Conjugation, Resonance, and Dienes

13 Specific rules governing the Diels-Alder reaction 

14 Other facts about the Diels-Alder reaction 

Lycopene is a red pigment found in tomatoes, watermelon, papaya, guava, and pink grapefruit. An antioxidant like vitamin E, lycopene contains many conjugated double bonds—double bonds separated by only one single bond—that allow jt electron density to delocalize and give the molecule added stability. In Chapter 16 we learn about such conjugated unsaturated systems. 

Much of Chapter 16 is devoted to the properties and reactions of 1,3-dienes. To understand these compounds, however, we must first learn about the consequences of having p orbitals on three or more adjacent atoms. Because the ability to draw resonance structures is also central to mastering this material, the key aspects of resonance theory are presented in detail. 

The word conjugation is derived from the Latin conjugatus, meaning to join.  

Chapter 16 is the first of three chapters that discuss the chemistry of conjugated molecules— molecules with overlapping p orbitals on three or more adjacent atoms. Chapter 16 focuses mainly on acyclic conjugated compounds, whereas Chapters 17 and 18 discuss the chemistry of benzene and related compounds that have a p orbital on every atom in a ring. 

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Radical Polymerization of CH2=CHZ 5 63 Chapter 16 Conjugation, Resonance, and Dienes... 

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