What is a tosylate group?

1 Answer
Truong-Son N.
Jul 19, 2016

A tosylate is the anion of tosylic acid.

This is tosylic acid (or p-toluenesulfonic acid):

![https://upload.wikimedia.org/](useruploads.socratic.org)

so the conjugate base is a tosylate. It is toluene (methylbenzene) with a sulfonate group attached on the 4-position.

Related are tosyl leaving groups because they are large and they tend to have a low "pKa" (making them thermodynamically unstable, i.e. making their bonds weak).

A common "tosyl" compound is tosyl chloride.

![https://upload.wikimedia.org/](useruploads.socratic.org)

NOTE: These actually have sulfonyl groups, not to be confused with sulfonate groups.

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