The preparation and characterization of 3-ethyl-1-pentanol



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It was the purpose of this investigation to synthesize 3-ethyl-l-pentanol, determine its physical constants, and characterise it by the preparation of certain derivatives. This was tried, using 3-bromo-pentane and ethylene oxide in a Grignard reaction. The 3-bromopentane was prepared by using 3-pentanol and hydrogen bromide. The reaction of 2-ethyl-1-bromobutane with formaldehyde was not used, due to the difficulty of preparation of the alkyl halide. After the reaction, it was found that the alcohol could not be isolated, due to the fact that it evidently rearranged and dehydrated to give a mixture of alcohol, unsaturated hydrocarbon, saturated hydrocarbon, ethylene brtmacdiydrin, and several other components. Two derivatives, the hydrogen-3-nitrophthalate and the 1-nitro-anthraquinone-2-carboxylate were prepared from a fraction of the alcohol which boiled from 148-152[degrees]. These derivatives gave carbon, hydrogen, and nitrogen analyses which agreed with those calculated for a seven carbon alcohol. The melting point for the 3-ethyl pentyl hydrogen 3-nitrophthalate was 144.5-145.5[degrees], and that for the 3-ethyl peatyl-1-nitroanthraquinone-2-carbaxylate was 105-106[degrees]. The dehydration product was refluxed with potassium permanganate solution to cleave the double bond and form either the acid or ketone which could then be identified, but the reeulting compound could not be identified, although it did give a positive ketone test in one part of the experiment. This compound was suspected to be 3,4-diethyl hexane, since the values for the physical constants for both cases were fairly close. It was concluded that the Grignard reaction gave 3-ethyl-l-pentanol, unsaturated hydrocarbon, a saturated hydrocarbon, 3-methyl hexene-2, hexene-3, ethylene bromohydrin, ethylene glycol, and 3,4-diethyl hexane.