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Structures of the Optically Active Monofluoro-Substituted Mandelic Acids: Relation to Their Racemic Counterparts and Thermochemical Properties

Structures of the Optically Active Monofluoro-Substituted Mandelic Acids: Relation to Their... The crystal structures of the three optically active monofluoro-substituted mandelic acids (C8H7FO3, Mr = 170.14) have been determined from low-temperature X- ray diffraction data. (R)-(-)-ortho-Fluoromandelic acid, monoclinic, P21, a = 8.356 (2), b = 10.842 (2), c = 8.544 (2) A, = 94.13(2)Degrees, Z = 4, m.p. 361.8 (5) K. (R)-(-)-meta-Fluoromandelic acid, monoclinic, P21, a = 8.493 (3), b = 5.8426 (7), c = 15.628 (3) A, = 104.10(2)Degrees, Z = 4, m.p. 394.2 (5) K. (R)-(-)-para-Fluoromandelic acid, monoclinic, C2, a = 8.464 (2), b = 5.8518 (13), c = 15.868 (2) A, = 107.56 (2)Degrees, Z = 4, m.p. 425.8 (5) K. The hydrogen-bonding schemes in these structures have been analysed and compared with the hydrogen-bond patterns in the equivalent racemic acids. The structural data from six other structures were included in the analysis, which led to a general description of the great variety of hydrogen-bond motifs observed in -hydroxycarboxylic acids. Differences between crystal structures of the racemic and enantiomerically pure fluoromandelic acids have been related to their melting enthalpies. The observed differences in the binary phase diagrams of the three acids can be rationalized in terms of their structural differences. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Acta Crystallographica Section B: Structural Science International Union of Crystallography

Structures of the Optically Active Monofluoro-Substituted Mandelic Acids: Relation to Their Racemic Counterparts and Thermochemical Properties

Structures of the Optically Active Monofluoro-Substituted Mandelic Acids: Relation to Their Racemic Counterparts and Thermochemical Properties

Acta Crystallographica Section B: Structural Science , Volume 53 (2): 280 – Apr 1, 1997

Abstract

The crystal structures of the three optically active monofluoro-substituted mandelic acids (C8H7FO3, Mr = 170.14) have been determined from low-temperature X- ray diffraction data. (R)-(-)-ortho-Fluoromandelic acid, monoclinic, P21, a = 8.356 (2), b = 10.842 (2), c = 8.544 (2) A, = 94.13(2)Degrees, Z = 4, m.p. 361.8 (5) K. (R)-(-)-meta-Fluoromandelic acid, monoclinic, P21, a = 8.493 (3), b = 5.8426 (7), c = 15.628 (3) A, = 104.10(2)Degrees, Z = 4, m.p. 394.2 (5) K. (R)-(-)-para-Fluoromandelic acid, monoclinic, C2, a = 8.464 (2), b = 5.8518 (13), c = 15.868 (2) A, = 107.56 (2)Degrees, Z = 4, m.p. 425.8 (5) K. The hydrogen-bonding schemes in these structures have been analysed and compared with the hydrogen-bond patterns in the equivalent racemic acids. The structural data from six other structures were included in the analysis, which led to a general description of the great variety of hydrogen-bond motifs observed in -hydroxycarboxylic acids. Differences between crystal structures of the racemic and enantiomerically pure fluoromandelic acids have been related to their melting enthalpies. The observed differences in the binary phase diagrams of the three acids can be rationalized in terms of their structural differences.

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Publisher
International Union of Crystallography
Copyright
Copyright (c) 1997 International Union of Crystallography
ISSN
0108-7681
eISSN
1600-5740
DOI
10.1107/S0108768196013419
Publisher site
See Article on Publisher Site

Abstract

The crystal structures of the three optically active monofluoro-substituted mandelic acids (C8H7FO3, Mr = 170.14) have been determined from low-temperature X- ray diffraction data. (R)-(-)-ortho-Fluoromandelic acid, monoclinic, P21, a = 8.356 (2), b = 10.842 (2), c = 8.544 (2) A, = 94.13(2)Degrees, Z = 4, m.p. 361.8 (5) K. (R)-(-)-meta-Fluoromandelic acid, monoclinic, P21, a = 8.493 (3), b = 5.8426 (7), c = 15.628 (3) A, = 104.10(2)Degrees, Z = 4, m.p. 394.2 (5) K. (R)-(-)-para-Fluoromandelic acid, monoclinic, C2, a = 8.464 (2), b = 5.8518 (13), c = 15.868 (2) A, = 107.56 (2)Degrees, Z = 4, m.p. 425.8 (5) K. The hydrogen-bonding schemes in these structures have been analysed and compared with the hydrogen-bond patterns in the equivalent racemic acids. The structural data from six other structures were included in the analysis, which led to a general description of the great variety of hydrogen-bond motifs observed in -hydroxycarboxylic acids. Differences between crystal structures of the racemic and enantiomerically pure fluoromandelic acids have been related to their melting enthalpies. The observed differences in the binary phase diagrams of the three acids can be rationalized in terms of their structural differences.

Journal

Acta Crystallographica Section B: Structural ScienceInternational Union of Crystallography

Published: Apr 1, 1997

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