20: Carboxylic Acids and Nitriles
- Page ID
- 448766
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)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: Why This Chapter?
- Carboxylic acids are present in many industrial processes and most biological pathways and are the starting materials from which other acyl derivatives are made. Thus, an understanding of their properties and reactions is fundamental to understanding organic chemistry. We’ll look both at acids and at their close relatives, nitriles ( RC≡N ), in this chapter and at carboxylic acid derivatives in the next chapter.
- 20.1: Naming Carboxylic Acids and Nitriles
- This page outlines the naming conventions for carboxylic acids and nitriles, detailing the systematic approach used in organic chemistry. It explains how to identify the functional groups and the rules for assigning names based on the longest carbon chain, substituents, and functional group priorities. Carboxylic acids are named with the suffix "-oic acid," while nitriles use the suffix "-nitrile." Examples are provided to illustrate proper naming techniques.
- 20.2: Structure and Properties of Carboxylic Acids
- This section discusses the structure and properties of carboxylic acids, highlighting their functional group (-COOH), which is responsible for their acidic behavior. The unique properties arise from hydrogen bonding, resulting in higher boiling points compared to similar compounds. Carboxylic acids are also polar, contributing to their solubility in water. Their acidity can be influenced by the electronegativity of adjacent groups, which stabilizes the carboxylate ion formed upon deprotonation.
- 20.3: Biological Acids and the Henderson-Hasselbalch Equation
- The page discusses biological acids and introduces the Henderson-Hasselbalch equation, which relates the pH of a solution to the pKa of an acid and the ratio of its conjugate base. It highlights the significance of this equation in understanding the behavior of weak acids and their conjugate bases in biological systems. The section emphasizes how this relationship plays a crucial role in buffer solutions, maintaining pH levels within living organisms.
- 20.4: Substituent Effects on Acidity
- You have already seen how the presence of an electron‑withdrawing or electron‑releasing group affects the stability of a positively charged carbocation. Now you see how these groups affect the stability of carboxylate anions, and in turn, determine the dissociation constant of a carboxylic acid.
- 20.5: Preparing Carboxylic Acids
- This section outlines various methods for synthesizing carboxylic acids, including oxidation of primary alcohols and aldehydes, as well as hydrolysis of nitriles. Additionally, it describes the reaction of Grignard reagents with carbon dioxide, which leads to the formation of carboxylic acids. These techniques highlight the versatility and reactivity of carboxylic acids in organic chemistry.
- 20.6: Reactions of Carboxylic Acids - An Overview
- This section provides an overview of the various reactions involving carboxylic acids, including their role as nucleophiles in acyl substitution reactions, the formation of acid derivatives, and their behavior in esterification and amidation processes. It also highlights the significance of carboxylic acids in biological systems and their reactions with bases, alcohols, and amines.
- 20.7: Chemistry of Nitriles
- This section covers the chemistry of nitriles, detailing their structure, properties, and methods of synthesis, such as from carboxylic acids or alkyl halides. Nitriles undergo hydrolysis to produce carboxylic acids and can participate in nucleophilic addition reactions. Their versatile reactivity makes them significant in organic synthesis.
- 20.8: Spectroscopy of Carboxylic Acids and Nitriles
- This section discusses the spectroscopy techniques used to analyze carboxylic acids and nitriles, focusing on IR and NMR spectroscopy. It highlights key spectral features, such as characteristic absorption peaks in IR that indicate functional groups. The section provides insights into interpreting NMR data to deduce structural information about these compounds.
- 20.9: Chemistry Matters—Vitamin C
- This section explores Vitamin C, highlighting its chemical structure as a carboxylic acid. It discusses its biological significance, including its role as an antioxidant and in collagen synthesis, and the health benefits associated with its intake. The section also touches on food sources rich in Vitamin C and its importance in preventing deficiency-related diseases.
- 20.12: Summary of Reactions
- The page provides a summary of reactions involving carboxylic acids and nitriles. It includes various types of reactions like nucleophilic acyl substitution, esterification, and reduction of carboxylic acids, as well as hydrolysis and reduction of nitriles. The focus is on how these compounds react under different conditions, highlighting key transformations and the chemical pathways that lead to different products.