We've prepared the solid acid in which boron oxide and sodium hydrogen sulfate are supported on silica gel(boric silica gel) as dehydrating agent or acid catalyst, alternative to concentrated sulfuric acid. And we've reported experiments of intramolecular dehydration of alcohols, utilizing this solid acid as laboratory experiment. Now, we have investigated the intramolecular dehydration of butanols and found that primary alcohols, secondary alcohol and tertiary alcohol can be identified by the rate of elimination. By analyzing with FTIR, we investigated the mechanism of these reactions. For the preparation of the reagent named �boric silica gel�, boric acid and silica gel for chromatography were mixed in a mortar with a mill, and this mixture was heated over the flame of gas burner. Boric silica gel and NaHSO4�H2O were mixed and heated in same method over. Then, the reagent for dehydration was prepared. We'll call this reagent �the solid acid�. We've developed an experiment to identify isomers of butanol utilizing the solid acid. Mixtures of the solid acid and butanols were heated at 150 ?, then butenes were generated as gas products. Measuring the volume of generated gases, we can identify primary alcohols, secondary alcohol and tertiary alcohol.As the figure above shows, these dehydrations will proceed in E1 elimination. We measured FTIR of the mixture of 2-butanol and the solid acid or 2-butanol and boric silica gel. When 2-butanol and the solid acid or 2-butanol and boric silica gel were mixed, the ester of boric acid and 2-butanol was easily generated. Then the hydrogen sulfate ion participated in the elimination of this ester as acid catalyst.

Identification of butanols' isomers by the elimination with solid acid

248th National Meeting (2014)

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