The Continuous Microwave Reactor CMR

microwave cavity 5, reaction coii 6, temperature sensor 7, heat exchanger 8, pressure reguiator 9, microprocessor controiier 10, product vessei. 

Commercial units (Fig. 3.2) had volumes up to 120 mL within the microwave /one, 80 mL within the cooling zone, and could be operated at flow rates up to 100 mL min k Under such arrangements, residence times in the microwave zone were typically 2-10 min. 

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The continuous microwave reactor (CMR) was the first microwave system designed specifically for organic reactions (see Fig. 9.4)91. In that regard, as with the MBR, the... 

A continuous MW reactor (CMR), which operates by passing a reaction mixture through a pressurized tubular microwave-transparent coil and a MW batch reactor (MBR), have been developed by CSIRO in Australia and are used for organic synthesis on the laboratory scale [8]. The CMR can be operated at pressures up to 1400 kPa and temperatures up to 200 °C and the MBR at pressures and temperatures up to 10 MPa and 260 °C. 

The continuous and batch microwave reactors have been particularly useful for heating reactions in which thermally labile products are formed. For example, alkyl 2-(hydroxymethyl)acrylates have considerable potential as functionalised monomers and synthons128. Published syntheses at ambient temperature, however, required several days and were not conducive to scale-up129-133. The microwave procedure involved a modified Baylis-Hillman reaction, in which the parent acrylate derivative was reacted with formalin in the presence of 1,4-diazabicyclo [2.2.2] octane (DABCO). Preparations from starting acrylates, including methyl, ethyl and n-butyl esters, were easily achieved within minutes with multiple passes through the CMR, at ca. 160-180°C (Scheme 9.16). Rapid cooling was required to limit hydrolysis, dimerisation and polymerisation. Yields... 

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