THE SELF-CONDENSATION OF A DERIVATIVE OF O-AMINOBENZALDEHYDE. STRUCTURE OF THE POLYCYCLIC BISANHYDRO TRIMER OF 2-AMINO-5-BROMOBENZALDEHYDE

The structure of the title compound tracosa-1(24),4(9),5,7,12(17),-13, 15,20,22-nonaene monohydrate, C23H18Br3N3O.H2O, a bisanhydro trimer hy drate formed from the acid-catalyzed self-condensation of 2-amino-5-br omobenzaldehyde, substantiates the geometry proposed for the similar t rimer of o-aminobenzaldehyde (OAB). The tricyclic molecule is an ethox y derivative rather than a hydroxy derivative as previously observed w ith OAB. Formation of the ethoxy derivative is a direct result of the condensation reaction having been carried out in ethanol. A water mole cule of crystallization appears to be strongly hydrogen bonded to one N atom (O-H...N 2.88 angstrom) and weakly hydrogen bonded to the proto nated N atom (N-H...O 3.28 angstrom).