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Published on: October 31, 2019
On the polymorphism of benzocaine; a low-temperature structural phase transition for form (II)
Eric J Chan1, A David Rae, T Richard Welberry
1Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia. echanj@rsc.anu.edu.au
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 P2(1)2(1)2(1) to P112(1) with gamma now 99.37 degrees. The structure is twinned, the twin rule corresponding to a 2(1) 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.
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