carboxylic acids and esters

Question 1

OH in carboxylic acids

Answer 1

form hydrogen bonds - high mps and bps compared to similar sized alkanes

Question 2

COOH solubility

Answer 2

COOH group very soluble in water due to H bonding but the hydrocarbon chain is non - polar so doesnt dissolve in water
short chain carboxylic acids dissolve easily in water - short hydrocarbon chain
longer chain carboxylic acid is less soluble - longer hydrocarbon chain

Question 3

carboxylic acid strength

Answer 3

acids as they donate protons
weak acids so equilibrium is to the left
react with alcohols to form esters

Question 3

naming esters

Answer 3

first part - chain attached to O - …thyl
second part - chain attached to double bond O - propanoic acid —- propanoate

Question 4

forming esters

Answer 4

carboxylic acid + alcohol
condensation reaction and conc H2So4 catalyst
reversible reaction
water is by product

Question 5

hydrolysis of esters

Answer 5

acid catalysed hydrolysis
-hard to get high yield of carboxylic acid and alcohol

base catalysed hydrolysis
-carboxylic acid reacts with NaOH and forms a salt of the acid
-increases the yield and shifts the position of the equilibrium to the right
-not appropriate if salt is not desired products

Question 6

production of soap

Answer 6

triesters + NaOH —–heat—-> 3sodium carboxylate/ soap + glycerol

Question 7

production of biodiesel

Answer 7

triesters + CH3OH —–heat—-> 3 methyl esters/ biodiesel + glycerol

Question 8

leaving groups for acid anhydrides

Answer 8

acid anhydrides are unsymmetrical so there are two possible products depending on the carbonyl group the nucleophile attacks

Question 9

Why are acid anhydrides are used more than acyl chlorides in acylation reactions

Answer 9

Cheaper
Less corrosive
Don’t react with water - less vulnerable to hydrolysis
Safer as product is carboxylic acid and acyl chlorides produce Hcl