Understanding Oxidation-Reduction Reactions in Organic Chemistry - CWRU Perspective, Essays (university) of Chemistry

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Organic Chemistry 4 th Edition Paula Yurkanis Bruice

Chapter 20

More About Oxidation–Reduction Reactions Irene Lee Case Western Reserve University Cleveland, OH

• (^) Oxidation is always coupled with reduction
• (^) Loss of electrons is oxidation
• (^) Gain of electrons is reduction
• (^) The oxidation state of a carbon atom equals the total number of its C–O, C–N, and C–X bonds

Hydrogen, sodium borohydride, and hydrazine are the reducing agents

Bromine and chromic acid are the oxidizing agents

Reduction by Catalytic Hydrogenation

Dissolving-Metal Reduction

LiAlH 4 is a stronger reducing agent than NaBH 4 LiAlH 4 is used to reduce compounds that are nonreactive toward NaBH 4

DIBAL allows the addition of one equivalent of hydride to an ester Replacing some of hydrogens of LiAlH 4 with OR groups decreases the reactivity of the metal hydride

NaBH 4 can be used to selectively reduce an aldehyde or a keto group in a compound

Oxidation of Alcohols

Mechanism of Alcohol Oxidation by

Chromic Acid

The oxidation of a primary alcohol can be stopped at the aldehyde if pyridinium chlorochromate (PCC) is used as the oxidizing agent