Biography & Contributions
Robert Grubbs [Robert H. Grubbs] is an American chemist and Nobel laureateborn on February 27, 1942
Awards & Medals
1975-78, Camille and Henry Dreyfus Teacher-Scholar Award
2000, ACS Herman F. Mark Polymer Chemistry Award
2002, Tolman Medal
2005, Nobel Prize
Grubbs’s main interests include
Organometallic chemistry
Catalysts
He developed
- Grubbs' catalyst
- Living polymerization method
- Olefin metathesis organic reactions
Metathesis reactions
Metathesis reactions also termed as exchange reactions. Metathesis is one of the most spectacular recent improvements in synthetic strategies for organic synthesis and polymer science.
Definition
Reactions in which the products are formed by the exchange of the ions present in the two reactants
Metathesis reactions not only take place among ionic compounds, they occur among other compounds such as Sigma Bond Metathesis and Olifin Metathesis. Metathesis reaction is a type of chemical reactions, which include combination, decomposition, and displacement.
Example 1]
NaCl(s) + 12 H2O [Na(H2O)6]+ + [Cl(H2O)6]-
Example 2]
AgNO3(s) + 12 H2O [Ag(H2O)6]+ + [NO3(H2O)6]-
Example 3]
MgCl2 (aq) + 2 NaOH (aq) --> Mg(OH)2 (s) + 2 NaCl (aq)
Metathesis mechanism
In the above example reaction between MgCl2 and NaOH, magnesium ion was originally paired with the chloride ion on the reactant side of the equation while the sodium ion was originally paired with the hydroxide ion.
Ions exchanging will take place between magnesium ion and sodium ion. On the product side, the magnesium is now paired with hydroxide ion forming an insoluble solid or precipitate called magnesium hydroxide.
Similarly sodium ion is now paired with the chloride ion forming a soluble strong electrolyte sodium chloride.
How to write metathesis mechanism
Step 1]
Break each reactant apart into the cation and anion present
Mg+ Cl2-
Na+ OH-
Step 2]
Exchange anions
Mg+ OH-
Na+ Cl-
Step 3]
Pairing of cation with anion
Mg(OH)2
NaCl
Step 4]
If one of the products formed is an insoluble solid, write the unbalanced molecular equation by placing the formulas for the reactants (along with physical states) on the left side of the arrow and write formulas for the products (along with physical states) on the right side of the arrow.
MgCl2 (aq) + NaOH (aq) --> Mg (OH)2 (s) + NaCl (aq)
Step 5]
Balance the equation
MgCl2 (aq) + 2 NaOH (aq) --> Mg (OH)2 (s) + 2 NaCl (aq)
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