Aldehydes and Ketones part 1

Chapter 2: Aldehydes and Ketones

Overview

• Chapter 15 Lecture from "Fifteen Fundamentals of General, Organic, and Biological Chemistry, 8th Edition."

• Presented by Christina A. Johnson, University of California, San Diego.

Outline of Content

• 15.1 The Carbonyl Group

• 15.2 Naming Simple Aldehydes and Ketones

• 15.3 Properties of Aldehydes and Ketones

• 15.4 Some Common Aldehydes and Ketones

• 15.5 Oxidation of Aldehydes

• 15.6 Reduction of Aldehydes and Ketones

• 15.7 Addition of Alcohols: Hemiacetals and Acetals

Key Concepts to Review

• Electronegativity and Molecular Polarity (Sections 4.9 and 4.10)

• Oxidation and Reduction (Section 5.6)

• Hydrogen Bonds (Section 8.2)

• Functional Groups (Section 12.2)

• Naming Alkanes (Section 12.6)

• Types of Organic Reactions (Section 13.5)

15.1 The Carbonyl Group

• Definition: A functional group where a carbon atom is double bonded to an oxygen atom (C=O).

• Polarity: Polar due to the electronegativity of oxygen compared to carbon; impacts reactivity.

• Bond Angles: Approximately 120° between substituents attached to the carbonyl carbon.

Classification of Carbonyl Compounds

• Aldehydes: Carbonyl group bonded to a hydrogen atom (RCHO) - end of a carbon chain.

• Ketones: Carbonyl group bonded to two carbon atoms (RCOR‘) - located within a carbon chain.

15.2 Naming Simple Aldehydes and Ketones

• Common Names: Aldehydes end in -aldehyde; ketones are named by the alkyl groups followed by 'ketone'.

• IUPAC Naming: Aldehydes replace final -e with -al; ketones replace final -e with -one. Numbering begins at the carbonyl carbon.

15.3 Properties of Aldehydes and Ketones

• Polarity: Moderately polar due to carbonyl group.

• Boiling Points: Higher than alkanes, lower than alcohols of similar weight due to absence of hydrogen bonding between molecules.

• Solubility: Soluble in organic solvents; those with <5-6 carbon atoms are soluble in water due to hydrogen bonding capability.

• Applications: Simple ketones are effective solvents for both polar and nonpolar substances.

15.4 Some Common Aldehydes and Ketones

• Many aromas and flavors result from naturally occurring aldehydes and ketones.

• Distinctive Odors: Several aldehydes and ketones exhibit unique scents, impacting their usage in flavor and fragrance industries.

Summary of Properties of Aldehydes and Ketones

• Polar molecules due to carbonyl groups.

• Cannot hydrogen bond with themselves, leading to specific boiling points.

• Liquids under standard conditions; many have characteristic odors; commonly less toxic than simple aldehydes.