Organic 2 Review Problem 323

Organic 2 Review Problem 323 - P REPARATIONS 307 regarded...

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PREPARATIONS 307 regarded systematically, in its fully "enolised" form, as 2-thiol-4,5-dihydroxy- pyrimidine. Required: Sodium, 1-3 g.; ethyl malonate, 10 g.; thiourea, 5*3 g.; absolute ethanol, 120 ml. Dissolve 1-3 g. of sodium in 30 ml. of absolute ethanol in a 250 ml. flask carrying a reflux condenser, then add 10 g. (9-5 ml.) of redistilled ethyl malonate, and place the flask on a boiling water-bath. Without delay, add a solution of 5-3 g. of thiourea in a minimum of boiling absolute ethanol (about ioo ml.). The sodium salt of thiobarbituric acid rapidly begins to separate. Fit the water-condenser with a calcium chloride guard-tube (Fig. 61, p. 105), and boil the mixture on the water-bath for i hour. Cool the mixture, filter off the sodium salt at the pump and wash it with a small quantity of cold acetone. Dissolve the salt in warm water and liberate the acid by the addition of 30 ml. of concentrated hydrochloric acid diluted with 30 ml. of water.
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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.

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