1-Hy­droxy-4-methyl­pyridinium chloride

Saini, A.; Dhanwant, K.; Thirumoorthi, R.

doi:10.1107/S2414314622010239

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 7| Part 10| October 2022| x221023

https://doi.org/10.1107/S2414314622010239

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1-Hydroxy-4-methylpyridinium chloride

Aarti Saini,^a Kisturi Dhanwant ^a and Ramalingam Thirumoorthi ^a ^*

^aDepartment of Chemistry, School of Chemical Sciences and Pharmacy, Central, University of Rajasthan, NH8, Bandarsindri, Ajmer-305817, India
^*Correspondence e-mail: thirumoorthi@curaj.ac.in

Edited by W. T. A. Harrison, University of Aberdeen, United Kingdom (Received 26 September 2022; accepted 23 October 2022; online 28 October 2022)

The title salt, C₆H₈NO⁺·Cl⁻, contains two cations and two anions in the asymmetric unit. The components are linked by O—H⋯Cl and C—H⋯Cl hydrogen bonds, leading to tetra- (square-planar) or penta-coordinated (square-pyramidal) chloride ions. The title salt is isostructural with its bromide analogue.

Keywords: chloride ion; crystal structure; hydrogen bond; hydroxy group; pyridinium ion.

CCDC reference: 2215272

Structure description

The title molecular salt, C₆H₈NO⁺·Cl⁻, 1, crystallizes with two 1-hydroxy-4-methylpyridinium cations and two chloride anions in the asymmetric unit in space group P2₁/c, indicating that proton transfer has occurred from HCl to the N-oxide O atoms (Fig. 1). The N—O bond lengths are 1.371 (2) and 1.379 (2) Å, which are comparable to its bromide analogue 2 (1.373 and 1.374 Å; Ryzhakova et al., 2012 ). The average N—O—H bond angle in 1 [103.9 (19)°] is significantly smaller compared to 2 (110.9°). However, the torsion angles C_Ar—N—O—H in 1 (62.9 and 57.4°) are very similar to those in 2 (62.8 and 57.6°).

Figure 1
ORTEP diagram of 1 with 50% displacement ellipsoid probability level.

In the extended structure of 1, one of the cations provides four hydrogen-bond donors (three C—H groupings and one O—H group) while the other cation provides five hydrogen-bond donors, i.e., one from the O—H group and four from C—H centres, all with chloride ion acceptors to form tetra/penta-coordinated anions (Table 1; Fig. 2). As expected, the H⋯Cl separation for the O—H⋯Cl hydrogen bonds (mean 1.97 Å) is much shorter than the H⋯Cl separation for the C—H⋯Cl hydrogen bonds (mean 2.79 Å).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1A⋯Cl2	0.86 (3)	2.03 (3)	2.8847 (19)	175 (3)
O2—H2A⋯Cl1	0.98 (3)	1.91 (3)	2.879 (2)	172 (3)
C2—H2⋯Cl1ⁱ	0.93	2.81	3.567 (2)	139
C5—H5⋯Cl1	0.93	2.73	3.519 (2)	143
C7—H7⋯Cl2	0.93	2.79	3.652 (3)	154
C8—H8⋯Cl1ⁱⁱ	0.93	2.72	3.618 (3)	162
C10—H10⋯Cl1ⁱⁱⁱ	0.93	2.81	3.672 (2)	155
C11—H11⋯Cl2^iv	0.93	2.74	3.646 (2)	164
Symmetry codes: (i) $[x, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]$ ; (ii) ; (iii) ; (iv) .

Figure 2
Two-dimensional packing diagram of 1.

Synthesis and crystallization

A 2.0 M solution of hydrochloric acid in Et₂O (0.167 ml, 5.49 mmol) was added dropwise to an ethanol (3 ml) solution of 4-methylpyridine N-oxide (0.2 g, 1.83 mmol). The reaction scheme is shown in Fig. 3. The reaction mixture was stirred for 2 h at room temperature followed by solvent evaporation using a rotary evaporator to obtain a solid. The obtained product was washed with diethyl ether and dried to get colorless solid. Yield: 82%, m.p. 114°C. ¹H NMR (500 MHz, CDCl₃, p.p.m.) δ 8.81 (d, 2H, J = 6.5 Hz), 7.70 (d, 2H, J = 6.5 Hz), 2.62 (s, 3H). ¹H NMR (CD₃OD, 500 MHz, p.p.m.): δ 8.70 (d, 2H, J = 6.5 Hz), 7.96 (d, 2H, J = 6 Hz), 2.70 (s, 3H). ¹³C{¹H} NMR (CDCl₃, 125 MHz, p.p.m.): 154.0, 138.9, 128.5, 21.7.

