SU611589A3 - Method of preparing di-4-chlorphenylsulfone - Google Patents

Description

a meter and a distillation column (with stainless steel gasket) connected to a Dean-Stark trap filled with chlorobenzene and including a reflux condenser. The mixture is heated to 245 ° C and the pressure is adjusted to 65 psi. inch (440 kPa). Chlorobenzene and water are distilled off from the upper part of the rectification column, where water is separated into the Dean and Stark apparatus, and chlorobenzene is returned to the flask through a distillation column. The reaction is maintained at boiling at 245 ° C, gradually reducing the pressure as the reaction proceeds. In addition, chlorobenzene is not added to the reaction vessel in addition to the Dean-Stark feed from the unit. After 16 hours of reaction, the mixture is poured into 20 liters of water; the precipitate is collected, washed with cold water (4 X 2 L), and recrystallized from 1,2-dichloroethane, to obtain a white solid with T.PL. 148-150 ° C. The formation of chlorobenzenesulfonic acid and chlorobenzene and concentrated sulfuric acid, in comparison with the subsequent formation of sulphons, proceeds very quickly, and the reaction conditions are not critical. Optimization of the yield of the desired di-4-chlorophenylsulfone (isomer 4,4-) depends only on the reaction conditions between 4-chlorobenzenesulfonic acid and chlorobenzene. The total yield of isomeric dichporpenylsulfones (in particular the amount of the desired di-4-chlorophenylsulfone, expressed in mol% based on the amount of chlorobenzene reacted) varies depending on the reaction temperature, the pressure at which the reaction takes place, the reaction time and the presence of an excess of chlorobenzene, which, if sulfuric acid is used, can be expressed as the ratio of chlorobenzene to sulfuric acid in the initial load. Of these variables, the reaction temperature is the most important. As the reaction progresses, the concentration of chlorobenzene in the reaction mixture decreases, and the concentration of higher boilers increases, so that in order to keep the mixture boiling, it is necessary to increase the reaction temperature and decrease the pressure. Chlorobenzene or an inert azeotroic agent is added to the reaction mixture at a rate corresponding to the formation of a hollow during the reaction of water, or to a decrease in the pressure at which the reaction occurs. The reaction mixture is highly acidic and requires structural materials that are not corrosive under the action of strong acids. While test vessels and equipment made of stainless steels, iikonel or monel alloys are used for test reactors of a small scale, without corrosion occurring to a large extent, reaction vessels and glass piping are preferred for large-scale designs. or covered with glass enamel. The reaction products can be separated, and di-4-chlorophenylsulfone, purified by any method known in the art, for example, selective washing with a solvent, fractional crystallization or centrifugation. Example 2. 1 l of chlorobenzene and 1 l of concentrated sulfuric acid are placed in a stainless steel reaction vessel equipped with a reservoir also containing chlorobenzene, a stirrer and a distillation column connected to a Dean-Stark nozzle filled with chlorobenzene and incorporating a reflux condenser. The reaction is carried out under continuous boiling for 10 hours at 220 ° C and an overpressure of 70 kPa (about 10 pounds per square inch), and the temperature is maintained at a constant level with the further introduction of chlorobenzene. Chlorobenzene and water are distilled off at the top of the distillation column, where water is separated in a Dean-Stark trap and chlorobenzene is returned to the flask through a distillation column. After 10 h, it was found that it was necessary to add an additional amount of 2.008 l of chlorobenzene and 0.521 l of chlorobenzene. These quantities were replaced with 0.55 liters of water that had accumulated in the Dean and Stark apparatus. From the results of the analysis of the reaction mixture, it was calculated that 28.78 mol of chlorobenzene reacted and 9.37 mol (equivalent to 18.74 mol of chlorobenzene) of dichlorophenylsulfones (yield 65%) were obtained together with 8.54 mol of chlorobenzenesulfonic acid. Analysis by infrared spectroscopy of the sulfone product shows 4.7% of the 2,4-isomer and 5.4% of the isomer 3.4, and hence 89.9% of the desired 4,4-isomer. The results of the analysis of the reaction mixture are given in table. Example 3. 0.2 l of chlorobenzene and 0.15 l of concentrated sulfuric acid are mixed in an apparatus similar to that described in example 2, except that a 1 liter glass reaction vessel is used. The reaction is carried out for 10 hours at 230 ° C and an overpressure of 70 kPa (about 10 pounds per square inch) with continuous boiling, and the temperature. by further administration, chlorobenzene is maintained at a constant level. After 10 hours, it was found that chlorobenzene was further added in an amount of 1000 ml (80 ml was replaced from the Dean and Stark apparatus with 84 ml of water). From the analysis of the reaction mixture, it was calculated that 5.48 mol of chlorobenzene reacted and 1.97 mol (equivalent to 3.94 mol of chlorobenzene) of dichlorophenylsulfones (yield 72%) were obtained together with 1.06 mol of chlorobenzenesulfonic acid. Analysis using infrared spectroscopy of the sulfonic product shows that 4% of the isomer of the 2.4 and 12% of the 3,4-isomer, and analysis using ultraviolet spectroscopy shows the total amount of the 2.4 and 3,4-isomers of 15%. Therefore, the product contains 85-86% of the desired 4,4-isomer.

