Organic 2 Review Problem 153

Organic 2 Review Problem 153 - P REPARATIONS 137(i CHO-r H...

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PREPARATIONS 137 (i) CHO -r H 2 XNHC 6 H 5 CH:NNHC«H 6 CH:NNHC 6 H 6 CH:NNHC,H fi I II I (z)CHOH CHOH CO -f H 2 NNHC 6 H 5 C:NNHC,H 6 I I -2H I I (CHOH) 3 * 3 > (CHOH), > (CHOH) 8 I I CH 2 OH CH 2 OH CH 8 OH 2 OH (III) (UlA) (UlB) (IIIC) Now phenylhydrazine will readily act as an oxidising agent, since it can accept two hydrogen atoms from another compound, being itself reduced to aniline and ammonia, C 6 H 5 NHNH 2 -f zH = C 6 H 5 NH 8 -f NH 8 . The second mole- cule of phenylhydrazine therefore oxidises the secondary alcohol group (> CHOH) of carbon atom (2) to a ketone (> C :O) group by removal of two hydro- gen atoms, giving the compound (UlB). The free >C:O group of the latter compound now condenses with a third molecule of phenylhydrazine, giving the osazone of glucose, or phenyl-glucosazone (IIIc). Fructose (V) under similar conditions gives first the phenylhydrazone (VA) by the direct condensation of the >C:O group of carbon atom 2 with one molecule of phenylhydrazine. The second molecule of phenylhydrazine then
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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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