pharmaceuticals and natural products
Acta Crystallographica Section C
Crystal Structure
which can be reproducibly obtained from methanol as a phase-
pure solid (Fig. 1).
Communications
ISSN 0108-2701
A new polymorph of N-(6-methyl-
pyridin-2-yl)mesitylenesulfonamide
Fangfang Pan and Ulli Englert*
Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52074
Aachen, Germany
2. Experimental
2.1. Synthesis and crystallization
Received 10 May 2013
The title compound was prepared according to the method
of Beloso et al. (2003). 2-Amino-6-methylpyridine (2.000 g,
18.49 mmol) and 2,4,6-methylphenylsulfonyl chloride (4.045 g,
18.49 mmol) were dissolved in dichloromethane (20 ml).
Sodium carbonate (2.003 g, 18.49 mmol) in water (20 ml) was
added dropwise. The reaction mixture was stirred overnight
and water (100 ml) was added. The organic layer was sepa-
rated and dried with anhydrous magnesium sulfate. The
solvent was evaporated and the resulting oil was suspended in
ethanol, and polymorph I was obtained as a white solid.
Colourless block-shaped crystals of polymorph II were grown
by slow evaporation of a solution of polymorph I in methanol
at room temperature.
Accepted 19 September 2013
A new polymorph is reported of the pharmaceutically active
sulfapyridine derivative, N-(6-methylpyridin-2-yl)mesitylene-
sulfonamide, in the zwitterionic form 2-methyl-6-{[(2,4,6-tri-
methylbenzene)sulfonyl]azanidyl}pyridin-1-ium, C15H18N2O2S.
The observed dimorphism is solvent dependent. The phase
described previously [Beloso, Castro, Garcıa-Vazquez, Perez-
Lourido, Romero & Sousa (2003). Z. Anorg. Allg. Chem. 629,
275–284] crystallizes from ethanol and several other organic
solvents, whereas the new form described here is obtained as a
phase-pure product from methanol. The molecules in both
dimorphic phases are very similar and adopt the conformation
which is also predicted for an individual molecule by force
field calculations. However, the two forms differ in their
packing and hydrogen bonding. Results from solvent-assisted
grinding indicate that the new form is less stable than the
previously published phase.
´
´
´
2.2. Refinement
Crystal data, data collection and structure refinement
details are summarized in Table 1. H atoms were treated as
˚
˚
riding, with C—H = 0.95 A for aryl or 0.98 A for methyl
groups, and with Uiso(H) = 1.2Ueq(C) for aryl and Uiso(H) =
1.5Ueq(C) for methyl groups. The N-bound H atom was
Keywords: crystal structure; pharmaceutically active
compounds; sulfapyridine derivatives; zwitterions;
polymorphism; packing polymorphs.
1. Introduction
Polymorphism is a common phenomenon in many classes of
compounds (McCrone, 1965), among them many nitrogen-
containing drugs. As far as the pharmaceutically active
sulfonamides are concerned, polymorphism is well docu-
mented for 4-amino-N-pyridinylbenzenesulfonamide (Bern-
stein, 1984; Burger et al., 1980; Gouda et al., 1977; Kuhnert-
¨
Brandstatter & Wunsch, 1969; Mesley & Houghton, 1967;
Pratt et al., 2011; Yang & Guillory, 1972). The title compound,
N-(6-methylpyridin-2-yl)mesitylenesulfonamide, (1), is a sul-
fapyridine derivative; Beloso et al. (2003) described a form to
which we will refer as phase I. The original authors crystallized
phase I from ethanol, but our experiments revealed that the
same phase is found from a variety of other organic solvents,
such as dichloromethane, acetone, tetrahydrofuran and pro-
pan-2-ol. We report here a new polymorph of N-(6-methyl-
pyridin-2-yl)mesitylenesulfonamide, denoted polymorph II,
Figure 1
Experimental powder pattern of the new polymorph, II (top profile,
black), and calculated pattern based on the single-crystal diffraction
result (bottom profile, red in the electronic version of the journal).
Acta Cryst. (2013). C69, 1217–1220
doi:10.1107/S0108270113025936
# 2013 International Union of Crystallography 1217