Nitroglycerine C3H5(NO3)3 is synthetized from glycerol C3H5(OH)3 according to : C3H5(OH)3 + 3 HNO3 ---> C3H5(NO3)3 + 3 H2O
But take care. It is not HNO3 that attacks glycerol (ou glycerine), but NO2+ produced by : HNO3 + 2 H2SO4 ---> NO2+ + H3O+ + 2 HSO4-
The following procedure has been by about 100 students each year in my high school lab for 25 years. There has never been any failure or accident.
Pour 3 ml concentrated HNO3 (65%) in a dry test tube, then the double (6 ml) of concentrated H2SO4 (96%) in another tube. Pour H2SO4 into HNO3. Do mix up thoroughly by pouring to- and fro- many times. This mixing warms up. Dip the tube into a 150 ml beaker filled with ice.
When the tube is colder than 10°C, add 10 drops gylcerine with a 5 ml syringe into the liquid mixture. This produces a turbid mixture which remains near the surface. Pour the liquid with a to and fro motiion for homogeneizing the solution. As the nitration reaction is exothermic the liquid should stay in the ice for at least 5 minutes. The temperature should never exceed 10°C.
At the end the turbid mixture should be dropped int the rest of ice. The ice melts and dissolves the excess of acids plus the remaining glycerine that has not been nitrated. Stir with the empty test tube. A large drop of oil will soon be observed on the bottom of the beaker : nitroglycerine.
Get rid of the ice, and of the greatest part of the liquid,. Pour the remaining liquid plus the oil into a filter paper and a funnel. The aqueous solution goes through the filter. At the end a large drop of oil remains in the filter.
Take hold of a 10 microlitres capillary (Blaubrand 708709) and dip it into the oil drop in the filter. Don’t punch the filter paper. A tiny droplet of oil stays in the tip of the capillary, about 1 microlitre. Hold the capillary with a pair of pliers or tongs horizontally at about 30 cm above the table. Place the droplet of nitroglycerine in the non gripped end. See...
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