Loew considers that all substances which enter into combination with aldehyde or ketone groups must be poisonous to life generally. For instance, hydroxylamine, diamide and its derivatives, phenylhydrazine, free ammonia, phenol, prussic acid, hydric sulphide, sulphur dioxide and the acid sulphites all enter into combination with aldehyde.
So again the formation of imide groups in the aromatic ring increases any poisonous properties the original substance possesses, because the imide group easily enters into combination with aldehyde; thus piperidine (CH2)5NH is more poisonous than pyridine (CH)5N; coniine NH(CH2)4CH-CH2-CH2CH3, is more poisonous than collidine N(CH)4C-CH-(CH3)2; pyrrol (CH)4NH than pyridine (CH)5N; and amarin,[38]
, than hydrobenzamide
.
[38] Th. Weyl (Lehrbuch der organischen Chemie) states (p. 385) that amarin is not poisonous, but Baccheti (Jahr. d. Chemie, 1855) has shown that 250 mgrms. of the acetate will kill a dog, 80 mgrms. a guinea-pig; and that it is poisonous to fishes, birds, and frogs: hydrobenzamide in the same doses has no effect.
If the theory is true, then substances with “labile” amido groups, on the one hand, must increase in toxic activity if a second amido group is introduced; and, on the other, their toxic qualities must be diminished if the amido group is changed into an imido group by the substitution of an atom of hydrogen for an alkyl.