2-Amino-4,6-dimethyl­pyridinium benzoate

Mohd Razip Asaruddin; Habibah A Wahab; Nornisah Mohamed; Mohd Mustaqim Rosli; Hoong-Kun Fun

doi:10.1107/S1600536810034811

. 2010 Sep 4;66(Pt 10):o2496. doi: 10.1107/S1600536810034811

2-Amino-4,6-dimethylpyridinium benzoate

Mohd Razip Asaruddin ^a, Habibah A Wahab ^b,^‡, Nornisah Mohamed ^a, Mohd Mustaqim Rosli ^c, Hoong-Kun Fun ^c,^*,^§

PMCID: PMC2983164 PMID: 21587493

Abstract

In the title compound, C₇H₁₁N₂ ⁺·C₇H₅O₂ ⁻, the 2-amino-4,6-dimethylpyridinium cation and the benzoate anion are linked by two N—H⋯O hydrogen bonds, forming an R ₂ ²(8) ring motif. The H atoms in both the methyl groups are rotationally disordered, with fixed site occupancies of 0.50. In the crystal structure, the molecules are stabilized by intermolecular N—H⋯O hydrogen bonds. A π–π interaction, with a centroid–centroid distance of 3.661 (2) Å, is also observed.

Related literature

For the biological activity of Schiff bases with azomethine linkages, see Dhar & Taploo (1982 ▶). For hydrogen bonding, see: Jeffrey (1997 ▶); Jeffrey & Saenger (1991 ▶). For graph-set descriptions of hydrogen-bond ring motifs, see: Bernstein et al. (1995 ▶).

Experimental

Crystal data

C₇H₁₁N₂ ⁺·C₇H₅O₂ ⁻
M _r = 244.29
Monoclinic,
a = 7.5362 (16) Å
b = 22.937 (4) Å
c = 8.2124 (14) Å
β = 109.820 (2)°
V = 1335.5 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 296 K
0.57 × 0.23 × 0.05 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS;p Bruker, 2009 ▶) T _min = 0.954, T _max = 0.996
7639 measured reflections
2336 independent reflections
1527 reflections with I > 2σ(I)
R _int = 0.029

Refinement

R[F ² > 2σ(F ²)] = 0.044
wR(F ²) = 0.127
S = 1.02
2336 reflections
199 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.10 e Å⁻³
Δρ_min = −0.14 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); 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/S1600536810034811/fj2327sup1.cif

e-66-o2496-sup1.cif^{(19.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810034811/fj2327Isup2.hkl

e-66-o2496-Isup2.hkl^{(114.8KB, 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
N1—H1N1⋯O2	1.04	1.65	2.683 (2)	172
N2—H1N2⋯O1	1.01	1.78	2.779 (2)	171
N2—H2N2⋯O1ⁱ	0.90	1.97	2.853 (2)	168

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Symmetry code: (i) Inline graphic .

Acknowledgments

This research was supported by Universiti Sains Malaysia (USM) under the University Research grant (No. 1001/PFARMASI/815004) and the Ministry of Science, Technology and Innovation through an R&D Initiative Grant (09-05-IFN-MEB 004). HKF and MMR also thank USM for the Research University Grant (No. 1001/PFIZIK/811160). MRA gratefully acknowledges a PhD scholarship from Universiti Malaysia Sarawak.

supplementary crystallographic information

Comment

This compound is derived from 2-amino-4,6-dimethylpyridine and benzaldehyde. Schiff bases provide more potential sites for both chemical and biological activities of compounds. Schiff bases with azomethine linkage were used as anti-infectious agents (Dhar et al., 1982). Pyridine and its derivatives play an important role in heterocyclic chemistry (Jeffrey, 1997). They are often involved in hydrogen-bond interactions (Jeffrey & Saenger, 1991).

The title 1:1 adduct compound contains an 2-amino-4,6-dimethylpyridinium cation and benzoate anion in the asymmetric unit. The parameters in (I), (Fig. 1), are within normal ranges. The 2-amino-4,6-dimethylpyridinium cation is planar with the maximum deviation of 0.005 (2)Å for atom C9. The H atoms of the methyl groups are disordered over two positions and with fixed site-occupancy factors of 0.50:0.50 for both of the methyl groups. The carboxylate group in benzoate anion is slightly twisted and make a dihedral angle of 7.2 (1)° with the attached benzene ring.

The 2-amino-4,6-dimethylpyridinium cation and benzoate anion groups are linked together by intermolecular N1—H1N1···O2 and N2—H1N2···O1 interactions (Table 1) forming an R²₂(8) ring motif. In the crystal structure, the molecules stabilized by intermolecular N—H···O hydrogen bonds (Table 1) and π-π interactions with Cg1—Cg2 = 3.661 (2)Å (Cg1 = N1/C8-C12, Cg2 = C1-C6).

Experimental

An ethanol solution (20 ml) of 2-amino-4,6-dimethylpyridine (1.22 g, Aldrich) and benzaldehyde (1.06 g, Merck) were mixed, heated on a hot plate and stirred with a magnetic stirrer. The reaction mixture was refluxed for 4h. The resulting condensation solution was allowed to cool slowly at room temperature to form brownish materials. Purification was done using thin layer chromatography (TLC) and silica gel column chromatography (CC) eluted by chloroform:methanol and n-hexane:ethyl acetate solvent system. Finally the pure compound was recrystallized in ethanol which afforded the C₇H₁₁N2⁺.C₇H₅O₂^- salt.