Theory of Molecular Volumes. 351 



If the compound possessed the " enolic " structure 



. 

 CH 3 • C=CH- C^ (C 6 H 10 O n On 



OH ° Ci H * 



it would show a similar volume to that of Ethyl Butyrate, 







CH 3 . CH 2 . CH 2 . Of 



OCVH 





since 0' = 2H and the double bond has no effect on the 

 volume {vide pro x.). 



The volume of the latter is 150*5, which is different from 

 the observed value by 153" 7 — 150*5 = 3*2. Since acetyl 

 (carboxylic oxygen) =3H, the difference between 0" (11*0) 

 and ; (7*4) =3*6, a result which accounts for the difference 

 in volume between Acetoacetic Ester and Ethyl Butyrate. 



No one would be inclined to doubt the existence of an 

 additive factor in molecular volumes from the evidence 

 adduced. This has previously been recognized, but the 

 agreement between calculation and experiment is closer than 

 on the basis of the old numbers. Since Ring compounds, 

 like the Aromatic, frequently possess side chains which are 

 of similar constitution to those of Paraffin derivatives, it will 

 be useful to give a few examples showing how such com- 

 pounds are dealt with. 



The old numbers = 11*0, H = 5'5 were obtained by a 

 comparison of Paraffin derivatives and Aromatic compounds, 

 and thus are inaccurate. It will be found that the change 

 in constitution marked by the arrangement of the 6 carbon 

 atoms in a ring results in a very considerable compression of 

 the molecule, without however affecting the relative volumes 

 of C and H, which is a general principle. 



In Paraffin derivatives at the B.P. 



VC.H M 



VC 7 H 14 



139-93 

 154-8 



V C 6 H M . 

 C 6 H 24 . 



A for Ho 



.... 139-93 

 .... 132-40 



A for 0... 



14*87 



7*53 



Thus 



C = 4H, 







or H 2 = V 



C 6 H 14 -GCH 



2 = 139-90- 



132-6 = 7-3, 



and since CH 2 = 



22-1, 0- 



= 14-8, 



Inch are similar 

 The relation = 



numbers. 



= 4 H is thus s 



i fact. 





