Question

The chemical formula of Ziegler-Natta catalyst is:
 A. $CuC{{l}_{2}}$
B. $NiC{{l}_{2}}$
C. $CrC{{l}_{3}}$
D. $TiC{{l}_{4}}$

Answer 1

Hint: In the preparation of High Density polyethene (HDPE) the catalyst used is called Ziegler-Natta catalyst. The Ziegler-Natta catalyst is used to prepare polymers from the monomers which contain double bonds in its structure.

Complete step by step answer:
- In the question it is given what the chemical formula of the Ziegler-Natta catalyst is.
- Ziegler-Natta catalyst was named by a German Chemist Karl Zeigler in 1950.
- The use of Ziegler-Natta catalyst was first demonstrated in the preparation of polyethene from ethylene.
- Generally alkyl derivatives are going to mix with titanium or aluminum tetrachloride to prepare Ziegler-Natta catalysts.
- Therefore the chemical formula of Ziegler-Natta catalyst is Titanium tetrachloride ($TiC{{l}_{4}}$ ).

- So, the correct option is D.

Additional information:
- Nowadays Ziegler-Natta catalysts contain mixtures of transition metal halides (like Vanadium tetrachloride, Zirconium tetrachloride).
- The chemical reaction which involves the Ziegler-Natta catalyst to prepare HDPE is as follows.
\[nC{{H}_{2}}=C{{H}_{2}}\xrightarrow{TiC{{l}_{4}}}\underset{HDPE}{\mathop{{{[-C{{H}_{2}}-C{{H}_{2}}-]}_{n}}}}\,\]
- In the above reaction n monomer of ethylene undergoes polymerization and forms HDPE as the product in the presence of Ziegler-Natta catalyst.
- Ziegler-Natta catalysts are also used in the preparation of LDPE (low density polyethene).
- Ziegler-Natta catalyst also used in the preparation of thermoplastic polymers.

Note: The method of polymerization in the presence of Titanium tetrachloride is extended to the polymerization of other olefins by a scientist Giulio Natta. That is why the name is as Ziegler-Natta catalyst. But the limitation of the Ziegler-Natta catalyst is we cannot prepare PVC (polyvinyl chloride).