The interaction of glutaraldehyde with poly(α,L‐lysine), n‐butylamine, and collagen. I. The primary proton release in aqueous medium

Abstract

AbstractThe interaction between poly(α,L‐lysine) (DP = 180) and glutaraldehyde was investigated in dilute aqueous solution by measurement of the kinetics of proton release at constant pH and temperature and at various concentrations of the reaction components. Under various conditions, the release of protons at constant pH appeared kinetically to be composed of at least two steps: an initial zero‐order reaction, followed by a slower reaction.At excess of polylysine amino groups, the pH optimum for the rates of reaction was at pH 9–10 (24–25°C). Under the conditions used and at pH 8, the initial rate of the second kinetic step was proportional to the glutaraldehyde concentration and was practically independent of polylysine concentration at pH 8 and 8.6, at an excess of amino groups. At pH values of 7, 8, and 8.6 the apparent overall energy of activation for the second kinetic step was 18–19 kcal/mole (temp. range 4–40°C). Comparing acetaldehyde with the difunctional glutaraldehyde, it was found that the rate of proton release was much smaller in the case of acetaldehyde. Comparing n‐butylamine with the macromolecular polylysine at equal concentrations of amino groups, the rates of proton release were much smaller in the case of n‐butylamine. Collagen in aqueous medium also interacted with glutaraldehyde in a manner analogous to polylysine, although the conditions were not quite comparable. In the case of collagen, the initial fast proton liberation step was relatively much larger than in the case of polylysine.A reaction scheme for the initial reaction steps is being proposed which includes primary complex formation between glutaraldehyde and polylysine. This dialdehyde–polyamino acid system is considered to serve as a model for tanning processes of hides and for fixation procedures.