Zur Kenntnis der Benzylpenicilloinsäure

The molar penamaldate value of benzylpenicilloic acid and the influence of large amounts of benzylpenicillin on the estimation of penamaldate values and penamaldate stabilities of benzylpenicilloic acid and ε-(benzylpenicilloyl-α-amido)-caproic acid have been determined. The molar penamaldate values of purified benzylpenicilloate and of benzylpenicillin hydrolyzed in alkali were equal, indicating that benzylpenicillin upon alkaline hydrolysis is converted to penicilloic acid exclusively, with no side reactions occurring to any considerable degree. Benzylpenicilloate mutarotates in neutral solution as well as in alkali, the reaction being unaffected by metal ion complexing with ethylene diamine tetraacetate. ε-(Benzylpenicilloyl-α-amido)-caproate also mutarotates in alkali; no mutarotation occurs however in neutral solution. Different mechanisms of epimerisation have therefore to be considered for the mutarotations of penicilloates and of α-amides of penicilloic acid respectively.     

Zur Stabilität der Metallkomplexe von Methantriessigsäure und cis,cis-1,3,5-Cyclohexantricarbonsäure

The stabilities of the Mn²⁺-, Co²⁺-, Ni²⁺-, Cu²⁺- and Zn²⁺-complexes with 2-(carboxymethyl)glutaric acid ( 2 ) and cis,cis-1,3,5-cyclohexanetricarboxylic acid ( 3 ) were measured potentiometrically at 25° and I = 0.5 (KNO₃). Beside the complexes ML^? protonated species MLH and MLH are also formed. Their stability constants are given in Table 1. A comparison between the stabilities of 2 or 3 and those of acetate, as a model for a monocarboxylate, or succinate and glutarate, as examples for dicarboxylates, indicates that in all species only one carboxylate is strongly bound whereas the second and third ones are probably not. The observation that Δlog K₁ = log K ? log K as well as Δlog K₂ = log K ? log K are practically constants with values of 0.34 ± 0.05 and 0.49 ± 0.07, respectively, for both ligands and the five metal ions studied is also in line with the proposed monodentate structures of the complexes ML^?, MLH and MLH.     

Zur Diazotierung aromatischer Amine in Schwefelsäure

The diazotization of 2-chloro-4,6-dinitroaniline, 2,6-dichloro-4-nitroaniline, and 4-nitroaniline in concentrated sulfuric acid is very strongly catalysed by water. At a given water concentration the reaction rates of these amines are in the ratio 50/20/1. The relation between the bimolecular rate constants k and the acidity function H₀ is very simple, the plots of log k versus H₀ being linear with a slope of 2.