058_Ho_15_RG_13__08 - Chem 058 J. Walcott CENTER FOR...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chem 058 CENTER FOR LEARNING AND TEACHING Handout #15 J. Walcott LEARNING STRATEGIES CENTER Spring 2008 Review Guide #13 Lectures: 4/21/08 – 4/25/08 Chapters 28 and 22 I. Polymers (continued from Review Guides #11 and #12) A. Step-Growth Polymerization (condensation) B. Chain-Growth Polymerization (addition) 1. Free radical polymerization 2. Anionic polymerization a. Group transfer polymerization uses silicon chemistry on α - β unsaturated systems that undergo a Michael type addition. The reactions can be done at reasonable temperatures and side reactions are limited because the stable silicon-protected enol replaces an enolate anion. The reactive silyl group is at the growing end of the polymer and can be removed by acid. b. Aldol group transfer polymerization is a reaction catalyzed by ZnBr 2 whereby silyl enol ethers, act as nucleophiles and add to aldehydes and ketones transferring the terminal silyl group in the process. The silyl groups minimize the dehydration reaction and can be removed by acid 3. Cationic Polymerization A carbocation initiator begins the reaction forming carbocation intermediates in forming the polymer. The carbocations obey all the stability rules – the molecule can rearrange. 4. Other - An alkoxide anion can initiate polymerization of epoxides. Acid will terminate the reaction. - An alkoxide anion can initiate polymerization of lactones. Acid will terminate the reaction - A carbocation can initiate polymerization of an alkene with an –OR group. An alcohol will terminate the reaction by forming an acetal that can be removed with acid to form an aldehyde or ketone. II. Amino Acids, Peptides, and Proteins Amino acids contain both an amino group and a carboxylic acid group. Each of the 20 commonly occurring amino acids has an amino group on the α -carbon, the carbon adjacent to the carboxylic
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 2

058_Ho_15_RG_13__08 - Chem 058 J. Walcott CENTER FOR...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online