C.S.MARVEL A N D N. TARKOY
832
[CONTRIBUTION FROM THE
VCJ1. 80
NOYESCHEMICAL LABORATORY, UNIVERSITY
OF I L L I N O I S ]
Heat Stability Studies on Chelates from Schiff Bases of Salicylaldehyde Derivatives.
I1 BY
c. s. h f A R V E L AND N. TARKOY' RECEIVED OCTOBER5, 1957
The influence of the sulfone group in the 5,5'-position of a his-salicylaldehyde Schiff base upon the heat stabilities of the corresponding metal chelates was studied, Best stabilities were found in the nickel and cadmium chelates, showing, respectively, 0.09 and 0.27% weight loss per hour at 250' in air, the corresponding values for 300" being 1.1 and 1.3%. The greatly enhanced heat stability of these chelates as compared with the 5,5'-methylene-bis-salicylaldehgde series was interpreted in terms of increased acidity of the phenolic groups, The heat degradation of the cobalt, nickel, iron and cadmium chelates seems t o be a thermal process.
I n continuation of former work2 on metal chelated aromatic polymeric Schiff bases of type I as an approach to the synthesis of heat-stable polymeric materials, the present study deals with the influence of electron-withdrawing groups, such as X in foriiiul:~I , on the stability of these chelates.
monomer of type I where X = -SO,-. This group is sufficiently electron withdrawing, is known for high thermal stability6 and seems also sterically suitable.' Attempts to introduce aldehyde groups into the 3- :md :
