Monomolecular films of phenolic esters.
Abstract The properties of three phenolic esters, characterized by gradual changes in their molecular constitution, have been evaluated in pure monomolecular films, as well as in mixed films with stearic acid. The pressure-area isotherms for the pure compounds reflect a similar orientation for compounds I (resorcinol monoundecanoate) and II (4-chlororesorcinol 1-undecanoate) at the air-water interface. At pressures corresponding to the limiting area per molecule, the molecules are apparently rather erect and anchored to the aqueous subphase surface by the phenolic-OH function; at lower pressures, the molecules are less erect, with their aliphatic chains randomly intertwined. The isotherm characteristics for III (4-chlorophenyl undecanoate), on the other hand, are compatible with an orientation in which the molecule is anchored to the aqueous subphase surface by its ester function, with both the aliphatic chain and the substituted phenyl ring projecting upwards. Isotherms for 1:1 mixtures of each of the phenolic esters with stearic acid indicate that the properties of the mixed films were controlled, generally, by the esters (at low pressures) and by stearic acid (at high pressures), after the esters had been forced out of area-determining positions in the films. The experimentally derived isotherms for the mixtures were compared with those calculated from the isotherms of the pure components, and observed deviations from additive behavior discussed.
Synthesis of phenolic esters with potential long-lasting insect-repellent properties
The synthesis of undecanoic acid esters of resorcinol, 4-chlororesorcinol, hexachlorophene, o-chlorophenol, and p-chlorophenol is described. The compounds were designed to provide, potentially, perdurable insect-repellent activity. When the synthesis of esters of resorcinol and 4-chlororesorcinol was attempted with undecanoic acid, under acid catalysis, principally ketones and ketoesters were isolated. The originally sought esters were obtained, however, by the reaction of the phenols with undecanoyl chloride in the presence of pyridine. The infrared, nuclear magnetic resonance, and mass spectra of the compounds are discussed.
Effect of the Spreading Solvent on Monolayer Properties
EFFECTS of the spreading solvent, rate of compression, and substrate water on monolayer properties have been the subject of much discussion1–11. Most attention has been directed at the spreading solvent. Volatile solvents are used to aid spreading and to facilitate accurate measurement of minute quantities of film-forming materials. One possible source of difficulty is retention of solvent in the monolayer; a second is effect of the solvent on the state of aggregation of the film material (size and shape of islands); a third is dissolution and spreading by the solvent of paraffin wax used in coating parts of the apparatus (float and foils).