.chapter 2 - carboxylic acids and its derivatives

what is the functional group of carboxylic acids?

• -COOH

properties of carboxylic acids?

• they are weak acids, so they only partially ionise water

• they will react with carbonates to produce CO2

  • this can be used as a test for carboxylic acids

esterification of carboxylic acids?

• carboxylic acids will react with alcohols

• this reaction is called esterification, it produces an ester

  • usually, sulfuric acid as a catalyst for this reaction

reaction of carboxylic acids with metal oxides?

• forms a salt and water

reaction of carboxylic acids with alkalis?

• a salt and water

reactions of carboxylic acids with carbonates?

• a salt, water and carbon dioxide

functional group of an ester?

-COO

uses of esters?

• plasticisers

• solvents (ethyl ethanoate)

• perfumes

• food flavourings (ethyl butrate, pineapple)

what is hydrolysis?

• the chemical breakdown of a compound in the presence of water or in aqueous solution

what 2 things can esters be hydrolysed

• by aqueous acid or alkali

acid hydrolysis?

• acid hydrolysis of an ester is the reverse of esterification

• the products are a carboxylic acid and an alcohol

alkaline hydrolysis?

• also known as the saponification and is irreversible

• if aqueous sodium hydroxide is the alkali, the salt sodium ethanoate is formed during alkaline hydrolysis

what are the products of the hydrolysis of esters?

• a carboxylate salt and an alcohol

hydrolysis of polyesters?

• polyesters are attacked readily by alkalines but much more slowly by acids

• a polyester will react with an alkali to cut the polymer chain and produce an alcohol and a carboxylate salt as with esters

• a polyester will also react with an acid to cut the polymer chain and produce an alcohol and carboxylic acids but this process is very slow

how are acyl chlorides formed?

• by reacting carboxylic acids with an inorganic compound called thionyl chloride (sulfur dichloride oxide)

where can acyl chlorides be derived from?

• carboxylic acids

  • they are also known as acid chlorides

reactants and products of acyl chlorides

• acyl chlorides are produced from a reaction between SOCl2 and a carboxylic acid

  • hydrogen chloride and sulfur dioxide gases are produced in the reaction

how to remove excess reagents from the acyl chloride?

• fractional distillation

  • hydrogen chloride and sulfur dioxide are given off as gases

what is a derivate of a carboxylic acid?

• a compound that can be hydrolysed to form the parent carboxylic acids

• carboxylic acid derivates have a common sequence of atoms in their structure, known as an acyl group

acyl group?

what are the 4 derivatives of carboxylic acids?

• ester

• acyl chlorides

• acid anhydrides

• amide

examples of acylated materials?

• amide

• acyl chlorides

• anhydride

what does the nucleophilic addition-elimination reaction happen with?

• acyl chlorides and acid anhydrides

• it is used to produce amides, carboxylic acids, and ester

mechanism for the nucleophilic addition-elimination reaction with acid anhydrides?

• this reaction can also be done with water or ammonia as a nucleophile

how is an acid anhydrides formed?

• by the removal of water from 2 carboxylic acids molecules, shown in the formation of ethanoic anhydride

reaction of acyl chlorides with alcohols to form esters?

• acyl chlorides react with alcohols to form esters

reaction of acyl chlorides with phenols to form esters?

what forms esters with phenols: carboxylic acids or acyl chlorides/acid anhydrides?

• carboxylic acids are not reactive enough to form esters with phenols

• acyl chlorides and acid anhydrides are both much more reactive than carboxylic acids and react with phenols to produce phenyl esters

  • neither reaction needs an acid catalyst

reaction of acyl chlorides with water to form carboxylic acids

• formation of carboxylic acids and hydrogen chloride fumes

reaction of acyl chlorides with ammonia?

• ammonia can act as a nucleophile by donating their lone pair of electrons

• ammonia reacts with acyl chlorides, forming a primary amide

reaction of primary amines with acyl chlorides?

• reacts in the same way as ammonia to form a secondary amide

reactions of acid anhydrides?

• react in a similar way to acyl chlorides with alcohols, phenols, water, ammonia and amines

• they are less reactive than acyl chlorides and used in laboratory preparations where acyl chlorides may be too reactive

equation for the formation of phenyl ethanoate from ethanoic anhydride and phenol?

• ethanoic anhydride + phenol —> phenyl ethanoate + ethanoic acid