Oxidation of Alcohols

Question 1

oxidation definition

Answer 1

addition of O or any EN group (O, N, X), or removal of Hs from a carbon atom, or increase # of bonds to O from C

Question 2

in general what alcohols turn into what?

Answer 2

1° ROH —> aldehyde, carbox. acid

2° ROH —> ketone

3° ROH —> n.r.

Question 3

chromium reagents

Answer 3

Cr (VI): transition metal, high oxidation state, needs e-, toxic, yellow/orange

Cr (III): deep blue/green, less toxic

Question 4

classic Cr reagents (all Cr 6+)

Answer 4

Na2Cr2O7: sodium dichromate

CrO3: chromium trioxide/Jones reagent

PCC: pyridium chloro chromate

Question 5

sodium dichromate

Answer 5

cheap

in H2SO4, H2O, with heat

Question 6

Jones reagent/chromium trioxide

Answer 6

milder than sodium dichromate & better yield

more expensive

in H2SO4, H2O, acetone, no heat, more dilute

Question 7

PCC

Answer 7

in CH2Cl2 (dry), acid not used

stops 1° ROH from overoxidizing “mild oxidizing agent”

decreases rearrangement rxns

Question 8

Na2Cr2O7 + CrO3 rxns w/ alcohols

Answer 8

1° ROH —> carbox. acid

2° ROH —> ketone

3° ROH —> n.r.

Question 9

PCC rxns w/ alcools

Answer 9

1° ROH —> aldehyde

2° ROH —> ketone

3° ROH —> n.r.

Question 10

Na2Cr2O7 + CrO3 active species

Answer 10

add H2SO4 and H2O, turns into chromic acid

Question 11

why use PCC

Answer 11

no H2SO4, H2O so NO H3O+ (in CH2Cl2 (dry))

stops rxn at aldehyde