o-Sulfamoylbenzoic acid

The title compound, C₇H₇NO₄S, contains an extensive hydrogen-bonded network involving three inter­molecular and three intra­molecular inter­actions that stabilize the structure.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.033
• wR factor = 0.089
• Data-to-parameter ratio = 15.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT430_ALERT_2_C Short Inter D...A Contact  O2     ..  O4      ..       2.86 Ang.

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

   1 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
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

---

S1. Comment

Saccharin is an old synthetic compound. Its derivatives have always been of interest due to their diverse applications (González-Álvarez et al., 2003; Culf et al., 1997). The open ring benzene sulfonamide derivatives of saccharin have shown cyclooxygenase-2 inhibitory action and act as analgesic and anti-inflammatory agents (Eatedal et al., 2002). The title compound is one of the very first derivatives of saccharin that was prepared by an indirect route involving hydroxymethylsaccharin (Groutas et al., 1993). In continuation of our research program to synthesize new biologically important 1,2-benzothiazine 1,1-dioxide molecules (Siddiqui et al., 2006; Siddiqui, Ahmad, Khan & Siddiqui, 2007; Siddiqui, Ahmad, Khan, Siddiqui & Ahmad, 2007), we embarked on derivatization of saccharin as well. Herein, we report the crystal structure of the title compound that has been synthesized by a straight forward method.

The structure of the title compound (Fig. 1) contains an extensive hydrogen bonded net work (Fig. 2). The acid and the amino hydrogen atoms are involved in three intermolecular H-bonds of the types O—H···O and N—H···O, respectively. The acid group, in its synplanar conformation, forms cyclic dimers, typical of the carboxylic acids, about inversion centers. The eight membered ring thus formed exhibits an R₂²(8)-type motif (Bernstein et al., 1994). One of the amino H-atoms, H1A is hydrogen bonded to O4 of a symmetry related molecule (details are in Table) thus resulting in chains of molecules. The second H-atom of the amino group, H1B, on the other hand, is hydrogen bonded to O3 of an adjacent molecule which is oriented in such a manner that its amino H1B is hydrogen bonded to the reference molecule, thus forming an eight membered ring S1ⁱⁱⁱ/O3ⁱⁱⁱ/H1B/N1/S1/O3/H1Bⁱⁱⁱ/N1ⁱⁱⁱ (details are in Table). In terms of graph-set presentation (Bernstein et al., 1994), this ring also exhibits an R₂²(8) hydrogen bonding pattern. The structure is further stabilized by three intramolecular interactions of the type C—H···O and N—H···O (details are in Table).

Related literature

For related literature, see: Bernstein et al. (1994); Culf et al. (1997); Eatedal et al. (2002); Groutas et al. (1993); González-Álvarez et al. (2003); Siddiqui et al. (2006); Siddiqui, Ahmad, Khan & Siddiqui (2007); Siddiqui, Ahmad, Khan, Siddiqui & Ahmad (2007).

S2. Experimental

Experimental: A mixture of saccharin (0.997 g, 5.5 mmol.) and sodium hydroxide (0.5 g, 12.5 mmol.) in distilled water (25 ml) was heated to reflux (1 hr), cooled to room temperature and acidified to pH = 4 (15% HCl). The reaction mixture was subjected to cooling in freezer overnight and white flakes-like product was filtered, washed with cold water and dried to yield 1.06 g of the title compound (5.3 mmol. 97%) which was recrystallized from a solution of MeOH and CHCl₃ (1:1) at 313 K to obtain colorless crystals.

S3. Refinement

H-atoms bonded to C-atoms were included in the refinements at geometrically idealized positions with C—H = 0.95 and 0.99 Å and U_iso = 1.2 times U_eq of the atoms to which they were bonded. The H-atoms bonded to N1 and O1 were allowed to refine with U_iso = 1.2 times U_eq of the parent atoms. The final difference map was free of any chemically significant features.

