Cyclopropanes energy content

Perhaps it is appropriate that this review be written some 100 years after the report of the first syntheses of cyclopropane derivatives by von Baeyer and Perkin and the formulation of the theory of ring strain by von Baeyer. The chemistry of small ring compounds has risen to prominence in the last 30 years. The popularity especially of the three-membered rings as intermediates in synthetic transformations has been due primarily to their latent energy content and to the almost endless number of chemical transformations in which these compounds and their derivatives can participate. New applications and novel permutations of the basic systems continue to appear at a fast pace. The fascinating chemistry... 

The inherent energy content of the cyclopropane ring demands that the method of introduction of a cyclopropyl subunit itself relies either on highly reactive intermediates or on irreversible or energetically, if not entropically, favored processes. Thus the synthesis of cyclopropane derivatives can be classified into three major categories 1,3 bond forming sequences (equation 4) carbene or carbenoid routes (equation 5) and rearrangement pathways (equations 6 and... 

In addition, the same studies that were carried out on the Pt(lll) crystal face result in reaction rates identical to those found on stepped crystal surfaces of platinum. These observations support the contention that well-defined crystal surfaces can be excellent models for polycrystalline supported metal catalysts. It also tends to verify Boudart s hypothesis that cyclopropane hydrogenolysis is an example of a structure-insensitive reaction. The initial specific reaction rates, which were reproducible.within 10%, are within a factor of two identical to published values for this reaction on highly dispersed platinum catalysts. The activation energies that were observed for this reaction, in addition to the turnover number, are similar enough on the various platinum surfaces so that we may call the agreement excellent. 

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