[4-(Methylsulfonyl)phenyl]acetic acid

In the crystal structure of the title compound, C9H10O4S, centrosymmetrically related molecules are linked into dimers by intermolecular O—H⋯O hydrogen bonds. Unconventional C—H⋯O hydrogen-bond interactions are also present, connecting dimers into a three-dimensional network.

In the crystal structure of the title compound, C 9 H 10 O 4 S, centrosymmetrically related molecules are linked into dimers by intermolecular O-HÁ Á ÁO hydrogen bonds. Unconventional C-HÁ Á ÁO hydrogen-bond interactions are also present, connecting dimers into a three-dimensional network.

Comment
The title compound, C 9 H 10 O 4 S, and its substituted derivatives have been found to possess an auxin-like activity (Parimalan et al., 2008;Giridhar et al., 2006). These compounds, which are predominantly found in fruits, can be used in the synthesis of pharmaceutical intermediates, some perfumes and non-steroidal anti-inflammatory drugs.
In the molecule of the title compound ( Fig. 1), bond lengths and angles agree well with those observed in similar compounds (Guo & Yuan, 2006;Hartung et al., 2004;Hodgson & Asplund, 1991). The S═O bond lengths within the SO 2 Me group are not significantly different, with an average value of 1.4366 (10) Å. The average bond length for the two C-S bonds is 1.762 (3) Å. In the crystal packing, centrosymmetrically related molecules are linked into dimers by intermolecular O-H···O hydrogen bonds (Table 1) generating an eight-membered ring of graph set R 2 2 (8) (Bernstein et al., 1995). The dimers are further linked into a three-dimensional network by unconventional C-H···O hydrogen bonding interactions. The corresponding phenylacetic acid derive without the SO 2 Me group (Hartung et al., 2004) forms helical columns of single enantiomers linked by hydrogen bonds between the acidic proton of one molecule and the methoxy O atom of a neighbouring molecule, to give an overall racemic structure.
Experimental 1-(4-Methanesulfonyl-phenyl)-ethanone (20 mmol), morpholine (60 mmol) and elemental sulfur (40 mmol) were added in a round-bottom flask and refluxed for 2 h at 398 K. A 3N solution of NaOH (20 ml) was then added, and the reaction mixture refluxed for an additional 30 min. After cooling, the mixture was filtered and the filtrate was acidified with HCl to pH 6. The solution was again filtered off and washed with ethyl acetate. The resulting aqueous fraction was finally acidified with diluted HCl, to yield the pure product as a white solid. Crystals suitable for X-ray analysis were obtained by slow evaporation of an ethanol/water (1:1 v/v) solution.

Refinement
All H atoms were placed at calculated positions and constrained to ride on their parent atoms, with O-H = 0.82 Å, C-H = 0.93-0.97 Å and with U iso (H) = 1.2 U eq (C) or 1.5 U eq (C, O) for hydroxy and methyl H atoms. Fig. 1. The molecular structure of the title compound, with the atom-labeling scheme and 50% probability displacement ellipsoids. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.