/ OCH2C6H5
C6H5C -- OCH2C6H5 --> C6H5CO2Na + C6H5CH2OCH2C6H5
\ ONa

Dibenzyl ether no doubt forms the chief impurity in benzyl benzoate.
Since the boiling-point of the former lies near that of the ester,
it is not removed during the process of purification by distillation.

The causes of variations in yield by the use of the older methods
can now be explained. When benzaldehyde is added TO THE ALCOHOLATE,
and especially when the latter is still warm, local overheating results;
in fact, the temperature may rise far above 100'0 with the result
that benzyl ether is formed. Simultaneously, the sodium benzylate
is converted into sodium benzoate, which is of no value for inducing
the desired reaction, and consequently very little benzyl benzoate
is obtained. The same side reactions explain the failure of this
experiment when the benzyl alcohol used in preparing the catalyst
(sodium benzylate) is contaminated with benzaldehyde.

The benzyl alcohol used in this preparation must be free
from impurities, especially aldehyde. One cc. dissolved in 50 cc.
of water and treated with a freshly prepared clear solution of
phenylhydrazine acetate should give no appreciable precipitate.
If it is not pure, it must first be treated with alkali
as described below.

The benzaldehyde should be titrated in order to determine its acidity.
If it is found to contain sufficient benzoic acid to react
with a considerable proportion of the sodium alcoholate, a poor