The preparation, characterization and dehydration of 2, 2-dimethyl-1-pentanol



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It was the purpose of this investigation to synthesize 2,2-di-methyl-l-pentanol, an alcohol which had not been previously prepared or characterized, to determine its physical constants, characterize it by the preparation of several coinmon derivatives, and to determine quantitatively and qualitatively the rearranged products obtained upon dehydration. The synthesis was accomplished by the following series of reactions: n-propyl magnesium bromide was prepared and treated with acetone, giving, on hydrolysis, 2-methyl-2-pentanol. This compound, after purification, was converted to 2-chloro-2-methyl pentane, by the action of cold concentrated hydrochloric acid. The Grignard reagent of 2-chloro-2-methyl pentane was prepared, and treated with carbon dioxide, giving, on hydrolysis, 2,2-di-methyl pentanoic acid, which was identified by boiling point, and preparation of the amide. The acid was converted to 2,2-dimethyl-l-pentanol by reduction with lithium aluminumhydride. The alcohol thus obtained was shown to have better than 99 mole % purity by gas-liquid partition chromatography. Eight derivatives were prepared. The rearrangement and dehydration of 2,2-dimethyl-l-pentanol was accomplished by heating the alcohol with 8% by weight of concentrated eulfurie acid at ita boiling point. The determination of the wnsaturated rearranged products was accomplished by oxonication of the double bond, and reductive cleavage of the ozonides with lithium aluminum hydride to give a mixture of alcohols. These alcohols were identified and determined quantitatively by gas-liquid partition chromatography. All five of the theoretically possible rearranged products were identified.