[26.4] carboxylic acid derivatives

a compound that can be hydrolysed to form the parent carboxylic acid

• esters • acyl chlorides • acid anhydrides • amides

the reaction of an alcohol with a carboxylic acid to form an ester

• reagents: carboxylic acid + alcohol • conditions: reflux and concentrated sulfuric acid cataylst • products: ester + water • naming: -yl from alcohol, -oate from CA

• carboxylic acids • acyl chlorides • acid anhydrides

unreactive compared to acids and acyl chlorides

structural isomers of CAs

• reverse of esterification • form a carboxylic acid + alcohol • heated under reflux • dilute HCl (aq) acts as a catalyst (doesn’t go in equation) • reversible reaction

• heated under reflux • NaOH (aq) • forms COOH + alcohol but metal ions present (aq) so carboxylate salt produced

• an acyl group (R-C=O) • an electronegative atom or group of atoms

• named from ‘parent’ CA • remove the -oic acid • replace with -oyl chloride • structure: C=O and Cl attached to C eg. ethanoic acid = ethanoyl chloride

• carboxylic acid + thionyl chloride (SOCl₂) • R-COOH + SOCl₂ -> R-COCl + SO₂ (g) + HCl (g)

• acyl chlorides must be kept dry as they react with water • reaction should be carried out in a fume cupboard as products are harmful

• good starting material as it can make lots of functional groups • acyl chloride group makes it very reactive • no need for catalyst • Cl and O are electron-withdrawing, increasing the positivty of C and susceptibility to nucleophilic attack • corrosive and produce harmful gases (HCl)

• esters • carboxylic acids • primary amides • secondary amides

• acyl chloride + alcohol -> ester + HCl (g) • room temperature • irreversible reaction • HCl - misty fumes observed

• acyl chloride + water -> carboxylic acid + HCl (g) • vigourous at room temperature • HCl - misty fumes observed

• acyl chloride + ammonia (NH₃) -> (1) amide + NH₄Cl • does produce HCl but HCl + excess NH₃ -> NH₄⁺Cl⁻ • violent reaction producing white smoke

• acyl chloride + primary amine -> N-amide + CH₃NH₃⁺Cl⁻ • violent reaction producing a white solid mixture • does produce HCl but HCl + excess primary amine -> CH₃NH₃⁺Cl⁻

• irreversible so better yield • no need for catalyst: happens ar room temp • reacts with phenol (COOH too weak)

• react in a similar way to acyl chlorides but are less exothermic, less corrosive and safer • cheaper • less reactive than acyl chlorides (less electron-withdrawing effect) so reactions are slower • requires gentle heating • instead of HCl as a product, makes R-COOH

• symmetrical molecule • O in middle, C=O attached to either side • -R attached to C • to name, basically split molecule in half and see which parent CA eg. ethanoic anhydride

• acid anhydride + alcohol -> ester + carboxylic acid • CA is safer than HCl

acyl chlorides are: • difficult to hand as they react very readily with water so need to be used in water-free conditions • react to produce corrosive HCl acid anhydrides are: • cheaper to produce • no as moisture sensitive • less corrosive • produce carboxylic acids, which are safer than HCl