intermediate is a cyclic periodic ester.C-C bond is cleaved and alcohols are oxidized.periodic acid, H 5IO 6 (or HIO 4♲H 2O).2° alcohol to ketone with any Cr(VI) reagent.1° alcohol to aldehyde with PCC (avoids further oxidation).1° alcohol to carboxylic acid with any Cr(VI) reagent, e.g., CrO 3.oxidation involves intermediate chromate ester.acid-catalyzed dehydration of a glycol (1,2-diol),.dehydration of an alcohol forms the more stable (more substituted) alkene.the major product in an elimination reaction is the more substituted alkene.predicts regiochemistry of alkene formation.rearrangements are commonly observed during dehydration.E2: less-substituted alcohols (unstable carbocations) show.E1: carbocation loses H+ to form an alkene.Initial protonation creates a good leaving group (H 2O) acid-catalyzed dehydration: 3° > 2° >1°įavored by relatively stable carbocation,Ībsence of nucleophile, high temperature.sulfonate esters are excellent leaving groups.alcohol + RSO 2Cl gives a sulfonate ester.SOCl 2 + alcohol gives alkyl halide, also with less rearrangement.PBr 3 + alcohol gives alkyl bromide, with less rearrangement than with HBr.rearrangements are possible, even with 1° alcohols. ![]() MeOH + HBr -> MeOH 2+ Br-> MeBr + H 2OĬoncerted displacement of H 2O by Br- (unstable carbocation) TBuOH + HBr -> tBuOH 2+ -> tBu+ -> tBuBrįavored by relatively stable carbocation (3°)
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