344 PRACTICAL ORGANIC CHEMISTRY SPECIAL REACTIONS. Metaformaldehyde. If boiled with water an aqueous solution is obtained which, owing to depoly-merisation, gives the reactions for formaldehyde. Acetaldehyde. 1. Iodoform reaction. To i ml. of the aldehyde solution, add 3 ml. of io% KI solution and io ml. of freshly prepared sodium hypochlorite solution. Yellow crystals of iodoform, CHI 3 , soorf separate. 2. Nitroprusside reaction. Add i ml, of a freshly prepared solution of sodium nitroprusside to the aldehyde or its solution. Add dil. NaOH solution in excess: a red coloration is produced. Paraldehyde. Gives some of the tests for acetaldehyde, but more feebly: e.g., it restores the colour to SchifFs reagent, gives a yellow resin with NaOH, and responds to the nitroprusside test. With ammoniacal AgNO 8 , it gives a silver mirror only after 2-3 minutes' warming. It does not give the iodoform reaction. To i ml. of paraldehyde in a test-tube add 5 ml. of dil. H
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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.