REACTIONS AND IDENTIFICATION 381 Tyrosine and cystine are colourless solids almost insoluble in water and in ethanol (tyrosine dissolves in hot water). They are readily soluble in dilute caustic alkali solution, in ammonia and mineral acids, but not in acetic acid. They are also classed as "neutral ampholytes." GENERAL REACTIONS. 1. Soluble in Na 2 CO 8 solution, with very slow evolution of CO 2 on heating. 2. React with nitrous acid to give nitrogen and the corresponding hydroxy-carboxylic acid. 3. Formaldehyde converts the basic NH 2 group into the neutral CH 2 :N group (Sorenson's reaction). 4. Form derivatives with benzoyl chloride and (more rapidly and conveniently) with 3,5-dinitrobenzoyl chloride. 5. Form deep blue copper salts usually sparingly soluble in water. 1. Solubility in Na 2 CO 3 solution. See Section 5 (p. 330), and also Test 2 for carboxylic acids (p. 347). 2. Action of nitrous acid. To a few ml. of 20% NaNO, solution add a few drops of cold dil. acetic acid. Pour the mixture into a
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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.