Sciencemadness Discussion Board

Thionyl Chloride Preparation

FloridaAlchemist - 19-6-2003 at 18:54

Here is something interesting:
Excess sulfur dioxide in conc Hydrochloric acid yields thionyl chloride.
SO2 + 2HCl = SOCl2 + H2O
Besure to use all glass apparatus.
Ref. JCS, 117, pg 1103, 1920
:)

BASF - 20-6-2003 at 06:46

Hmm. sounds very interesting!
Is this a precipitation-reaction?
Is SOCl2 insoluble in polar solvents?

Anything else about pressure/reaction-temperature?

Thionyl Chloride Reference

FloridaAlchemist - 20-6-2003 at 19:51

I wish I could give you more details but
I need the JSC Journal Society Chemistry
reference 117, pg 1103, (1920) to get the details for it. :o
If this works for the homelab it would open lots of possibilities.:)

Organikum - 20-6-2003 at 22:23

The MERCK says thionylchloride is hydrolized by water to form SO2 and HCl. :o . What makes me guess that the water formed has to be removed immediately. Dean Stark trap?

The traditional way of preparation is by the action of SO3 on SCl2.
Hm. More and more it loks to me SO3 is one of the main keys.....

Re: thionyl Chloride synthesis

solo - 7-7-2003 at 13:46

Someone at the Hive posted this some time ago.....

'If you want to make thionyl chloride here are a couple of non-suicidal routes you can take:

[1] Pass sulphur trioxide through disulphur dichloride - SO3 + S2CL2 -> SOCL2 + SO2 + S
[2] Pass sulphur dioxide through phosphorus pentachloride - SO2 + PCL5 -> SO2CL2 + POCL3

Passing chlorine gas over molten sulphur can easily make S2CL2. The disulphur dichloride vapour is condensed and redistill to give a pale yellow liquid (bp 138 C).

SO3 is made by heating ferric sulphate (Fe2(SO4)2 -> Fe2O3 + 3SO3 ) or by heating sodium hydrogen sulphate ( 2NaHSO4 -> Na2S2O7 + H2O, Na2S2O7 -> Na2SO4 + SO3 ). The water vapour will have to be removed in the second reaction with something like calcium oxide.

You can also make phosphoryl chloride by passing SO3 thru PCl3 ( PCl3 + SO3 -> POCl3 + SO2 )

The most versatile reaction would be to make PCL5 and pass SO2 through it. This produces both thionyl chloride and phosphoryl chloride ( PCl5 + SO2 -> POCL3 + SOCl2 ) which can be separated by fractional distillation ( Bp SOCl2 78 C, Bp POCl3 107 C ). The SO2 is conveniently made by adding concentrated sulphuric acid to copper metal and drying the gas produced before passing into the PCl5.

PCl5 can be synthesised using a 2 stage procedure, first from CL and P to make PCl3, then Cl and PCl3 to make PCL5. The most difficult component of this whole scheme is making the phosphorus"......solo


Note: Not to go unnoticed, I see the editing button now for correcting posts and just editing....congratulation, it's a nice feature!

[Edited on 7-7-2003 by solo]