Organic 2 Review Problem 129

Organic 2 Review Problem 129 - P REPARATIONS 113 Formic...

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PREPARATIONS 113 Formic Acid, HCOOH (in aqueous solution), and Lead Formate, (HCOO) 2 Pb. When a mixture of anhydrous glycerol and crystalline oxalic acid, (COOH) 2 ,2H 2 O, is heated the glycerol undergoes esterification, giving first glyceryl monoxalate (A): the latter, however, decomposes as the temperature CH 3 (OH)-CH(OH)-CH 2 (OH) + (COOK) 2 -» H 2 O + CH 2 (OH)-CH(OH)-CH 2 O-CO COOH (A) CH 2 (OH)-CH(OH)-CH 2 -OCO-COOH -> CO 2 + CH 2 (OH)-CH(OH)-CH 2 O-CO-H (B) CH 2 (OH) CH(OH)-CH 2 O-CO-H + H 2 O -^CH 2 (OH)CH(OH)-CH 2 (OH) + HCOOH reaches about 100°, losing carbon dioxide and giving glyceryl monoformate (B). On further heating, particularly if more oxalic acid is added, the mono- formate is hydrolysed (the necessary water being provided both by the oxalic acid and by the first reaction), and consequently a distillate of aqueous formic acid is obtained. Required: Glycerol, 70 ml.; oxalic acid, 40 g.; lead carbonate. Since glycerol is a very hygroscopic substance, it may be
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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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