Productos de la policondensación del ácido cítrico, el etilenglicol y alcoholes alifáticos de cadena larga

Abstract

The polycondcnsation of citric a cid with ethylene glycol was carried out in the presence of a long-chain aliphatic alcohol (n-decyl, n-dodecyl and n-octadecyl alcohol). The proportions of the reagents were chosen so that the system does not reach the gel point. Under che experimental conditions of the synthesis oligomers but no polymers were obtained. These products form colloi­dal stable dispersions in water; although, as the size of the chain of the aliphatic alcohol increases the formation of che sol is more difficult. The characterization of thc products as well as che verification of the addition of che aliphatic alcohol to the molecules of che oligomer was done using ¹H NMR spectroscopy. The products of the polycondensation of citric acid, ethylene glycol and the aliphatic alcohols begin to decompose above 153 ºC. The temperature of decomposition is not sensitive to the presence of small amounts of aliphatic groups derived from the lineal alcohol, or to the increase of their length. When hydroxyl groups are the end groups of oligomer chains, che products have a higher thermal stability than those possessing terminal caiboxyl groups.