Comment

The title compound, (I), is one of the n-aliphatic amides and has recently been studied as a possible agent for growth inhibition of human neuroblastoma cell lines (Rocchi et al., 1998) and inhibitory effects on DNA synthesis on hepatoma cells (Lea et al., 1993).

The powder diffractogram data for (I) were reported in 1950 (Matthews et al., 1950), as part of a study on derivatives of fatty acids, and the unit cell was determined five years later (Turner & Lingafelter, 1955) using Weissenberg photographs, to give a = 9.94 Å, b = 5.79 Å, c = 10.02 Å and = 100.9°. Examination of the systematic absences showed the space group to be P2₁/a; however, no atomic coordinates were published. We have solved and refined the crystal structure of butyramide at 150 K, to give a final R value of 0.041. There is a 12° difference in the angle between the two determinations. In (I), the bond lengths and angles are within expected values (Allen et al., 1987), with the C-C bond lengths in the range 1.5057 (18)-1.515 (2) Å and with N1-C1 and O2-C1 bond lengths of 1.3257 (15) and 1.2395 (13) Å, respectively. There is a relative twist of the carbon chain from planarity, with torsion angles C1-C2-C3-C4 and N1-C1-C2-C3 of 177.41 (21) and 151.62 (12)°, respectively. The packing consists of centrosymmetric dimers, linked through a pair of N-HO hydrogen bonds [2.9470 (15) Å]. The other amine H atom is used to hydrogen bond to an adjacent dimer unit which is approximately perpendicular (73°), through an N-HO hydrogen bond [2.8496 (14) Å], resulting in the formation of a three-dimensional criss-crossed ribbon structure (Fig. 2).

Figure 1 View of (I), showing the atom labelling scheme. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2 The packing in (I), showing the butyramide dimer unit which forms a hydrogen-bonded (dashed lines) criss-cross ribbon motif.

Experimental

As part of an experimental polymorph screen on adenine, (I) was obtained from a 0.3 M aqueous solution of (I), to which approximately 0.15 g of adenine was added, and which was stirred on a hotplate at 303 K for 3 d. This solution was filtered, then evaporated at room temperature (10 ml solution, in 75 × 25 mm vessels) in an attempt to crystallize adenine, as it has been found that the solubility of purine and pyrimidine bases increases in aqueous amide solutions (Herskovits & Bowen, 1974). Colourless block-like crystals of (I) were formed after a number of days.

Crystal data

C4H9NO Mr = 87.12 Monoclinic, P 21 /c a = 9.814 (3) Å b = 5.9232 (17) Å c = 9.701 (3) Å = 112.070 (4)° V = 522.6 (3) Å3 Z = 4 Dx = 1.107 Mg m-3 Mo K radiation Cell parameters from 1237 reflections = 2.2-25.4° = 0.08 mm-1 T = 150 (2) K Block, colourless 0.38 × 0.20 × 0.16 mm

Data collection

Bruker SMART APEX diffractometer scans Absorption correction: multi-scan(SADABS; Sheldrick, 1996)Tmin = 0.971, Tmax = 0.987 4321 measured reflections 1244 independent reflections 993 reflections with I > 2(I) Rint = 0.021 max = 28.3° h = -13 12 k = -7 7 l = -12 12

Refinement

Refinement on F2 R[F2 > 2(F2)] = 0.041 wR(F2) = 0.111 S = 1.01 1244 reflections 91 parameters All H-atom parameters refined w = 1/[2(Fo2) + (0.064P)2 + 0.0651P] where P = (Fo2 + 2Fc2)/3 (/)max < 0.001 max = 0.19 e Å-3 min = -0.12 e Å-3

Table 1 Hydrogen-bond geometry (Å, °) D-HA D-H HA DA D-HA N1-H1O2i 0.92 (2) 2.03 (2) 2.9470 (15) 176 (1) N1-H2O2ii 0.89 (2) 1.98 (2) 2.8496 (14) 168 (1) Symmetry codes: (i) -x+1, -y, -z+1; (ii) .

H atoms were refined independently with an isotropic model.

Data collection: SMART (Bruker, 2000); cell refinement: SAINT; data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2000) and MERCURY (Bruno et al., 2002); software used to prepare material for publication: SHELXL97.