Crystal structure of 2-bromobenzoic acid hydrazide, C7H7BrN2O

Abstract

C7H7BrN2O, monoclinic, P121/c1 (no. 14), a = 12.769(3) A, b = 12.754(3) A, c = 5.026(1) A, = 99.874(4)°, V = 806.5 A 3 , Z =4 ,Rgt(F) = 0.028, wRref(F 2 ) = 0.074, T = 293 K. Source of material The title compound was synthesized by the reaction of ethyl ester of 2-bromobenzoic acid with hydrazine hydrate (80 %) in absolute ethanol. The reaction mixture was refluxed for 7 h. The excess of solvent was distilled off, the residue was filtered and washed with water. Colorless thin needle-shaped single crystals suitable for Xray analysis were obtained by recrystallization from 60 % ethanol. Experimental details While the H atoms bound to N atoms were refined freely due to their importance in hydrogen bonding, the H atoms attached to C atoms were refined using conventional restraints. Discussion Aromatic hydrazides are a very important intermediate especially in the field of heterocyclic chemistry. Aromatic hydrazide have been used for the synthesis of various biologically active five membered heterocycles such as 2,5-disubstituated-1,3,4oxadiazoles, 5-substituted-2-mercapto-1,3,4-oxadiazoles etc. Due to its versatilities in the synthesis of various heterocyclic compounds, we have synthesized the title compound and report its structure. The r.m.s. deviation from plane is 0.678 A in the molecular structure of the title compound. Within phenyl ring, the bond lengths lie between 1.376(4) A and 1.386(3) A highlighting the aromatic character. The valence angle C2–C1–C6 of 121.1(2)° is larger than the standard value (120°). The opening of this angle is due to the presence of the bromo group on C1, which involves a decrease of the ring angles on C1 (118.2 (2)°) and C6 (118.2(2)°). The C7—O1 bond distance (1.225(3) A) is compatible with respective distances in a related structure [2] and smaller than those usually observed in carboxylic acids (1.365 A). The structure is influenced by quite interesting intra- and intermolecular hydrogen bonding which stabilizes the whole crystal structure.