chlorine can be preferably introduced in gaseous form into the starting material p-tert.butyl-toluene, and according to the method, an inert gas (e.g. nitrogen, argon, etc.) is introduced into the starting material p-tert.butyl-toluene. It can also be added. This chlorination can be carried out in the absence of a solvent or in the presence of a suitable solvent. Examples of such solvents include inert, especially halogenated hydrocarbons such as carbon tetrachloride or chlorinated benzenes. The reaction can be carried out under normal pressure or under increased pressure, especially under slightly increased pressure. The reaction can also be carried out batchwise or continuously. The reaction is carried out between about -20°C and +35°C, especially between about -10°C and +35°C.
Performed at 10°C. However, the reaction can be carried out even at temperatures below -20℃;
It doesn't make sense from an economic standpoint. In yet another embodiment of the invention, the reaction is carried out at about 5°C to 35°C, especially 15°C to 25°C. For exothermic reactions, the temperature is controlled by a suitable cooling device (eg a water bath or cooling coil). The energy required for the dissociation of halogen molecules into atoms (radicals) is preferably achieved by the action of high-energy radiation. Irradiation with a UV-illuminator (eg a medium or high pressure mercury lamp) is preferred. However, other light sources can also be used in the method of the invention. The condition in each case is that their radiant energy is sufficient to split the chlorine molecules into radicals;
There must be a sufficient amount in the spectrum of the light source with wavelengths below 488 nm. Examples of other light sources include sunlight, fluorescent lights, incandescent bulbs, laser light, and the like. However, so-called radical formers can also be used. Radical formers suitable for this purpose include organic compounds commonly used for side chain chlorination which can be activated (e.g. thermally or by light) in the temperature range used in the present invention. Examples include peroxide and azoisobutyronitrile. The introduction of chlorine and the formation of radicals are preferably balanced against each other so that all chlorine is absorbed (ie, no chlorine escapes from the reaction mixture). The molar ratio of chlorine to the starting material to be converted is:
The ratio is 1:1. However, the molar ratio of chlorine can also be lowered (for example from 0.5:1 to 0.9:1) if, for example, the reaction is to be interrupted prematurely. Such early termination of the reaction can be advantageous, especially when the reaction is carried out in the upper temperature range, i.e. from 10°C to 35°C, and can avoid the formation of high boiling components (e.g. dichlorinated products, etc.). can be avoided as much as possible. In this case, unreacted p-tert.butyl-toluene can be recovered, preferably by distillation. The obtained p-tert.butyl-benzyl chloride can be suitably purified by distillation.
Thus, in this method, the compound is obtained with a purity of at least 95%. However, the chlorinated product can also be further processed in the crude state if desired. p-tert. p- of butyl-benzyl chloride
Any conversion to tert.butyl-benzaldehyde can be carried out in a manner known per se, for example by reaction with hexamethylenetetramine (Sommelet reaction: Houben-Weyl, Messoden der Organizien Chemie).
Methoden der Organischen Chemie) 7/1
Vol. 194, 1954, G. Thieme, Stuttgart (see G. Thieme, Stuttgart). However, p-tert.butyl-benzyl chloride can also be hydrolyzed to p-tert.butyl-benzyl alcohol or used as an alkylating agent and the like. The hydrochloric acid (gaseous) that forms as a result of the reaction according to the invention can be absorbed, for example, by means of customary gas scrubbing equipment. If water is used as the cleaning liquid, a usable aqueous hydrochloric acid solution is obtained. The following examples illustrate the invention. Example (a) In a round bottom flask equipped with a thermometer, a magnetic stirrer, a chlorine inlet tube, a reflux condenser and a hydrogen chloride absorption device filled with water, p-tert.butyl-toluene is added.
I put 50g. A medium-pressure mercury lamp (250 W) adjacent to the reaction vessel was turned on, and introduction of chlorine was started while stirring. The reaction vessel was cooled with a cooling bath so that the temperature did not exceed 30°C. After 80% of the p-tert.butyl-toluene had reacted (GC), the reaction was stopped. Blow nitrogen into the reaction vessel;
The reaction product was then distilled. 9g of p-tert.butyl-toluene was recovered and the purity was 95% (MMR/
35 g of p-tert.butyl-benzyl chloride with GC) were obtained. Also, in this distillation, p-tert.
Butyl-benzal chloride 4g, p-tert.butyl-chlorobenzyl-benzyl chloride
8 g and 5 g of residue were also obtained. (b)-(d) Further chlorination was carried out in the same manner as above using the amount of p-tert.butyl-toluene, temperature and conversion rate. The results are summarized in the table below.

