Match the technique to the purpose: recrystallise impure solids, dry cloudy organic layers, separate immiscible phases and use reflux or distillation to control volatile mixtures.
This question is about the nitration of methyl benzoate.
The equation for the reaction is shown.
Procedure
Step 1 Weigh between 1.9 g and 2.1 g of methyl benzoate in a conical flask.
Step 2 Slowly add of concentrated sulfuric acid to the methyl benzoate with swirling and place the flask in an ice-water bath to cool.
Step 3 Place of concentrated nitric acid into a test tube.
Cool the nitric acid by immersing the test tube in an ice-water bath before slowly adding of concentrated sulfuric acid.
Allow this nitrating mixture to cool.
Step 4 Using a teat pipette, add the nitrating mixture very slowly to the conical flask, ensuring the temperature does not exceed .
Step 5 Allow the flask to stand at room temperature for about 15 minutes and then pour the contents into a beaker containing some crushed ice. Impure methyl 3-nitrobenzoate will form.
Step 6 Recrystallise the methyl 3-nitrobenzoate using methanol as the solvent.
Step 7 Weigh the dry crystals and determine their melting temperature.
During recrystallisation in Step 6, the methyl 3-nitrobenzoate is dissolved in a minimum volume of hot methanol and the hot mixture filtered.
The filtrate is cooled, and the resulting crystals filtered and rinsed with ice-cold methanol.
State why methanol is a suitable solvent for use in the recrystallisation of methyl 3-nitrobenzoate.
State the purpose of each of the filtrations during the recrystallisation of methyl 3-nitrobenzoate.
Give the purpose of rinsing the crystals, stating why the methanol is ice-cold.
