Study Set Content:
Organohalides react with magnesium to produce
- Grignard reagents, RMgX
Grignard reagents react with carbonyl compounds to yield
alcohols
Limitation of Grignards reagent
If other reactive functional groups are present in the same molecule, Grignard reagent cannot be prepared from an organohalide
Mechanism of the Addition of a Grignard Reagent
- Grignard reagents act as nucleophilic carbon anions
- Intermediate alkoxide is protonated to produce the alcohol
- 3° alcohols react with (what)through carbocation intermediate
HCl, HBr, or by SN1
1° and 2° alcohols are converted into halides by treatment with
- SOCl2 or PBr3 via SN2 mechanism
Reaction of alcohols with p-toluenesulfonyl chloride in pyridine yields
- alkyl tosylates, ROTos
- C-O bond remains intact and configuration at a chirality center is maintained
- C-O bond remains intact and configuration at a chirality center is maintained
Resulting alkyl tosylates react like
alkyl halides
Tertiary alcohols are dehydrated using
- acid-catalyzed reactions
Follows Zaitsev's rule and yields a more stable
alkene
Reactivity is the result of the nature of the
carbocation intermediate
Conversion of Alcohols into Esters
- Reaction can be carried out in a single step with the use of a
strong acid as catalyst
- Accomplished by reagents, such as KMnO4, CrO3, and Na2Cra207
Oxidation of Alcohols
reagents
- KMnO4, CrO3, and Na2Cra207
Primary alcohols are oxidized to either
- aldehydes or carboxylic acids
used to prepare aldehyde from a primary alcohol
dichloromethane
Secondary alcohols oxidize easily to give
ketones
Secondary alcohols oxidize easily to give ketones Effective with inexpensive reagents such as
- Na2Cr2O7 in acetic acid
- Done to overcome incompatibility that might arise by protecting the interfering functional group
Protection of Alcohols
