1-Ethyl-5-methyl-3-methyl­sulfanyl-1H-pyrazole-4-carboxylic acid

In the crystal structure of the title compound, C₈H₁₂N₂O₂S, the mol­ecules are linked into centrosymmetric dimers by a pair of strong O—H...O hydrogen bonds. Inter­molecular S...S contacts between adjacent dimers generate a sheet-like structure running parallel to the (211) plane.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.005 Å
• Disorder in main residue
• R factor = 0.054
• wR factor = 0.152
• Data-to-parameter ratio = 12.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT199_ALERT_1_C Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_C Check the Reported _diffrn_ambient_temperature .        293 K
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         N1
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         C7
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        C7'
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.18
PLAT301_ALERT_3_C Main Residue  Disorder .........................      13.00 Perc.
PLAT340_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          5
PLAT720_ALERT_4_C Number of Unusual/Non-Standard Label(s) ........          5

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

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

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S1. Comment

Pyrazole and its derivatives represent one of the most important classes of compounds, possessing a wide spectrum of biological activities (Iovu et al., 2003), such as antibacterial, fungicidal, herbicidal and insecticidal. In the course of our systematic studies aimed at the synthesis of new bioactive compounds, we synthesized the title compound, (I), the structure of which is reported here.

The pyrazole ring is planar, the largest deviation from planarity being 0.009 (4) Å for atom C1. Bond distances and angles (Table 1) are as expected for this type of compound. In the crystal structure, centrosymmetrically related molecules are linked into dimers by intermolecular O—H···O hydrogen bonds (Table 2 and Fig. 2), thus generating rings of graph-set motifs R²₂(8) (Bernstein et al., 1995). Intermolecular contacts between S atoms of adjacent dimers [S1···S1ⁱⁱ = 3.5374 (17) Å; symmetry code: (ii) 1 − x, −y, −z] are observed, generating a sheet-like structure running parallel to the (211) plane.

S2. Experimental

To a solution of ketene S,S-acetal (23.43 g, 0.1 mol) in ethanol (50 ml), 80% hydrazine hydrate (6.3 g,0.1 mol) was added slowly. The mixture was stirred for 3 h at room temperature to give ethyl 3-methyl-5-methylthio-1H-pyrazol-4-carboxylate, (1). NaOH (1 g) and and Et₂SO₄ (0.77 g, 5 mmol) in chloroform (50 ml) were added slowly to the mixture of (1) (1.0 g, 5 mmol) with stirring for 5 h at room temperature to give ethyl 1-ethyl-5-methyl-3- methylthiopyrazole-4-carboxylate, (2). Compound (2) was hydrolyzed under reflux for 3 h and after cooling acidified to pH 3.0, to give (I). Single crystals suitable for X-ray diffraction studies were isolated by recrystallization from ethanol and MeCN (m.p. 466.5 K).

S3. Refinement

All H atoms were placed in calculated positions, with C—H = 0.96 or 0.97 Å and O—H = 0.82 Å, and included in the final cycles of refinement using a riding model, with U_iso(H) values of 1.2 or 1.5 times U_eq of the parent atoms. The ethyl group is disordered; atoms C7 and C8 and related H atoms were refined over two positions with occupancies 0.751 (10) and 0.249 (10) for the major and minor components, respectively.

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1999); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. View of the title compound, with 35% probability displacement ellipsoids. Only the major component of the disordered C7/C8 ethyl group is shown.
	Fig. 2. Molecular packing of the title compound, viewed along the a axis. Hydrogen bonds and S···S contacts are shown as dashed lines.

1-ethyl-5-methyl-3-methylthio-1H-pyrazole-4-carboxylic acid

Crystal data

C8H12N2O2S	Z = 2
Mr = 200.27	F(000) = 212
Triclinic, P1	Dx = 1.321 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.949 (2) Å	Cell parameters from 1010 reflections
b = 8.330 (2) Å	θ = 2.6–25.0°
c = 8.368 (2) Å	µ = 0.29 mm^−1
α = 71.267 (4)°	T = 293 K
β = 80.761 (5)°	Prism, colourless
γ = 74.291 (5)°	0.22 × 0.18 × 0.12 mm
V = 503.5 (2) Å^3

Data collection

Bruker SMART 1000 CCD area-detector diffractometer	1765 independent reflections
Radiation source: fine-focus sealed tube	1253 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.022
ϕ and ω scans	θmax = 25.0°, θmin = 2.6°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −9→7
Tmin = 0.939, Tmax = 0.966	k = −9→7
2645 measured reflections	l = −9→9

