Peroxides

Definition

Peroxides are a class of chemical compounds that contain an oxygen-oxygen single bond (O-O). They are highly reactive and can participate in various chemical reactions, including those found in radical reactions, ethers, and chain-growth polymers.

5 Must Know Facts For Your Next Test

1. Peroxides can initiate and propagate radical chain reactions due to the labile nature of the O-O bond.
2. The decomposition of peroxides can generate free radicals, which are important in the formation of ethers through the Williamson ether synthesis.
3. Peroxides, such as benzoyl peroxide, are used as initiators in the free-radical polymerization of vinyl monomers to form chain-growth polymers.
4. Organic peroxides are often used as bleaching agents and oxidizing agents in various industrial and household applications.
5. Excessive exposure to peroxides can be hazardous, as they can lead to tissue damage and other health issues.

Review Questions

• Explain the role of peroxides in radical reactions and how they can initiate and propagate these reactions.
  • Peroxides are highly reactive due to the labile nature of the O-O bond, which can easily break to generate free radical intermediates. These free radicals can then initiate a chain reaction by abstracting hydrogen atoms from other molecules, forming new radicals that can continue the propagation of the reaction. The decomposition of peroxides, such as benzoyl peroxide, is a common method of generating free radicals for use in radical reactions, including those involved in the synthesis of ethers and chain-growth polymers.
• Describe the importance of peroxides in the synthesis of ethers, particularly in the context of the Williamson ether synthesis.
  • Peroxides play a crucial role in the Williamson ether synthesis, which is a common method for the preparation of ethers. In this reaction, the decomposition of a peroxide, such as diethyl peroxide, generates free radicals that can then react with alkoxide ions to form the desired ether product. The free radicals produced from the peroxide act as reactive intermediates, facilitating the nucleophilic substitution reaction between the alkoxide and an alkyl halide to create the ether linkage.
• Analyze the use of peroxides as initiators in the free-radical polymerization of vinyl monomers to form chain-growth polymers, and explain how this process works.
  • Peroxides, such as benzoyl peroxide and di-tert-butyl peroxide, are widely used as initiators in the free-radical polymerization of vinyl monomers to form chain-growth polymers. These peroxides decompose to generate free radicals, which can then react with the vinyl monomers, such as styrene or methyl methacrylate, to form active chain ends. The propagation of the reaction occurs as these active chain ends continue to add more monomers, resulting in the formation of high molecular weight macromolecules. The use of peroxides as initiators is crucial in controlling the rate and extent of polymerization, allowing for the synthesis of a wide range of chain-growth polymers with desired properties.

Related terms

Radical Reaction: A chemical reaction that involves the formation and propagation of free radical intermediates, which are species with unpaired electrons.

Ether: A functional group or compound that contains an oxygen atom connected to two alkyl or aryl groups.

Chain-Growth Polymer: A type of polymer formed by the successive addition of monomers to a growing chain, resulting in a high molecular weight macromolecule.