N-(4-Methylphenyl)-N′-phenylbutanediamide monohydrate

In the title hydrate, C17H18N2O2·H2O, the dihedral angles formed by the aromatic rings of the benzene and methylbenzene groups with the mean planes of the attached NH—C(O)—CH2 fragments are 12.6 (4) and 23.3 (3)°, respectively, while that between the two aromatic rings is 73.7 (2)°. In the crystal, the water molecule accepts two and makes two hydrogen bonds. The molecules are packed into layers parallel to (101) by O—H⋯O and N—H⋯O hydrogen-bonding interactions.

In the title hydrate, C 17 H 18 N 2 O 2 ÁH 2 O, the dihedral angles formed by the aromatic rings of the benzene and methylbenzene groups with the mean planes of the attached NH-C(O)-CH 2 fragments are 12.6 (4) and 23.3 (3) , respectively, while that between the two aromatic rings is 73.7 (2) . In the crystal, the water molecule accepts two and makes two hydrogen bonds. The molecules are packed into layers parallel to (101) by O-HÁ Á ÁO and N-HÁ Á ÁO hydrogen-bonding interactions.
BSS thanks the University Grants Commission, Government of India, New Delhi, for the award of a research fellowship under its faculty improvement program.

Comment
The amide and sulfonamide moieties are important constituents of many biologically significant compounds. As a part of a study of the substituent effects on their structures and other aspects of this class of compounds (Gowda et al., 2000(Gowda et al., , 2007Saraswathi et al., 2011a,b), in the present work, the structure of the title compound, isolated as a monohydrate has been determined ( Fig. 1) The dihedral angle between the phenyl ring and the adjacent NH-C(O)-CH 2 segment is 12.6 (4) ° and that between the 4-methylphenyl ring and the adjacent NH-C(O)-CH 2 segment is 23.3 (3) °, compared to the values of 62.1 (2) °f ormed between the benzene ring and the NH-C(O)-CH 2 segment in the two halves of (II), and 32.8 (1) ° in (III). In the title compound, the dihedral angle between the two aromatic rings is 73.7 (2) °. The crystal packing is stabilized through N1-H1N···O2, N2-H2N···O3, O3-H31···O1 and O3-H32···O3 hydrogen bonding (Table 1) and results in layers as shown in Fig.2.

Experimental
Succinic anhydride (0.01 mol) in toluene (25 ml) was treated drop wise with aniline (0.01 mol) also in toluene (20 ml) with constant stirring. The resulting mixture was stirred for one hour and set aside for an additional hour at room temperature for completion of the reaction. The mixture was then treated with dilute hydrochloric acid to remove unreacted aniline. The resultant N-(phenyl)succinamic acid was filtered under suction and washed thoroughly with water to remove the unreacted succinic anhydride and succinic acid. The compound was recrystallized to constant melting point from ethanol.
The N-(phenyl)succinamic acid obtained was then treated with phosphorous oxychloride and excess of p-toluidine at room temperature with constant stirring. The resultant mixture was stirred for 4 h, kept aside for additional 6 h for completion of the reaction and poured slowly into crushed ice with constant stirring. It was kept aside for a day. The resultant solid, N-(phenyl),N-(4-methylphenyl)-succinamide monohydrate, was filtered under suction, washed thoroughly with water, dilute sodium hydroxide solution and finally with water. It was recrystallized to constant melting point from a mixture of acetone and chloroform.
Colorless needles were grown in a mixture of acetone and chloroform at room temperature.

Refinement
The H atoms of the NH groups were located in a difference map and later restrained to the distance N-H = 0.86 (2) Å.
The H atoms of the water molecule were located in difference map and were refined with the O-H and H-H distances restrained to 0.85 (2) Å and 1.365 Å, respectively, thus leading to the angle of 107 ° (Nardelli, 1999). The other H atoms supplementary materials sup-2 were positioned in their idealized geometries using a riding model with aromatic C-H = 0.93 Å, methyl C-H = 0.96 Å and methylene C-H = 0.97 Å. All H atoms were refined with isotropic displacement parameters (set to 1.2 times of the U eq of the parent atom). Fig. 1. The asymmetric unit of the title compound showing atom labelling and with displacement ellipsoids drawn at the 50% probability level. The hydrogen bond is shown as a dashed line.