Diazo compounds may be explosive and should be handled with care. Very often, the diazocarbonyl compound is prepared and immediately used via treatment of the corresponding acid chloride with an excess of diazomethane (see Eq. (18) below for an example). Reactions mediated by copper are typically on the order of hours, and in some cases, slow addition of the diazocarbonyl compound is necessary. Reactions should be carried out under an inert atmosphere in anhydrous conditions.