Transparency Characteristics of Several Cholesteryl Esters

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Abstract
Transparency characteristics are reported for cholesteryl myristate, decanoate, and nonanoate from the solid to the isotropic liquid phases. The procedure involves heating a sample between calcium fluoride plates in a brass holder in a Cary 14 spectrophotometer. Changes in transmittance at fixed wavelengths (3000, 4000, 5000, 7000, and 25,000 A) were recorded continuously as the temperature was allowed to change slowly. The transparency characteristics of cholesteryl nonanoate while being cooled from the liquid phase are also described. All transitions which occur are observed. By comparison with other techniques this method compares very favorably with regard to the detection of transitions and dichroic scattering. The shapes of the transparency curves vary markedly between compounds; the degree of light scattering varies as a function of the incident light wavelength. However, the temperature ranges over which the transitions occur for a particular compound are reproducible irrespective of the light wavelength.