Redox

Oxida t ion - R educt ion R ea ct ions

Oxidation-Reduction Reactions

O x ida tio n- R educ tio n R ea c tio ns

• Involves changes in oxidation state resulting from changes in covalent bonding between atoms of different E N values • ↓ .S . – reduction ; ↑ .S . – oxidation O O • oxidation is always coupled with reduction

R eduction at carbon increases the number of C ¬H bonds or decreases the number of C ¬O , C ¬N, or C ¬X bonds. O xidation at carbon decreases the number of C ¬H bonds or increases the number of C ¬O , C ¬N, or C ¬X bonds.

reduc ing a g ent - compound that is oxidized ox idizing a g ent - compound that is reduced

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C ha ng es in ox ida tio n s ta te

The oxidation state of a carbon atom equals the total number of its C ¬O , C ¬N, and C ¬X bonds.

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Oxidation-Reduction Reactions

R educ tio n O x ida tio n

x ida tio n- R educ tio n R ea c tio ns

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Oxidation-Reduction Reactions

E xercise: Indicate whether each of the following reactions is an oxidation reaction, a reduction reaction, or neither:

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Reduction Reactions

I . C a ta lytic H ydro g ena tio n I I . M eta l – A m m onia R educ tio n I I I . M eta l-H ydride R educ tio ns I V. D eox yg ena tio n R ea c tio ns V. R educ ing a N itro S ubs tituent

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Reduction Reactions

I . C a ta lytic H ydro g ena tion

A . A lkenes a nd A lk ynes 1.

• R eduction by Addition of Two Hydrogen Atoms • In the presence of a metal catalyst such as platinum, palladium, or nickel, hydrogen (H 2) adds to the double bond of an alkene to form an alkane. • The catalyst decreases the energy of activation by breaking the H-H bond. HO M OLYTIC C LE AVAG E • P latinum and palladium are used in a finely divided state chem31 adr 7 ads orbed on charcoal (P t/ , P d/ ) C C

Reduction Reactions

C a ta lytic H ydrog ena tio n Triple B o nds E xample: o f D o uble a nd

R educ tio n by A dditio n o f Tw o H ydro g...