Styrene can autoinitiate free radical polymerization and form polystyrene in the absence of an initiator. At temperatures >100 °C, radicals form due to homolysis of the T bond in the vinyl group. In the study of this reaction, researchers have found 1,2-diphenylcyclobutane in samples of heated styrene. The following mechanism for the formation of 1,2-diphenylcyclobutane has been proposed: Step 1: Homolysis of the vinyl T bond in a styrene molecule Step 2: Homolysis of the vinyl T bond in a second styrene molecule Step 3: Tail-to-tail addition of the radicals from Steps 1 and 2 Step 4: Radical coupling of the diradical formed in Step 3 (a) Use curved arrow notation to show the steps in this mechanism. (b) Are the steps in this mechanism consistent with those for free radical polymerization? (c) Why is the use of an initiator such as benzoyl peroxide more efficient in the synthesis of polystyrene than autoinitiated polymerization?

Styrene can autoinitiate free radical polymerization and form polystyrene in the absence of an initiator. At temperatures >100 °C, radicals form due to homolysis of the T bond in the vinyl group. In the study of this reaction, researchers have found 1,2-diphenylcyclobutane in samples of heated styrene. The following mechanism for the formation of 1,2-diphenylcyclobutane has been proposed: Step 1: Homolysis of the vinyl T bond in a styrene molecule Step 2: Homolysis of the vinyl T bond in a second styrene molecule Step 3: Tail-to-tail addition of the radicals from Steps 1 and 2 Step 4: Radical coupling of the diradical formed in Step 3 (a) Use curved arrow notation to show the steps in this mechanism. (b) Are the steps in this mechanism consistent with those for free radical polymerization? (c) Why is the use of an initiator such as benzoyl peroxide more efficient in the synthesis of polystyrene than autoinitiated polymerization?

Organic Chemistry

8th Edition

ISBN:9781305580350

Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Publisher:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Chapter29: Organic Polymer Chemistry

Section: Chapter Questions

Problem 29.34P: Radical polymerization of styrene gives a linear polymer. Radical polymerization of a mixture of...

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