This PowerPoint presentation titled "Chromium (Cr) Based Oxidizing Reagents" offers an in-depth exploration of the role of chromium compounds as powerful oxidizing agents in chemical reactions. It covers the fundamental principles, oxidation mechanisms, and redox behavior of chromium in different oxidation states, particularly Cr(VI). The presentation discusses widely used reagents such as PCC (Pyridinium chlorochromate), PDC (Pyridinium dichromate), Jones reagent (Chromic acid), and Collins reagent, highlighting their preparation, reaction conditions, selectivity, and safety considerations. Real-world laboratory applications, environmental impact, and green chemistry alternatives are also discussed. This content is useful for chemistry students, academic professionals, and researchers involved in synthetic organic or inorganic chemistry.

1. CHROMIUM (Cr) BASED
OXIDIZING REAGENTS
ST. XAVIER’S COLLEGE AHMEDABAD
ROLL NO. – 24-PCH -105

2. TABLE OF CONTENT:
Types of reagents for oxidation of
alcohol
Cr based reagents :
Jones reagents
PCC pyridinium chloro chromate
Collins reagents
PDC pyridinium dichromate

3. OXIDATION OF ALCOHOL
C
H3 OH
H
H
C
H3 H
O
C
H3
OH
O
Controlled
oxidation
Increase in o.s
Increase in o.s
Removal of H
Removal of H
R
OH
H
R R
O
R
[O]
-2 +2 +3
+2
0
R OH
Uncontrolled
oxidation :
R
O
OH

4. Oxidation
Of Alcohol
Cr Based
Reagent
Jones
Reagent
Pcc
Collins
Reagent
Pdc
Mn Based
Reagents
Kmno4/Mno2
Corey Gilman -
Ganem Reagent
DMSO
Based
Swern
Oxidation
Selective
Oxidizing Agent

5. JONES REAGENT
 CrO3 +H2SO4 + acetone
 K2Cr2O7 + H2SO4 + acetone
 HCrO7 + H2SO4 + acetone
 Application
R
OH
H
R R
O
R
Jones reagent
Jones reagent

6. R OH R
O
OH
CrO3 +H2SO4 + acetone

7. R
OH
H
R R
O
R
CrO3 +H2SO4 + acetone

8. JONES REAGENT IS BEST IN FORMING
KETONE AND DOES NOT GIVES
ALDEHYDE
 Due to strong acidic conditions jones reagent is not
used in acid sensitive functional groups. –NBOC ,
acetal group
 It is uncontrolled reagent directly formed Acid from
alcohol.
DRAWBACK :

9. REACTIONS :
OH
CH3
C
H2 CH3
CH3
C
H2 CH3
O
Jones reagent
OH O
Jones reagent
OH O
Jones reagent

10. COLLINS REAGENT :
 CrO3 + Py CrO3Py
 In basic medium.
 Useful in acid sensitive functional group.
 It does controlled oxidation of primary alcohol and
forms aldehyde.
 Give ketone for secondary alcohol
 Applications :
R H
O
R OH
CrO3Py
R
OH
H
R R
O
R
CrO3Py

11. REACTIONS :
OH
CH3
CH3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
CH3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
C
H3
C
H2
O
CH3
OH
C
H3
O
CH3
O
C
H3
O
CH3
CH3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
CH3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
C
H3
C
H2
O
O
CH3
CH3
O
O
O
CH3
CH3
OH

12. PCC [ PYRIDINIUM CHLORO
CHROMATE ]
CrO3 + Py + HCl
Not moisture sensitive.
Excess reagent not required.
It is slight acidic but buffered by NaOAc.
Cr
O
O
Cl
O
–
N
+
H
PCC

13. APPLICATIONS :
R H
O
R OH
PCC
R
OH
H
R
PCC
EXAMPLES :
O
O
OH
C
H3
C
H3
C
H3
O
O
O
C
H3
C
H3
C
H3

14. BABBLER OXIDATION:
CH3
O
C
H3 OH
PCC can also oxidize tertiary alcohol
through [3,3] sigma tropic
rearrangement .

15. PDC PYRIDINIUM DICHROMATE
Cr
3–
O
O
O
O
H Cr
3–
O
O
OH
CrO3 + H2O
Dimer
Cr
3–
O
O
O
O
–
Cr
3–
O
O
O
–
N
+
H
N
+
H

16. APPLICATIONS :
 It is good oxidizing agent
 It gives clean reaction
 It shows solvent effect
 It is not acidic
PDC DCM
PDC DMF

17. C
H3
CH3
CH3
O
CH3
C
H3
OH
CH3
PDC
DCM
R
OH
C
H3
O
H
C
H2
OH
C
H2
O