Marc Zimmermann¹, Dennis Domke¹, Michael Schween^1,

This article first describes photochemical bromination reactions of two different reactants proceeding via electron septet intermediates according to the radical substitution reaction mechanism (S_R). The case comparison is intended to enable learners – high school or university first-year organic chemistry students – to work out the concept of hyperconjugation, which is very significant for organic chemistry, by intertwining experimental results and theoretical interpretation (of free radical intermediates) closely. Since students often do not succeed in transferring concepts they have already learned from one mechanism to another, the second step will be to transfer and apply the concept of hyperconjugation to carbenium ions as reactive intermediates by means of an analogous experimental case comparison of first-order nucleophilic substitution reactions (S_N1).

hyperconjugation, concept development, concept transfer and application, contrasting cases, reaction mechanisms