Reductive elimination reactions

this file may contain
1. Definition
2. Mechanism
3. Examples
4. Application
5. References

1. Presentation title:
Presented by: Muhammad Ayyan Khan
Reductive Elimination
Reactions

2. Contents
1. Definition
2. Mechanism
3. Examples
4. Application
5. References

3. Reductiveelimination
reactions
Reductive eliminationis an elementary step in
organometallic chemistry in which the
oxidation state of the metal center decreases
while forming a new covalent bond between
two ligands. It is the microscopic reverse
ofoxidativeaddition, and is often the product-
forming step in many catalytic processes.

4. Areductive elimination reactionis one in which the
oxidation state of the metal decreases by two units and
the coordination number of the metal decreases
Oxidative addition and reductive elimination reactions
are, in principle, reversible. However, in practice, one
direction is normally thermodynamically favoured over
the other. Oxidative addition and reductive elimination
reactions play a major role in many catalytic processes

5. Reductive elimination is the reverse of oxidative addition. To
illustrate this distinction, consider the following equilibrium:
The forward reaction involves formal oxidation of the metal,
accompanied by an increase in coordination number; it is an
OA. The reverse reaction is an example of RE, which
involves a decrease in both oxidation number and
coordination number. RE reactions often involve elimination
of molecules such as
R-H -R-R' R-x H-H (R, R' = alkyl, aryl; X = halogen)

6. The opposite of oxidative addition, where two ligands couple
and eliminate from a metal centre, is known as reductive
elimination
Reductive elimination reactions require both eliminating fragments
to be cisto each other, and are best thought of as the reverse of the
concerted form of oxidative addition. Oxidative addition and
reductive elimination reactions are, in principle, reversible.
However, in practice, one direction is normally thermodynamically
favoured over the other. Oxidative addition and reductive
elimination reactions play a major role in many catalytic processes

7. An example of reductive elimination reaction which
occurs in the catalytic hydrogenation of alkenes.
This final step in the hydrogenation cycle produces
the alkanereaction product and regenerates the square
planar rhodium catalyst.

9. Show that the reaction
Identifying oxidative addition and reductive elimination
is an example of an oxidative addition reaction.
Answer In order to identify an oxidative addition reaction, we need to
establish the valence electron counts and oxidation states of both the
starting material and the product. The four-coordinate square planar Rh
starting material contains an η 1 -alkynylligandas well as three neutral
phosphine ligands; it is therefore a 16-electron Rh(I) species. The six-
coordinate octahedral product contains two η 1-alkynyl ligands , a
hydride ligand, and three neutral phosphine ligands; it is therefore an 18-
electron Rh(III) species. The increase in both coordination number and
oxidation number by 2 identifies it as an oxidative addition.

10. Show that the reaction
is an example of reductive
elimination.
As we know that in reductive elimination reaction two ligand
remove from metal atom and couple to form new species
behind oxidation number of metal atom decrease
In this example where two ligands Ph and Clcouple and
eliminate from a metal centre

11. APPLICATIONS
A reductive elimination is used to produce product
and regenerate the catalyst.
Reductive elimination has found widespread application
in academia and industry, most notable
beinghydrogenation,theMonsanto acetic acid
process,hydroformylation,andcross-coupling reactions.In
many of these catalytic cycles, reductive elimination is
the product forming step and regenerates the catalyst;
however, in theHeck reactionandWacker
process,reductive elimination is involved only in catalyst
regeneration, as the products in these reactions are
formed viaβ–hydride elimination.

12. Refrence:
1.Inorganic Chemistry, 6th Edition by ‘’Shriver and
Atkins’’
2.Coordination Chemistry by
‘’Fred Basoloand Ronald C.
Johnson’’

13. THANK YOU