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Untersuchungen in der Benztropylium‐Reihe. IV. Die Bildungsenthalpien des 2,7‐Dimethyl‐4,5‐benztropons, des 2,7‐Dodecamethylen‐4,5‐benztropons und des 2,7‐Pentamethylen‐4,5‐benztropons
Author(s) -
Schmid R. W.,
KlosterJensen Else,
Kováts E.,
Heilbronner E.
Publication year - 1956
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.19560390322
Subject(s) - chemistry , coplanarity , tropone , steric effects , methylene , medicinal chemistry , standard enthalpy of formation , stereochemistry , geometry , mathematics
Abstract The enthalpies of formation of 2,7‐dimethyl‐4,5‐benzotropone (I), 2,7 ‐ pentamethylene‐ 4,5 ‐ benzotropone (III) and 2,7 ‐ dodeca‐methylene‐ 4,5‐benzotropone (II) have been determined by combustion calorimetric methods. The loss of 36 kcal/moles in delocalisation energy for III relative to I and II is due to the steric inhibition of coplanarity of the 4,5‐benzo‐tropone‐system in III.