Sciencemadness Discussion Board

SO2Cl2 rxn with water or alcohol

Jor - 15-8-2009 at 09:25

I was surprised that sulfuryl chloride reacts only very slowly with water, but very volently with alcohols. Why is this? Because they react in a different mechanism? I was thinking that water's oxygen nucleophilic attacks the sulfur of sulfuryl chloride. But why is this reaction slow? Is the sulfur sterically hindered? Or is there any step in the reaction of water with sulfuryl chloride to H2SO4 and HCl wich is very slow?

I was thinking that the oxygen of SO2Cl2 does a nucleophilic attack on the electrophilic carbon of ethanol. Another possible option for me was the formation of EtCl, but I tried igniting the formed gas, wich I couldn't do so it had to be HCl.

Can you guys help me what exactly is happening?

thaflyemcee - 15-8-2009 at 10:13

The reaction to form alkyl chlorides from the alcohols is way more exothermic than the reaction to form HCl from thionyl chloride and water because the products aren't stabilized as much by the solvent. Acids in water are (as you know) generally stable unless you're adding huge amounts of anhydrous acid to water. The free energy change is also less overall, I'm guessing.