(R)-(3-Carb­oxy-2-hy­droxy­prop­yl)tri­methyl­aza­nium chloride

Ng, S.W.

doi:10.1107/S160053681201598X

organic compounds

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ISSN: 2056-9890

Volume 68| Part 5| May 2012| Page o1416

doi:10.1107/S160053681201598X

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(R)-(3-Carboxy-2-hydroxypropyl)trimethylazanium chloride

Seik Weng Ng ^a,^b ^*

^aDepartment of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia, and ^bChemistry Department, Faculty of Science, King Abdulaziz University, PO Box 80203 Jeddah, Saudi Arabia
^*Correspondence e-mail: seikweng@um.edu.my

(Received 8 April 2012; accepted 12 April 2012; online 18 April 2012)

In the title salt (common name L-carnitine hydrochloride), C₇H₁₆NO₃⁺·Cl⁻, the organic cation features a carboxylic part (–CO₂H) having unambigous single- and double-bonds [1.336 (2), 1.211 (2) Å]. There is a large N—C—C bond angle [115.9 (1)°] for the C atom connected to the bulky trimethylamino substituent. In the crystal, the acid H atom forms a hydrogen bond to the chloride anion, whereas the hydroxyl H atom forms a longer hydrogen bond to the anion, generating a helical chain running along [001].

Related literature

For racemic carnitine hydrochloride, see: Tomita et al. (1974 ); Yunuskhodzhaev et al. (1991 ). For R-carnitine, see: Gandour et al. (1985 ).

Experimental

Crystal data

C₇H₁₆NO₃⁺·Cl⁻
M_r = 197.66
Orthorhombic, P 2₁ 2₁ 2₁
a = 6.3043 (3) Å
b = 11.5256 (7) Å
c = 13.4905 (8) Å
V = 980.23 (10) Å³
Z = 4
Mo Kα radiation
μ = 0.36 mm⁻¹
T = 100 K
0.40 × 0.30 × 0.20 mm

Data collection

Agilent Technologies SuperNova Dual diffractometer with Atlas detector
Absorption correction: multi-scan CrysAlis PRO (Agilent, 2012 ) T_min = 0.869, T_max = 0.931
6682 measured reflections
2251 independent reflections
2191 reflections with I > 2σ(I)
R_int = 0.033

Refinement

R[F² > 2σ(F²)] = 0.027
wR(F²) = 0.072
S = 1.09
2251 reflections
117 parameters
2 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.28 e Å⁻³
Δρ_min = −0.19 e Å⁻³
Absolute structure: Flack (1983 ), 926 Friedel pairs
Flack parameter: 0.01 (5)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯Cl1	0.85 (1)	2.18 (1)	3.022 (1)	176 (2)
O3—H3⋯Cl1ⁱ	0.83 (1)	2.51 (2)	3.209 (1)	142 (2)
Symmetry code: (i) $[-x+{\script{1\over 2}}, -y, z-{\script{1\over 2}}]$ .

Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001 ); software used to prepare material for publication: publCIF (Westrip, 2010 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053681201598X/xu5512sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S160053681201598X/xu5512Isup2.hkl

Supporting information file. DOI: 10.1107/S160053681201598X/xu5512Isup3.cml

checkCIF report

Comment top

A model for the binding of L-carnitine to the carnitine acetyltransferase enzyme has been proposed on the basis of the crystal structure of L-carnitine (Gandour et al., 1985). L-Carnitine, a zwitterionic compound that is biosynthesized from lysine and methinonine, is the vitamin B_T; it is also avaliable commerically as the hydrochloride salt. The crystal structure of racemic carnitine hydrochloride has been previously reported (Tomita et al., 1974; Yunuskhodzhaev et al., 1991). In the crystal structure of L-carnitine hydrochloride (Scheme I), the carboxyl –CO₂ part carries the acid hydrogen (Fig. 1). This part has unambigous single- and double-bonds [1.336 (2), 1.211 (2) Å]. The three-atom C_carboxyl–C–C_{trimethylamino} unit shows a large angle [115.9 (1) °] for the atom connected to the bulky trimethylamino substituent. The acid hydrogen forms a hydrogen bond to the chloride anion (Table 1). Oddly, the hydroxy group does not engage in any hydrogen bonding interactions.

