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52 Pages·2007·1.42 MB·Portuguese

Química Orgânica I
Ciências Farmacêuticas
Bioquímica
Química
AFB QO I 2007/08 1
alcohols
(cid:1)
Adaptado de
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Organic Chemistry, 6th Edition; Wade
(cid:2)
Organic Chemistry, 6th Edition; McMurry
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Typical reactions of alcohols
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Two general classes of reaction
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At the carbon of the C–O bond
(cid:2)
At the proton of the O–H bond
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Types of Alcohol Reactions
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Dehydration to alkene
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Oxidation to aldehyde, ketone
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Substitution to form alkyl halide
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Reduction to alkane
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Esterification
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Tosylation
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Williamson synthesis of ether
=>
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Summary Table
=>
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Oxidation States
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Easy for inorganic salts
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CrO 2- reduced to Cr O
4 2 3
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KMnO reduced to MnO
4 2
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Oxidation: loss of H , gain of O, O , or X
2 2 2
(cid:1)
Reduction: gain of H or H-, loss of O, O , or
2 2
X
2
(cid:1)
Neither: gain or loss of H+, H O, HX
2
=>
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Oxydation
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1º Carbons
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2º Carbons
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3º Carbons
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Oxidation of 1° Alcohols
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1° alcohol to aldehyde to carboxylic acid
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Difficult to stop at aldehyde
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Use pyridinium chlorochromate (PCC) to
limit the oxidation.
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PCC can also be used to oxidize 2° alcohols
to ketones.
OH N H CrO3Cl O
CH CH CH CH CH CH CH CH
3 2 2 2 3 2 2
=>
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Oxidation of 2° Alcohols
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2° alcohol becomes a ketone
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Reagent is Na Cr O /H SO
2 2 7 2 4
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Active reagent probably H CrO
2 4
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Color change: orange to greenish-
blue
OH O
Na Cr O / H SO
2 2 7 2 4
CH CHCH CH CH CCH CH
3 2 3 3 2 3
=>
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Mechanism of Chromic Acid
Oxidation
(cid:1)
Alcohol forms a chromate ester followed by
elimination with electron transfer to give ketone
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