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Ungewöhnliches Strukturmerkmal kristalliner Phthalsäure
Author(s) -
Ermer Otto
Publication year - 1981
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19810640623
Subject(s) - chemistry , planarity testing , phthalic acid , crystal structure , torsion (gastropod) , dihedral angle , molecule , crystallography , benzene , ring (chemistry) , stereochemistry , hydrogen bond , organic chemistry , medicine , surgery
Unusual Structural Feature of Crystalline Phthalic Acid In crystalline phthalic acid the strain resulting from repulsion between the carboxylic groups is only partially relieved by rotating these groups out of the plane of the benzene ring around the (HOO)CC bonds. This is also achieved through a surprisingly large deviation of 20.3 (1)° from planarity of the (HOO)CCCC (OOH) torsion angle, as confirmed by an accurate redetermination of the crystal structure. This torsion angle may be smaller in the free molecule, i.e. packing forces appear at least partly responsible for its high value in the crystal.