Evaluation of Vaporization Enthalpies and Vapor Pressures of Various Aroma and Pharmacologically Active Compounds by Correlation Gas Chromatography

Résumé du livre

Scientists in the pharmaceutical, food, and aroma industries can benefit from reliable thermochemical data. Vaporization enthalpy and vapor pressure data are not available for all compounds. Furthermore, some literature data is conflicting. The goal of this work was to use a method called correlation gas chromatography (CGC) to generate reliable vaporization enthalpy data in instances where other experimental methods are not applicable. Vapor pressures of the targets were also calculated in cases where the required literature data on the standards used in this technique were available. CGC involves making a standard cocktail that includes a mixture of standards and one or more unknowns. Reliable literature values for vaporization enthalpy must be available for the standards in order to evaluate the vaporization enthalpy of the targets. From the retention time of both the standards and their vapor pressures, it was possible to evaluate the vapor pressures of the targets. The compounds examined were structurally diverse. There included saturated and unsaturated compounds, cyclic and acyclic, aliphatic and aromatic, lactones, aldehydes, carboxylic acid derivatives, profens, and alcohols. Despite structural differences, their properties can be separated into two broad categories: aroma compounds and pharmacologically active compounds. Each class of compounds brought about unique challenges. Some were oils that were extracted and characterized prior to measurement. Aldehydes proved to be unstable. Some carboxylic acids gave poor peak shapes requiring a search for a suitable column. Additionally, some of the profens displayed liquid crystal behavior- adding additional complications. Vaporization enthalpies were measured for nepetalactone, whiskey lactone, menthalactone, trans-2-hexenal, 2,6-dimethyl-5-heptenal, 2,6-nonadienal, trans-2-nonenal, trans, trans-2,4-decadienal, 2-butyl-2-octenal, patchouli alcohol, and Fenoprofen. Vapor pressures were measured for nepetalactone, whiskey lactone, menthalactone, and Fenoprofen. Vaporization enthalpy and vapor pressure values for the standards were all within experimental error of literature values, except in the case of 2-tetradecanol.