N-Hydro­xy­piperidinium chloride

[(CH₂)₅NHOH]⁺·Cl⁻ contains a six-membered piperidinium ring with a chair conformation, linked to chloride ions by N—H...Cl and O—H...Cl hydrogen bonds. The hydroxy substituent is in an equatorial site.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.028
• wR factor = 0.061
• Data-to-parameter ratio = 18.8

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

Crystals of a by-product isolated during the synthesis of a chloral adduct by reaction of N-hydroxypiperidine and chloral hydrate (Zinner et al., 1965; Kliegel et al., 2001) proved to be N-hydroxypiperidine hydrochloride (N-hydroxypiperidinium chloride), (I) (Fig. 1). The salt, which has been well known for a long time (Wernick & Wolffenstein, 1898; Thesing & Mayer, 1956), probably originates from the formation of HCl during the reaction by partial decomposition of chloral hydrate, the mechanism of which is not clear. The presence of water and the basic reagent (N-hydroxypiperidine) might produce HCl and dichloroacetic acid, or chloroform which could be the source for HCl (Fairbrother, 1973; Lutnitskii, 1975).

The cation contains a six-membered piperidinium ring with a normal chair conformation (dihedral angle magnitudes 56.4–57.8°), and the hydroxy substituent in the equatorial site. Bond lengths and angles differ slightly from those in piperidinium chloride (Rérat, 1960; Dattagupta & Saha, 1975; Gaudet et al., 1989). In particular, there is some asymmetry in the molecular dimensions as a result of the presence of the OH H atom, which has a staggered conformation about the N—O bond. The two O—N—C angles differ significantly [111.4 (1) and 106.3 (1)°], the distortion presumably resulting from intramolecular (the OH H atom is on the side of the larger angle) or intermolecular (hydrogen bonds) steric interactions. There is also a slight alternation in the values of the endocyclic bond angles, with those at C1, C3, and C5 being exactly tetrahedral [109.6 (1)°], and those at C2, C4 [111.3 (1)°] and especially at N [112.9 (1)°] being slightly larger. The N—O bond length, 1.418 (2) Å, is similar to that in protonated hydroxylamine (H₂NOH·HCl), 1.411 (2) Å (Shi et al., 1987).

Two cations and two anions are linked about a centre of inversion by O—H···Cl and N—H···Cl hydrogen bonds, to produce a ten-membered hydrogen-bonded ring: O···Cl = 2.967 (1), O—H = 0.92 (2), H···Cl = 2.05 (2) Å, O—H···Cl = 170 (2)°; N···Cl = 3.044 (1), N—H = 0.91 (2), H···Cl = 2.14 (2) Å, N—H···Cl = 170 (1)°; O···Cl···N = 112.0 (1)°. These units are linked by weaker (van der Waals) forces, with a possible intermolecular C—H···O bond, C···O = 3.374 (2), H···O = 2.44 Å, C—H···O = 159°, and a possible C—H···Cl bond [C···Cl = 3.624 (2), H···Cl = 2.71 Å and C—H···Cl = 156°].

S2. Experimental

Crystals were obtained as a by-product of the reaction of chloral hydrate and N-hydroxypiperidine (Kliegel et al., 2001).

Computing details

Data collection: D*TREK (Molecular Structure Corporation, 2001); cell refinement: D*TREK; data reduction: D*TREK; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: TEXSAN (Molecular Structure Corporation, 1997); software used to prepare material for publication: TEXSAN (MSC, 1997).

Figures

Fig. 1. View of the title structure shown with 50% ellipsoids.

(I)

Crystal data

C5H12NO^+·Cl^−	F(000) = 296
Mr = 137.61	Dx = 1.262 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.7107 Å
a = 7.1304 (5) Å	Cell parameters from 4174 reflections
b = 7.0213 (5) Å	θ = 2.9–27.8°
c = 14.4857 (9) Å	µ = 0.44 mm^−1
β = 93.333 (4)°	T = 173 K
V = 724.00 (7) Å^3	Block, colorless
Z = 4	0.20 × 0.20 × 0.20 mm

Data collection

Quantum CCD diffractometer	1526 independent reflections
Radiation source: X-ray tube	1230 reflections with I > 3σ(I)
Graphite monochromator	Rint = 0.029
area detector scans	θmax = 27°, θmin = 2.9°
Absorption correction: multi-scan (D*TREK; Molecular Structure Corporation, 2001)	h = −8→9
Tmin = 0.86, Tmax = 0.92	k = −8→8
6650 measured reflections	l = −17→15

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	0 constraints
R[F^2 > 2σ(F^2)] = 0.028	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.061	Weighting scheme based on measured s.u.'s w = 1/[σ^2(Fo)]
S = 1.63	(Δ/σ)max = 0.001
1526 reflections	Δρmax = 0.26 e Å^−3
81 parameters	Δρmin = −0.29 e Å^−3

Special details

Experimental. Data were collected in 0.50° oscillations with 60.0 s exposures. A sweep of data was done using ϕ oscillations from 0.0 to 190.0° at χ = -90° and a second sweep was performed using ω oscillations between -23.0 and 18.0° at χ = -90.0°. The crystal-to-detector distance was 38.83 mm. The detector swing angle was -10.0°. The absorption correction is based on a three-dimensional analysis of symmetry-equivalent data and is performed along with batch scaling in a single step.

