This chapter presents a straightforward discussion of the chemistry of carboxylic acids (formerly called “fatty acids”) and nitriles. As usual, we begin with a description of how the compounds are named. We then consider the subtleties of their structure, and how these structural features influence physical properties, such as boiling point. We place considerable emphasis on the dissociation of carboxylic acids and the effect of substituents on acid strength. We have already encountered a number of methods for preparing carboxylic acids. We shall review these methods, and learn about two additional procedures. The only reactions of carboxylic acids that we study in detail in this chapter are reduction and decarboxylation, although two other common reactions of carboxylic acids, alpha substitution and nucleophilic acyl substitution, will be described in later chapters. We will then look at the formation of nitriles and their chemical reactivity; and our discussion of carboxylic acid and nitrile chemistry concludes with a look at the infrared and NMR spectra of these compounds, with emphasis on the characterization of carboxylic acids. 20.0: Chapter Objectives and Introduction to Carboxylic Acids This page provides an overview of carboxylic acids, their historical significance, industrial applications, and naturally occurring examples. Carboxylic acids, such as acetic and citric acid, have been used historically in various applications. The text highlights the structure and properties of both saturated and unsaturated fatty acids, illustrating their significance in biological systems. Additionally, it introduces carboxylic acid derivatives and hints at their upcoming discussion. 20.1: Naming Carboxylic Acids and Nitriles This section focuses on the IUPAC naming of carboxylic acids and nitriles, detailing how to write and interpret their names and structures. It emphasizes understanding the priority of functional groups, especially for molecules with multiple functionalities, and highlights key naming conventions. Common and IUPAC names for carboxylic acids and the process for naming salts, dicarboxylic acids, and nitriles are explained. 20.2: Structure and Properties of Carboxylic Acids The document explains the properties and behaviors of carboxylic acids, highlighting their molecular geometry, acidity, and physical properties. Carboxylic acids have a carboxyl group which influences their acidity, making them more acidic than alcohols due to resonance stabilization. The document also discusses their higher boiling points due to hydrogen bonding and outlines their solubility in water, which decreases with increasing carbon chain length. 20.3: Biological Acids and the Henderson-Hasselbalch Equation This section discusses the dissociation of carboxylic acids in living cells and buffered solutions, emphasizing the relation between dissociation levels, pH, and pKa. Using the Henderson-Hasselbalch equation, one can calculate the percentages of dissociated and undissociated acids. At physiological pH (around 7.3), carboxylic acids are mostly in their deprotonated form, hence they are often referred to by their anion names, like acetate instead of acetic acid. 20.4: Substituent Effects on Acidity This page discusses the effects of substituents on the acidity of carboxylic and substituted benzoic acids. It highlights the inductive effect, where electron-withdrawing groups like fluorine increase acidity by stabilizing the carboxylate anion. Electron-donating groups have the opposite effect. The page also covers the ortho-effect in benzoic acids, influencing acidity regardless of substituent type, and provides examples and exercises related to acidity influenced by different substituents. 20.5: Preparing Carboxylic Acids The text outlines various methods for preparing carboxylic acids, focusing on oxidation, hydrolysis of nitriles, and carboxylation of Grignard reagents. It describes how primary alcohols and aldehydes can be oxidized using agents like potassium permanganate, while alkyl arene side-chains and alkenes can also be transformed into carboxylic acids through oxidations. Additionally, transforming Grignard reagents into carboxylic acids involves their reaction with carbon dioxide. 20.6: Reactions of Carboxylic Acids - An Overview The section outlines the ability to identify four types of reactions involving carboxylic acids: 1) Deprotonation forming carboxylate salts for substitution; 2) Nucleophilic acyl substitution for creating derivatives (e.g. esters, amides); 3) Reduction by reagents like LiAlH4; 4) Alpha substitution by removing the proton alpha to the carbonyl. It suggests reviewing related study notes and covers exercises for applying these concepts. 20.7: Chemistry of Nitriles This section on nitriles covers their preparation and reactions. Nitriles can be synthesized by nucleophilic attack of a cyanide ion on an alkyl halide or by dehydrating primary amides. Mechanisms for these processes, including the use of thionyl chloride, are discussed. Nitrile reactions include hydrolysis to carboxylic acids, reduction to amines using lithium aluminum hydride, and reactions with Grignard reagents to form ketones. 20.8: Spectroscopy of Carboxylic Acids and Nitriles The page discusses objectives and information related to the spectroscopy of carboxylic acids and nitriles. It covers identifying infrared absorptions and approximate 1H NMR absorption for carboxylic acids. Carboxylic acids have characteristic IR absorptions due to hydrogen bonding dimers. The 1H NMR for carboxylic acids shows deshielded protons in the 10-12 ppm range. Nitriles have distinctive CN stretching in the IR spectrum at 2250 cm?????. 20.S: Carboxylic Acids and Nitriles (Summary)