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)] = 0.054	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.152	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0597P)^2 + 0.4305P] where P = (Fo^2 + 2Fc^2)/3
1765 reflections	(Δ/σ)max = 0.002
142 parameters	Δρmax = 0.35 e Å^−3
6 restraints	Δρmin = −0.42 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	Occ. (<1)
S1	0.39085 (14)	0.07713 (14)	0.17200 (11)	0.0691 (4)
O1	0.4592 (3)	−0.2942 (3)	0.3703 (3)	0.0693 (7)
O2	0.3836 (4)	−0.3938 (3)	0.6462 (3)	0.0707 (7)
H2	0.4384	−0.4859	0.6285	0.106*
N1	0.1322 (5)	0.1300 (4)	0.5849 (4)	0.0924 (12)
N2	0.1926 (5)	0.1983 (4)	0.4200 (4)	0.0859 (11)
C1	0.1917 (5)	−0.0417 (5)	0.6442 (4)	0.0670 (10)
C2	0.1440 (6)	−0.1434 (6)	0.8214 (5)	0.0830 (13)
H2A	0.2095	−0.1256	0.8986	0.124*
H2B	0.1710	−0.2651	0.8296	0.124*
H2C	0.0208	−0.1045	0.8495	0.124*
C3	0.2943 (4)	−0.0945 (4)	0.5110 (4)	0.0526 (8)
C4	0.3836 (4)	−0.2687 (5)	0.5080 (4)	0.0539 (8)
C5	0.2901 (5)	0.0609 (5)	0.3759 (4)	0.0584 (9)
C6	0.3458 (7)	0.3092 (6)	0.0833 (5)	0.0898 (14)
H6A	0.2214	0.3555	0.0819	0.135*
H6B	0.3995	0.3379	−0.0303	0.135*
H6C	0.3924	0.3585	0.1506	0.135*
C7	−0.0091 (8)	0.2523 (8)	0.6644 (7)	0.0690 (19)	0.751 (10)
H7A	−0.0719	0.3490	0.5784	0.083*	0.751 (10)
H7B	−0.0921	0.1910	0.7406	0.083*	0.751 (10)
C8	0.0935 (8)	0.3146 (9)	0.7594 (8)	0.083 (2)	0.751 (10)
H8A	0.1592	0.2162	0.8394	0.125*	0.751 (10)
H8B	0.0141	0.3901	0.8183	0.125*	0.751 (10)
H8C	0.1724	0.3772	0.6810	0.125*	0.751 (10)
C7'	0.108 (2)	0.2462 (18)	0.6982 (17)	0.067 (6)	0.249 (10)
H7'1	0.1715	0.3376	0.6482	0.080*	0.249 (10)
H7'2	0.1489	0.1791	0.8089	0.080*	0.249 (10)
C8'	−0.089 (2)	0.323 (2)	0.711 (3)	0.098 (8)	0.249 (10)
H8'1	−0.1300	0.3669	0.5993	0.146*	0.249 (10)
H8'2	−0.1141	0.4156	0.7614	0.146*	0.249 (10)
H8'3	−0.1472	0.2333	0.7789	0.146*	0.249 (10)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0827 (7)	0.0813 (7)	0.0406 (5)	−0.0260 (5)	0.0116 (4)	−0.0163 (4)
O1	0.0772 (17)	0.0727 (17)	0.0493 (13)	−0.0098 (13)	0.0104 (12)	−0.0198 (12)
O2	0.090 (2)	0.0600 (16)	0.0522 (14)	−0.0139 (14)	0.0078 (13)	−0.0123 (12)
N1	0.141 (3)	0.062 (2)	0.0533 (18)	−0.013 (2)	0.034 (2)	−0.0176 (16)
N2	0.128 (3)	0.066 (2)	0.0478 (17)	−0.021 (2)	0.0248 (18)	−0.0118 (15)
C1	0.086 (3)	0.060 (2)	0.0479 (19)	−0.0190 (19)	0.0153 (18)	−0.0150 (17)
C2	0.105 (3)	0.077 (3)	0.052 (2)	−0.023 (2)	0.028 (2)	−0.0136 (19)
C3	0.0540 (19)	0.061 (2)	0.0433 (17)	−0.0171 (16)	0.0046 (14)	−0.0171 (15)
C4	0.0515 (19)	0.066 (2)	0.0445 (18)	−0.0175 (17)	0.0005 (15)	−0.0150 (16)
C5	0.071 (2)	0.064 (2)	0.0411 (17)	−0.0213 (18)	0.0069 (15)	−0.0168 (16)
C6	0.130 (4)	0.090 (3)	0.049 (2)	−0.047 (3)	0.003 (2)	−0.006 (2)
C7	0.066 (4)	0.083 (5)	0.060 (3)	−0.023 (3)	−0.004 (3)	−0.019 (3)
C8	0.085 (4)	0.093 (5)	0.080 (4)	−0.030 (4)	−0.006 (3)	−0.030 (3)
C7'	0.128 (17)	0.050 (9)	0.033 (8)	−0.028 (10)	0.003 (9)	−0.026 (6)
C8'	0.100 (17)	0.090 (15)	0.086 (14)	−0.003 (12)	0.026 (12)	−0.036 (11)

