Chemistry: electrical and wave energy – Processes and products – Processes of treating materials by wave energy
Patent
1996-06-25
1999-08-03
Gorgos, Kathryn L.
Chemistry: electrical and wave energy
Processes and products
Processes of treating materials by wave energy
2041573, 2041576, 422186, C07C 100, B01D 5300, C07F 100, B01J 1908
Patent
active
059320753
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a method and apparatus for performing chemical reactions using microwave energy. The invention is particularly suitable for chemical synthesis or kinetics studies.
In this specification, the term "chemical reaction" means a process involving the making and/or breaking of at least one chemical bond within or between one or more substances so as to produce one or more new substances.
BACKGROUND ART
It is known that the rate of chemical reactions can be accelerated to decrease reaction times by several orders of magnitude by using microwave energy, provided the reaction medium includes at least one solvent or reactant having a high dielectric loss tangent so as to couple effectively with the microwaves. Such accelerated reaction times, however, usually involve the generation of high temperatures and pressures, particularly in sealed reaction vessels, and there exists a need to provide effective reaction monitoring, control and safety facilities on the microwave heating equipment.
The applicant's prior International Application No. PCT/AU89/00437 (Publication No. WO 90/03840) discloses a laboratory flow-through unit for conducting microwave initiated chemical reactions on a continuous basis which incorporates reaction monitoring and control facilities. However, the monitoring and control facilities on this known unit are located outside the microwave irradiation zone. Furthermore, this known unit does not meet laboratory applications that are not suited to continuous processes.
Apparatus for performing chemical reactions on a batch basis that includes facilities to monitor temperature and pressure within the reaction vessel is disclosed by D. Constable, K. Raner, P. Somlo and C. Strauss in the article "A New Microwave Reactor Suitable for Organic Synthesis and Kinetics Studies", Journal of Microwave Power and Electromagnetic Energy, Vol. 27 No. 4, 1992, pages 195-198 (the disclosure of which is incorporated herein by cross-reference). In this reactor, a reaction vessel having a screw-cap lid with pressure and temperature monitoring fittings, is situated within a microwave cavity. The reaction vessel also contains a stirrer bar, which is magnetically driven from outside the microwave cavity.
Although the Constable et al. reactor includes facilities to monitor reaction conditions within the microwave irradiation zone, its only controllable input is the power level of the microwaves. Thus in the Constable et al. reactor it is not possible, for example, to controllably cool the reaction products nor to add or subtract from the vessel's contents during the course of a reaction.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a microwave reactor and methods for performing chemical reactions which embody control features additional to those of the Constable et al. reactor.
According to the invention, there is provided a reactor for performing chemical reactions under the influence of microwave radiation comprising a vessel for containing substances for a chemical reaction, said vessel being adapted to withstand internal pressures generated by said substances during the course of a chemical reaction, said adaptation including the provision of a cover containing means for monitoring the vessel contents as microwave energy is applied thereto and wherein the cover also supports a heat exchange means for immersion in the vessel contents.
Preferably the vessel is for placement within a microwave cavity. Alternatively microwave radiation may be introduced interiorly of the vessel by means associated with the cover.
The heat exchange means is for preheating said substances or for cooling said contents when desired, for example during the progress of a chemical reaction, most usually an exothermic reaction, or upon completion of the heating stage for a reaction.
Preferably the means for monitoring the vessel contents comprises temperature and/or pressure measuring means.
The invention in a second aspect provides a method for performing a chemical re
REFERENCES:
patent: 1191916 (1916-07-01), Brooks et al.
patent: 1523563 (1925-01-01), Snelling
patent: 1746731 (1930-02-01), Koehler
patent: 2958638 (1960-11-01), Tarnity
patent: 3458418 (1969-07-01), Beckmann
patent: 4507188 (1985-03-01), Chu
patent: 5033541 (1991-07-01), D'Silva
Raner Kevin David
Strauss Christopher Roy
Thorn John Stanley
Trainor Robert William
Commonwealth Scientific and Industrial Research Organisation
Gorgos Kathryn L.
Wong Edna
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