Organic 2 Review Problem 169

Organic 2 Review Problem 169 - P REPARATIONS 153 presence o...

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PREPARATIONS 153 presence of aluminium isopropoxidc, Al • [OCH(CH 3 ) 2 ] 3 , the overall reaction may be represented as a reduction of the carbonyl group of the aldehyde or ketone, with oxidation of the isopropanol to acetone: R-CHO + HO-CH(CH 8 ), -> RCH 2 OH + OC(CH 3 ) 2 R 2 CO + HO-CH(CH 8 ), -* R 2 CHOH + OC(CH 3 ), In view of the boiling-points of acetone (57°) and isopropanol (82°), the acetone can be steadily distilled off from the reaction-mixture, and the reduction ultimately becomes virtually complete. This type of reduction has the advantage of requiring only mild conditions, and also of leaving unaffected various groups such as olefine groups, nitro groups, and halogen atoms in aliphatic compounds, which might be affected by other more vigorous reagents. For example, brornal under the above conditions gives tribromoethanol (or avertin): CBr 3 -CHO -»• CBr 3 -CH 2 OH. The immunity of olefine groups has made this type of reduction of particular value in steroid investigations. In the following preparation to illustrate the Meerwein-Ponndorf-Verley reduc-
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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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