N-Methyl-2-pyrrolidone hydro­chloride

The cation of the title compound, C₅H₁₀NO⁺ Cl⁻, has the five-membered ring in a very shallow envelope conformation. An inter­ionic O—H...Cl hydrogen bond links the Cl⁻ anion to the cation.

Key indicators

• Single-crystal X-ray study
• T = 200 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.030
• wR factor = 0.072
• Data-to-parameter ratio = 10.5

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT027_ALERT_3_A _diffrn_reflns_theta_full (too) Low ............      24.74 Deg.

Author Response:

 The measurement was only performed up to 49.48 Degree in 2Theta because due to
 the size of the crystal there were only reflections observed up to 24.74 Degree
 However, the ratio of observed data to parameter is larger than 10 (10.55), and
 the data is sufficiently precise for the hydrogen atoms to be clearly resolved
 in the difference electron-density map. Furthermore, all hydrogen atoms could
 be refined freely.


Alert level C
THETM01_ALERT_3_C  The value of sine(theta_max)/wavelength is less than 0.590
            Calculated sin(theta_max)/wavelength =    0.5888
PLAT023_ALERT_3_C Resolution (too) Low [sin(th)/Lambda < 0.6].....      24.74 Deg.
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         C3
PLAT355_ALERT_3_C Long    O-H Bond (0.82A)   O      -   H      ...       1.03 Ang.

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           24.74
           From the CIF: _reflns_number_total               1192
           Count of symmetry unique reflns          723
           Completeness (_total/calc)            164.87%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       469
           Fraction of Friedel pairs measured     0.649
           Are heavy atom types Z>Si present        yes

   1 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   4 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   4 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The five-membered ring of N-Methyl-2-pyrrolidonium cation adopts a slightly pronounced envelope conformation in the solid state (Fig. 1), with C3 as the flap atom (C1—C2—C3—C4 = 13.4 (3) °). The O—H unit adopts an eclipsed conformation and is nearly coplanar to the ring-plane (C4—N—C1—C2 = -2.2 (2) °). The N—C1 distance [1.296 (3) Å] is substantially shorter than the sum of the covalent radii (d_cov.: C—N 1.47, C=N 1.27 Å, Holleman, 2007), which indicates partial double-bond character for this bond. A similar situation is found for the O—C1 bond [1.297 (3) Å], which also lies in the range between a single and a double bond (d_cov.: C—O 1.43, C=O 1.23 Å), indicating a certain degree of charge-delocalization along the N—C1—O unit.

In the crystal structure, the C₅H₉NO⁺ cation and the Cl^- anion are linked by an O—H···Cl hydrogen-bond with a relatively short donor-acceptor distance. Interestingly, no further hydrogen-bonds were found (Fig. 2).

Related literature

For data on the neutral compound, see: Müller et al. (1996). For an alternative method of preparation, see: Utsumi (1981). For related literature, see: Holleman (2007).

S2. Experimental

N-Methyl-2-pyrrolidone was obtained from Merck Co. and was used as recieved. HCl_conc. (24.64 g, 250 mmol) was added dropwise to a stirred solution of N-Methyl-2-pyrrolidone (4.957 g, 50 mmol) in CH₂Cl₂ (40 mL) at 0°C. The clear aqueous layer was separated and was then evaporated to dryness in vacuo. The colourless, crystalline residue was sublimed (10^-3 mbar, 60°C) for purification. Yield: 5.597 g (41.28 mmol, 83%). Mp. = 94 °C. CHN-analysis: found, C 43.20, N 10.01, H 6.44%; calc. C 44.29, N 10.33, H 7.43%. ¹H-NMR (DMSO-d₆, 25 °C, 250 MHz): δ = 1.86 (quint, 2H, ²J_H—H = 7.6 Hz), 2.16 (t, 2H, ²J_H—H = 7.6 Hz), 2.66 (s, 3H), 3.27 (t, 2H, ²J_H—H = 7.6 Hz), 11.5 (s, 1H). ¹³C{¹H}-NMR (DMSO-d₆, 25 °C, 250 MHz): δ = 17.5, 29.4, 30.4, 48.9, 174.3. Crystallization from a saturated CH₂Cl₂ solution at ambient temperature gave colourless crystals.

S3. Refinement

All hydrogen atoms were found in difference syntheses, and refined freely.

Computing details

Data collection: Collect (Nonius, 1999); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Windows version (Farrugia, 1997) of ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

	Fig. 1. Molecular structure of (I), showing the atomic numbering scheme and displacement ellipsoids drawn at the 50% probability level.
	Fig. 2. Packing diagram for (I), viewed down the a axis. Hydrogen-bonds are indicated by dashed lines.

N-Methyl-2-pyrrolidone hydrochloride

Crystal data

C5H10NO^+·Cl^−	F(000) = 288
Mr = 135.59	Dx = 1.301 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 4313 reflections
a = 6.1391 (2) Å	θ = 3.1–24.7°
b = 8.9537 (2) Å	µ = 0.46 mm^−1
c = 12.5976 (4) Å	T = 200 K
V = 692.46 (4) Å^3	Block, colourless
Z = 4	0.28 × 0.25 × 0.20 mm

Data collection

Nonius KappaCCD diffractometer	1124 reflections with I > 2σ(I)
Radiation source: rotating anode	Rint = 0.094
Graphite monochromator	θmax = 24.7°, θmin = 3.2°
Detector resolution: 9 pixels mm^-1	h = −7→7
phi/ω–scan	k = −10→10
8273 measured reflections	l = −14→14
1192 independent reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.030	All H-atom parameters refined
wR(F^2) = 0.072	w = 1/[σ^2(Fo^2) + (0.031P)^2 + 0.1465P] where P = (Fo^2 + 2Fc^2)/3
S = 1.04	(Δ/σ)max < 0.001
1192 reflections	Δρmax = 0.15 e Å^−3
113 parameters	Δρmin = −0.20 e Å^−3
0 restraints	Absolute structure: Flack (1983), 471 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.04 (9)

