Studies of neutralizing properties of antacid preparations. Part 4: Application of Weibull distribution function to neutralization of dihydroxyaluminum sodium carbonate.

The rate of neutralization of hydrochlorid acid by dihydroxyaluminum sodium carbonate (DHASC) has been studied by pH-stat method. The neutralization process was examined by monitoring the appearance of aluminum and sodium ions in the reaction medium. The Weibull distribution function was applied to the quantitative interpretation of neutralization rate data. All mathematically meaningful parameters derived from this distribution function were useful for consideration of the mechanism according to which the neutralization of DHASC occurs.

Acyl silicates and acyl aluminates as activated intermediates in peptide formation on clays.

Glycine reacts with heating on dried clays and other minerals to give peptides in much better yield than in the absence of mineral. This reaction was proposed to occur by way of an activated intermediate such as an acyl silicate or acyl aluminate (i.e., the anhydride of a carboxylic acid with Si-OH or Al-OH), analogous to acyl phosphates involved in several biochemical reactions including peptide bond synthesis. We confirmed the proposed mechanism by trapping the intermediate, as well as by direct spectroscopic observation of a related intermediate. The reaction of amino acids on periodically dried mineral surfaces represents a widespread, geologically realistic setting for prebiotic peptide formation via in situ activation.