[Table] The obtained yield is the recovered p-tert.butyl-
It concerns isolated (distilled) products without regard to toluene. In this case, the numbers are naturally higher. Purity was determined by gas chromatography and confirmed by nuclear magnetic resonance. The impurities consist primarily of approximately equivalent amounts of p-chloro-tert.butyl-toluene and m-tert.butyl-benzyl chloride. The latter is produced from m-tert.butyl-toluene, which is already present at about 3-6% in commercial grade p-tert.butyl-toluene. (e) Same method as above except for changing the temperature.
A series of experiments were conducted. After 2/3 of the p-tert.butyl-toluene was consumed, the ratio of the produced p-tert.butyl-benzyl chloride to the produced p-chloro-tert.butyl-toluene was measured by gas chromatography. . The results are summarized in Table 2 and further graphed as shown in the attached drawing. (f) After 80% or more conversion, further series of experiments were performed and analyzed. The results are also summarized in Table 2 and shown graphically in the accompanying drawings.

[Table] Hexamethylenetetramine was added to a three-neck flask equipped with a thermometer, magnetic stirrer, and reflux condenser.
17g, water 9ml, ethanol 6ml and 95% p-tert.
21.5 g of butyl-benzyl chloride was added.
While stirring, the mixture was slowly warmed to 45°C. At this temperature, the mixture initially appeared slurry-like and then became a dilute solution. An exothermic reaction then occurred. The temperature was kept at 45°C in a water bath until the reaction weakened. Then mix the mixture again at 45
The mixture was stirred for 30 minutes while warming to ℃. The reflux condenser was replaced with a distillation tube, and ethanol was distilled off from the mixture under slightly reduced pressure (70 torr). Next, the distillation tube was removed and a water separator was attached so that the separated water could flow back into the reaction vessel. About 60 liters of water into the water separator
ml and 10 ml of toluene and the mixture was treated with 60 ml of water. The mixture was heated to 140°C. At the beginning of the steam distillation, the pH value was adjusted to 4.5-5 with 60% sulfuric acid. The liquid in the water separator was changed several times. The organic phase was separated from the distillate and the aqueous fraction was extracted with ether. The ether extract and the organic phase were combined and washed with approximately 20 ml of 15% sulfuric acid, water, 10% aqueous sodium carbonate solution, and finally with water again.
It was then concentrated. In this way, a total of 14.7 g of crude product was obtained and distilled in a 5 cm Widmer fractionating tube at 17 Torr to obtain 11.8 g (60%) of p-tert.butyl-benzaldehyde with a purity of 92% (NMR/GC ).

[Brief explanation of the drawing]

The figure shows the selectivity [=p-tert.butyl-benzyl chloride/p-chloro-tert.butyltoluene] as a function of temperature in Examples (e) and (f). In the figure,

[Formula] Conversion rate: 2/ 3; i.e. 2/3 of the starting material consumed

[Formula] Conversion Rate: Shows 80%.

Claims (1)

[Claims] 1. Reacting p-tert.butyltoluene with chlorine at a temperature of about -20°C to +35°C under the action of high-energy radiation and/or in the presence of a radical former, optionally comprising: p-tert.butyl-benzene, which is characterized in that the obtained p-tert.butyl-benzyl chloride is purified as necessary and then converted into p-tert.butyl-benzaldehyde by a method known per se. Method for producing derivatives. 2. Process according to claim 1, characterized in that the chlorination is carried out at a temperature of about 5°C to 35°C. 3. Process according to claim 1, characterized in that the chlorination is carried out at a temperature of about -10°C to +10°C. 4. Process according to claim 1, characterized in that the chlorination is carried out at a temperature of 15°C to 25°C. 5. Any one of claims 1 to 4, characterized in that the obtained p-tert.butyl-benzyl chloride is converted to p-tert.butyl-benzaldehyde by reacting with hexamethylenetetramine. or the method described in paragraph 1.