Please enable JavaScript.
Coggle requires JavaScript to display documents.
PAG 6 - Coggle Diagram
PAG 6
6.3 - Preparation of Methyl 3-nitrobenzoate
Part 1 - preparation
2) Add concentrated nitric and sulfuric acid in the test tube and place into the ice bath (nitrating mixture)
3) Use a dropping pipette to add the mixture from the test tube to the conical flask - stir continuously and make sure the temperature remains below 10 degree
4) Add 25g of crushed ice to the conical flask and stir until it melts and a precipitate forms
5) Filter the precipitate under reduced pressure to obtain the impure crystals
6) Wash the crystals with cold water (make sure to leave a few spare)
1) Add concentrated sulfuric acid to the sample of the methyl benzoate in a conical flask and place in an ice bath
Part 2 - recrystallisation
Heat 10cm3 of ethanol using water bath
Dissolve impure compound in the minium volume of hot ethanol in a test tube
Filter the hot solution to remove any insoluble imputirites
Leave the filtrate to cool
Use a vacuum filter to separate crystals from the solution
Wash the crystals with distilled water and leave the vacuum on to dry them
Vacuum filtration
Uses Buchner funnel and flask (thicker walls to cope with vacuum)
Use rather than gravitational filtration if large amount of solid are produced
Ways product may be lost
Crystals lost when filtering/ washing
Product may stay in solution after recrystallisation
Side reactions may occur
Part 3: Thin layer chromatography
Draw a pencil line 1cm from the bottom of the TLC plate - mark three equally space cross along the line
Use capillarty tubes to spot samples from part 1 and 2
Add the solvent to the bottom of the beaker and cover with a watch glass to prevent solvent evapouration
Place TLC into the beaker, make sure the solvent is below the pencil line, place watch glass on top again
Remove TLC plate when the solvent is 1cm from the top, and mark the solvent front with pencil
When spots become visible, mark ligtly with pencil and calculate the Rf values
If the sample if too concnetrate, the spots would overlap
Place the plate in a fume cupboard until all of the solvent has evaporated