The synthesis, characterization and dehydration of 3-ethyl-1-pentanol



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Three different methods of the synthesis of 3-ethyl-1-pentanol have been carried out in the laboratory and the merits of each are discussed. The first method involves the bromination of 2-ethyl-1-butanol, followed by a Grignard reaction with paraformaldehyde. The second method is the bromination of 3-pentanol and followed by a Grignard reaction with ethylene oxide. The last method is the bromination of 2-ethyl-1-butanol, a Grignard with carbon dioxide to produce the acid corresponding to the desired alcohol and subsequent reduction of the acid with lithium aluminum hydride. The last method is the most successful for two reasons: 1) The carbon dioxide Grignard is the most efficient reaction, and 2) the purification of the acid is simple by neutralization and extraction methods resulting in the purest product, 1. e., better than 98 mole % pure. Preparation of five new derivatives of 3-ethyl-1-pentanol were attempted in order to characterize the alcohol. These are: The 3,5-dinitrobenzoate, the alpha-napthylcarbamate, the 4-diphenylcarbamate, the alpha-napthylamine complex of the 3,5-dinitrobenzoate, and the amide of the acid resulting from the oxidation of the alcohol. The physical constants of the alcohol have also been obtained. The alcohol has been dehydrated with boric acid and the resulting olefin mixture analysed on the mass spectrometer? it shows practically no rearrangement. Dehydration with sulfuric acid as a catalyst, ozonization of the resulting olefins, and cleavage of the ozonides with lithium aluminum hydride are also reported. The resulting alcohols have been analyzed with a vapor phase chromatography unit which indicates that the alcohol upon dehydration rearranges to give six different olefins as products.