I. The Ionization of Amino Acids and Other Polyfunctional Organic Compounds in the Solvent Sulfuric Acid. II. Studies on the Chemistry of Azlactones. III. Miscellaneous Observations on Amino Acid Derivatives. IV. The Nodal Silver Stain: its Mechanism and Relation to the Potassium Loss of Isolated Nerve

Citation

O'Brien, Joseph Lloyd (1952) I. The Ionization of Amino Acids and Other Polyfunctional Organic Compounds in the Solvent Sulfuric Acid. II. Studies on the Chemistry of Azlactones. III. Miscellaneous Observations on Amino Acid Derivatives. IV. The Nodal Silver Stain: its Mechanism and Relation to the Potassium Loss of Isolated Nerve. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/120A-V997. https://resolver.caltech.edu/CaltechTHESIS:09292017-150042637

Abstract

The ionization of thirty compounds, including amino acids, α-acylamino acids, amides and related compounds, in the solvent sulfuric acid has been determined by cryoscopic measurements. The results for the aliphatic amino acids clearly illustrate the phenomenon of polybasic ionization in sulfuric acid and are also significant to the discussion of the mechanisms for certain acid-catalyzed reactions. Sulfuric acid is found to catalyze both the dehydrative cyclization of α-acylamino acids and the bimolecular elimination of hydrazine from benzhydrazide.

A sulfuric acid catalyzed Erlenmeyer synthesis is described which gives an excellent yield of 2-phenyl-4-benzal-5-oxazolone, obtained as a mixture of the geometrical isomers. The stereochemistry of this condensation is considered and it is suggested that sulfuric acid inhibits the mutarotation of the intermediate addition product. The satisfactory yield with benzoylsarcosine provides definitive evidence for the existence of an oxazolonium ion intermediate.

Several reactions of amino acid derivatives are described, among them the cleavage of benzenesulfonylglycine by acetyl chloride. The structure of the so-called anhydropeptides is considered and it is concluded that a 5-imidazolone structure is unlikely.

The nodal silver stain is shown to be a vital stain. A mechanism for this stain is presented and shown to be similar to the process which probably causes the initial potassium loss of isolated nerve.

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