4-(sec-Butyl­amino)-3-nitro­benzoic acid

Shivanagere Nagojappa Narendra Babu; Aisyah Saad Abdul Rahim; Shafida Abd Hamid; Chin Sing Yeap; Hoong-Kun Fun

doi:10.1107/S1600536809021655

. 2009 Jun 13;65(Pt 7):o1557–o1558. doi: 10.1107/S1600536809021655

4-(sec-Butylamino)-3-nitrobenzoic acid

Shivanagere Nagojappa Narendra Babu ^a, Aisyah Saad Abdul Rahim ^a,^‡, Shafida Abd Hamid ^b, Chin Sing Yeap ^c,^§, Hoong-Kun Fun ^c,^*,^¶

PMCID: PMC2969477 PMID: 21582841

Abstract

The asymmetric unit of title compound, C₁₁H₁₄N₂O₄, consists of two crystallographically independent molecules (A and B). In each, intramolecular N—H⋯O hydrogen bonds generate S(6) ring motifs. The mean plane of the nitro group forms dihedral angles of 4.5 (3) and 0.5 (3)° with the benzene ring in molecules A and B, respectively. In molecule A, there is disorder of the butylamino group which corresponds to an approximate 180° rotation about the N—C(H) bond, forming two sites with refined occupancies of 0.722 (6) and 0.278 (6). Molecule B is similarly disordered but in addition there is further rotational disorder about the C(H)—C(H₂) bond giving a ratio of occupancies for three components of 0.42:0.35:0.23. In the crystal structure, intermolecular O—H⋯O hydrogen bonds link molecules into centrosymmetric dimers generating R ₂ ²(8) ring motifs. The crystal structure is also stabilized by weak intermolecular C—H⋯O interactions.

Related literature

For the synthesis of bioactive heterocycles using nitro benzoic acid derivatives as the starting materials, see: Burgey et al. (2006 ▶); Ishida et al. (2006 ▶); Semple et al. (2006 ▶); Narendra Babu et al. (2009 ▶). For hydrogen-bond graph-set motifs, see: Bernstein et al. (1995 ▶). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986 ▶).

Experimental

Crystal data

C₁₁H₁₄N₂O₄
M _r = 238.24
Monoclinic,
a = 6.9722 (4) Å
b = 15.7250 (8) Å
c = 21.8111 (11) Å
β = 101.896 (3)°
V = 2340.0 (2) Å³
Z = 8
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 110 K
0.57 × 0.08 × 0.04 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.922, T _max = 0.995
23247 measured reflections
4600 independent reflections
3357 reflections with I > 2σ(I)
R _int = 0.049

Refinement

R[F ² > 2σ(F ²)] = 0.070
wR(F ²) = 0.165
S = 1.08
4600 reflections
335 parameters
2 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.56 e Å⁻³
Δρ_min = −0.60 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809021655/lh2837sup1.cif

e-65-o1557-sup1.cif^{(28KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809021655/lh2837Isup2.hkl

e-65-o1557-Isup2.hkl^{(225.4KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1A—H1OA⋯O2Aⁱ	0.82	1.83	2.646 (3)	175
O1B—H1OB⋯O2Bⁱⁱ	0.82	1.80	2.618 (3)	172
N2A—H2NA⋯O4A	0.80 (3)	1.97 (3)	2.630 (4)	139 (3)
N2B—H2NB⋯O4B	0.88 (3)	1.90 (3)	2.627 (4)	139 (3)
C5A—H5AA⋯O3Aⁱⁱⁱ	0.93	2.44	3.316 (4)	157
C5B—H5BA⋯O3B^iv	0.93	2.47	3.253 (4)	142

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) .

Acknowledgments

SNNB, ASAR and SAH acknowledge Universiti Sains Malaysia (USM) for a University Research Grant for the synthetic chemistry work (No. 1001/PFARMASI/815026). SNNB thanks USM for a Postdoctoral Research Fellowship. HKF thanks USM for a Research University Golden Goose Grant (No. 1001/PFIZIK/811012). CSY thanks the Malaysian Government and USM for the award of the post of Research Officer under the Science Fund Grant (No. 305/PFIZIK/613312).

supplementary crystallographic information

Comment

The synthesis of bioactive heterocycles such as substituted benzimidazolones, benzimidazoles and 1-substituted benzotriazole carboxylic acids, (Burgey et al., 2006; Ishida et al., 2006; Semple et al., 2006), can be achieved from nitro benzoic acid derivatives as the starting materials. As part of our ongoing synthesis programme, (Narendra Babu et al., 2009), we have synthesized the title compound as an intermediate and herein present its crystal structure.

The asymmetric unit of title compound (I), (Figs. 1 and 2), consists of two crystallographically independent molecule A and B. Intramolecular N2A—H2NA···O4A and N2B—H2NB···O4B hydrogen bonds generate S(6) ring motifs (Bernstein et al., 1995). The nitro group for molecule A is almost planar with the benzene ring whereas the nitro group for molecule B is essentially coplanar with benzene ring [dihedral angle, A = 4.5 (3)° and B = 0.5 (3)°].

In molecule A there is disorder of the butylamino group which corresponds to an approximate 180° rotation about the N-C(H) bond forming two sites with refined occupancies of 0.722 (6) and 0.278 (6). Molecule B is similarly disordered but in addition there is further rotational disorder about the C(H)-C(H₂) bond giving a ratio of occupancies for three components of 0.42:0.35:0.23 (see Fig. 1).

In the crystal structure, intermolecular O—H···O hydrogen bonds (see Table 1) link molecules into centrosymmetric dimers (Fig. 3) to generate R₂²(8) ring motifs (Bernstein et al., 1995). The crystal structure is further stabilized by weak intermolecular C—H···O interactions (Table 1).

Experimental

Ethyl 4-(sec-butylamino)-3-nitro-benzoate (0.2 g, 0.00075 mol) and KOH (0.084 g, 0.0015 mol) was refluxed in aqueous ethanol (5 ml) for 3 h. After completion of the reaction, ethanol was distilled off and the reaction mixture was diluted with water (5 ml). The aqueous layer was washed with dichloromethane (5 ml x 2) and acidified with concentrated hydrochloric acid to afford yellow solid. Recrystallisation of the crude product with hot ethyl acetate afforded yellow crystals.