| 摘要 |
1,201,287. Bis - benzoxazolyl - thiophenes. CIBA Ltd. 30 Sept., 1968 [4 Oct., 1967], No. 46375/68. Heading C2C. Bis - (benzoxazolyl) - thiophenes of the general formula where R 1 and R 2 are the same or different and each represents hydrogen, C 1-22 alkyl, aralkyl (with 1 to 7 carbon atoms in the alkyl group, aryl, carboxylic acid or a functionally converted carboxylic group, n and m are 1 to 4, R 3 and R 4 are hydrogen or C 1-10 hydrocarbon, are prepared by reacting approximately stoichiometric amounts of the amines with the dicarboxylic acid in an inert atmosphere and in a reaction medium comprising about 1 to 8 times their weight of a compound selected from where X is Cl or Br, a is at least 1, R 7 and R 8 are H, C 1-7 alkyl, chloroalkyl or bromoalkyl, or R 7 and R 8 when attached to vicinal carbon atoms of a benzene ring rogether form a 5-6- membered ring, and R 9 and R 10 are H, or C 1-7 alkyl, chloroalkyl or bromoalkyl, the reaction medium being a liquid at 60‹ C., the reaction mixture being raised to and maintained at a temperature of from 140‹ C. to the boiling point until the theoretical amount of water is removed from the reaction mixture. A catalyst is preferably used. Conventional methods of recovery may be used, but it is preferred to treat the reaction mixture with 2-10% of a strong base and 8-15% of an absorbent clay by weight of starting materials, refluxing until no more water is recovered, filtering above about 120‹ C. and recovering the product from the filtrate. Reference has been directed by the Comptroller to Specification 1,115,614. |
