Author Topic: Willgerodt Reaction / evil H2S  (Read 737 times)

0 Members and 1 Guest are viewing this topic.

ning

  • Guest
Willgerodt Reaction / evil H2S
« on: April 29, 2004, 04:33:00 AM »
So, ning thought the chinese willgerodt synthesis patent sounded very nice. Combined with calcium acetate method, it could produce P2P in an OTC way in very large quantities. However, there is a certain matter to be dealt with. And that is the large amounts of H2S evolved by that reaction.
What is needed is an efficient way to absorb/destroy H2S in fairly large quantities.

Any suggestions? One was to use strong NaOH solution. This would produce NaSH and Na2S, which are useful for other things. Perhaps cheaper, lime might be used , to produce CaS. Would this work? Is there a better way?

Ning wonders if the hydrolysis step could be base catalyzed instead of acid catalyzed, to eliminate the release of the H2S in the first place. Hive minds, what say ye?

EDIT:

Oh, it seems that such a hydrolysis is very possible! They do it in

https://www.thevespiary.org/rhodium/Rhodium/chemistry/willgerodt.ptc.html


Nice! No more H2S!


Nicodem

  • Guest
(NH4)2Sx
« Reply #1 on: April 29, 2004, 10:52:00 AM »
I don't think much of H2S would come from that reaction. Mostly amonium polysulfide is formed since sulphur should bee used in excess.
Anyway if you want to be cautious anyway, introducing the gases into a lime suspension is more than enough.


ning

  • Guest
So you're saying that when the formed ...
« Reply #2 on: May 02, 2004, 10:41:00 PM »
So you're saying that when the formed thioamide is hydrolyzed, it will react with the excess of sulfur and ammonia present in the mixture to form polysulfides?

Here:

https://www.thevespiary.org/rhodium/Rhodium/chemistry/willgerodt.html

the equation states H2S is formed on hydrolytic workup.

I sure hope you're right!


Nicodem

  • Guest
You are right
« Reply #3 on: May 03, 2004, 12:54:00 PM »
Sorry, I thought you were talking about the Willgerodt reaction.
Yes, H2S might form during the hydrolysis, though given that H2SO4 is used some of H2S would probably bee oxidized before leaving the mixture. H2S is not such a big problem. You can smell that shit from the lowest concentration and driving the outlet of the reflux into a water solution of a base is no science.
(Thio)amides can bee hydrolised with NaOH(aq), but you would have to acidify the reaction mixture in order to isolate the product and that would again release H2S. You would not gain anything. It would still stink.


ning

  • Guest
What if...
« Reply #4 on: May 04, 2004, 02:19:00 AM »
What if the hydrolysis mixture contained nitric acid? I'm pretty sure that would not hurt our phenylacetic acid, but could it destroy the formed H2S?

Or, how about if the basic hydrolysis was done with "oxy-clean"--Na2CO3 + Na2CO4, which would oxidize the formed Na2S into something nicer, so when the mixture was acidified, there'd bee no gas release?