Die potentiometrische Bestimmung von Eisen mit Permanganat nach einer neuen Methode

Ohne Zusammenfassung     

Reflections on the Philosophy of Chemistry and a Rallying Call for Our Discipline

Biology in the popular mind remains tied to the doctrines of the struggle forsurvival and the survival of the fittest. Physics is linked to the heat deathof the universe – the inexorable march towards greater disorder,increasing entropy. Our field, on the other hand, focuses on orderedstructures, molecules and crystals, and their aggregates, and what holdsthem together. The philosophy of chemistry is centered on affinity,cohesion, the architecture of the very small, attraction, harmony, and, ifyou permit, beauty. Our discipline is the voice of the twenty-first century,a message, a clarion call of life, of hope. This paper addresses failures ofreductionist and deterministic claims in the face of the cussedness ofchemical facts. It will examine uncertainty principles, Edmund Whitaker'spostulates of impotence, Gerald Holton's themata, Isaiah Berlin's warning –and the wisdom of the Chinese. We can teach the world the need for humilityin the face of the wonder and mystery of our world. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis of 7-Deamidocephalosporin Lactone. Preliminary Communication

Condensation of azetidinone 1 with mercaptan 3 gave compound 5 . Bromination of 5 afforded two isomeric bromohydrins 11a and 11b which differ in the configuration at C(4). Acetylation and reduction with zinc and acetic acid of the above bromohydrins gave 7-deamidocephalosporin lactone ( 14 ).     

Synthese eines steroidischen 17 β-Pyrrolinons. Partialsynthetische Versuche in der Reihe der Herzgifte. 10.Mitteilung

Synthesis of a steroidal 17 β-pyrrolinone We describe the synthesis of 4′-(3 β-hydroxy-androst-5-ene-17 β-yl)-3′-pyrrolin-2′-one (6) starting from 3β-acetoxy-21-hydroxy-pregn-5-ene-20-one (1).     

Metal complexes with macrocyclic ligands. XIII. The complexation of Cu2+ with triazacycloalkanes

The potentiometric study of the complexation of Cu²⁺ with 1,4,7-triazacyclononane ( 1 ), 1,4,8-triazacyclodecane ( 2 ) 1,5,9-triazacyclododecane ( 3 ) has shown that CuL, CuL₂ and (CuLOH)₂ are the main species present in solution. Their stabilities (Table 1) and their absorption spectra (Table 2) indicate facial coordination of the cyclic triamines in a distorted octahedral geometry. The formation and dissociation kinetics have been measured by stopped-flow techniques. The formation in acetate buffer can be described by the reaction of Cu²⁺ and CuAcO⁺ with the monoprotonated species of the ligand. The bimolecular rate constants for these complexations (Table 3) decrease when the ring size increases. In contrast the dissociation induced by acid is only little affected by the ring size. Thus for these complexes the rate of formation and not that of the dissociation determines the overall stability.