tailieunhanh - Lecture Organic chemistry: Chapter 18 - L. G. Wade, Jr.

Chapter 18 introduce to Ketones and Aldehydes. After completing this chapter, students will be able to: Draw and name ketones and aldehydes, and use spectral information to determine their structures; propose single-step and multistep syntheses of ketones and aldehydes from compounds containing other functional groups; predict the products and propose mechanisms for the reactions of ketones and aldehydes with oxidizing and reducing agents, amines, alcohols, and phosphorus ylides;. | Chapter 18 Copyright © 2010 Pearson Education, Inc. Organic Chemistry, 7th Edition L. G. Wade, Jr. Ketones and Aldehydes Chapter 18 Carbonyl Compounds Chapter 18 Carbonyl Structure Carbon is sp2 hybridized. C═O bond is shorter, stronger, and more polar than C═C bond in alkenes. Chapter 18 Ketone Nomenclature Number the chain so that carbonyl carbon has the lowest number. Replace the alkane -e with -one. 3-methyl-2-butanone 4-hydroxy-3-methyl-2-butanone C H 3 C O C H C H 3 C H 3 C H 3 C O C H C H 3 C H 2 O H 1 2 3 4 1 2 3 4 Chapter 18 Ketone Nomenclature (Continued) For cyclic ketones, the carbonyl carbon is assigned the number 1. 3-bromocyclohexanone O B r 1 3 Chapter 18 C H 3 C H 2 C H C H 3 C H 2 C H O Aldehydes Nomenclature The aldehyde carbon is number 1. IUPAC: Replace -e with -al. 3-methylpentanal 1 2 3 5 Chapter 18 Carbonyl as Substituent On a molecule with a higher priority functional group, a ketone is an oxo and an aldehyde is | Chapter 18 Copyright © 2010 Pearson Education, Inc. Organic Chemistry, 7th Edition L. G. Wade, Jr. Ketones and Aldehydes Chapter 18 Carbonyl Compounds Chapter 18 Carbonyl Structure Carbon is sp2 hybridized. C═O bond is shorter, stronger, and more polar than C═C bond in alkenes. Chapter 18 Ketone Nomenclature Number the chain so that carbonyl carbon has the lowest number. Replace the alkane -e with -one. 3-methyl-2-butanone 4-hydroxy-3-methyl-2-butanone C H 3 C O C H C H 3 C H 3 C H 3 C O C H C H 3 C H 2 O H 1 2 3 4 1 2 3 4 Chapter 18 Ketone Nomenclature (Continued) For cyclic ketones, the carbonyl carbon is assigned the number 1. 3-bromocyclohexanone O B r 1 3 Chapter 18 C H 3 C H 2 C H C H 3 C H 2 C H O Aldehydes Nomenclature The aldehyde carbon is number 1. IUPAC: Replace -e with -al. 3-methylpentanal 1 2 3 5 Chapter 18 Carbonyl as Substituent On a molecule with a higher priority functional group, a ketone is an oxo and an aldehyde is a formyl group. Aldehydes have a higher priority than ketones. 3-methyl-4-oxopentanal 3-formylbenzoic acid 1 3 4 1 3 C H 3 C C H C H 3 C H 2 C H O O C O O H C H O Chapter 18 Common Names for Ketones Named as alkyl attachments to —C═O. Use Greek letters instead of numbers. methyl isopropyl ketone a-bromoethyl isopropyl ketone C H 3 C O C H C H 3 C H 3 C H 3 C H C O C H C H 3 C H 3 B r Chapter 18 Historical Common Names acetone acetophenone benzophenone Chapter 18 Boiling Points Ketones and aldehydes are more polar, so they have a higher boiling point than comparable alkanes or ethers. They cannot hydrogen-bond to each other, so their boiling point is lower than comparable alcohol. Chapter 18 Solubility of Ketones and Aldehydes Good solvent for alcohols. Lone pair of electrons on oxygen of carbonyl can accept a hydrogen bond from O—H or N—H. Acetone and acetaldehyde are miscible in water. Chapter 18 Formaldehyde Gas at room temperature. Formalin