Figure 3
Reaction scheme.

The slow evaporation of a dichloromethane solution of 1 produced good quality, pale-yellow, rhombus-shaped crystals.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	C₆H₈NO⁺·Cl⁻
M_r	145.58
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	296
a, b, c (Å)	7.1610 (16), 26.271 (6), 7.7474 (17)
β (°)	95.495 (3)
V (Å³)	1450.8 (6)
Z	8
Radiation type	Mo Kα
μ (mm⁻¹)	0.44
Crystal size (mm)	0.11 × 0.09 × 0.06

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2014 )
T_min, T_max	0.953, 0.974
No. of measured, independent and observed [I > 2σ(I)] reflections	41123, 3354, 2663
R_int	0.051
(sin θ/λ)_max (Å⁻¹)	0.652

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.042, 0.129, 1.06
No. of reflections	3354
No. of parameters	171
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.34, −0.26
Computer programs: APEX2 (Bruker, 2014), SAINT (Bruker, 2013 ), SHELXS97 (Sheldrick, 2008 ), SHELXL (Sheldrick, 2015 ), ORTEP-3 for Windows (Farrugia, 2012 ) and publCIF (Westrip, 2010 ).

Structural data

CCDC reference: 2215272

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314622010239/hb4415sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314622010239/hb4415Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314622010239/hb4415Isup3.cml

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2014); cell refinement: SAINT (Bruker, 2013); data reduction: SAINT (Bruker, 2013); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: publCIF (Westrip, 2010).

1-Hydroxy-4-methylpyridinium chloride top

Crystal data top

C₆H₈NO⁺·Cl⁻	F(000) = 608
M_r = 145.58	D_x = 1.333 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 7.1610 (16) Å	Cell parameters from 9290 reflections
b = 26.271 (6) Å	θ = 2.8–24.5°
c = 7.7474 (17) Å	µ = 0.44 mm⁻¹
β = 95.495 (3)°	T = 296 K
V = 1450.8 (6) Å³	Needle, colorless
Z = 8	0.11 × 0.09 × 0.06 mm

Data collection top

Bruker APEXII CCD diffractometer	2663 reflections with I > 2σ(I)
ω scans	R_int = 0.051
Absorption correction: multi-scan (SADABS; Bruker, 2014)	θ_max = 27.6°, θ_min = 1.6°
T_min = 0.953, T_max = 0.974	h = −9→9
41123 measured reflections	k = −34→34
3354 independent reflections	l = −10→10

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.042	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.129	w = 1/[σ²(F_o²) + (0.0646P)² + 0.4782P] where P = (F_o² + 2F_c²)/3
S = 1.06	(Δ/σ)_max = 0.001
3354 reflections	Δρ_max = 0.34 e Å⁻³
171 parameters	Δρ_min = −0.25 e Å⁻³
0 restraints

