Background and overview[1]
To date, diaryl sulfones have been used as plasticizers, disintegrants, pesticides, single-technology auxiliaries, dyes, etc. For all of these applications, the impurities contained in the diarylsulfones are not detrimental. Recently it has been proposed to use certain diaryl sulfones as monomers to prepare various high molecular weight polymers and copolymers. The preparation of the diarylsulfone compound bis(3,5-dimethyl-4-hydroxyphenyl)sulfone consists in reacting 2,6-dimethylphenol with sulfuric acid under very specific conditions and includes a special recrystallization step, by The reaction of phenols with sulfuric acid to prepare diarylsulfonamides is known. However, the diarylsulfones thus obtained so far have been pink, rust-colored or brown crystals, indicating that they contain impurities in the form of various color bodies.
Preparation[1]
Bis(3,5-dimethyl-4-hydroxyphenyl)sulfone is prepared as follows: A 500 ml flask is equipped with a thermometer, a stirrer and a condenser equipped with a DeanStark trap to collect water. Add 122g of 2,6-xylenol and 20ml of heptane to the flask. The flask is then heated to a temperature of 50 to 60°C. Over 5 minutes, approximately 40 g of concentrated sulfuric acid was added to the mixture of heptane and lylenol. Heat to 155-170°C and maintain gentle reflux at this temperature until SeanStark-Palle has collected 13ml of water, approximately 1.5-3 hours. During the reaction, sulfone began to adhere to the sides of the reaction vessel, and when the reaction was complete, a thick sulfone filter cake formed. After the reaction, the reaction mixture was cooled to about 60°C, then 100 ml of methanol was added, the container was reheated to about 80°C, and reflux was maintained at this temperature for about 30 minutes. Under reflux conditions, start the stirrer so that the white sulfone filter cake is dissolved in the form of clay from the side of the reaction vessel to form a suspension. Cool to room temperature again, and filter through a Buchner funnel. The separated filter cake is dissolved in methanol and 50 ml of water to obtain about 62 g of white crystal material product. The sulfone thus formed is then dissolved in 150 g of toluene sodium hydroxide solution. Approximately 300 α-methanol was added to the solution. The mixture was then stirred and slowly neutralized with acetic acid to a pH of 4-6. During neutralization, the product precipitated as a fine white powder, which was filtered off. The precipitate was washed with 100 ml of ethanol and water and dried in a heated oven at 100°C for 24 hours to obtain fresh pure bis(3,5-dimethyl-4-hydroxyphenyl)sulfone.
Main reference materials
[1] US3383421
