Study of the chemistry of hexafluorothioacetone has shown that it is very reactive with nucleophilic reagents. An example is sodium bisulfite, which adds to give Bunte salts in a manner opposite to that normally expected. Such reverse additions also take place with mercaptans, in which case disulfides are formed. Mercaptans also add in the normal manner to give dithio hemiketals. Unusual methylenephosphoranes are formed by reaction of ...