Abstract
As part of a basic study of the secondary Li electrode, the reactions of tetrahydrofuran (THF) with Li have been evaluated. Tetrahydrofuran is reductively cleaved by Li to lithium n‐butoxide 
, the enolate anion of acetaldehyde, and ethylene. The 
anion is reduced by Li to 
which further reacts with 
to form a brown film on Li. The brown film appears to be composed of an 
polymer and 
. These products were observed to form irrespective of electrolyte purification procedure. In fact, highly purified media reacted most readily with Li presumably due to the absence of protective film‐forming gases such as 
and 
. Extended preelectrolysis of 
electrolytes formed large amounts of basic material, as expected. The same experiment performed on 
electrolyte revealed essentially no change in the medium's pH. Apparently, the
from 
and the basic material from THF degradation effectively neutralize each other. A mechanism which accounts for Li‐cyclic ether reactivity is proposed.