Another
curious point which Ladenburg has lately proved is that cadaverine
(one of the products of flesh decomposition) is identical with
pentamethylinediamine, and that its imine is the same as piperidine.
The synthesis of coniine by Ladenburg is one of the most notable
achievements of modern chemistry. He at first supposed that this
alkaloid was piperidine in which two hydrogen atoms were replaced by
the isopropyl radical (C_{3}H_{7}), its formula being taken as
C_{5}H_{9}(C_{3}H_{7})NH. But he has since changed his view, as will
be seen from what follows. In its synthesis 1,000 grammes of picoline
were first converted into alphapicoline, 380 grammes being obtained.
This was heated with paraldehyde, whereby it was converted into
allylpyridine (48 grammes), and this by reduction with sodium yielded
alpha-propylpyridine, a body in almost every respect identical with
coniine. The more important difference was its optical inactivity, but
he succeeded in splitting up a solution of the acid tartrate of the
base by means of _Penicillium glaucum_. Crystals separated which had a
dextro-rotatory power of [_a_]_{D} = 31 deg. 87' as compared with the
[_a_]_{D} = 13 deg. 79' of natural coniine. This brief account conveys but
a faint idea of the difficulties which were encountered in these
researches.
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