tailieunhanh - Ebook Organic chemistry (11th edition): Part 2

(BQ) Part 2 book "Organic chemistry" presents the following contents: Conjugated unsaturated systems, aromatic compounds, reactions of aromatic compounds, nucleophilic addition–elimination at the acyl carbon, reactions at the α carbon of carbonyl compounds-enols and enolates, amino acids and proteins, nucleic acids and protein synthesis,. | CHAPTER 13 Conjugated Unsaturated Systems W_ . _ hat do the colors of a plant a carrot your favorite pair of blue jeans and our ability to see all have in common They all result from molecules that have a sequence of alternating double and single bonds. This bonding pattern leads to a phenomenon known as conjugation. Conjugated compounds include b-carotene which produces the orange color of carrots chlorophyll a which is the green pigment that carries on photosynthesis and indigo the pigment that gives your blue jeans their distinctive color. It is the conjugation of their double bonds and the way these compounds interact with light both visible and ultraviolet that produces their colors. Moreover such molecules also have unique aspects of reactivity because the anions cations and radical species formed from them possess greater than normal stabilization. As a result they can participate in a large and unique spectrum of organic chemistry. IN THIS CHAPTER WE WILL CONSIDER conjugation and resonance structures based on radicals cations and anions the unique physical properties of conjugated systems especially as observed by UV-Vis spectroscopy a special transformation named the Diels-Alder reaction that can combine conjugated molecules known as 1 3-dienes with certain partners to create six-membered rings containing up to four new chirality centers WHY DO THESE TOPICS MATTER At the end of the chapter we will see just how Otto Diels and Kurt Alder first discovered the reaction that would later bear their names and garner them the Nobel Prize noting that it was nearly discovered by a number of other people who had done the same chemistry but could not figure out what they had made photo credits house plant Media Bakery carrot Image Source blue jeans Media Bakery 581 582 CHAPTER 13 CONJUGATED UNSATURATED SYSTEMS INTRODUCTION At its essence a conjugated system involves at least one atom with ap orbital adjacent to at least one p bond. The adjacent atom with thep .