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** Electronic and hydrophobic substituent constants **

Several electronic substituent constants were defined so as to represent both global and particular electronic effects. The a values obtained unambiguously from experimentally accessible data or from the many possible reaction series are called primary values and the corresponding set the primary standard. The o values derived from the primary values, by rescaling with modified q constants or correlation equations, are called secondary values and the corresponding set the secondary standard. [Pg.145]

Phosphorus electronic constants or are electronic substituent constants derived from the dissociation constants of dialkylphosphinic acids for substituent groups directly bonded to a phosphorus atom [Mastryukova and Kabachnik, 1971]. Assuming the alkyl groups exert only an inductive effect, these electronic constants can be distinguished as Oy inductive constant and o resonance constant [Charton and Charton, 1978]. [Pg.154]

Charton inductive constants - electronic substituent constants (O inductive electronic constants) [Pg.59]

Er radical parameter - electronic substituent constants E-state index - electrotopological state indices E-state fields electrotopological state indices E-state topological parameter (Tl ) [Pg.165]

Dewar-Grisdale approach electronic substituent constants (O field/resonance effect separation) [Pg.106]

FM method Dewar-Grisdale approach electronic substituent constants [Pg.179]

The charge transfer constant Cp (or group charge transfer) is an electronic substituent constant defined from the dissociation constant of a complex between tetracya-noethylene and an X-substituted parent compound [Hetnarski and O Brien, 1975] [Pg.154]

This definition is analogous to that used for a electronic substituent constants and accounts for the formation ability of a charge-transfer complex (CTC), such as the n -complex formation ability of aromatic systems. [Pg.154]

Fibonacci numbers -> symmetry descriptors (O Merrifield-Simmons index) fieid effect -> electronic substituent constants fieid-fitting alignment -> aiignment ruies [Pg.177]

Electronic information is combined with shape and steric information to characterize molecules in - charged partial surface area descriptors. Other approaches, different from those closely related to quantum-chemistry, refer to electronic descriptors, such as - electronic substituent constants, - electrotopological state indices, -> topological charge indices. - Reactivity indices and - resonance indices are also related to electronic descriptors. [Pg.144]

At first sight these may appear to be reasonably diverse in terms of their chemistry even though there are three halogens in the set. The it values are nicely spread out from hydrophilic (-1.23) to hydrophobic (1.44) but, unfortunately, so are the o values. In general there is no correlation between the hydrophobic substituent constant it and the electronic substituent constant o, but for this set the squared correlation coefficient between these two physicochemical properties is 0.95. In much the same way as the methyl-futile set is uninformative, so would this set be in terms of distinguishing electronic effects from hydrophobic effects in any QSAR model derived from it. [Pg.162]

See also in sourсe #XX -- [ Pg.986 ]

See also in sourсe #XX -- [ Pg.986 ]

** Electronic and hydrophobic substituent constants **

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