PREPARATIONS 93 Iodoform forms yellow crystals, of m.p. 120°, and has a charac-teristic odour. For reactions of iodoform, see pp. 390-392. Oximes. Both aldehydes and ketones usually condense readily with free hydroxyl-amine, HONH 2 , to give crystalline oximes: CH 3 CHO + H 2 NOH -> CH 3 CHrNOH + H 2 O Acetaldehyde Acetaldoxime (CHg) 2 CO -f H 2 NOH -> (CH 3 ) 2 C:NOH + H 2 O Acetone Acetoxime Since hydroxylaminc is usually available only in the form of its salts, e.g., the hydrochloride or sulphate, the aqueous solution of these salts is treated with sodium acetate or hydroxide to liberate the base before treatment with the aldehyde or ketone. Most oximes are weakly amphoteric in character, and may dissolve in aqueous sodium hydroxide as the sodium salt, from which they can be liberated by the addition of a weak acid, e.g., acetic acid. Oximes have four important uses: (1) Being crystalline compounds which usually have sharp melting-points, they are used to characterise the parent aldehydes and ketones. (2)
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.