Special details top

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

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
C1	0.3022 (3)	0.78000 (7)	0.4800 (3)	0.0457 (4)
H1	0.400319	0.800303	0.449620	0.055*
C2	0.1436 (3)	0.80150 (8)	0.5313 (3)	0.0500 (5)
H2	0.133207	0.836765	0.534577	0.060*
C3	−0.0028 (3)	0.77163 (8)	0.5785 (2)	0.0448 (4)
C4	0.0191 (3)	0.71936 (8)	0.5702 (3)	0.0496 (5)
H4	−0.075402	0.698063	0.602249	0.060*
C5	0.1785 (3)	0.69878 (8)	0.5152 (3)	0.0488 (5)
H5	0.191540	0.663677	0.506589	0.059*
C6	−0.1788 (3)	0.79546 (12)	0.6313 (3)	0.0711 (7)
H6A	−0.166953	0.831849	0.629104	0.107*
H6B	−0.283357	0.785194	0.552116	0.107*
H6C	−0.198791	0.784606	0.746382	0.107*
C7	0.6459 (3)	0.54962 (9)	0.3558 (3)	0.0571 (5)
H7	0.608047	0.564925	0.454901	0.069*
C8	0.7375 (3)	0.50418 (9)	0.3661 (3)	0.0564 (5)
H8	0.761757	0.488208	0.472987	0.068*
C9	0.7952 (3)	0.48143 (8)	0.2181 (3)	0.0485 (5)
C10	0.7595 (3)	0.50710 (8)	0.0630 (3)	0.0477 (5)
H10	0.799599	0.493306	−0.037661	0.057*
C11	0.6660 (3)	0.55255 (8)	0.0555 (3)	0.0477 (5)
H11	0.641024	0.569680	−0.049225	0.057*
C12	0.8943 (4)	0.43125 (10)	0.2289 (4)	0.0741 (7)
H12A	0.905880	0.419521	0.346807	0.111*
H12B	0.823683	0.406943	0.156757	0.111*
H12C	1.016852	0.435067	0.190073	0.111*
N1	0.3148 (2)	0.72972 (6)	0.47417 (19)	0.0405 (4)
N2	0.6116 (2)	0.57173 (6)	0.2021 (2)	0.0474 (4)
CL1	0.15453 (8)	0.58405 (2)	0.27982 (7)	0.05342 (17)
CL2	0.59963 (8)	0.64306 (2)	0.69818 (7)	0.05963 (19)
O1	0.4730 (2)	0.70951 (7)	0.4144 (2)	0.0599 (4)
O2	0.5160 (3)	0.61737 (6)	0.1905 (3)	0.0670 (5)
H1A	0.517 (4)	0.6892 (11)	0.495 (4)	0.084 (10)*
H2A	0.393 (4)	0.6090 (12)	0.228 (4)	0.088 (9)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0450 (10)	0.0393 (10)	0.0525 (11)	−0.0037 (8)	0.0041 (8)	0.0030 (8)
C2	0.0510 (11)	0.0393 (10)	0.0586 (12)	0.0063 (8)	0.0000 (9)	−0.0050 (9)
C3	0.0394 (9)	0.0594 (12)	0.0348 (9)	0.0058 (8)	−0.0009 (7)	−0.0047 (8)
C4	0.0439 (10)	0.0559 (12)	0.0493 (11)	−0.0069 (9)	0.0056 (8)	0.0053 (9)
C5	0.0588 (12)	0.0363 (10)	0.0524 (11)	−0.0026 (8)	0.0114 (9)	0.0003 (8)
C6	0.0472 (12)	0.099 (2)	0.0664 (15)	0.0218 (12)	0.0036 (11)	−0.0100 (14)
C7	0.0726 (14)	0.0504 (12)	0.0525 (12)	0.0004 (10)	0.0271 (10)	−0.0030 (10)
C8	0.0690 (14)	0.0532 (12)	0.0494 (12)	0.0051 (10)	0.0174 (10)	0.0066 (10)
C9	0.0457 (10)	0.0430 (10)	0.0585 (12)	−0.0016 (8)	0.0146 (9)	0.0006 (9)
C10	0.0516 (11)	0.0458 (11)	0.0476 (11)	−0.0038 (9)	0.0145 (9)	−0.0070 (9)
C11	0.0477 (10)	0.0474 (11)	0.0492 (11)	−0.0048 (8)	0.0116 (8)	0.0034 (9)
C12	0.0871 (19)	0.0566 (14)	0.0821 (18)	0.0209 (13)	0.0252 (14)	0.0068 (13)
N1	0.0429 (8)	0.0426 (8)	0.0373 (8)	0.0066 (7)	0.0097 (6)	−0.0004 (6)
N2	0.0494 (9)	0.0346 (8)	0.0616 (10)	0.0001 (7)	0.0216 (8)	0.0019 (7)
CL1	0.0606 (3)	0.0456 (3)	0.0555 (3)	−0.0034 (2)	0.0130 (2)	0.0013 (2)
CL2	0.0654 (4)	0.0611 (4)	0.0534 (3)	0.0105 (3)	0.0104 (2)	0.0046 (2)
O1	0.0613 (9)	0.0643 (10)	0.0585 (9)	0.0200 (8)	0.0288 (8)	0.0073 (8)
O2	0.0717 (11)	0.0387 (8)	0.0967 (13)	0.0096 (7)	0.0401 (9)	0.0097 (8)

Geometric parameters (Å, º) top

C1—N1	1.325 (3)	C7—H7	0.9300
C1—C2	1.361 (3)	C8—C9	1.390 (3)
C1—H1	0.9300	C8—H8	0.9300
C2—C3	1.386 (3)	C9—C10	1.380 (3)
C2—H2	0.9300	C9—C12	1.495 (3)
C3—C4	1.384 (3)	C10—C11	1.367 (3)
C3—C6	1.499 (3)	C10—H10	0.9300
C4—C5	1.367 (3)	C11—N2	1.335 (3)
C4—H4	0.9300	C11—H11	0.9300
C5—N1	1.332 (3)	C12—H12A	0.9600
C5—H5	0.9300	C12—H12B	0.9600
C6—H6A	0.9600	C12—H12C	0.9600
C6—H6B	0.9600	N1—O1	1.371 (2)
C6—H6C	0.9600	N2—O2	1.379 (2)
C7—N2	1.326 (3)	O1—H1A	0.86 (3)
C7—C8	1.361 (3)	O2—H2A	0.98 (3)

