2,4,6-Trimethyl­anilinium chloride

The title compound, C₉H₁₄N⁺·Cl⁻, is a hydro­chloric acid salt of 2,4,6-trimethyl­aniline. In the crystal structure, all the hydrogen-bond donors and acceptors are involved in hydrogen bonds. The packing can be described as columns, two ion-pairs wide, propagating along the a axis. The columns are formed through N—H...Cl hydrogen bonds linking pairs of cations and anions around centers of symmetry and further connecting these pairs in the [100] direction. In addition, the aromatic rings on each side of the columns are stacked above each other, indicating π–π stacking (the distance between aromatic rings is 4.811 Å).

Key indicators

• Single-crystal X-ray study
• T = 90 K
• Mean [sigma](C-C)= 0.003 Å
• R factor = 0.049
• wR factor = 0.138
• Data-to-parameter ratio = 20.4

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S1. Comment

The title compound, (I), was a by-product during our attempts to synthesize 2-[(2,4,6-trimethylphenyl)amino]-3-pyridinecarboxylic acid, a potential anti-inflammatory compound (Ting et al., 1990).

The asymmetric unit of the crystal I (Fig. 1) consists of a 2,4,6-trimethylbenzenaminium cation and a chloride anion·In the crystal of I, all the available hydrogen bonding donors and acceptors are involved in the three-dimensional hydrogen bonding network. The molecules in the crystal form columns with a width of two molecules along the a axis through N—H···Cl hydrogen bonds (Table 1). The N—H···Cl hydrogen bonds link pairs of molecules around a center of symmetry and further connect these pairs of molecules in the [1 0 0] direction. Moreover, the aromatic rings on each side of the columns are stacked face-to-face, suggesting π-π stacking may provide additional stablitity to the crystal structure (Fig. 2).

Related literature

For related literature, see: Ting et al. (1990).

S2. Experimental

Pyridine (3.78 g, 47.8 mmol) was introduced to a round bottom flask containing 2-chloronicotinic acid (7.32 g, 46 mmol) and 2,4,6-trimethylaniline (6.55 g, 48.5 mmol), followed by addition of p-toluenesulfonic acid (1.2 g, 6.98 mmol) dissovled in 20 ml of water. The solution was then refluxed overnight. After workup, both the desired product, 2-[(2,4,6-trimethylphenyl)amino]-3-pyridinecarboxylic acid, and some by-products, including the title compound, were obtained. Crystals of the title compound were grown from methanol solution by slow evaporation.

Computing details

Data collection: COLLECT (Nonius, 2002); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO-SMN (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL/PC (Sheldrick, 1995); software used to prepare material for publication: SHELXL97 and local programs.

Figures

	Fig. 1. The molecular structure of (I), with displacement ellipsoids drawn at the 50% probability level (arbitrary spheres for the H atoms).
	Fig. 2. A packing diagram of (I) along a axis.

2,4,6-Trimethylanilinium chloride

Crystal data

C9H14N^+·Cl^−	F(000) = 368
Mr = 171.66	Dx = 1.233 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 4.811 (1) Å	Cell parameters from 2207 reflections
b = 15.373 (3) Å	θ = 1.0–27.5°
c = 12.509 (2) Å	µ = 0.35 mm^−1
β = 90.99 (3)°	T = 90 K
V = 925.0 (3) Å^3	Thick needle, colorless
Z = 4	0.40 × 0.13 × 0.03 mm

Data collection

Nonius KappaCCD area-detector diffractometer	2121 independent reflections
Radiation source: fine-focus sealed tube	1453 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.046
Detector resolution: 18 pixels mm^-1	θmax = 27.5°, θmin = 2.1°
ω scans at fixed χ = 55°	h = −6→6
Absorption correction: multi-scan (SCALEPACK; Otwinowski & Minor, 1997)	k = −19→19
Tmin = 0.873, Tmax = 0.990	l = −16→16
4000 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.138	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0771P)^2] where P = (Fo^2 + 2Fc^2)/3
2121 reflections	(Δ/σ)max < 0.001
104 parameters	Δρmax = 0.64 e Å^−3
0 restraints	Δρmin = −0.35 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
C1	0.6201 (5)	0.08520 (15)	0.23416 (18)	0.0171 (5)
C2	0.4224 (5)	0.03061 (15)	0.27942 (17)	0.0175 (5)
C3	0.3333 (5)	0.05229 (15)	0.38169 (17)	0.0199 (5)
H3	0.2016	0.0158	0.4153	0.024*
C4	0.4299 (5)	0.12513 (14)	0.43603 (18)	0.0181 (5)
C5	0.6277 (5)	0.17733 (15)	0.38738 (17)	0.0179 (5)
H5	0.6980	0.2268	0.4244	0.021*
C6	0.7249 (4)	0.15857 (15)	0.28554 (18)	0.0161 (5)
C7	0.3084 (5)	−0.04773 (16)	0.22143 (19)	0.0229 (6)
H7A	0.4541	−0.0920	0.2161	0.034*
H7B	0.2455	−0.0307	0.1495	0.034*
H7C	0.1515	−0.0715	0.2609	0.034*
C8	0.3174 (5)	0.14835 (17)	0.54347 (19)	0.0249 (6)
H8A	0.4618	0.1780	0.5860	0.037*
H8B	0.2601	0.0953	0.5805	0.037*
H8C	0.1568	0.1870	0.5341	0.037*
C9	0.9377 (5)	0.21750 (15)	0.23440 (19)	0.0210 (6)
H9A	1.1011	0.1832	0.2150	0.031*
H9B	0.9933	0.2631	0.2851	0.031*
H9C	0.8561	0.2442	0.1700	0.031*
N1	0.7035 (4)	0.06625 (12)	0.12322 (13)	0.0173 (5)
H1A	0.5682	0.0848	0.0769	0.026*
H1B	0.7285	0.0079	0.1154	0.026*
H1C	0.8653	0.0944	0.1092	0.026*
Cl1	0.20588 (11)	0.12054 (4)	−0.02006 (4)	0.0188 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0180 (12)	0.0185 (12)	0.0147 (11)	0.0054 (10)	0.0009 (9)	−0.0003 (10)
C2	0.0176 (12)	0.0165 (12)	0.0184 (12)	0.0023 (10)	0.0002 (9)	0.0019 (10)
C3	0.0255 (13)	0.0158 (12)	0.0186 (12)	0.0018 (10)	0.0037 (10)	0.0049 (10)
C4	0.0230 (13)	0.0167 (12)	0.0146 (11)	0.0066 (10)	−0.0002 (9)	0.0012 (10)
C5	0.0225 (13)	0.0152 (12)	0.0158 (12)	0.0032 (10)	−0.0026 (10)	−0.0015 (9)
C6	0.0159 (12)	0.0142 (12)	0.0182 (12)	0.0041 (10)	−0.0014 (9)	−0.0005 (10)
C7	0.0243 (13)	0.0199 (13)	0.0246 (13)	−0.0044 (11)	0.0045 (10)	−0.0003 (11)
C8	0.0363 (16)	0.0207 (13)	0.0179 (12)	0.0035 (11)	0.0053 (11)	−0.0005 (10)
C9	0.0224 (13)	0.0180 (13)	0.0226 (13)	0.0007 (10)	0.0033 (10)	−0.0020 (11)
N1	0.0185 (10)	0.0160 (10)	0.0174 (10)	−0.0014 (8)	0.0021 (8)	−0.0015 (8)
Cl1	0.0212 (3)	0.0177 (3)	0.0177 (3)	−0.0002 (2)	0.0026 (2)	−0.0009 (2)

