Gas Chromatography - Quantitative Analysis > Derivatization > Page 57

One very popular esterifying reagent is diazomethane.

However, diazomethane is carcinogenic and can be extremely unstable. All reactions should be carried out in a fume hood and any stored solutions of diazomethane in diethyl ether should be restricted to a maximum of 100 ml and kept in a refrigerator. The materials must never be overheated as there is a risk of explosion.

Despite the dangers, the reagent is very effective. Providing its use is restricted to microscale reactions and sensible precautions are taken, it is normally safe to use.

Diazomethane is a yellow gas but is used in the form of an ethereal solution. Its reacts with an organic acid in the following manner,

 

RóCOOH + CH2N2RóCOOĖCH3 + N2

When the reaction is complete, the yellow color persists and thus the reagent acts as its own indicator. An apparatus, developed by Schlenk and Gellerman (11) for esterification with diazomethane is shown in figure 37.