N1—C1—C2	118.98 (19)	C7—C8—H8	119.7
N1—C1—H1	120.5	C9—C8—H8	119.7
C2—C1—H1	120.5	C10—C9—C8	117.57 (19)
C1—C2—C3	121.03 (19)	C10—C9—C12	121.8 (2)
C1—C2—H2	119.5	C8—C9—C12	120.7 (2)
C3—C2—H2	119.5	C11—C10—C9	120.85 (19)
C4—C3—C2	117.21 (18)	C11—C10—H10	119.6
C4—C3—C6	122.0 (2)	C9—C10—H10	119.6
C2—C3—C6	120.8 (2)	N2—C11—C10	118.36 (19)
C5—C4—C3	120.56 (19)	N2—C11—H11	120.8
C5—C4—H4	119.7	C10—C11—H11	120.8
C3—C4—H4	119.7	C9—C12—H12A	109.5
N1—C5—C4	119.06 (19)	C9—C12—H12B	109.5
N1—C5—H5	120.5	H12A—C12—H12B	109.5
C4—C5—H5	120.5	C9—C12—H12C	109.5
C3—C6—H6A	109.5	H12A—C12—H12C	109.5
C3—C6—H6B	109.5	H12B—C12—H12C	109.5
H6A—C6—H6B	109.5	C1—N1—C5	123.14 (17)
C3—C6—H6C	109.5	C1—N1—O1	117.29 (16)
H6A—C6—H6C	109.5	C5—N1—O1	119.49 (16)
H6B—C6—H6C	109.5	C7—N2—C11	123.68 (18)
N2—C7—C8	118.9 (2)	C7—N2—O2	119.18 (17)
N2—C7—H7	120.5	C11—N2—O2	117.14 (18)
C8—C7—H7	120.5	N1—O1—H1A	104 (2)
C7—C8—C9	120.6 (2)	N2—O2—H2A	103.9 (18)

N1—C1—C2—C3	0.6 (3)	C12—C9—C10—C11	178.9 (2)
C1—C2—C3—C4	−0.4 (3)	C9—C10—C11—N2	0.6 (3)
C1—C2—C3—C6	−178.7 (2)	C2—C1—N1—C5	0.4 (3)
C2—C3—C4—C5	−0.8 (3)	C2—C1—N1—O1	177.09 (18)
C6—C3—C4—C5	177.5 (2)	C4—C5—N1—C1	−1.6 (3)
C3—C4—C5—N1	1.8 (3)	C4—C5—N1—O1	−178.24 (18)
N2—C7—C8—C9	0.4 (4)	C8—C7—N2—C11	−1.7 (3)
C7—C8—C9—C10	1.3 (3)	C8—C7—N2—O2	178.9 (2)
C7—C8—C9—C12	−179.4 (2)	C10—C11—N2—C7	1.2 (3)
C8—C9—C10—C11	−1.8 (3)	C10—C11—N2—O2	−179.39 (18)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···Cl2	0.86 (3)	2.03 (3)	2.8847 (19)	175 (3)
O2—H2A···Cl1	0.98 (3)	1.91 (3)	2.879 (2)	172 (3)
C2—H2···Cl1ⁱ	0.93	2.81	3.567 (2)	139
C5—H5···Cl1	0.93	2.73	3.519 (2)	143
C7—H7···Cl2	0.93	2.79	3.652 (3)	154
C8—H8···Cl1ⁱⁱ	0.93	2.72	3.618 (3)	162
C10—H10···Cl1ⁱⁱⁱ	0.93	2.81	3.672 (2)	155
C11—H11···Cl2^iv	0.93	2.74	3.646 (2)	164

Symmetry codes: (i) x, −y+3/2, z+1/2; (ii) −x+1, −y+1, −z+1; (iii) −x+1, −y+1, −z; (iv) x, y, z−1.

Acknowledgements

We thank IIT Kanpur for Single-crystal XRD data collection and CURaj for infrastructure facilities. Authors contributions are as follows. Conceptualization, RT; methodology, AS, KD and RT; investigation, RT; writing (original draft), AS; writing (review and editing of the manuscript), RT; visualization, RT; funding acquisition, RT; resources, RT; supervision, RT.

Funding information

Funding for this research was provided by: Council of Scientific and Industrial Research, India [grant No. 01(2970)/19/EMR-II dated: 20th June 2019 to Ramalingam Thirumoorthi] and DST, India for FIST to Department of Chemistry, CURaj [grant No. SR/FST/CSI-257/2014(C)].

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