Monobrominate, you say. What about thiocyanate? - just add in soln 1.2 eqv of
KSCN and then dropping bromine. This will be very fun product. BTW, the
rodano-derivative can be reduced to Shulgin's dream - bare thio group :)
Courtesy of Assholium - posted here originally, and archived at
https://www.thevespiary.org/rhodium/Rhodium/chemistry/2cb-new.txt (https://www.thevespiary.org/rhodium/Rhodium/chemistry/2cb-new.txt)
Post 108811 (https://www.thevespiary.org/talk/index.php?topic=11960.msg10881100#msg10881100)
(dormouse: "Thiocyanation of 2C-H -Rhodium", Novel Discourse)The thiocyanation of mononuclear aromatic compounds with thiocyanogen is normally restricted to amines and phenols, though it may be applied even to benzene if carried out in the presence of Friedel-Crafts catalysts, which presumably polarize the S-S bond of thiocyanogen. Similarly, the polar character of the S-Cl bond in thiocyanogen chloride makes this a more powerful reagent than thiocyanogen for such electrophilic substitutions. As with halogenations, the rate of these thiocyanations is affected by the polarity of the solvent.
PhX + Cl.SCN --> p-C6H4X.SCN + HCl: (X = )NMe2 > OH > OMe > NHBz > NHAc > OPh > NMeAc
This is identical with the order of reactivities of these benzene derivatives in nuclear substitutions by molecular halogen in acetic acid.
Interesting, no? SWIM has much more references to give, it will take some time though (including thiocyanation of the very unreactive benzene). Rhodium, SWIM thinks the Al(SCN)3 article was viewed over (was it in Acta Chem. Scand.?)
Now that we know a cheap oxidizing agent like sodium perborate can be used to generate both (SCN)2 and a halogen, we can make the reaction more 'user friendly' and elegant by generating both simultaneously to create the more reactive thiocyanogen halide.
Vitus, SWIM is very glad to see your enthusiasm! SWIM is confident we will develop a procedure, but we must tread our path slowly and under well-informed premises. The more information we gather, the more random articles we retrieve, the more ideas we come up with and are able to support, then the more knowledge we gain and the chances of success will increase.
(sorry for all the blabbering ... SWIM had a good day in the library. :P )
Edit: Almost forgot your question Vitus! No, SWIM thinks you have to do the thiocyanation at the end - although you might be able to form the free thiol (-SH) for the 2C-T-X's. Rhodium knows much better.
Also, has anyone ever considered (OCN)2 or straight cyanogen? SWIM has a small one line reference to its existence. (Ugghh! - why can't SWIM ever be satisfied? Always has to want more and more and ...)
10.1016/S0040-4039(01)85790-7 (http://dx.doi.org/10.1016/S0040%2D4039%2801%2985790%2D7)
Organic Syntheses, CV 7, 435 (http://www.orgsyn.org/orgsyn/default.asp?formgroup=base_form_group&dataaction=db&dbname=orgsyn)
(http://www.orgsyn.org/orgsyn/default.asp?formgroup=base_form_group&dataaction=db&dbname=orgsyn). As Rhodium so eloquently put it, a roundabout way seems to be necessary to introduce the OCN group. The discussion in the article hints at the reasons behind this; hardly surprisingly, the aryl cyanates have activated cyano groups. Maybe someone could comment on the potential side-effects of putting this into one's body...Post 190955 (https://www.thevespiary.org/talk/index.php?topic=7400.msg19095500#msg19095500)
(Antoncho: "CH3-C6H5SO2*CH3O - an OTC methylating agent?", Chemistry Discourse) andPost 108811 (https://www.thevespiary.org/talk/index.php?topic=11960.msg10881100#msg10881100)
(dormouse: "Thiocyanation of 2C-H -Rhodium", Novel Discourse)). Still, Rhodium did say in the first thread thatThe literature does not clearly answer if 2 KSCN + Br2 produces KBr + BrSCN or 2KBr + (SCN)2, so the active thiocyanation agent may either be BrSCN or (SCN)2
- So at least my misunderstanding was in good company. ;)