Question

The catalyst used for olefin polymerization is:
A. Raney nickel catalyst
B. Merrifield catalyst
C. Wilkinson catalyst
D. Ziegler-Natta catalyst

Answer 1

The polymerization of alkene is known as olefin polymerization. A hydrocarbon solution containing ${\text{TiC}}{{\text{l}}_{\text{4}}}$ and ${\text{AlE}}{{\text{t}}_{\text{3}}}$ is used for the olefin polymerization. ${\text{AlClE}}{{\text{t}}_2}$ is used as co-catalyst.

Complete Step by step answer: Raney nickel catalyst is used for the reduction of unsaturated compounds to saturated compounds, not from olefin polymerization, so option (A) is not correct.
Merrifield catalyst is used in organic synthesis for various chemical compounds, not for olefin polymerization, so option (B) is not correct.
Wilkinson catalyst is used for hydrogenation of alkene to form alkane, not for olefin polymerization The formula of this catalyst is ${\text{RhCl}}{\left( {{\text{pp}}{{\text{h}}_{\text{3}}}} \right)_{\text{3}}}$ . It is a homogeneous catalyst so, option (C) is not correct.
Ziegler-Natta catalyst is used for olefin polymerization. The combination of ${\text{TiC}}{{\text{l}}_{\text{4}}}$ and ${\text{AlE}}{{\text{t}}_{\text{3}}}$ is known as the Ziegler-Natta catalyst. The starting unit is ${\text{TiC}}{{\text{l}}_5}$ which reacts with ${\text{AlE}}{{\text{t}}_{\text{3}}}$ to form ${\text{TiC}}{{\text{l}}_4}{\text{Et}}$. Ziegler-Natta catalyst is a heterogeneous catalyst.

Therefore, option (D) Ziegler-Natta catalyst is correct.

Note: This ${\text{TiC}}{{\text{l}}_4}{\text{Et}}$ contains a vacant site at which an alkene coordinates so, the titanium complex accepts pi-electron density from an alkene. Then the ethyl group migrates at alkene so, again a vacant site is created. Final olefin polymer release by $\beta -$ hydrogen elimination. The polymer obtained by the Ziegler-Natta catalyst is highly ordered and crystalline. The arrangement is known as isostatic. The Wilkinson catalyst is $16$, electron square planar complex. The oxidation state of Rh metal is $+ 1$. It converts alkene into alkane by oxidative addition of hydrogen and alkene followed by migratory insertion and then reductive elimination.