nitrogen(IV) oxide; silica gel in tetrachloromethane T=30°C; 1 h;

N,N,N',N,-tetramethylethylenediamine in hexane 1.5 h;

<b>With</b>&nbsp; <a href="#" onclick="return RXDsubstances(event, this, '472690', constants.ctx, '0')">toluene-4-sulfonic acid</a>&nbsp;<b>in</b>&nbsp; <a href="#" onclick="return RXDsubstances(event, this, '635760', constants.ctx, '0')">toluene</a> <br />&nbsp;RefluxDean-Stark;&nbsp;<br /> &nbsp;