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Posts Tagged ‘Resonance

Organic Chemistry for Marxists

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In chemistry, a substance is defined by its molecular structure. One substance, one structure: if you alter the structure, it is by definition a different molecule. But often things are not that simple.

When considering how some molecules react, it is often necessary to draw them as though they existed as two or more resonance forms. The thiocyanate ion drawn above has two resonance forms, one with the negative charge on the sulphur atom, one with it on the nitrogen. Some reactions occur at the S end, some at the N end. Resonance forms allow us to see  why: they occur wherever the negative charge is located.

When we draw resonance forms, it is important to understand what we are not saying. Neither of these forms really exists; what really exists is something like an average, with the negative charge existing partially over the S, partly over the N.

Resonance forms are convenient fictions that exist only in the minds of chemists, but they are good at allowing us to predict the outcomes of chemical reactions, so we still freely use them despite knowing they are not true representations of the real world.

Which is fine, apparently, unless you’re a Marxist.

In the Soviet Union in the late 1940s, some Soviet chemists declared that resonance forms were incompatible with Marxist theory and should not be used. Marx taught that only the material world was important, making these imaginary structures at best a seductive illusion that would retard progress in the field, and at worst a threat to the very fabric of society.

Whether these scientists truly failed to recognise the models’ utility or were simply trying to gain personal advancement through a display their patriotic Marxier-than-thou attitude is debatable; nevertheless, it grew into a major controversy, probably much to the embarrassment of more practical people who just wanted their reactions to work. A conference was held in 1951 to lay down the law once and for all. The result was a report that stated that the theory of resonance, together with certain unwelcome theories from physics and biology “present a united front in the fight of reactionary bourgeois idealism against materialism.”

Utility won out in the end, and the resonance theory eventually came to be recognised for what it is: a useful tool to understand the behaviour of molecules, depending on and representing reality, but not even pretending to be a perfect depiction of it. But throughout the 1950s in the Soviet Union, textbooks rarely dared to mention resonance.

The Marxist scientist declared that resonance forms were a just a model. And they were absolutely right. Where they went wrong is thinking this was a bad thing.



Drawn from “A Soviet Marxist View of Structural Chemisty: The Theory of Resonance Controversy” by Loren R Graham:


Written by The S I

August 17, 2011 at 11:59 pm