Lupton

Swain C G and E C Lupton 1968. Field and Resonance Components of Substituent Effects. Journal of tl American Chemical Society 90 4328-4337. 

Table 15 contains the C chemical shifts of some selected indazoles. The major difference between indazoles and isoindazoles lies in the chemical shifts of carbons C-3 and C-7a. The substituent chemical shifW (SCS) induced by the substituent in position 3 have been discussed using an empirical model (770MR(9)716). The model that gives the best results, AS = OS + + c and 3i are the Swain-Lupton parameters and 5 is the Schaefer... 

Hansch-Leo hydrophobic substituent parameter Hammett sigma constants Modtried Swam Lupton constants... 

Fujita and Nishioka have attempted to place ortho effects on the same numerical scale as meta and para effects. They assume that the normal ortho electronic effect can be represented by the standard substituent constant appropriate to the reaction (cr, cr", cr, cr°), that the steric effect is given by E , and that the proximity effect is measured by the Swain-Lupton Then a multiple LFER is written... 

Lupton, D., Aldinger, F. and Schulze, K., Niobium in Corrosive Environments, Niobium 81, Proceedings of the International Symposium, San Francisco, edited by Harry Stuart, The Metallurgical Society of AIME, 533-560, (1981)... 

Lupton, D. and Aldinger, F., Possible Substitutes for Tantalum in Chemical Plant Handling Mineral Acids, in Trends in Refractory Metals, Hard Metals, and Special Materials and Their Technology, Proceedings of the 10th Plansee Seminar, Reutte, Austria 101-130 (1981)... 

As suggested by Roberts and Moreland many years ago (1953), the acidity constants of 4-substituted bicyclooctane-l-carboxylic acids provide a very suitable system for defining a field/induction parameter. In this rigid system the substituent X is held firmly in place and there is little possibility for mesomeric delocalization or polarization interactions between X and COOH (or COO-). Therefore, it can be assumed that X influences the deprotonation of COOH only through space (the field effect) and through intervening o-bonds. On this basis Taft (1956, p. 595) and Swain and Lupton (1968) were able to calculate values for o and crR. 

Here we will not discuss these problems and the intriguing observation that am and strong correlation which is, however, difficult to explain (reviews Charton, 1981 Cook et al., 1989 Hansch et al., 1991). These questions were intensively studied in the 1970s and 1980s, leading gradually to the development of field and resonance parameters denoted by F and R respectively (after an original proposal of Swain and Lupton, 1968), which can be considered as independent of each other. The secondary parameters R + and R reflect the potential for an additional mesomeric donor-acceptor interaction (as in 7.7, and the opposite type with a donor instead of NQ2 and the reaction site as acceptor). 

Analogous DSP treatments, but with differences with regard to the basis of the calculations, were proposed by Charton (1981) and by Swain s group (Swain and Lupton, 1968 Swain et al., 1983). The potential significance of polarizability effects resulted in a triple substituent parameter treatment (Taft, 1983). A slightly different... 

The only groups in Table 9.5 with negative values of CT/ are the alkyl groups methyl and tert-butyl. There has been some controversy on this point. One opinion is that CT/ values decrease in the series methyl, ethyl, isopropyl, /ert-butyl (respectively, — 0.046, —0.057, —0.065, —0.074). Other evidence, however, has led to the belief that all alkyl groups have approximately the same field effect and that the a/ values are invalid as a measure of the intrinsic field effects of alkyl groups. Another attempt to divide ct values into resonance and field contributions is that of Swain and Lupton, who have shown that the large number of sets of ct values (cTm, <3p, a, a+, CT/, csp etc., as well as others we have not mentioned) are not entirely independent and that linear combinations of two sets of new values F (which expresses the field-effect contribution) and R (the resonance contribution) satisfactorily express 43 sets of values. Each set is expressed as... 

Swain and Lupton (2q) have recently presented a modified form of the dual substituent parameter treatment. In this treatment, the p/parameters were... 

Table IV lists comparative SD and / values for fittings of all of the reactions of Table II and III with each of the gr scales derived in this paper. The comparison includes figures for fittings with F and R values of Swain and Lupton (S L) and fitting with the Hammett equation. We believe the results given in Table IV provide a clear confirmation of the uniqueness and limited generality of the o/2(ba) scale. Very consistently, the fit achieved by the or (BA) scale is shown in Table IV to be superior by significant factors to that achieved by any of the other scales or by the simple op treatment. This fact is clearly reflected in the overall / values and the similarly weighted root-mean-square / values, F = y/lfnif lN, sum taken over all reactions. The value of F is. 067 for the basis sets of Table II (compare with overall / of. 058). The comparable F values are. 140 for Or, . 088 for S L, and. 155 for 0(p) with the data differences as explained in Table IV. For all sets of Table IV, the corresponding figures are. 073 for o (ba). -143 for a%, . 097 for S L, and. 209 for 0(py...

According to earlier considerations, the effects of m-substituents have been considered generally to be of the sigma zero type. Swain and Lupton have questioned this conclusion. We have proceeded in the following manner to obtain evidence on the issue. From all the known data, 11 sets of meta substituent reaction series data were found which meet the minimum substituent criterion for basis sets. These reactions are listed in Table XI, with the pT .Pr. ... 

A rival analysis of substituent effects into field (equivalent to inductive) and resonance components was proposed many years ago by Swain and Lupton °, was later slightly corrected by Hansch and colleagues and fairly recently has been substantially modified... 

A table of correlations between seven physicochemical substituent parameters for 90 chemical substituent groups has been reported by Hansch et al. [39]. The parameters include lipophilicity (log P), molar refractivity MR), molecular weight MW), Hammett s electronic parameters (a and o ), and the field and resonance parameters of Swain and Lupton F and R). 

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