carboxylic acids and esters Flashcards
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what functional group does a carboxylic acid contain
- carboxyl functional group
what does the carboxyl group contain
- carbonyl group
- hydroxyl group
what type of acid is a carboxylic acid
organic acid
where are carboyxlic acid found
- medicines
- fruit juices
- vinegar
- rhubarb leaves
wht are carboxylic acids and it’s derivatives used for
- used in organic synthesis as starting materials or intermediates in the formation of more useful compounds
- such as painkiller, aspirin, can be synthesised from salicyclic acid
describe the solubility of carboyxlic acids
- C=O and O-H bonds in carboxylic acids are polar allowing carboxylic acids to form hydrogen bonds with water moleculess
describe the solubility of carboxylic acid regarding the length of carbon chain
- carboxylic acids with up to four carbon atoms are soluble in water
- as the number of carbon atoms increases the solubility decreases as the non polar carbon chain has a greater effect on the overall polarity of the molecule
describe solutbility of dicarboxylic acids
- two polar carboxyl groups to form hydrogen bonds
- solids at room temperature
- dissolve readily in water
Describe the strength of carboxylic acids
- classified as weak acids
- when dissolved in water carboxylic acids partially dissociate
Decribe acid reactions of carboxylic acids and wht they form
- redox and neutralisation reactions
- redox reactions with metals
- neutralisation reactions with bases (alkalis, metal oxides and carbonates)
- in reactions carboxlic acids from carboxylate salts
how are carboxylate salts named
- named by changing the ic acid ending of the carboxylic acid to -ate
describe redox reactions of carboxylic acids with metals
- aqueous solutions of carboxylic acids react with metal in a redox reaction to form hydrogen gas and a carboxylate salt
- observe metal dissappearing and effervesence as hydrogen gas is evolved
describe the reaction of carboxylic acidswith metal oxides
- form a salt and water
describe reactoion of carboxylic acids with alkalis
- form a salt and water
- may not see a reaction as two solutions react together to form an aquous solution of the salt
describe reaction of carboxylic acids and carbonates
- carbon dioxide gas appear
- if carboxylic acids is in excess a solid carbonate would disappear
How to test for the carboxyl group and wht do these distinguish between
- neutralisation reaction of carboxylic acids with carbonates
- carboxylic acid are only common organic compounds sufficiently acidic to react with carbonates
- used for distinguiishing carboxylic acids from phenols
- phenols are not acidic enough to react with carbonates
what is a derivative of a carboxylic acid
- compound that can be hydrolysed to form a parent carboxylic acid
- carboxylic acid derivative have a common equence of atoms in their structure - acyl group
name common derivative or carboxylic acids
- ester
- acyl chloride
- acid anhydride
- amide
how is an ester named
- names after the parent carboxylic acids from which its derived
- to name the ester remove oic iffux from parent carboxylic acid and replace with oate
- alkyl chain attatched to oxygen atom of COO group is added as first word in the name
- eg ethanoic acid and methanol produce methl ethanoate and water
how is an acyl chloride named
- named after the parent carboxylic acid ffrom which it is derived
- remove oic acid suffic from the parent carboxylic acid and replace with oyl chloride
how is an acid anhydride formed
- removal of water from two carboxylic acid molecules
what is esterification
- reaction of an alcohol with a carboxylic acid to form an ester and water
- alcohol is warmed with a carboxylic acid with a small amount of concentrated sulfuric acid acts as a catalyst
what is the smell of esters
esters are sweet smelling liquids
describe the hydrolysis of esters
- esters can be hydrolysed by aqueous acid or alklai
what is hydrolysis
chemical breakdown of a compound in the prescence of water or in an aqueous solution
what is acid hydrolysis of an ester
- acid hydrolysis of an ester is the reverse of esterification
how do you carry out acid hydrolysis
- the ester is heated under reflux with dilute aqueous acid
- ester is broken down by water with the acid acting as a catlyst
what are the products of acid hydrolysis
- carvoxylic acid and an alcohol
what is alkaline hydrolysis of an ester
- known a saponification
- irreversible
- ester heated under reflux with aqueous hydroxide ions
what does alklaline hydrolysis of an ester produce
- a carboxylate ion and an alcohol
describe the preparation of an acyl chlorides
- can be prepared directly from their parent carboxylic acid
- by reaction with thionyl chloride SOCl2
- also produces SO2 and HCL evolved as gases leaving just the acyl chloride
why should acyl chlorides be prepared in a fume cupboard
- products are harmful
describe the reactivity of acyl chlorides
- acyl chlorides are very reactive and are very useful in organic synthesis
- easily converted into carboxylic acid derviatives such a esters and amides with good yields
- react with nuclophiles by losing the chloride ion whilst retaining the C=O double bond
how are esters formed by acyl chloride
acyl chlorides react with alcohols to form esters
describe the reaction of acyl chlorides with phenols and why carboxylic acids are not used
- form esters
- carboxylic acids are not reactive enough to form esters with phenols
- acyl chlorides and acid anhydrides are both much more reactive than carboxylic acid and react with phenols to produce phenyl esters
- neither reaction needs an acid catalyst
describe the reactants used to form phenol ethanoate
- ethanoyl chloride and phenol
decribe the reaction of acyl chlorides with water
- when water is added to acyl chloride a violent reaction takes place with the evolution of dense steamy hydrogen chloride fumes
- a carboxylic acid is formed
describe the reaction of acyl chlorides with ammonia and amines
- ammonia and amines can act as nucleophiles by donating the lone pair of electrons on the nitrogen atom to an electron deficient species
- the reaction with acyl chlorides form amides
describe the reaction of ammonia with acyl chlorides
- forms primary amide
what is a primary amide
nitrogen atom attatched to one carbon atom
how many bonds can nitrogen make
- 3 bonds
- 1 lone pair
what is the reaction between primary amine and an acyl chloride
- same way as ammonia
- form a seconday amide
what is a secondary amide
- nitrogen atom is attatched to two carbon atoms
describe the reactions that take place with acid anhydrides
- acid anyhdrides react in a similar way to acyl chlorides with alchols, phenols, water, ammonia and amines
- less reactive than acyl chlorides and are more useful in some labratory preparations where acyl chloride may be too reactive
what is produced when an anhydride reatcs with an alcohol
- forms a salt and a carboxylic acid
