Acta Crystallographica Section B

Volume 65, Part 4 (August 2009)

research papers

Acta Cryst. (2009). B65, 509-515 [ doi:10.1107/S0108768109018898 ]

On the polymorphism of benzocaine; a low-temperature structural phase transition for form (II)

E. J. Chan, A. D. Rae and T. R. Welberry

Abstract: A low-temperature structural phase transition has been observed for form (II) of benzocaine (BZC). Lowering the temperature doubles the b-axis repeat and changes the space group from P2₁2₁2₁ to P112₁ with [gamma] now 99.37 °. The structure is twinned, the twin rule corresponding to a 2₁ screw rotation parallel to a. The phase transition is associated with a sequential displacement parallel to a of zigzag bi-layers of ribbons perpendicular to b*. No similar phase transition was observed for form (I) and this was attributed to the different packing symmetries of the two room-temperature polymorphic forms.

Keywords: polymorphism; pharmaceuticals; phase transitions; twinning.


	Structure factor file (CIF format) (77.0 kbytes) [ doi:10.1107/S0108768109018898/so5027Isup2.hkl ] Contains datablock I

	Structure factor file (CIF format) (60.1 kbytes) [ doi:10.1107/S0108768109018898/so5027IIsup3.hkl ] Contains datablock II

	Structure factor file (CIF format) (376.8 kbytes) [ doi:10.1107/S0108768109018898/so5027IIIsup4.hkl ] Contains datablock III

Notes:

To open or display or play some files, you may need to set your browser up to use the appropriate software. See the full list of file types for an explanation of the different file types and their related mime types and, where available links to sites from where the appropriate software may be obtained.

The download button will force most browsers to prompt for a file name to store the data on your hard disk.

Where possible, images are represented by thumbnails.

Search: From to Advanced search