| 摘要 |
PURPOSE:To obtain a heating medium having a low freezing point and excellent thermal stability by reacting biphenyl with a methylating agent to give a methylbiphenyl and treating methylbiphenyl under a specific condition. CONSTITUTION:Biphenyl is methylated or transmethylated with a methylating agent in the presence of a catalyst and then 3-methylbiphenyl and/or 4,4'- dimethylbiphenyl is at least partially separated from the prepared methylbiphenyl to give the objective heating medium which contains 40-100wt.% of the methylbiphenyl, <=50wt.% 4-methylbiphenyl in methylbiphenyl and <=20wt.% of 4,4'-dimethylbiphenyl in dimethyl biphenyl. |
