A polyimide which is obtained by a reaction of an aromatic diamine having a 1,1,1-trifluoro-2,2-ethanediyl group (C(CF.sub.3)H), as a linkage skeleton, with a tetracarboxylic dianhydride is easily dissolved in an organic solvent and exhibits excellent film forming properties. In addition, the thus-obtained polyimide can be used for an optical film and a display device.

The present invention has the effect of making it possible to produce 1,1,1-trifluoro-2,2-bisarylethane efficiently by a simple procedure by condensing a mixture of fluoral and hydrogen fluoride with an aryl compound under anhydrous conditions. The purity of the 1,1, 1-trifluoro-2, 2-bisarylethane obtained can be raised by a simple purification method such as crystallization or distillation. The obtained 1,1,1-trifluoro-2,2-bisarylethane can be increased in purity by a simple purification method such as crystallization operation or distillation.

The present invention has the effect of making it possible to produce 1,1,1-trifluoro-2,2-bisarylethane efficiently by a simple procedure by condensing a mixture of fluoral and hydrogen fluoride with an aryl compound under anhydrous conditions. The purity of the 1,1, 1-trifluoro-2, 2-bisarylethane obtained can be raised by a simple purification method such as crystallization or distillation. The obtained 1,1,1-trifluoro-2,2-bisarylethane can be increased in purity by a simple purification method such as crystallization operation or distillation.

The present invention has the effect of making it possible to produce 1,1,1-trifluoro-2,2-bisarylethane efficiently by a simple procedure by condensing a mixture of fluoral and hydrogen fluoride with an aryl compound under anhydrous conditions. The purity of the 1,1, 1-trifluoro-2, 2-bisarylethane obtained can be raised by a simple purification method such as crystallization or distillation. The obtained 1,1,1-trifluoro-2,2-bisarylethane can be increased in purity by a simple purification method such as crystallization operation or distillation.