| 摘要 |
1467275 Preparation of 2,2<SP>1</SP>,3,3<SP>1</SP>-tetracarboxydiphenyl ether and its dianhydride GENERAL ELECTRIC CO 2 May 1974 [22 June 1973] 19315/74 Heading C2C [Also in Division C3] 2,2<SP>1</SP>,3,3<SP>1</SP> - Tetracarboxydiphenyl ether dianhydride (and the free acid form) are obtained by heating 3-nitrophthalic anhydride at 210- 260‹ C. in the presence of 0À1-10 wt. per cent, based on the weight of the 3-nitrophthalic anhydride, of a nitrite salt of an alkali metal an alkaline earth metal, silver or cadmium. The preparation may be effected under melt conditions or in the presence of an inert organic solvent. The dianhydride is a curing agent for epoxy resins and a starting material for polyetherimides. |
