Interaction Factors Special Ortho Effects

H-bonding occurs intramolecularly between ortho-substituted donors and acceptors like in o-nitrophenol. In terms of H-bonding between aromatic ortho substituents, the octanol-water system seems to be sensihve to a very restricted class. The only clear-cut cases result from a carbonyl group directly attached to the ring acting 

The AGD/LogP algorithm [54, 55] is based on logP contributions of separate atoms, structural fragments and intramolecular interactions between different fragments. These contributions have been derived from an ACD/Labs internal database of over 18 400 structures for which one or more experimental log P values have been published. The log P increments are stored in the internal databases of logP contributions  

The database of Garbon Atom Gontribuhons contains increments for different types of carbons that are not involved in any funchonal group. They differ by their state of hybridization (sp, sp sp ), number of attached hydrogens or branching (primary, secondary, tertiary and quaternary), cyclization (cyclic and noncyclic) and aromaticity (nonaromahc, aromatic and fused aromatic). 

If during log P calculahon, fragmental or intramolecular interaction contribu-hons are not found in the internal databases, they are calculated by special secondary algorithms. In such cases the calculated logP values are provided with larger uncertainty limits ( 0.6 or greater). 

The careful analysis of fragmental (/ and aliphatic interaction (aliph-F.jit) increments [54] is a strong point of ACD/LogP. Fragmental increments are represented as a sum of smaller (atomic and bond) increments and aliphatic interactions as a product of Hammett-type constants (F,j = These secondary relahons 

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