摘要：

The concept of activation volume derived from high pressure kinetics is shown to be an interesting parameter for the investigation of crowded transition states. In the free radical copolymerisation of maleic anhydride with mono- and poly-substituted olefins, increasing substitution of the comonomer involves greater pressure acceleration and hence more negative activation volumes and later transition states. This result may be of substantial synthetic importance. The concept of steric activation volume is introduced and a linear relationship between ΔV≠σ and the size of the substituent is developed.

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