Dear Sergio,

Dimethylsulfoxide (DMSO) is very stable solvent; has a boiling point of 189 C.

Carbon-S bonds are very strong bonds and are not broken upon ultrasound waves employed for a lengthy time. DMSO vapor has  an unpleasant odor. It might be that the combination of the suspended phosphorus and the DMSO vapor gives the smell you have experienced.

Hoping this will be helpful,

Rafik

Thanks a lot Rafik!

Be careful with a posible reduction of the sulfone check this web

http://www.organic-chemistry.org/synthesis/S1H/reductionssulfoxides.shtm

There are plenty of methods and some of the layers of black phosphorus could be oxidized...

Thanks Santiago. If I understand the information contained in the link correctly, could dimethyl sulfide and dimethyl disulfide be responsible for the strong smell?

Dears

All the reactions indicated in the link are undertaken in reducing conditions in the presence of certain reagents. As I understood from the question that there are no reagents similar to those in the link are present in the vessel of sergio.

If dimethylsulfide is produced from dimethylsulfoxide a very strong smell (cabbage-like smell) is observed however since its boiling point is 37 it will disappear immediately due to the heat generated by sonication.

Rafik

That was very informative, Rafik. Thanks a lot for your help. 

Phosphorus black is somehow a reducing agent, not very strong this is true, however the Snell may come from a reduction to sulfide in the presence of black phosphorus whose layers may be oxidised

Gracias Santiago!

Thanks Vladimir.

Dear afkham,

Would you please send me the link or reference for your answer?

Thanks,

Rafik