Organic synthesis and the unification of chemistry--a reappraisal.

Abstract

Proclaiming Louis Pasteur as the “Founder of Stereochemistry”, the distinguished Scottish chemist, Crum Brown, addressing a late nineteenth-century audience of Edinburgh savants, drew attention—as Pasteur had incessantly done—to the intimate relationship between living organisms and the optical activity of compounds sustaining them. It seemed to Crum Brown “that we must go very much further down in the scale of animate existence than Buridan's ass, before we come to a being incapable of giving practical expression to a distinct preference for one of two objects differing only in being one to the right and the other to the left”. Crum Brown's lecture must have been entertaining, but it was also motivated by a serious desire to do justice to a particular assertion of Pasteur—an assertion which had, moreover, been misunderstood and dismissed by no less a chemical genius than Wilhelm Ostwald. Writing at a time when the majority of his colleagues were stressing the resemblances between inorganic and organic compounds, Pasteur had insisted that he “could not point out the existence of any more profound distinction between the products formed under the influence of life and all others” than that “artificial products have … no molecular asymmetry”. Pasteur was obliged to concede that the chemist might produce enantiomorphic pairs of isomers, but without resorting to a manual separation of crystals he was powerless to imitate Nature's performance, powerless to fabricate by chemical means a separate optical isomer, divorced from its partner. Now it was not only Crum Brown who felt that chemists had brushed aside this proposition of Pasteur. In his 1898 Presidential Address to the chemical section of the British Association, Professor F. R. Japp also complained that the possible vitalistic implications of Pasteur's distinction between natural and artificial products had been misapprehended or tacitly ignored.