Refinement. H11 and H12 (bonded to N and O respectively) were refined isotropically; the other H atoms were fixed in idealized sites.

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

	x	y	z	Uiso*/Ueq
Cl1	0.24319 (5)	0.09979 (6)	1.08369 (2)	0.0288 (1)
O1	0.1190 (2)	−0.0039 (2)	0.83651 (7)	0.0312 (3)
N1	0.1981 (2)	0.1649 (2)	0.87582 (8)	0.0177 (3)
C1	0.0638 (2)	0.3262 (2)	0.86723 (9)	0.0237 (4)
C2	0.1571 (2)	0.5054 (2)	0.9058 (1)	0.0289 (4)
C3	0.3365 (2)	0.5492 (2)	0.8576 (1)	0.0298 (4)
C4	0.4680 (2)	0.3798 (2)	0.8663 (1)	0.0285 (4)
C5	0.3741 (2)	0.2008 (2)	0.82795 (9)	0.0231 (4)
H1	0.0249	0.3458	0.8019	0.028*
H2	−0.0468	0.2972	0.9019	0.028*
H3	0.0698	0.6125	0.8967	0.035*
H4	0.1880	0.4879	0.9720	0.035*
H5	0.3053	0.5756	0.7921	0.036*
H6	0.3980	0.6609	0.8865	0.036*
H7	0.5796	0.4062	0.8321	0.034*
H8	0.5055	0.3597	0.9318	0.034*
H9	0.4595	0.0924	0.8379	0.028*
H10	0.3438	0.2167	0.7615	0.028*
H11	0.227 (2)	0.142 (3)	0.937 (1)	0.044 (5)*
H12	0.007 (3)	−0.020 (3)	0.865 (1)	0.067 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.0277 (2)	0.0386 (2)	0.0195 (2)	−0.0037 (2)	−0.0034 (1)	0.0078 (2)
O1	0.0382 (7)	0.0242 (6)	0.0317 (6)	−0.0101 (6)	0.0064 (5)	−0.0127 (5)
N1	0.0217 (6)	0.0176 (6)	0.0137 (6)	0.0008 (5)	0.0010 (4)	−0.0006 (4)
C1	0.0189 (7)	0.0252 (9)	0.0274 (7)	0.0053 (7)	0.0036 (6)	0.0065 (6)
C2	0.0330 (9)	0.0173 (8)	0.0379 (9)	0.0047 (8)	0.0143 (7)	0.0035 (7)
C3	0.0321 (9)	0.0237 (9)	0.0344 (9)	−0.0055 (7)	0.0078 (7)	0.0043 (6)
C4	0.0203 (8)	0.035 (1)	0.0306 (8)	−0.0022 (8)	0.0042 (6)	0.0058 (7)
C5	0.0197 (7)	0.0282 (9)	0.0221 (7)	0.0066 (7)	0.0064 (5)	0.0018 (6)

Geometric parameters (Å, º)

O1—N1	1.418 (2)	C2—H4	0.98
O1—H12	0.92 (2)	C3—C4	1.516 (2)
N1—C1	1.484 (2)	C3—H5	0.98
N1—C5	1.490 (2)	C3—H6	0.98
N1—H11	0.91 (2)	C4—C5	1.514 (2)
C1—C2	1.515 (2)	C4—H7	0.98
C1—H1	0.98	C4—H8	0.98
C1—H2	0.98	C5—H9	0.98
C2—C3	1.524 (2)	C5—H10	0.98
C2—H3	0.98
CL1···O1^i	2.967 (1)	O1···C3^iii	3.506 (2)
CL1···N1	3.044 (1)	O1···C2^iii	3.595 (2)
O1···C1^ii	3.374 (2)
N1—O1—H12	105 (1)	C2—C3—C4	109.6 (1)
O1—N1—C1	111.4 (1)	C2—C3—H5	109.4
O1—N1—C5	106.3 (1)	C2—C3—H6	109.4
O1—N1—H11	108 (1)	C4—C3—H5	109.4
C1—N1—C5	112.9 (1)	C4—C3—H6	109.4
C1—N1—H11	109 (1)	H5—C3—H6	109.5
C5—N1—H11	109 (1)	C3—C4—C5	111.3 (1)
N1—C1—C2	109.6 (1)	C3—C4—H7	109.0
N1—C1—H1	109.4	C3—C4—H8	109.0
N1—C1—H2	109.4	C5—C4—H7	109.0
C2—C1—H1	109.4	C5—C4—H8	109.0
C2—C1—H2	109.4	H7—C4—H8	109.5
H1—C1—H2	109.5	N1—C5—C4	109.6 (1)
C1—C2—C3	111.2 (1)	N1—C5—H9	109.4
C1—C2—H3	109.0	N1—C5—H10	109.4
C1—C2—H4	109.0	C4—C5—H9	109.4
C3—C2—H3	109.0	C4—C5—H10	109.4
C3—C2—H4	109.0	H9—C5—H10	109.5
H3—C2—H4	109.5
O1—N1—C1—C2	−177.3 (1)	C1—N1—C5—C4	57.7 (1)
O1—N1—C5—C4	−179.9 (1)	C1—C2—C3—C4	−56.4 (2)
N1—C1—C2—C3	56.6 (2)	C2—C1—N1—C5	−57.8 (1)
N1—C5—C4—C3	−56.5 (2)	C2—C3—C4—C5	56.4 (2)

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