The Monoclinic Form of Acetaminophen at 150K

The crystal structure of the anti-inflammatory agent acetaminophen [N-(4-hydroxyphenyl)acetamide, C₈H₉NO₂] has been refined using a Siemens SMART three-circle automatic diffractometer with a charge-coupled device (CCD) detector at 150 K. Monoclinic crystals of acetaminophen were grown from ethanol solution (m.p. 443-444 K). The crystal structure exhibits two kinds of hydrogen bonds [2.656 (2) Å, OH donates to O=C; 2.914 (2) Å, HO accepts from HN]. The molecules form a pleated sheet parallel to the (101) plane. The sheets are stacked along [010]. The molecules within a stack are held together by van der Waals interactions. Molecules from different sheets form `head-to-tail'-type dimers.

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