MRC National Institute for Medical Research, London
Science for Health
Historical note
This satirical comment on Kekule's proposed structure for Benzene provides an early example of the role of monkeys in the service of science. It was published in 1886 in a supplementary issue of the Journal of the German Chemical Society (Berichte der Deutschen Chemischen Gesellschaft).
On the Constitution of Benzene by F. W. Findig
"For some time the constitution of benzene has engaged the attention of the greatest living chemists. In these circumstances I cannot refrain from joining in the discussion of the problem. It is clear that the viewpoint from which the constitution of benzene has hitherto is short-sighted and unsatisfactory. I have made a fresh start, setting out from the principle that the sciences are ordained to render the each other mutual help. I have discovered that zoology is capable of rendering the greatest service in clearing up the behaviour of carbon atom. I am going to try to make this clear to the reader, although I doubt whether he will be able to grasp the idea."
"Just as the carbon atom has 4 affinities, so the members of the family of four–handed animals possess four hands, with which they seize other objects and cling to them. If we now think of a group of six members of this family, e.g. Macacus cynocephalus, forming a ring offering each other alternately one and two hands, we reach a complete analogy with Kekule’s benzene-hexagon: (Fig. 1)."
"Now, however, the aforesaid Macacus cynocephalus, besides its own four hands, possesses also a fifth gripping organ in the shape of a caudal appendix. By taking this into account, it becomes possible to link the 6 individuals of the ring together in another manner. In this way, one arrives at the following representation: (Fig. 2)."
It appears to me highly probable that a complete analogy exists between Macacus cynocephalus and the carbon atom. In this case, each C–atom also possesses a caudal appendix, which, however, cannot be included among the normal affinities, although it takes part in the linking. Immediately this appendix, which I call the ‘caudal residual affinity’, comes into play, a second form of Kekule’s hexagon is produced; this, being obviously different from the first, must behave differently.
Thus, depending upon conditions, a benzene ring will assume one or other of these two forms, and will correspondingly possess a constantly changing constitution.
"It is impossible to conceive of a more beautiful example of tautomerism than the one facing us here. The hypothesis that a molecule is able to change its constitution, and rearrange itself comfortably, in accordance with the needs of the experimenter, belongs to the most magnificent conquests of the searching and critical spirit of man; this achievement, applied to the benzene theory, stands out as a brilliant guiding star to future research!"
Private Laboratory,
Schnurrenburg–Mixpickel. May 1886.
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