Computing details

Data collection: COLLECT (Nonius, 1998); cell refinement: DENZO (Otwinowski & Minor, 1997); data reduction: SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SAPI91 (Fan, 1991); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

	Fig. 1. ORTEPII (Johnson, 1976) drawing of the title compound with displacement ellipsoids plotted at 50% probability level.
	Fig. 2. Unit cell packing of the title compound showing intramolecular hydrogen bonds; only the H-atoms involved in H-bonds have been shown.

o-Sulfamoylbenzoic acid

Crystal data

C7H7NO4S	F(000) = 832
Mr = 201.20	Dx = 1.562 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 3769 reflections
a = 12.200 (4) Å	θ = 4.2–27.5°
b = 15.824 (6) Å	µ = 0.36 mm^−1
c = 9.012 (4) Å	T = 173 K
β = 100.45 (2)°	Prism, colourless
V = 1710.9 (11) Å^3	0.20 × 0.18 × 0.14 mm
Z = 8

Data collection

Nonius KappaCCD area-detector diffractometer	1952 independent reflections
Radiation source: fine-focus sealed tube	1718 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.024
ω and φ scans	θmax = 27.5°, θmin = 4.2°
Absorption correction: multi-scan (SORTAV; Blessing, 1997)	h = −15→15
Tmin = 0.932, Tmax = 0.952	k = −19→20
3769 measured reflections	l = −11→11

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)] = 0.033	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.089	H atoms treated by a mixture of independent and constrained refinement
S = 1.04	w = 1/[σ^2(Fo^2) + (0.044P)^2 + 1.65P] where P = (Fo^2 + 2Fc^2)/3
1952 reflections	(Δ/σ)max < 0.001
127 parameters	Δρmax = 0.34 e Å^−3
0 restraints	Δρmin = −0.42 e Å^−3

Special details

Experimental. IR (Neat, ν_max, cm^-1): NH 3321 (br), CO 1715, SO₂ 1270 and 1157; ¹H-NMR (400 MHz, DMSO-d₆) δ: 7.18 (s, 2H, NH₂), 7.62–7.75 (m, 3H, aromatic), 7.95 (m, 1H, aromatic); ¹³C-NMR δ: 169.0, 141.1, 132.1, 131.8, 130.9, 129.3, 127.3. LRMS (FAB⁺): m/z: 202 [M]⁺ (53.5%), 403 [2M]⁺ (18.3%).

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.

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

	x	y	z	Uiso*/Ueq
S1	0.32466 (3)	0.08825 (2)	0.29800 (4)	0.01783 (13)
O1	−0.03197 (9)	0.10966 (8)	0.06197 (17)	0.0358 (3)
H1	−0.0561 (18)	0.0621 (14)	0.031 (3)	0.043*
O2	0.12390 (9)	0.03527 (7)	0.07062 (14)	0.0262 (3)
O3	0.42650 (9)	0.11678 (7)	0.39115 (13)	0.0253 (3)
O4	0.25219 (9)	0.03529 (7)	0.36559 (13)	0.0241 (3)
N1	0.36169 (11)	0.03865 (8)	0.16031 (16)	0.0220 (3)
H1A	0.3086 (16)	0.0220 (12)	0.090 (2)	0.026*
H1B	0.4203 (16)	0.0615 (12)	0.131 (2)	0.026*
C1	0.24768 (12)	0.18088 (9)	0.23164 (17)	0.0186 (3)
C2	0.29921 (14)	0.25731 (10)	0.2747 (2)	0.0284 (4)
H2	0.3740	0.2578	0.3277	0.034*
C3	0.24279 (15)	0.33333 (10)	0.2413 (2)	0.0328 (4)
H3	0.2792	0.3854	0.2704	0.039*
C4	0.13346 (14)	0.33287 (10)	0.1656 (2)	0.0293 (4)
H4	0.0940	0.3845	0.1444	0.035*
C5	0.08186 (13)	0.25648 (10)	0.12075 (18)	0.0243 (3)
H5	0.0070	0.2567	0.0681	0.029*
C6	0.13656 (12)	0.17981 (9)	0.15061 (16)	0.0186 (3)
C7	0.07735 (12)	0.10081 (9)	0.09228 (17)	0.0195 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0154 (2)	0.0169 (2)	0.0196 (2)	0.00077 (13)	−0.00111 (14)	−0.00002 (13)
O1	0.0156 (6)	0.0250 (6)	0.0617 (9)	0.0008 (5)	−0.0062 (5)	−0.0151 (6)
O2	0.0168 (5)	0.0228 (6)	0.0371 (7)	−0.0011 (4)	0.0003 (5)	−0.0100 (5)
O3	0.0184 (5)	0.0264 (6)	0.0271 (6)	0.0022 (4)	−0.0064 (4)	−0.0048 (5)
O4	0.0226 (5)	0.0226 (6)	0.0271 (6)	0.0013 (4)	0.0047 (4)	0.0059 (4)
N1	0.0161 (6)	0.0244 (7)	0.0248 (7)	−0.0027 (5)	0.0018 (5)	−0.0059 (5)
C1	0.0167 (7)	0.0175 (7)	0.0202 (7)	−0.0015 (5)	−0.0002 (6)	−0.0002 (6)
C2	0.0250 (8)	0.0204 (8)	0.0351 (9)	−0.0030 (6)	−0.0072 (7)	−0.0007 (7)
C3	0.0352 (9)	0.0166 (8)	0.0414 (10)	−0.0048 (7)	−0.0070 (8)	−0.0009 (7)
C4	0.0348 (9)	0.0170 (7)	0.0325 (9)	0.0040 (7)	−0.0031 (7)	0.0027 (7)
C5	0.0236 (8)	0.0220 (8)	0.0244 (8)	0.0024 (6)	−0.0031 (6)	0.0014 (6)
C6	0.0185 (7)	0.0178 (7)	0.0181 (7)	−0.0006 (6)	0.0000 (6)	0.0000 (5)
C7	0.0172 (7)	0.0210 (7)	0.0187 (7)	0.0004 (6)	−0.0007 (6)	−0.0020 (6)

