( 466 ) 
wards, Marckwaup *) defended his standpoint in such a manner that 
no further controversyhas taken place. 
Although the theoretical aspect of the question might be considered 
as solved, it still occurred to me that from an experimental point 
of view, the synthesis might be capable of some improvement. 
MareKkwarp starts from methylethylmalonic acid; of this the acid 
brucine salt is made in which now occurs an asymmetric carbon atom in 
CH, 
“the residue of the methylethylmalonic acid: CO,H .C———CO,H . Br. 
Non, 
Owine to the influence of the active brucine, the two possible 
forms will not be produced in equal quantities and as a transfor- 
mation between the two forms is possibly owing to the ionisation, 
the solution, on evaporation, will only deposit one salt, as during the 
crystallisation the equilibrium between the two forms is constantly 
being restored. The active brucine salt is now heated at 170° when 
earbon dioxide is eliminated and the brucine salt of methylethyl- 
acetic acid is formed. As this elimination of carbon dioxide will 
take place exclusively, or nearly so, at the free carboxyl group, the 
result will be a brucine salt of active methylethyl acetic or in other 
words /-valerie acid. By acidification with dilute sulphuric acid, distil- 
lation in steam and rectification, Marckwa.p obtained a product which 
in a 10 e.m. tube showed a rotation of [elp = —1°.7 which corre- 
sponds with not quite 10°/, of /-valeric acid. Marckwarp attributes 
this low yield of active material to the high temperature employed 
(170°), which may have caused atomic shiftings. 
The problem appeared to me of too great importance not to try 
and obtain a better yield of active valeric acid by altering the 
modus operandi. The idea struck me that it ought to be possible to 
considerably lower the temperature at which carbon dioxide is 
eliminated and thus remove one cause of atomic shifting. 
In my preliminary experiments 1 used the methylethyimalonic acid 
itself which melts at 118° and of which it is stated in the literature 
that it rapidly loses its carbon dioxide at 180°. As a rule the acids, 
which possess two carboxyl groups attached to one carbon atom, 
lose carbon dioxide when heated above their melting point; we rarely 
find, however, in the literature cases where this temperature is correctly 
indieated and very often, at least in the case of substances melting at 
low temperature, the uniform temperature of 170°—180 is accepted. 
The methylethylmalonic acid was now heated in vacuo at 130° in 
1) Ber. 37, 1368. 
