Looped Animation

There are tokens on my chessboard, if selected by clicking leftbutton I want them to rotate, if I click again it should stop. What would be the proper way to do that in unity? I tried to write a simple function with no success yet. I either have a unending loop or the token only moves for 1 frame. Here is what ive tried... Every variable was declared.

--------------In my update function-------------------------

if(selectionX > 0 && selectionY > 0 && (Input.GetMouseButtonUp(0)))

     {
         SelectToken();
     }

private void SelectToken() { Vector3 vec = Vector3.up;

     SelectedToken = Tokens[selectionX, selectionY];

     while(SelectedToken != null)
     {
         vec.y *= (90 * Time.deltaTime);
         Tokens[selectionX, selectionY].transform.Rotate(vec);

         if(Input.GetMouseButtonUp(0))
         {
             SelectedToken = null;
         }
        

}