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
Cl	0.98418 (9)	1.03603 (5)	0.63590 (4)	0.04228 (18)
O	1.0110 (3)	0.73233 (15)	0.57419 (11)	0.0400 (3)
N	0.8324 (3)	0.51346 (18)	0.59226 (13)	0.0323 (4)
C1	0.8497 (3)	0.6551 (2)	0.61169 (14)	0.0305 (4)
C2	0.6698 (4)	0.7117 (2)	0.67914 (17)	0.0363 (5)
C3	0.5168 (5)	0.5788 (3)	0.6863 (2)	0.0553 (6)
C4	0.6445 (4)	0.4457 (3)	0.64539 (19)	0.0413 (5)
C5	0.9858 (5)	0.4241 (3)	0.5312 (2)	0.0445 (5)
H41	0.568 (4)	0.387 (3)	0.5962 (18)	0.043 (7)*
H21	0.612 (4)	0.803 (3)	0.647 (2)	0.054 (7)*
H31	0.479 (5)	0.559 (3)	0.752 (3)	0.080 (9)*
H22	0.724 (4)	0.743 (3)	0.745 (2)	0.056 (7)*
H51	1.018 (6)	0.342 (4)	0.571 (3)	0.092 (11)*
H42	0.701 (4)	0.380 (3)	0.702 (2)	0.051 (7)*
H52	0.914 (6)	0.383 (4)	0.472 (3)	0.092 (11)*
H32	0.389 (6)	0.591 (4)	0.641 (3)	0.098 (12)*
H53	1.106 (5)	0.480 (3)	0.511 (2)	0.059 (8)*
H	0.994 (6)	0.843 (4)	0.596 (3)	0.094 (10)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl	0.0466 (3)	0.0332 (3)	0.0470 (3)	−0.0062 (2)	−0.0023 (3)	−0.0018 (2)
O	0.0382 (8)	0.0316 (7)	0.0502 (8)	−0.0046 (8)	0.0125 (7)	0.0001 (6)
N	0.0339 (9)	0.0299 (9)	0.0331 (8)	−0.0008 (7)	0.0029 (7)	−0.0009 (7)
C1	0.0298 (10)	0.0314 (10)	0.0302 (10)	−0.0018 (8)	−0.0012 (8)	0.0026 (7)
C2	0.0348 (11)	0.0390 (12)	0.0351 (11)	0.0037 (9)	0.0035 (9)	−0.0005 (9)
C3	0.0445 (15)	0.0556 (14)	0.0657 (16)	−0.0099 (14)	0.0194 (14)	−0.0082 (12)
C4	0.0417 (11)	0.0408 (13)	0.0414 (11)	−0.0127 (10)	0.0023 (11)	0.0017 (11)
C5	0.0469 (13)	0.0338 (11)	0.0526 (13)	0.0048 (12)	0.0086 (13)	−0.0041 (10)

Geometric parameters (Å, º)

Cl—H	1.80 (4)	C2—H22	0.93 (3)
O—C1	1.297 (3)	C3—C4	1.516 (3)
O—H	1.03 (4)	C3—H31	0.87 (3)
N—C1	1.296 (3)	C3—H32	0.98 (4)
N—C5	1.455 (3)	C4—H41	0.94 (2)
N—C4	1.465 (3)	C4—H42	0.99 (2)
C1—C2	1.483 (3)	C5—H51	0.91 (3)
C2—C3	1.519 (3)	C5—H52	0.94 (4)
C2—H21	0.98 (3)	C5—H53	0.93 (3)
C1—O—H	110 (2)	C4—C3—H32	108 (2)
C1—N—C5	125.78 (19)	C2—C3—H32	112 (2)
C1—N—C4	112.53 (16)	H31—C3—H32	111 (3)
C5—N—C4	121.57 (18)	N—C4—C3	103.71 (17)
N—C1—O	121.02 (18)	N—C4—H41	108.8 (14)
N—C1—C2	112.45 (17)	C3—C4—H41	114.0 (15)
O—C1—C2	126.52 (18)	N—C4—H42	107.5 (15)
C1—C2—C3	103.08 (18)	C3—C4—H42	113.9 (14)
C1—C2—H21	108.9 (15)	H41—C4—H42	108.6 (19)
C3—C2—H21	117.0 (15)	N—C5—H51	107 (2)
C1—C2—H22	110.2 (16)	N—C5—H52	109 (2)
C3—C2—H22	113.6 (16)	H51—C5—H52	103 (3)
H21—C2—H22	104 (2)	N—C5—H53	111.6 (18)
C4—C3—C2	106.0 (2)	H51—C5—H53	114 (3)
C4—C3—H31	107 (2)	H52—C5—H53	111 (3)
C2—C3—H31	112 (2)
C5—N—C1—O	1.6 (3)	O—C1—C2—C3	172.9 (2)
C4—N—C1—O	177.57 (19)	C1—C2—C3—C4	13.4 (3)
C5—N—C1—C2	−178.2 (2)	C1—N—C4—C3	10.8 (3)
C4—N—C1—C2	−2.2 (2)	C5—N—C4—C3	−173.1 (2)
N—C1—C2—C3	−7.4 (3)	C2—C3—C4—N	−14.6 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O—H···Cl	1.03 (4)	1.80 (4)	2.8330 (14)	176 (3)