Applications of these catalysts are discussed.

1. 5. Lindlar’s & Adam’s Catalyst
Dr. Shivendra Singh
UGC-NET-JRF, PhD-IIT Indore

2. Reduction reactions
Reduction
reactions
Catalytic
hydrogenation
H2 with
metals
Hydride
transfer
LAH, NaBH4
Dissolving
metals
Birch

3. PtO2•H2O
…Lindlar’s& Adam’sCatalyst

4. …Lindlarcatalyst
 A Lindlar catalyst is a heterogeneous catalyst that consists of
palladium deposited on calcium carbonate which is then poisoned
with various forms of lead or sulphur.
 It is used for the hydrogenation of alkynes to
alkenes (i.e. without further reduction into
alkanes) and is named after its inventor Herbert
Lindlar.

5. …Lindlarcatalyst:Synthesis
 It is prepared by the reduction of palladium chloride in a slurry of
calcium carbonate (CaCO3) followed by the addition of lead acetate.
 A variety of other "catalyst poisons" have been used, including lead
oxide and quinoline.
 The palladium content of the supported catalyst is usually 5% by
weight.

6. …Lindlarcatalyst:Applications
1. The catalyst is used for the hydrogenation of alkynes to alkenes (i.e.
without further reduction into alkanes). The lead serves to deactivate the
palladium sites, further deactivation of the catalyst with quinoline
enhances its selectivity, preventing formation of alkanes. Thus if a
compound contains a double bond as well as a triple bond, only the triple
bond is reduced. E.g.
Phenylacetylene Styrene

7. …Lindlarcatalyst:Applications
2. Alkyne hydrogenation is always stereoselective, occurring via syn
addition to give the cis-alkene.
For example the hydrogenation of acetylenedicarboxylic acid using
Lindlar catalyst gives maleic acid rather than fumaric acid.

8. …Lindlarcatalyst
Partial reduction of alkynes;

9. …Lindlarcatalyst
Comprehensive Organic Name Reactions and Reagents, by Zerong Wang
Copyright © 2010 John Wiley & Sons, Inc.

10. …Lindlarcatalyst:Examples
Jonathan Clayden (University of Manchester), Nick Greeves (University of Liverpool), Stuart Warren (University of Cambridge); Organic
Chemistry, 2nd edition.

11. …Lindlarcatalyst:Examples
Jonathan Clayden (University of Manchester), Nick Greeves (University of Liverpool), Stuart Warren (University of Cambridge); Organic
Chemistry, 2nd edition.

12. …Lindlarcatalyst:Mechanism
Comprehensive Organic Name Reactions and Reagents, by Zerong Wang
Copyright © 2010 John Wiley & Sons, Inc.

13. …Lindlarcatalyst:Summary
1. Synthesis
2. Application: Alkynes to cis-alkene.
3. Mechanism

14. 6. Adam’s Catalyst
Dr. Shivendra Singh
UGC-NET-JRF, PhD-IIT Indore

15. …Adam’scatalyst
 Adams' catalyst, also known as platinum dioxide, is usually represented
as platinum(IV) oxide hydrate, PtO2•H2O.
 It is a catalyst for hydrogenation and hydrogenolysis in organic
synthesis.
 This dark brown powder is commercially available.
 The oxide itself is not an active catalyst, but it becomes active after
exposure to hydrogen whereupon it converts to platinum black, which
is responsible for reactions.
PtO2•H2O

16. …Adam’scatalyst:Preparation
 It is prepared from chloroplatinic acid H2PtCl6, by fusion with sodium
nitrate.
 The first published preparation was reported by V. Voorhees and Roger
Adams. The procedure involves first preparing a platinum nitrate which
is then heated to expel nitrogen oxide.
H2PtCl6 + 6 NaNO3 → Pt(NO3)4 + 6 NaCl (aq) + 2 HNO3
Pt(NO3)4 → PtO2 + 4 NO2 + O2
PtO2•H2O

17. …Adam’scatalyst:Application
 Adams' catalyst is used for many applications. It has shown to be valuable
for hydrogenation, hydrogenolysis, dehydrogenation, and oxidation
reactions.
PtO2•H2O
 Hydrogenation occurs with syn stereochemistry when used on an alkene
resulting in a alkane.
 Some of the most important transformations include the hydrogenation of
ketones to alcohols and the reduction of nitro compounds to amines.

18.  However, reductions of alkenes can be performed with Adam's catalyst in
the presence of nitro groups without reducing the nitro group.
 When reducing nitro compounds to amines, platinum catalysts are preferred
over palladium catalysts to minimize hydrogenolysis.
 The catalyst is also used for the hydrogenolysis of phenyl phosphate esters,
a reaction that does not occur with palladium catalysts. The pH of the
solvent significantly affects the reaction course, and reactions of the
catalyst are often enhanced by conducting the reduction in neat acetic
acid, or solutions of acetic acid in other solvents.
…Adam’scatalyst:Application PtO2•H2O

19. …Adam’scatalyst:Application PtO2•H2O
Jonathan Clayden (University of Manchester), Nick Greeves (University of Liverpool), Stuart Warren (University of Cambridge); Organic
Chemistry, 2nd edition.

20. …Adam’scatalyst:Application PtO2•H2O
MODERN METHODS OF ORGANIC
SYNTHESIS, W. CARRUTHERS , IAIN
COLDHAM

21. …Adam’scatalyst:Application PtO2•H2O
Strategic Applications of Named Reactions in Organic Synthesis, László Kürti and Barbara Czakó, UNIVERSITY OF PENNSYLVANIA

22. …Adam’scatalyst:Mechanism
https://chem.libretexts.org/Bookshelves/Organic_Chemistry/
PtO2•H2O

23. …Adam’scatalyst:Summary PtO2•H2O
1. Preparation:
2. Mechanism:
3. Application:

24. …Next:Anhydrous AlCl3
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