2011 Volume 27 Pages 57-58
Trisiloxane-containing alicyclic tetracarboxylic dianhydride was derived from 5-norbornene-endo-2,3-dicarboxylic anhydride and 1,1,3,3,5,5-hexamethyltrisiloxane. This dianhydride could be divided into two crystals with different melting points: 143.5 - 144.5°C and 119.5 - 121.5°C. The crystal system of the low-melting-point dianhydride is triclinic, space group is P1, and number of molecules in a unit cell (Z) is two with lattice parameters a = 14.033(4)Å, b = 15.602(5)Å, c = 7.603(4)Å, α = 101.72(3)°, β = 105.19(3)°, γ = 64.82(2)°. From the finding that (R,R) and (S,S) existed in pairs within a unit cell, it is concluded that this dianhydride is a racemic isomer.