mbart - 10-6-2012 at 09:55
Hi everybody.
I follow this site for quite a while now and to be honest, I have already achieved a (very) lot from you guys.
I have a question that I hope somebody can help me with.
Do not ask me why but the "S"-group fascinates me although this concernes a, very, large group (and smells like hell...
)).
At the moment I'm trying to prepare a thiophenol directly from a phenol ring but without succes so far. Hence my question;
Is it possible to convert a phenol into a thiophenol directly, without the intermediate step, chlorination for example?
I tried 2 reactions in the past that I did with thiourea, once in H2O and once in MeOH, but according the TLC no reaction occurred not even after 3.5
hours.
I did found 2 Rxs on the Internet, first one,http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv6p0824 and the second ; google "preparation
from phenol or thiophenol" example 13. Biggest issues are that, with the first reaction the suppliers of N,N-dimethylthiocarbamyl chloride are suppose
to think the stuff has to be more expensive then gold I guess, very expencive and at the second the phosphotungstic potassium on alumina is not for
sale at all here. BTW, by here I mean the Netherlands.
Wanna startup a reaction with lawesson's reagent now but... does that make sense? I can't find any on the internet about it.
Useless to say that I work with a fumehood, wear gloves etc. It's nasty stuff I know, but if something new will be discovered in chemistry I think it
will come from this side.
Thanks so far.
gypsyNo2 - 11-6-2012 at 15:43
One thing I know about Org. Synth is that if they say a reaction works, it works. I've not done much sulfur chemistry o the only thing I can do is try
and find out where the problem is. So I have some Q's
1. was your nitrogen dry ?
2. Are you sure you hit 270C ?
Have had many issues with reactions under N2 and the problem was wet nitrogen.
Good Luck
GypsyNo2
mbart - 11-6-2012 at 16:50
You are definitely right concerning orgsyn.
About your the Q,s, I didn't do this reaction because the N,N-dimethylthiocarbamyl chloride is so expencieve over here.
I would like to give it a try but even if it will work, to prepare by chlorination in 2 steps will probably be cheaper
This is bodering me for quite a while now and did 2 Rx's in the past.
Tried to replace the O for an S with the thiourea, once in MeOH and once in H2O.
But even after 3,5 hr no reaction according the TLC.
You think give it a try with Lawessons reagent has a chance to succeed?
Got that one in stock and I need to get rid of it anyway...smells like bbbrrrrr
!
Lambda-Eyde - 13-6-2012 at 13:41
Starting from phenol might prove difficult. You can subject bromobenzene to a grignard reaction with sulfur powder to get thiophenol. Bromobenzene is
simple to prepare from benzene, which in turn is easily made from sodium benzoate at low cost.
mbart - 14-6-2012 at 14:12
Yep, but the challange is to prepare from the phenol directly. Anyway, I don't think there is a solution for this. Why is it I've been sitting behind
the pc searching to find this reaction on paper but couldn't find (so far)? Even in 2 steps I think it will be difficult because that phenol itself is
so strongly activated. The reaction with the Lawesson's was no succes so far. Maybe after that one I will try some with sulfuric acid. Thanks for your
posts anyway and I'll keep on trying. Ofcouse if any will happen I will tell you immediatly.
DJF90 - 14-6-2012 at 17:19
One of the first few hits on google.
I think you'll find its a Smiles rearrangement...
http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv6...
EDIT: My bad. Its not a Smiles rearrangement. Its a Newman-Kwart rearrangement. Just seems like a subset of the Smiles to me though.
[Edited on 15-6-2012 by DJF90]
mbart - 15-6-2012 at 02:55
Yeah, for me as well that was one of the first hits to show up, that's why I mentioned it in my first post;
(I did found 2 Rxs on the Internet, first one, http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv6... and the second ; google "prepar....).
But the second thing you are talking about, the Smiles rearrangement, fuXXing beautyfull man!
I never thought about that one...because I am not well known with it I guess.
Now, first I'm gonna do is find out how that reaction exactly works and I'll get back to you guy's.
Hope this will help me proceed this story.
Will try to be online later on but usually I work at night, with my boss (red. pimp...because for me all boss's are, except for Mr. Springfield 
ofcouse) always watching over my shoulder.
Thanks a lot indeed!!