Effect of phenyl group

Individual substituent effects of phenyl groups in substituted methanes and ethanes are not additive either (278), but decrease with progressive substitution In methane derivatives the first a-SCS (144) is 23.5, file second (144 — 145) 20.7, and the third (145 — 146) 14.7 (278). Although these values differ markedly from those of corresponding methylated compounds (methyl instead of phenyl) (169), the tendencies are in good qualitative agreement in both cases. 

The considerable accelerating effect of the double bond as a consequence of the it-participation is by no mehns appreciably enhanced by introducing one or two phenyl groups into conjugation with a double bond. The authors believe this to preclude both the formation of an intermediate classical cation and the specific steric effects of phenyl groups. 

Cross-linked elastomers have been studied with regard to their moduli (particularly plateau values), effects of peroxide cross linking, adhesive interactions with atomic force microscopy tips, and the effects of phenyl-group modifications. Investigations on networks containing fillers include the effects of silica or polysilicate nanoparticles, zero... 

The results indicate that the monomer is mostly opened at the siloxane bond, linking the dimethylsiloxane units, e.g., at site c, as expected. However, a considerable fraction is opened also at site a (57). The above result is somewhat strange. Considering the two possible structures of the active propagation center, 10a and 10b, the latter should be disfavoured due to the inductive and steric effects of phenyl groups. 

The deactivating effect of phenyl group relative to a CCI3 group on s-triazines is noted below,but comparison with hydrogen as a substituent does not appear to have been reported in heterocycles. 

The stabilizing effects of vinyl groups (in allylic radicals) and phenyl groups (in benzyl radicals) are very significant and can be satisfactorily rationalized in resonance terminology ... 

A substantial intramolecular protective effect by phenyl groups in polymers is shown by the low G values for Hz and crosslinking in polystyrene (substituent phenyl) and in polyarylene sulfones (backbone phenyl), as well as many other aromatic polymers. The relative radiation resistance of different aromatic groups in polymers has not been extensively studied, but appears to be similar, except that biphenyl provides increased protection. Studies on various poly(amino acid)s indicate that the phenol group is particularly radiation resistant. 

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