Related literature top

For racemic carnitine hydrochloride, see: Tomita et al. (1974); Yunuskhodzhaev et al. (1991). For R-carnitine, see: Gandour et al. (1985).

Experimental top

L-Carnithine hydrochloride as supplied by Sigma Chemical Company consists of colorless prismatic crystals, and was used without purification.

Computing details top

Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top

Fig. 1. Thermal ellipsoid plot (Barbour, 2001) of C₇H₁₆NO₃^+.Cl^- at the 70% probability level; hydrogen atoms are drawn as spheres of arbitrary radius.

(R)-(3-Carboxy-2-hydroxypropyl)trimethylazanium chloride top

Crystal data top

C₇H₁₆NO₃⁺·Cl⁻	F(000) = 424
M_r = 197.66	D_x = 1.339 Mg m⁻³
Orthorhombic, P2₁2₁2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 3837 reflections
a = 6.3043 (3) Å	θ = 2.3–27.5°
b = 11.5256 (7) Å	µ = 0.36 mm⁻¹
c = 13.4905 (8) Å	T = 100 K
V = 980.23 (10) Å³	Prism, colorless
Z = 4	0.40 × 0.30 × 0.20 mm

Data collection top

Agilent Technologies SuperNova Dual diffractometer with Atlas detector	2251 independent reflections
Radiation source: SuperNova (Mo) X-ray Source	2191 reflections with I > 2σ(I)
Mirror monochromator	R_int = 0.033
Detector resolution: 10.4041 pixels mm^-1	θ_max = 27.5°, θ_min = 2.3°
ω scan	h = −8→8
Absorption correction: multi-scan CrysAlis PRO (Agilent, 2012)	k = −12→15
T_min = 0.869, T_max = 0.931	l = −16→17
6682 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.027	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.072	w = 1/[σ²(F_o²) + (0.0381P)² + 0.129P] where P = (F_o² + 2F_c²)/3
S = 1.09	(Δ/σ)_max = 0.001
2251 reflections	Δρ_max = 0.28 e Å⁻³
117 parameters	Δρ_min = −0.19 e Å⁻³
2 restraints	Absolute structure: Flack (1983), 926 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.01 (5)

Crystal data top

C₇H₁₆NO₃⁺·Cl⁻	V = 980.23 (10) Å³
M_r = 197.66	Z = 4
Orthorhombic, P2₁2₁2₁	Mo Kα radiation
a = 6.3043 (3) Å	µ = 0.36 mm⁻¹
b = 11.5256 (7) Å	T = 100 K
c = 13.4905 (8) Å	0.40 × 0.30 × 0.20 mm

Data collection top

Agilent Technologies SuperNova Dual diffractometer with Atlas detector	2251 independent reflections
Absorption correction: multi-scan CrysAlis PRO (Agilent, 2012)	2191 reflections with I > 2σ(I)
T_min = 0.869, T_max = 0.931	R_int = 0.033
6682 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.027	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.072	Δρ_max = 0.28 e Å⁻³
S = 1.09	Δρ_min = −0.19 e Å⁻³
2251 reflections	Absolute structure: Flack (1983), 926 Friedel pairs
117 parameters	Absolute structure parameter: 0.01 (5)
2 restraints

