4 Lap worth, Latent Polarities of Atoms 



etc., where it is clear that the doubly linked carbon atoms 

 and the carbonyl group are to be labelled as in the scheme 



C=C-C=0 

 + — + — 



and 

 CN-H 



— + 



-c-c-oo 



I 



CN H 



As a considerable step in advance of this may be quoted 

 the fact, foreseen and established by the writer eighteen years 

 ago, that the hydrogen atoms of the y-position in ethyl crotonate 

 have properties precisely corresponding with those of the hydrogen 

 atoms in the a-position in saturated carbonyl compounds 

 (Trans. Chem. Soc, 1901, 79, 1273), so that the formulation 

 H-CH 2 CH :CH*COOEt must be adopted to express this. 

 + - 



Combining this with the scheme developed immediately 

 above there results the extended form : 



OEt 



H - CH 2 - CH = CH - C = O, 



+ - + - + - 



and although, at present, it is difficult to find direct justifica- 

 tion for the implied relative polarities of the two bracketed 

 carbon atoms, the weight of evidence in favour of the con- 

 clusion that the carbonyl group tends to develop alternate 

 — and + latent polarities in a chain of atoms is so considerable 

 that it seems reasonable to proceed with the further develop- 

 ment of the principle in the confident belief that this solitary 

 hiatus will disappear in due course. 



The polar properties of crotonic aldehyde are no doubt 

 to be represented by a precisely similar scheme, and the 

 more recent work of Raper and of Mrs. MacLean on the 

 synthetic production, from aldol and crotonic aldehyde, of 

 compounds containing straight chains of eight carbon atoms 

 furnishes evidence of this, and suggests that the biochemical 

 synthesis of fatty acids is regulated by the principle of 

 alternating latent polarities. 



2 CH 3 -CH : CH-CHO->CH 3 -CH : CHCHCH 2 GH : CHCH : 6 



I 

 OH 



- + 



It must now be evident from the cases already dealt with,, 

 that the whole order of alternating latent polarities is determined 



