Crystal structure of 4-[(2-hy-droxy-3-meth-oxy-benz-yl)amino]-benzoic acid hemihydrate.

Saima Kamaal,Musheer Ahmad,Arif Ali,Necmi Dege,Md Serajul Haque Faizi,Mayank Gupta,Turganbay Iskenderov

doi:10.1107/s2056989018018455

Abstract

In the crystal of the title vanilline derivative, 2C15H15NO4·H2O, the secondary amine mol-ecule is accompanied by half equivalent of water. The mol-ecule is non-planar, with torsion angle Car-yl-CH2-NH-Car-yl of -83.9 (2)°. In the crystal, the system of O-H⋯O hydrogen bonds, including bridging water mol-ecules residing on crystallographic twofold axes, results in a two-dimensional layered structure. Within the layers, there are also weak N-H⋯π inter-actions involving the vanilline benzene ring.

Highlights

In the crystal of the title vanilline derivative, 2C15H15NO4ÁH2O, the secondary amine molecule is accompanied by half equivalent of water
The system of O—HÁ Á ÁO hydrogen bonds, including bridging water molecules residing on crystallographic twofold axes, results in a two-dimensional layered structure
The title compound is obtained by reduction of reported (Kamaal et al, 2018) (E)-4-(2-hydroxy-3-methoxybenzylideneamino)benzoic acid with sodiumborohydride

Summary

Chemical context

The title compound is obtained by reduction of reported (Kamaal et al, 2018) (E)-4-(2-hydroxy-3-methoxybenzylideneamino)benzoic acid with sodiumborohydride. The Schiff base is formed by condensation of 4-aminobenzoic acid with o-vanilline. Both p-aminobenzoic acid and o-vanilline have biological importance, for example as a bacterial cofactor involved in the synthesis of folic acid (Robinson, 1966). Another example is benzocaine, the ethyl ester of p-aminobenzoic acid, which is a local anaesthetic. The reported C—N distance in crystal structure of the ethyl 4-[(E)-(4-hydroxy-3-methoxybenzylidene)amino]benzoate Schiff base is 1.274 (2) A (Ling et al, 2016) and in the zwitterion it is 1.312 A (Kamaal et al, 2018). While the N—H group is not involved in traditional hydrogenbonding interactions, there are intermolecular N—HÁ Á Á interactions within the layers (Table 1, Fig. 3)

Database survey

Synthesis and crystallization

Refinement