N,N′-Dibenzylethylenediammonium dichloride

Abstract

The isolation and crystalline structure of N,N′-dibenzylethylenediammonium dichloride, C16H22N22+·2Cl−, is reported. This was obtained as an unintended product of an attempted Curtius rearrangement that involved benzylamine as one of the reagents and 1,2-dichloroethane as the solvent. Part of a series of reactions of a course-based undergraduate research experience (CURE), this was not the intended reaction outcome. The goal of the course was to engage students as active participants in a laboratory experience which applies the foundational techniques of a synthetic organic laboratory, using the Curtius rearrangement as a tool for the assembly of medicinally significant scaffolds. The isolation of the title compound, N,N′-dibenzylethylenediammonium dichloride, the result of the 1,2-dichloroethane solvent outcompeting the Curtius isocyanate intermediate in the reaction with the nucleophilic amine, confirms the importance of conducting research at the undergraduate level where the outcome is not predetermined. The solid-state structure of N,N′-dibenzylethylenediammonium dichloride was found to feature an all-trans methylene-ammonium backbone. Strong N—H...Cl hydrogen bonds and C—H...Cl interactions lead to a layered structure with pseudo-translational symmetry emulating a C-centered setting. Different phenyl torsion angles at each end of the molecule enable a more stable packing by allowing stronger hydrogen-bonding interactions, leading to a more ordered but lower symmetry and modulated structure in P21/n.

Keywords

• crystal structure
• side reaction
• hydrogen bonding
• pseudo-translation
• modulation