Most alcohols, especially the ones used as raw materials for the synthesis of ether oxygen­ates, have very high microwave absorptivity. Table 2 shows attained temperatures if 50 ml of typical alcohols at room temperature is heated for 1 min at microwave power of 560 W and frequency of 2.45 GHz [15]. The data indicate the benefits of using microwave irradia­tion, such as effective and efficient use of energy, to the synthesis of ether oxygenates. Reac­
tion relying on microwave can also be easily terminated by turning the supply of microwave irradiation off, thus further reaction or decomposition of the target compounds can be avoided resulting into higher selectivity. Also, reaction could reach completion in shorter time due to rapid heating, thus development of a compact process for a more efficient ener­gy utilization could be possible.

Using solid catalysts, instead of homogeneous ones, rapid heating on the surface of the cata­lysts likely occur upon microwave irradiation. Due this localized heating, the actual temper­ature at which reaction takes place may be higher than the measured bulk temperature as depicted in Figure 4, thus significantly increasing reaction rates compared to those with the conventional heating.

Tt E

bulk temperature, TB

catalyst surface

(where reaction takes place) surface temperature, Ts

Solid Catalysts

Figure 4. Phenomenon for microwave-assisted solid catalyzed reaction