benzylchloride1 - 19-8-2008 at 12:41
A previous thread mentioned the preparation of p-toluene sulfonyl bromide from sodium p-toluene sulfonate, bromine, and water by simply stirring the
reactants together and filtering the product off.
Bromination of sodium p-toluenesulphinate; p-toluenesulphonyl (tosyl) bromide
SyntheticPage 18 (2001)
Submitted 27th Jun 2001, published 28th Jun 2001
Original Location: http://www.syntheticpages.org/pages/18
This page accessed: Sat, 02 Feb 2008 11:39:45 +0000
Daniel Hamza (d.hamza@sussex.ac.uk),
A contribution from the Caddick group, University of Sussex, UK
Chemicals Used
p-toluenesulfinic acid sodium salt (TsNa), 30.4g, 171mmol; distilled water, 1000mL; bromine,29g,
9.35mL, 188mmol carbon tetrachloride (can still buy from Aldrich)
Procedure
TsNa is dissolved in water and filtered to obtain a clear solution. Bromine is added dropwise over about
30min with rapid stirring and venting to allow for build-up of bromine gas. A yellow precipitate of crude
TsBr is observed. Mixture is stirred for a further 30min following complete addition of the bromine. Filter
off the crude TsBr and wash well with water. Dry thoroughly in vacuo overnight. Typical crude yield of
dry powdery solid, 63-69%. Recrystallisation from carbon tetrachloride First dissolve in minimum hot
CCl4 and hot filter to remove any insoluble oily solid. Allow to cool and filter off crystals of TsBr. Wash
with very cold CCl4 (-20oC) Do not air dry for more than a few seconds or crystals will go off. Final
overall yield approx 50%
Author's Comments
This is a quick, easy and cheap way to make gram quantities of TsBr. There does not seem to be a ready
alternative to the use of CCl4 for the recrystallisation step which is a pity as the compound is rather
soluble in this solvent. The product does not withstand drying and is best kept moist with CCl4. This
makes assessing yields a bit tricky as well as when using in a reaction. Removal of excess solvent just
prior to the reaction under a stream of nitrogen is a reasonable compromise, but be careful as it really does
go off if dried. Purity is best determined by TLC and melting point since other methods of analysis (ie
NMR, IR) do not readily distinguish between the product and the possible impurities. Does not mass spec
A possible synthesis of the chloride can be derived from this procedure. 1. Run chlorine gas into a aqueous solution of the sodium p-toluenesulfonate.
2. dissolve the sodium p-toluenesulfonate in aqueous sodium hypochlorite and add HCl to produce chlorine in situ. I am currently pursuing the second
route.
Experimental:
5.0 g sodium toluene sulfonate was dissolved in 100 mL of 10% sodium hypochlorite (pool chlorinator) in a 250 flask in a fume hood. a magnetic stir
bar was added, along with a pressure equalizing addition funnel. The mixture was stirred until the solid dissolved which resulted in a clear greenish
solution. 6 M HCl was placed in the addition funnel and slowly added to the flask. A reaction occured, the mixture became turbid and a thick foam
formed.
Klute - 19-8-2008 at 13:12
Unfortuanly, you will not obtain any sulfonyl chloride by chlorianting sodium sulfonate! It is the sodium salt of the sulfinic acid that forms
the sulfonyl chloride!
I guess you are refering to a post of Aliced25 on the subjcet, where I pointed ou the same thing.... The only way I know of to form sulfonyl
chlorides from sulfonates is S2Cl2, but it is said to be a dirty reaction, yielding a product pretty impur....
It would be interesting to see what you obtain, although I guess it will form mainly ring-chlorianted products....
Ar-SO2Na + Br2 = Ar-SO2-Br + NaBr
but not:
Ar-SO3Na + Br2 = Ar-SO2-Br + ....
Sulfinic acid: R-SO2H
Sulfonic acid: R-SO2-OH
Your best shot at sulfonyl chlorides is via chlorination of thiols, disulfides, thiosulfates and isothioureas.
But forming a aromatic disulfide/thiol can be a bit tricky, depending on what you need it for, aliphatic sulfonyl chlorides can be as usefull..
On possible pathway is too react an somewhat activated arene with S2Cl2 in presence of a lewis acid to the disulfide, and chlorinate that in presence
of aq. AcOH.... Pretty dirty chemistry.
[Edited on 19-8-2008 by Klute]
benzylchloride1 - 19-8-2008 at 13:21
I mis-read the procedure, but I wonder what the product is. I filtered off the precipitate and I am currently drying it. I ran the reaction in test
tubes and produced the same precipitate. The precipitate has a strange odor with a chlorine tinge to it.
Klute - 19-8-2008 at 16:17
Try forming a sulfonamide with it, adding the suspected sulfonyl chloride to a solution of aq. NH3 and NaOH (10%). If a yellow/orange precipitate
forms, chances are it is indeed the sulfonyl chloride.
You could check the products solubility in toluene also.
Sauron - 19-8-2008 at 18:46
Arylsulfonyl chlorides are best made by chlorosulfonic acid.
And if you can't buy chlorosulfonic acud, you make it out of oleum and dry HCl rather cautiously because there is a lott of heat of reaction to
remove, and neither oleum nor chlorosulfonic acid respond well to the most likely coolant - water.
The resulting mixture of oleum and chlorosulfonic acid needs to be distilled. Oh jon oh joy.
panziandi - 21-8-2008 at 04:49
perhaps a nicer method of preparation would follow this procedure http://www.orgsyn.org/orgsyn/pdfs/CV7P0508.pdf
It describes a method of preparing m-trifluoromethylbenzenesulphonyl chloride from the diazonium compound using copper (I) and sulphur dioxide. They
show results for other substituted benzenesulphonyl chlorides looking at yields of 70+% for most of them.
Perhaps nicer than the good old chlorosulphonic acid method?
Klute - 21-8-2008 at 05:06
Indeed, that looks like a good options, the reactants are cheap, you just need to make/find the correspodning aniline, which could be made by the
conventional nitration-reduction scheme:
for TsCl:
Nitration of toluene, seperation of isomers---reduction--> p-aminotoluene---diazotation/SO2/Cu(I)--->sulfonyl halide
A bit lenghty, but attainable.
Ullmann - 21-8-2008 at 12:05
Antoncho on the old hive did alot of talk on that aniline to tosyl chloride route via copper...
Thats alot of wasted chemical for a not so interesting product IMHO, search better and skip this one IMHO
panziandi - 21-8-2008 at 12:56
well yes, for something as simple as toulenesulfonyl chloride it may have a 50% yield and be a bit wasteful but it's safer than other methods and
requires cheap and otc chemicals. but i think this method is most suited to complex substituted sulphonyl chlorides from the anilines as
chlorosulphonation may cause the group to enter at the wrong site (determined by groups on the ring etc) or cause decomposition to some groups
perhaps?