Question

Give an example of coordination polymerization. Name the chemists responsible for the discovery of this method of polymerization.

Short answer

An example of coordination polymerization is the production of polyethylene from ethylene using a transition metal catalyst, specifically the Ziegler-Natta catalyst. The overall reaction can be represented as: $$n{C}_2{H}_4\to [-C{H}_2-C{H}_2-{]}_n$$ The chemists responsible for the discovery of this method of polymerization are Karl Ziegler and Giulio Natta.

Step-by-step solution

Example of Coordination Polymerization

Coordination polymerization is a type of polymerization process that involves the formation of polymers through the coordination of monomer units and catalysts. An important example of coordination polymerization is the production of polyethylene from ethylene using a transition metal catalyst, specifically the Ziegler-Natta catalyst.

Chemical Reaction Involved

The Ziegler-Natta catalyst promotes the formation of polyethylene (PE) from ethylene ($C_2{H}_4$). The overall reaction can be represented as: $$n{C}_2{H}_4\to [-C{H}_2-C{H}_2-{]}_n$$ Where n is the number of repeating units in the polymer chain.

Name the Chemists Responsible for the Discovery

Coordination polymerization, specifically the discovery of the Ziegler-Natta catalyst, can be attributed to two chemists: Karl Ziegler and Giulio Natta. Karl Ziegler discovered the transition metal catalysts that could be used for the polymerization of ethylene in 1953. Giulio Natta discovered the stereospecific polymerization process of other olefins using similar catalysts in 1954.

Key concepts

Ziegler-Natta Catalyst

The Ziegler-Natta catalyst is a revolutionary tool in the world of polymer chemistry, responsible for the efficient production of polymers like polyethylene and polypropylene. At the heart of this catalyst is a transition metal—commonly titanium or a similar metal—combined with an organoaluminum compound. This combination acts to control how individual monomer units link together, ensuring that the resulting polymer chains are long and well-organized.

• Ziegler-Natta catalysts allow the precise control over the polymerization process.
• They produce polymers with specific structures and low branching, leading to improved material properties.

This catalyst type is named after its discoverers, Karl Ziegler and Giulio Natta, who were awarded the Nobel Prize in Chemistry in 1963 for their work.

Transition Metal Catalysts

Transition metal catalysts are essential players in various chemical reactions, especially in polymerization processes. These catalysts form complexes with the monomer molecules and facilitate their transformation into long chains.

• Transition metal catalysts typically contain metals like titanium, nickel, or zirconium.
• They can initiate polymerization at room temperatures, making the process energy efficient and cost-effective.

The ability of these catalysts to produce high molecular weight polymers with specific structural arrangements makes them invaluable in industrial applications.

Polyethylene Production

Polyethylene, or PE, is one of the most common types of plastic used globally. Its production principally involves the polymerization of ethylene gas, a simple hydrocarbon, using a catalyst like the Ziegler-Natta catalyst. Ethylene ( C_2H_4 ) molecules are linked together in a chain, forming polyethylene's robust yet flexible structure.

• The resulting polymer can vary in density and branching, affecting its mechanical properties.
• Common products made from polyethylene include plastic bags, bottles, and toys.

The efficiency of producing polyethylene with transition metal catalysts has made it a key material in various industries.

Karl Ziegler

Karl Ziegler was a German chemist whose work in polymer chemistry led to groundbreaking advances in the creation of plastics. In the early 1950s, he discovered methods to polymerize ethylene effectively using specific metal catalysts.

• Ziegler's introduction of organometallic catalysts allowed for the commercial production of high-density polyethylene (HDPE).
• This innovation led to new applications and products due to polyethylene's enhanced properties.

Ziegler's contributions have left a lasting impact on material science and the plastics industry.

Giulio Natta

Giulio Natta, an Italian chemist, expanded upon Karl Ziegler's work by focusing on the polymerization of other olefins, a class of hydrocarbons. His research led to the production of stereoregular polymers, where the arrangement of monomer units in the polymer chain is structured in a regular pattern.

• Natta's work allowed for the creation of polypropylene, another widely used polymer.
• His discoveries in controlling polymer stereochemistry resulted in plastics with superior strength and flexibility.

Giulio Natta's pioneering efforts extended the possibilities of polymer design and manufacturing.