Organic Chemistry 2: Chapter 12 - Oxidation and Reduction

oxidation

increase in C-Z bonds, decrease in C-H bonds

reduction

decrease in C-Z bonds, increase in C-H bonds

alkyne-->alkene

reduction

alkane-->alkene

oxidation

3 types of reduction

H2 with metal catalyst, dissolving metal reductions, NaBH4 or LiAlH4

what reagents are used in dissolving metal reduction

Na/NH3

reduction of alkenes

forms alkane by addition of H2

what happens during the reduction of an alkene

pi bond breaks, two new C-H bonds formed

reduction of an alkene only occurs in the presence of a

metal catalyst

during reduction of alkenes, H2 adds in

syn fasion

the lower the heat of hydrogenation, the

more stable the alkene

trans alkenes are ________ stable than cis

more

less crowded double bonds react

faster

during reduction of an alkyne, adding 2 equivalents forms an

alkane

during reduction of an alkyne, adding 1 equivalent in syn fashion forms a

cis alkene

during reduction of an alkyne, adding 1 equivalent in anti fashion forms a

trans alkene

H2/Pd catalyst forms

alkane

H2/Lindlars Catalyst forms

cis alkene

Na/NH3 forms a

trans alkene

alkyl halides are reduced to alkanes with the

loss of X- as a leaving group

epoxide rings open to form

alcohols

alkyl halides and epoxides undergo what form of reaction

SN2

what catalyst is used on reduction of alkyl halides and epoxide rings

LiAlH4/H2O

unhindered methyl and 1 alkyl halides are ______________ to be reduced than 2 and 3*

easier

in unsymmetrical epoxides, H- attacks

the less substituted carbon

in unsymmetrical epoxides the OH ends up on

the more substituted carbon

2 categories of oxidizing agents

oxygen-oxygen bonds, metal-oxygen bonds

examples of O-O oxidizing agents

O2, O3, H2O2, (CH3)3COOH, peroxyacids

exmaples of peroxyacids

RCO3H, mCPBA

epoxidation

addition of a single oxygen atom to form epoxide

what happens during epoxidation

pi bond is broken, two new C-O bonds form

what reagent is used for epoxidation

peroxyacids

how many steps does epoxidation take

1

epoxidation occurs with ______ addition

syn

oxidative cleavage of alkenes forms

2 carbonyl groups

oxidative cleavage of alkenes forms either

ketones or aldehydes

ozonolysis

1. O3 / 2. Zn, H2O

how many steps is ozonolysis

2

addition of a pi bond during ozonolysis forms a

molozonide

to draw any oxidative cleavage product:

1. locate all pi bonds, 2. replace each C=C with 2 C=O

oxidative cleavage of an internal alkyne yields

2 carboxylic acids

oxidative cleavage of a terminal alkyne forms a

carboxylic acid + CO2

reagents used for oxidative cleavage of an alkyne

1. O3 / 2. H2O

oxidation of a 1* alcohol yields

aldehydes or carboxylic acids

oxidation of 2* alcohol yields

ketones

oxidation of 3* alcohol yields

nothing. does not occur

2* alcohols are oxidized to ketones using

any Cr6+ oxidant

commons reagents for oxidation of 2* alcohols

1. K2Cr2O7 / 2. H2SO4, H2O or PCC

1* alcohols are oxidized to aldehydes using

PCC in CH2Cl

1* alcoholds are oxidized to carboxylic acids in

harsher conditions, such as Na2Cr2O7, K2Cr2O7, or CrO3 in the presence of H2O and H2SO4

first step to oxidation of 1* alcohol to carboxylic acid

oxidation to aldehyde

second step to oxidation of 1* alcohol to carboxylic acid

reaction with H2O

third step to oxidation of 1* alcohol to carboxylic acid

further oxidation to carboxylic acid