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

	x	y	z	U_iso*/U_eq
Cl1	0.16829 (6)	−0.02923 (3)	1.11989 (3)	0.01599 (10)
O1	0.11377 (16)	0.20168 (9)	1.01683 (8)	0.0153 (2)
H1	0.123 (3)	0.1372 (11)	1.0468 (14)	0.032 (6)*
O2	0.09374 (17)	0.09692 (9)	0.87751 (9)	0.0164 (2)
O3	0.03544 (17)	0.23605 (10)	0.69856 (8)	0.0146 (2)
H3	0.066 (4)	0.1658 (10)	0.6948 (18)	0.047 (7)*
N1	0.38932 (18)	0.40990 (10)	0.62406 (10)	0.0107 (2)
C1	0.1083 (2)	0.19013 (12)	0.91830 (11)	0.0113 (3)
C2	0.1258 (2)	0.30406 (12)	0.86490 (11)	0.0120 (3)
H2A	0.2287	0.3542	0.9001	0.014*
H2B	−0.0138	0.3435	0.8659	0.014*
C3	0.1976 (2)	0.28843 (12)	0.75711 (10)	0.0103 (3)
H3A	0.3279	0.2390	0.7552	0.012*
C4	0.2485 (2)	0.40787 (13)	0.71538 (11)	0.0109 (3)
H4A	0.1132	0.4470	0.6989	0.013*
H4B	0.3182	0.4540	0.7680	0.013*
C5	0.6024 (2)	0.35642 (13)	0.64467 (12)	0.0151 (3)
H5A	0.6887	0.3582	0.5843	0.023*
H5B	0.5834	0.2758	0.6661	0.023*
H5C	0.6741	0.4003	0.6971	0.023*
C6	0.2902 (3)	0.35091 (15)	0.53684 (11)	0.0198 (4)
H6A	0.3867	0.3552	0.4800	0.030*
H6B	0.1563	0.3895	0.5203	0.030*
H6C	0.2628	0.2694	0.5531	0.030*
C7	0.4241 (3)	0.53502 (13)	0.59814 (12)	0.0187 (3)
H7A	0.5126	0.5402	0.5386	0.028*
H7B	0.4954	0.5742	0.6533	0.028*
H7C	0.2871	0.5723	0.5856	0.028*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cl1	0.02265 (18)	0.01262 (16)	0.01271 (18)	0.00108 (14)	0.00145 (14)	0.00228 (14)
O1	0.0237 (6)	0.0118 (5)	0.0104 (5)	0.0005 (5)	0.0008 (4)	0.0021 (4)
O2	0.0218 (5)	0.0124 (5)	0.0150 (5)	−0.0037 (4)	−0.0005 (5)	−0.0013 (4)
O3	0.0161 (5)	0.0142 (5)	0.0135 (6)	−0.0021 (5)	−0.0049 (4)	−0.0009 (4)
N1	0.0103 (6)	0.0117 (5)	0.0102 (6)	0.0002 (5)	0.0010 (5)	0.0014 (5)
C1	0.0073 (6)	0.0149 (7)	0.0118 (7)	0.0007 (6)	0.0006 (5)	0.0008 (6)
C2	0.0126 (7)	0.0121 (6)	0.0112 (7)	0.0013 (6)	0.0002 (5)	0.0003 (5)
C3	0.0095 (6)	0.0109 (6)	0.0106 (7)	0.0008 (5)	−0.0011 (5)	0.0004 (6)
C4	0.0114 (6)	0.0115 (6)	0.0099 (7)	0.0010 (6)	0.0024 (5)	0.0004 (6)
C5	0.0118 (7)	0.0180 (7)	0.0155 (8)	0.0044 (6)	0.0011 (6)	0.0008 (6)
C6	0.0210 (8)	0.0305 (9)	0.0081 (8)	−0.0080 (7)	−0.0022 (6)	−0.0002 (6)
C7	0.0167 (7)	0.0134 (7)	0.0260 (9)	−0.0003 (7)	0.0062 (6)	0.0078 (7)

Geometric parameters (Å, º) top

O1—C1	1.3363 (18)	C3—C4	1.521 (2)
O1—H1	0.848 (9)	C3—H3A	1.0000
O2—C1	1.2105 (18)	C4—H4A	0.9900
O3—C3	1.4262 (18)	C4—H4B	0.9900
O3—H3	0.833 (9)	C5—H5A	0.9800
N1—C6	1.4956 (19)	C5—H5B	0.9800
N1—C7	1.5000 (19)	C5—H5C	0.9800
N1—C5	1.5042 (18)	C6—H6A	0.9800
N1—C4	1.5188 (18)	C6—H6B	0.9800
C1—C2	1.5018 (19)	C6—H6C	0.9800
C2—C3	1.534 (2)	C7—H7A	0.9800
C2—H2A	0.9900	C7—H7B	0.9800
C2—H2B	0.9900	C7—H7C	0.9800