Example 4. In the table; Figure 2 shows the results of the experiments carried out under the conditions of Example 2 in a glass grill apparatus with an overpressure of 70 kPa (about 10 pounds per square inch) at different temperatures and a reaction time of 10 hours.

For comparison, natural results at temperatures below 20 ° C or at atmospheric pressure are natural.

Example 5. Experiments were carried out under the conditions of example 2, characterized in that a reaction vessel of 22.5 liters of glass lined with glass lined with glass was used. The reaction is carried out at 235 ° C for 10 hours at an overpressure of 210 kPa (about 30 pounds per 1 KI; inch). The initial charge of chlorobenzene to sulfuric acid varies. The results are presented in table. 3

Example 6. The experiments were carried out under the conditions of example 5 with the difference that the initial charge ratio of chlorobenzene to sulfuric acid in each experiment was 1.6 - The elevated pressure at which the experiments were carried out varied, the results are shown in Table. four.

Example 7. A mixture of 2 l of chlorobenzene and concentrated sulfuric acid (sp. Weight 1.84) was loaded as described in example 1 into a 4 l stainless steel vessel. Chlorobenzene and water are distilled off from the top of the distillation column, where water is separated in a Dean-Stark apparatus, and chlorobenzene is returned to the flask through a distillation column. During the reaction, chlorobenzene is added in order to keep the mixture boiling at the required temperature. The reaction time is 12 hours and the initial pressure is 270 kPa (40 pounds per square inch). Results presented in Table. five.

The overall yield of dichlorophenylsulfones with increasing temperature of the reaction mixture increases, but the number of undesirable

2, 3,4-isomers.

The yield of di-4-chlorophenylsulfone is improved by increasing the pressure in the reaction vessel above atmospheric.

The method described above for introducing further amounts of chlorobenzene or an inert azeotronic substance into the boiling reaction mixture allows the reaction to be controlled and maintains the reaction temperature and pressure mostly constant, but it can lead to difficulties in the subsequent removal of di-4-chlorofinyl sulfone excess chlorobenzene in the reaction mixture. Controlling the reaction temperature and reducing the boiling conditions by reducing the pressure manually or automatically results in less chlorobenzene by the end of the reaction, and does not require such a large reaction vessel for a given performance of di-4-chlorophenylsulfone. Therefore, it is preferred as a means of keeping the reaction mixture boiling at the desired temperature.

The conditions and experimental data associated with controlling and controlling the reaction by lowering the pressure as the reaction proceeds are similar to what was described above on controlling and controlling by adding chlorobenzene. However, the initial reaction in order to maintain the boiling conditions occurs at higher pressures, which can reach 1000 kPa (about 145 pounds per square inch), because the boiling point of chlorobenzene is 245 ° C at 900 kPa (about 130 psi). inch). As the amount of chlorobenzene in the reaction mixture decreases as it is replaced by less volatile reaction products, to keep the reaction mixture at the boiling point at the desired temperature, the pressure is then reduced by nocTeneimo.

The conditions for optimizing the yield of di-4-chlorophenylsulfone preferably assume a chlorobenzene: sulfuric acid loading ratio in the range 2.5: 1–3: 5: 1, a temperature in the range 220-260 ° C, preferably 235-255 ° C, and more preferably 242-248 ° C, the reaction time is 14-18 hours, and an initial overpressure of 400-900 kPa (ranging from about 60 to about 130 psig).

Example 8. Further experience was carried out as described in Example 1, except that the temperature was varied, the reaction time was 16 hours. The results are shown in Table. 6

The results show that with an increase in the reaction temperature, the overall yield of dichlorophenylsulfones and di-4-chlorofinylsulfone increases, but the yield of undesirable isomers in the reaction mixture also increases.

As can be seen from Example 1, the total yield of sulfones increases as the reaction proceeds. It has also been established that the amount of di-4-chlorophenylsulfone in the reaction mixture will decrease by about t between 12 and 16 hours at 245 ° C. However, since the total yield of sulfone increases over time, the actual amount of di-4-chlorophenylsulfone also increases.

Table 5

Table 6