Carboxylic Acids & Derivatives – Key Vocabulary

Traditional vocabulary flashcards covering key terms, reagents, mechanisms, and spectroscopic data for carboxylic acids and their derivatives.

Carboxylic acid

An organic compound that contains the –COOH functional group and is named with the suffix “oic acid.”

Dicarboxylic acid

A compound containing two –COOH groups; named with the suffix “dioic acid.”

Carboxylate salt

The product formed when a carboxylic acid is deprotonated by a strong base; named by replacing “ic acid” with “ate.”

pKa (carboxylic acids)

A measure of acid strength; most carboxylic acids have pKa values between 4 and 5.

Resonance-stabilized conjugate base

The carboxylate ion whose negative charge is delocalized over two oxygen atoms, explaining the acidity of carboxylic acids.

Henderson–Hasselbalch equation

Relates pH, pKa, and the ratio of conjugate base to acid; predicts that carboxylic acids exist mainly as carboxylate salts at physiological pH.

Electron-withdrawing substituent effect

Groups that pull electron density from the –COOH increase acidity; the effect decreases with distance from the acid group.

Nitrile hydrolysis

Conversion of a –C≡N group to a carboxylic acid when treated with aqueous acid (or base).

Grignard carboxylation

Reaction of a Grignard reagent with CO₂, followed by acid work-up, to give a carboxylic acid.

LiAlH₄ reduction of acids

Powerful hydride reduction turning carboxylic acids into primary alcohols.

Borane (BH₃) reduction

Selective reagent that reduces carboxylic acids to alcohols without affecting ketones or aldehydes.

Carboxylic acid derivative

A compound with the same oxidation state as a carboxylic acid, such as acid halides, anhydrides, esters, amides, and nitriles.

Acid halide (acid chloride)

Derivative named by replacing “ic acid” with “yl halide”; the most reactive derivative toward nucleophiles.

Acid anhydride

Derivative named by replacing “ic acid” with “anhydride”; prepared from acid chlorides or by heating some acids.

Ester

Derivative named by stating the alkyl group bonded to oxygen followed by the acid name with “ate” ending.

Amide

Derivative obtained by replacing “ic”/“oic acid” with “amide”; possesses a C–N bond with partial double-bond character.

Nitrile

Derivative named by replacing “ic acid” with “nitrile”; contains a –C≡N group.

Reactivity order (derivatives)

Acid halide > anhydride > ester ≈ nitrile > amide.

Nucleophilic acyl substitution

Mechanism where a nucleophile attacks a carbonyl, forming a tetrahedral intermediate that collapses to replace the leaving group.

Thionyl chloride (SOCl₂)

Reagent that converts carboxylic acids to acid chlorides with evolution of SO₂ and HCl.

Hydrolysis of acid chloride

Reaction with water giving the parent carboxylic acid and HCl.

Alcoholysis of acid chloride

Conversion of an acid chloride to an ester upon treatment with an alcohol (often with pyridine).

Aminolysis of acid chloride

Formation of an amide from an acid chloride and two equivalents of ammonia (or an amine).

Lithium tri(t-butoxy)aluminum hydride

Selective hydride reagent that reduces acid chlorides to aldehydes without over-reduction to alcohols.

Gilman reagent (lithium dialkyl cuprate)

Organocuprate that converts acid chlorides to ketones by single alkyl addition.

Acetic anhydride

An acid anhydride produced by heating acetic acid; used widely in acetylation reactions.

Fischer esterification

Reversible acid-catalyzed conversion of a carboxylic acid and alcohol into an ester and water.

Saponification

Base-promoted hydrolysis of an ester yielding a carboxylate salt and an alcohol.

DIBAH (diisobutylaluminum hydride)

Bulky hydride reagent that reduces esters to aldehydes under controlled conditions.

Amide hydrolysis

Conversion of an amide to a carboxylic acid under strongly acidic or basic aqueous conditions.

Amide reduction

Treatment with excess LiAlH₄ converts an amide into an amine.

Nitrile dehydration

Formation of a nitrile by dehydrating an amide (e.g., using SOCl₂ or P₂O₅).

Nitrile reduction

LiAlH₄ converts nitriles to primary amines.

Nitrile to ketone

Reaction of a nitrile with a Grignard reagent followed by aqueous acid work-up to produce a ketone.

IR carbonyl stretch (1650–1850 cm⁻¹)

Frequency range in IR spectra; exact wavenumber helps identify the carbonyl derivative type.

Conjugated carbonyl IR shift

A conjugated carbonyl absorbs at a lower wavenumber than a non-conjugated one.

¹³C NMR carbonyl region (160–185 ppm)

Typical chemical shift for carbonyl carbons of carboxylic acids and derivatives.

¹³C NMR nitrile carbon (115–130 ppm)

Signature region for the carbon atom of a –C≡N group.

¹H NMR acid proton (~12 ppm)

Downfield singlet characteristic of the acidic proton in carboxylic acids.