C1—O1—H1	112.9 (14)	N1—C4—H4A	108.3
C3—O3—H3	106.3 (18)	C3—C4—H4A	108.3
C6—N1—C7	108.35 (12)	N1—C4—H4B	108.3
C6—N1—C5	109.41 (12)	C3—C4—H4B	108.3
C7—N1—C5	107.84 (12)	H4A—C4—H4B	107.4
C6—N1—C4	112.76 (11)	N1—C5—H5A	109.5
C7—N1—C4	106.82 (11)	N1—C5—H5B	109.5
C5—N1—C4	111.47 (11)	H5A—C5—H5B	109.5
O2—C1—O1	122.86 (14)	N1—C5—H5C	109.5
O2—C1—C2	124.29 (14)	H5A—C5—H5C	109.5
O1—C1—C2	112.83 (12)	H5B—C5—H5C	109.5
C1—C2—C3	111.95 (11)	N1—C6—H6A	109.5
C1—C2—H2A	109.2	N1—C6—H6B	109.5
C3—C2—H2A	109.2	H6A—C6—H6B	109.5
C1—C2—H2B	109.2	N1—C6—H6C	109.5
C3—C2—H2B	109.2	H6A—C6—H6C	109.5
H2A—C2—H2B	107.9	H6B—C6—H6C	109.5
O3—C3—C4	109.21 (11)	N1—C7—H7A	109.5
O3—C3—C2	111.29 (11)	N1—C7—H7B	109.5
C4—C3—C2	107.87 (11)	H7A—C7—H7B	109.5
O3—C3—H3A	109.5	N1—C7—H7C	109.5
C4—C3—H3A	109.5	H7A—C7—H7C	109.5
C2—C3—H3A	109.5	H7B—C7—H7C	109.5
N1—C4—C3	115.93 (12)

O2—C1—C2—C3	−19.23 (19)	C7—N1—C4—C3	−178.16 (13)
O1—C1—C2—C3	159.77 (12)	C5—N1—C4—C3	−60.59 (16)
C1—C2—C3—O3	70.19 (14)	O3—C3—C4—N1	−78.63 (15)
C1—C2—C3—C4	−170.02 (12)	C2—C3—C4—N1	160.28 (11)
C6—N1—C4—C3	62.93 (16)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···Cl1	0.85 (1)	2.18 (1)	3.022 (1)	176 (2)
O3—H3···Cl1ⁱ	0.83 (1)	2.51 (2)	3.209 (1)	142 (2)

Symmetry code: (i) −x+1/2, −y, z−1/2.

Experimental details

Crystal data
Chemical formula	C₇H₁₆NO₃⁺·Cl⁻
M_r	197.66
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	100
a, b, c (Å)	6.3043 (3), 11.5256 (7), 13.4905 (8)
V (Å³)	980.23 (10)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.36
Crystal size (mm)	0.40 × 0.30 × 0.20

Data collection
Diffractometer	Agilent Technologies SuperNova Dual diffractometer with Atlas detector
Absorption correction	Multi-scan CrysAlis PRO (Agilent, 2012)
T_min, T_max	0.869, 0.931
No. of measured, independent and observed [I > 2σ(I)] reflections	6682, 2251, 2191
R_int	0.033
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.027, 0.072, 1.09
No. of reflections	2251
No. of parameters	117
No. of restraints	2
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.28, −0.19
Absolute structure	Flack (1983), 926 Friedel pairs
Absolute structure parameter	0.01 (5)

Computer programs: CrysAlis PRO (Agilent, 2012), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), X-SEED (Barbour, 2001), publCIF (Westrip, 2010).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···Cl1	0.85 (1)	2.18 (1)	3.022 (1)	176 (2)
O3—H3···Cl1ⁱ	0.83 (1)	2.51 (2)	3.209 (1)	142 (2)

Symmetry code: (i) −x+1/2, −y, z−1/2.

Acknowledgements

I thank the Ministry of Higher Education of Malaysia (grant No. UM·C/HIR/MOHE/SC/12) for supporting this study.

References

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