Chem-15- Organic- Carboxylic acids + esters

what are carboxylic acids

compounds that contain a carboxyl group (COOH)

explain the position of equlibrium for the dissociation of carboxylic acids

RCOOH → ← RCOO^- +H⁺

Equlibrium lies to the left as it is a weak acid

what is the name of the ion RCOO^-

carboxylate ion

Explain the high boiling points of carboxylic acids

can form Hydrogen bonds and specifically dimers

draw a dimer structure between two carboxylic acids

describe the solubility of carboxylic acids in water

highly soluble but get less soluble as chain length increases

what are the 2 methods of making a carboxylic acid

1. oxidising a primary alcohol into an aldehyde and then into a carboxylic acid (heat under reflux)

2. Hydrolysis (reacting with water) of a nitrile (dilute acid + heat under reflux)

carboxylic acid + base → ?

carboxylate salt + water

neutralisation

carboxylic acid + carbonates

CO2 + carboxylate salt + water

carboxylic acid + PCl₅

POCl₃ + HCl + CH₃COCl

carboxylic acid + alcohol and what catalyst is required

Sulfuric acid catalyst

ester ethanoate (-coo-) + water

this process is called esterfication

carboxylic acid + reducing agent (lithium aluminum hydride- strong)

primary alcohol + water

what are acyl chlorides

compounds with the group COCl

describe reaction: acyl chloride + water

→ carboxylic acid + water

reaction is vigorous, and you may see steamy/white fumes of HCl

describe reaction: acyl chloride + alcohol in heat under reflux

ester + HCl

violently at room temp

describe reaction: acyl chloride + conc ammonia

→ primary amide + HCl

violently at room temp

describe reaction: acyl chloride + primary amine

→ secondary amide + HCl

violently at room temp

what is the functional group of an ester

RCOOR’

what is the reaction and conditions needed to form an ester

Esterification (carboxylic acid + alcohol) is a reversible reaction done in the presence of an acid catalyst

Done with heat under reflux

describe the hydrolysis of an ester under acidic conditons

forms a carboxylic acid and alcohol

describe the reaction of an ester + dilute alkali (OH^-)

carboxylate salt (RCOO^-) + alcohol

in aqeuous conditions so considered a base hydrolysis

why is the acid hydrolysis reversible whereas the base hydrolysis isnt

because the base hydrolysis forms a carboxylate salt which is very stable and unlikely to react with the alcohol again.

what are diols and dicarboxylic acids

Diols: two -OH groups

Dicarboxylic acids: two -COOH groups

How is a polyester formed from a dicarboxylic acid and a diol?

A dicarboxylic acid has two -COOH groups and a diol has two -OH groups. A -COOH group reacts with an -OH group to form an ester link, COO, and H2O is eliminated. Because both monomers have two reactive ends, they can keep joining to form a long chain. This is condensation polymerisation.