Geometric parameters (Å, º)

S1—C5	1.744 (3)	C3—C4	1.439 (5)
S1—C6	1.790 (4)	C6—H6A	0.9600
O1—C4	1.265 (4)	C6—H6B	0.9600
O2—C4	1.284 (4)	C6—H6C	0.9600
O2—H2	0.8200	C7—C8	1.506 (7)
N1—C1	1.330 (5)	C7—H7A	0.9700
N1—N2	1.375 (4)	C7—H7B	0.9700
N1—C7'	1.518 (9)	C8—H8A	0.9600
N1—C7	1.522 (6)	C8—H8B	0.9600
N2—C5	1.321 (5)	C8—H8C	0.9600
C1—C3	1.390 (4)	C7'—C8'	1.525 (10)
C1—C2	1.499 (5)	C7'—H7'1	0.9700
C2—H2A	0.9600	C7'—H7'2	0.9700
C2—H2B	0.9600	C8'—H8'1	0.9600
C2—H2C	0.9600	C8'—H8'2	0.9600
C3—C5	1.415 (5)	C8'—H8'3	0.9600
C5—S1—C6	100.31 (18)	C3—C5—S1	126.3 (3)
C4—O2—H2	109.5	S1—C6—H6A	109.5
C1—N1—N2	113.4 (3)	S1—C6—H6B	109.5
C1—N1—C7'	120.7 (6)	H6A—C6—H6B	109.5
N2—N1—C7'	115.3 (6)	S1—C6—H6C	109.5
C1—N1—C7	129.0 (4)	H6A—C6—H6C	109.5
N2—N1—C7	117.0 (4)	H6B—C6—H6C	109.5
C5—N2—N1	104.0 (3)	C8—C7—N1	103.2 (4)
N1—C1—C3	106.1 (3)	C8—C7—H7A	111.1
N1—C1—C2	122.6 (3)	N1—C7—H7A	111.1
C3—C1—C2	131.3 (4)	C8—C7—H7B	111.1
C1—C2—H2A	109.5	N1—C7—H7B	111.1
C1—C2—H2B	109.5	H7A—C7—H7B	109.1
H2A—C2—H2B	109.5	N1—C7'—C8'	103.8 (9)
C1—C2—H2C	109.5	N1—C7'—H7'1	111.0
H2A—C2—H2C	109.5	C8'—C7'—H7'1	111.0
H2B—C2—H2C	109.5	N1—C7'—H7'2	111.0
C1—C3—C5	104.9 (3)	C8'—C7'—H7'2	111.0
C1—C3—C4	128.1 (3)	H7'1—C7'—H7'2	109.0
C5—C3—C4	127.0 (3)	C7'—C8'—H8'1	109.5
O1—C4—O2	122.1 (3)	C7'—C8'—H8'2	109.5
O1—C4—C3	119.3 (3)	H8'1—C8'—H8'2	109.5
O2—C4—C3	118.6 (3)	C7'—C8'—H8'3	109.5
N2—C5—C3	111.5 (3)	H8'1—C8'—H8'3	109.5
N2—C5—S1	122.2 (3)	H8'2—C8'—H8'3	109.5
C1—N1—N2—C5	1.5 (5)	C5—C3—C4—O2	175.2 (3)
C7'—N1—N2—C5	146.7 (7)	N1—N2—C5—C3	−0.6 (5)
C7—N1—N2—C5	−170.3 (4)	N1—N2—C5—S1	177.3 (3)
N2—N1—C1—C3	−1.8 (5)	C1—C3—C5—N2	−0.4 (4)
C7'—N1—C1—C3	−144.9 (7)	C4—C3—C5—N2	178.6 (3)
C7—N1—C1—C3	168.8 (4)	C1—C3—C5—S1	−178.2 (3)
N2—N1—C1—C2	179.5 (4)	C4—C3—C5—S1	0.8 (5)
C7'—N1—C1—C2	36.4 (9)	C6—S1—C5—N2	7.7 (4)
C7—N1—C1—C2	−9.9 (7)	C6—S1—C5—C3	−174.7 (3)
N1—C1—C3—C5	1.3 (4)	C1—N1—C7—C8	93.0 (6)
C2—C1—C3—C5	179.9 (4)	N2—N1—C7—C8	−96.6 (5)
N1—C1—C3—C4	−177.7 (4)	C7'—N1—C7—C8	1.0 (10)
C2—C1—C3—C4	0.8 (7)	C1—N1—C7'—C8'	−115.4 (11)
C1—C3—C4—O1	173.9 (4)	N2—N1—C7'—C8'	102.2 (11)
C5—C3—C4—O1	−4.9 (5)	C7—N1—C7'—C8'	0.0 (10)
C1—C3—C4—O2	−6.0 (6)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O1^i	0.82	1.79	2.599 (4)	169

Symmetry code: (i) −x+1, −y−1, −z+1.