Geometric parameters (Å, º)

C1—C6	1.389 (3)	C7—H7A	0.9800
C1—C2	1.396 (3)	C7—H7B	0.9800
C1—N1	1.480 (3)	C7—H7C	0.9800
C2—C3	1.397 (3)	C8—H8A	0.9800
C2—C7	1.504 (3)	C8—H8B	0.9800
C3—C4	1.386 (3)	C8—H8C	0.9800
C3—H3	0.9500	C9—H9A	0.9800
C4—C5	1.393 (3)	C9—H9B	0.9800
C4—C8	1.501 (3)	C9—H9C	0.9800
C5—C6	1.395 (3)	N1—H1A	0.9100
C5—H5	0.9500	N1—H1B	0.9100
C6—C9	1.517 (3)	N1—H1C	0.9100
C6—C1—C2	123.0 (2)	C2—C7—H7C	109.5
C6—C1—N1	119.44 (19)	H7A—C7—H7C	109.5
C2—C1—N1	117.4 (2)	H7B—C7—H7C	109.5
C1—C2—C3	116.8 (2)	C4—C8—H8A	109.5
C1—C2—C7	122.06 (19)	C4—C8—H8B	109.5
C3—C2—C7	121.2 (2)	H8A—C8—H8B	109.5
C4—C3—C2	122.4 (2)	C4—C8—H8C	109.5
C4—C3—H3	118.8	H8A—C8—H8C	109.5
C2—C3—H3	118.8	H8B—C8—H8C	109.5
C3—C4—C5	118.5 (2)	C6—C9—H9A	109.5
C3—C4—C8	120.6 (2)	C6—C9—H9B	109.5
C5—C4—C8	120.9 (2)	H9A—C9—H9B	109.5
C4—C5—C6	121.5 (2)	C6—C9—H9C	109.5
C4—C5—H5	119.3	H9A—C9—H9C	109.5
C6—C5—H5	119.3	H9B—C9—H9C	109.5
C1—C6—C5	117.8 (2)	C1—N1—H1A	109.5
C1—C6—C9	122.2 (2)	C1—N1—H1B	109.5
C5—C6—C9	120.1 (2)	H1A—N1—H1B	109.5
C2—C7—H7A	109.5	C1—N1—H1C	109.5
C2—C7—H7B	109.5	H1A—N1—H1C	109.5
H7A—C7—H7B	109.5	H1B—N1—H1C	109.5
C6—C1—C2—C3	−0.8 (3)	C3—C4—C5—C6	1.1 (3)
N1—C1—C2—C3	−176.3 (2)	C8—C4—C5—C6	−177.2 (2)
C6—C1—C2—C7	179.0 (2)	C2—C1—C6—C5	0.5 (3)
N1—C1—C2—C7	3.5 (3)	N1—C1—C6—C5	175.93 (19)
C1—C2—C3—C4	1.2 (3)	C2—C1—C6—C9	−179.4 (2)
C7—C2—C3—C4	−178.5 (2)	N1—C1—C6—C9	−4.0 (3)
C2—C3—C4—C5	−1.4 (3)	C4—C5—C6—C1	−0.7 (3)
C2—C3—C4—C8	176.9 (2)	C4—C5—C6—C9	179.2 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···Cl1	0.91	2.18	3.081 (2)	172
N1—H1B···Cl1^i	0.91	2.33	3.181 (2)	155
N1—H1C···Cl1^ii	0.91	2.36	3.146 (2)	145

Symmetry codes: (i) −x+1, −y, −z; (ii) x+1, y, z.