Geometric parameters (Å, º)

S1—O4	1.4319 (12)	C1—C6	1.419 (2)
S1—O3	1.4402 (11)	C2—C3	1.391 (2)
S1—N1	1.6010 (15)	C2—H2	0.9500
S1—C1	1.7844 (16)	C3—C4	1.384 (2)
O1—C7	1.3194 (18)	C3—H3	0.9500
O1—H1	0.84 (2)	C4—C5	1.389 (2)
O2—C7	1.2152 (18)	C4—H4	0.9500
N1—H1A	0.860 (19)	C5—C6	1.387 (2)
N1—H1B	0.88 (2)	C5—H5	0.9500
C1—C2	1.386 (2)	C6—C7	1.491 (2)
O4—S1—O3	118.00 (7)	C4—C3—C2	119.80 (15)
O4—S1—N1	109.00 (8)	C4—C3—H3	120.1
O3—S1—N1	105.70 (7)	C2—C3—H3	120.1
O4—S1—C1	107.17 (7)	C3—C4—C5	119.58 (14)
O3—S1—C1	106.49 (7)	C3—C4—H4	120.2
N1—S1—C1	110.39 (8)	C5—C4—H4	120.2
C7—O1—H1	104.7 (15)	C6—C5—C4	121.87 (14)
S1—N1—H1A	116.0 (13)	C6—C5—H5	119.1
S1—N1—H1B	112.8 (12)	C4—C5—H5	119.1
H1A—N1—H1B	116.7 (18)	C5—C6—C1	118.08 (13)
C2—C1—C6	119.82 (14)	C5—C6—C7	118.66 (13)
C2—C1—S1	116.01 (11)	C1—C6—C7	123.24 (13)
C6—C1—S1	123.95 (11)	O2—C7—O1	122.80 (14)
C1—C2—C3	120.82 (15)	O2—C7—C6	124.16 (13)
C1—C2—H2	119.6	O1—C7—C6	113.01 (13)
C3—C2—H2	119.6
O4—S1—C1—C2	129.47 (14)	C4—C5—C6—C1	1.1 (2)
O3—S1—C1—C2	2.32 (15)	C4—C5—C6—C7	−177.08 (16)
N1—S1—C1—C2	−111.95 (14)	C2—C1—C6—C5	−1.8 (2)
O4—S1—C1—C6	−45.14 (15)	S1—C1—C6—C5	172.67 (12)
O3—S1—C1—C6	−172.29 (13)	C2—C1—C6—C7	176.32 (15)
N1—S1—C1—C6	73.44 (15)	S1—C1—C6—C7	−9.3 (2)
C6—C1—C2—C3	0.9 (3)	C5—C6—C7—O2	157.01 (16)
S1—C1—C2—C3	−173.97 (15)	C1—C6—C7—O2	−21.1 (2)
C1—C2—C3—C4	0.7 (3)	C5—C6—C7—O1	−21.2 (2)
C2—C3—C4—C5	−1.4 (3)	C1—C6—C7—O1	160.75 (15)
C3—C4—C5—C6	0.5 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O2^i	0.84 (2)	1.90 (2)	2.731 (2)	169 (2)
N1—H1A···O2	0.86 (2)	2.24 (2)	2.867 (2)	130 (2)
N1—H1A···O4^ii	0.86 (2)	2.21 (2)	2.987 (2)	150 (2)
N1—H1B···O3^iii	0.88 (2)	2.11 (2)	2.976 (2)	168 (2)
C2—H2···O3	0.95	2.36	2.805 (2)	108
C5—H5···O1	0.95	2.37	2.709 (2)	100

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