Received 19 May 2009
The title compound, also known as isopimaric acid, C20H30O2, was isolated from slash pine rosin. There are two unique molecules in the unit cell. The two cyclohexane rings have classical chair conformations. The cyclohexene ring represents a semi-chair. The molecular conformation is stabilized by weak intramolecular C-HO hydrogen-bonding interactions. The molecules are dimerized through their carboxyl groups by O-HO hydrogen bonds, forming R22(8) rings.
Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: AT2789 ).
This work was supported by the Natural Science Fund of Jiangsu Province under grant No. BK2006011 and the National Natural Science Foundation of China under grant No. 30571466.
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