| 摘要 |
1376051 Dibenzofuran-formaldehyde and dibenzothiophene-formaldehyde resins EASTMAN KODAK CO 24 Feb 1972 [1 March 1971] 8499/72 Heading C3R [Also in Division G2] A dibenzofuran-formaldehyde resin is made by the reaction of paraformaldehyde in formic acid with dibenzobenzofuran at 100‹ C. The solid reactant is dissolved in dichloromethane and residual formic acid is removed by extraction with aqueous K 2 CO 3 . Evaporation of the dichloromethane gives the resin. A dibenzothiophene-formaldehyde resin may be similarly made starting with dibenzothiophene.
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