Structure cristalline et moléculaire de l'aminohémiacétal du dimère de la carboéthoxy-3 méthyl-5 formyl-5 pyrazoline-Δ2, C₁₆H₂₄N₄O₆

Abstract

Crystals of C16H24N406 are monoclinic, space group P21/a with a= 10-182 (3), b= 9.567 (3), c= 10.161 (3) A; fl= 112"33 °, Z=2. The crystal structure was solved by direct methods and refined in the last cycles by a full-matrix least-squares method. The hydrogen atoms were included in the refinement. The final R value is 0.060 for 881 reflexions. This crystal structure is compared with the structure of the aminal of the dimer of 3-ethoxycarbonyl-5-methyl-5-formyl-2-pyrazoline. The two compounds have nearly the same configuration. The transformation of an amino hemiacetal function to an amino acetal one occurs with retention of configuration. The cohesion of crystals of C16H24N406 results from hydrogen bonding OH...O (2.790 ~) and van der Waals interactions.