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                          How to make HgCl2 by ZyGoat
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ZyGoat has seen several Hive posts relating to the use of Hg2Cl2 as a substitute 
for HgCl2 in the Al/Hg reductive amination procedure. Hg2Cl2 is inferior to HgCl2 
due to its insolubility. Making HgCl2 is not difficult - here's the procedure:

You will need:

Mercury (thermometers, mercury switches, old barometers, suppliers to watch and 
	clock repairers (ever heard of a mercury pendulum?), blood pressure 
	measuring device from medical supplies)
Concentrated sulphuric acid (boiled battery acid, plumbing supplies, drain cleaner)
Sodium carbonate (washing soda) or sodium bicarbonate
Hydrochloric acid (pool supplies, if you have sulphuric acid you can make 
	hydrochloric with salt)


[1] HgSO4
Measure 20g Hg and place in a 100ml conical flask. Do not use a round bottom 
flask, as all the mercury will not react. Add 60 ml concentrated H2SO4 (should be 
at least 94%) to the flask and fit a single hole stopper with a tube leading 
outside. This reaction produces lots of SO2 that will give you chemically induced 
asthma if breathed. Now slowly heat the flask. Bubbles of SO2 will rise from the 
acid/mercury interface. Maintain a vigorous bubbling of SO2 by adjusting the heat. 
A white crystalline deposit of HgSO4 will appear. The mercury should be completely 
reacted after about 30 minutes. Allow the reaction mixture to cool and pour off 
the acid. Pour the crystals/acid into 750 ml hot water and filter. Keep the liquid.

[2] HgCl2
Make up 500 ml saturated sodium(bi)carbonate solution. Add this to the HgSO4/acid 
solution in small quantities until effervesscence upon addition stops and a red-brown
percipitate forms. Filter off the percipitate. Add some more (bi)carbonate solution 
to the filtrate to ensure all the HgSO4 has been reacted. Filter and repeat until no 
more red-brown percipitate forms. Wash percipitate with DH2O. Place in a 500 ml 
beaker and create a suspension with 20 ml DH2O. Make up a solution of 20 ml strong 
hydrochloric acid in 100 ml DH2O. Add this to the suspension in small quantities with 
good stirring. The solution will change from brown-red to yellow and finally a white 
curdy percipitate will be present in the liquid. Stop addition of the HCl when the 
white percipitate appears. It is important that the solution pH should be near neutral 
as excess hydrochloric acid will prevent the HgCl2 crystallizing in the next stage. 
Evaporate off most of the water either outside or fit a single hole stopper with 
a tube leading outside to vent the steam away. Cool, filter the HgCl2 and dry. 
Yield 19.37g white crystals. For greater purity recrystallize from boiling DH2O.

Be very careful with HgCl2. Ingestion of 1/2 g has been known to be fatal. 
Don't heat in an open container above 300 C as it will volatise and end up in 
your lungs. Always wear gloves when handling HgCl2 and its solutions.

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