Tosyl group

In organic chemistry, a toluenesulfonyl group (tosyl group, abbreviated Ts or Tos) is a univalent functional group with the chemical formula −SO2−C6H4−CH3. It consists of a tolyl group, −C6H4−CH3, joined to a sulfonyl group, −SO2−, with the open valence on sulfur. This group is usually derived from the compound tosyl chloride, CH3C6H4SO2Cl (abbreviated TsCl), which forms esters and amides of toluenesulfonic acid, CH3C6H4SO2OH (abbreviated TsOH). The para orientation illustrated (p-toluenesulfonyl) is most common, and by convention tosyl without a prefix refers to the p-toluenesulfonyl group. The tosyl terminology was proposed by German chemists Kurt Hess and Robert Pfleger in 1933 on the pattern of trityl and adopted in English starting from 1934. The toluenesulfonate (or tosylate) group refers to the −O−SO2C6H4CH3 (–OTs) group, with an additional oxygen attached to sulfur and open valence on an oxygen. In a chemical name, the term tosylate may either refer to the salts containing the anion of p-toluenesulfonic acid, TsO−M+ (e.g., sodium p-toluenesulfonate), or it may refer to esters of p-toluenesulfonic acid, TsOR (R = organyl group).