Practical paper

Question 1

Prep of an ester from carboxylic acid and alcohol
until distillation

Answer 1

1- alcohol and conc.H2SO4 in a pear shaped flask with anti bumping granules
2- add solution of carboxylic acid with small out of alcohol dropwise
3- swirl and heat under reflux
4- change apparatus for distillation and collect at 2c each side of bpt

Question 2

Prep of an ester form carboxylic acid and alcohol after distillation

Answer 2

1- place in separating funnel with Na2CO3 and invert, vent gas
2- remove stopper, allow layers to separate and discard aqueous layer
3- add anhydrous Na2SO4 and swirl until no longer cloudy
4- filter to remove Na2SO4
5- distill and collect at the bpt

Question 3

Prep of methyl 3-nitrobenzoate

Answer 3

1- place benzoate in conical flask with conc.H2SO4, place in ice bath
2- make nitrating mix with equal parts HNO3 and H2SO4, in an ice bath
3- add nitrating mix dropwise, keeping under 10c
4- let sit at room temp for 15 mins
5- pour over ice and attire until ice has melted
6- Buchner filtration
7- dissolve in minimum hot ethanol and recrystallised with cold water
8- filter again and dry in oven

Question 4

Why is TMS used in NMR

Answer 4

• produces one signal that is well separated from the other signals
• doesn’t react with other compounds in the sample