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As part of a study having for its object the examination of the oxygen-carrying properties of chelate compounds of the type exemplified by salicylaldehyde ethylenediimine cobalt ("Salcomine") (I) CH2-CHp I I CH-N N=CH a large number of substances were prepared and tested in an effort to determine the structural requirements for activity and to discover chelates with oxygencarrying properties superior to those of I. Among the practical improvements sought were (a) greater stability than Salcomine in repeated passage through the cycle of oxygenation and deoxygenation; (b) greater oxygen capacity (over the capacity of one atom of oxygen per mole of chelate possessed by Salcomine) ; and (e) increased rates of oxygenation and deoxygenation under conveniently atlainable temperature and pressure conditions.In pursuing these objectives modifications were made in the structure of I by using polyamines other than ethylenediamine, using substituted salicylaldehydes or other substances of related structures, and using other metals in place of cobalt. Most of the substances used in preparing the many analogs of I studied were well-known compounds, many of them prepared in this laboratory by established methods.2 In a number of cases, however, compounds hitherto, unreported were required. The syntheses of a number of these are described in this paper. One of the ends sought in this work was to increase the proportion of metal in the complexes and thus to increase the percentage yield of oxygen obtained when these substances are used as reversible oxygen carriers. One of the possible means to this end was to use in place of salicylaldehyde compounds containing two o-hydroxyaldehyde groupings per benzene nucleus. Only one such com-1 The work described in this paper was carried out as part of a program of research under Division 11, Section 1, of the National Defense Research Committee, under a contract between the Office of Scientific Research and Development and the University of California.2 All of the final chelate compounds were prepared and tested in other laboratories, with which we collaborated. Presumably much of this work will be reported elsewhere. 741

Ozonization of Allylic Systems 293 but are strongly dependent on degree of esterification, being highest for degree of esterification in the range 0.3 to 0.5. Enzyme-deesterified pectins form weaker ionic-bonded gels than do aciddeésterified pectins. Philadelphia, Pa.

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