Real-time imaging and spectroscopy during microwave assisted chemistry

Abstract

An instrument and associated method are disclosed for conducting microwave assisted chemical reactions. The instrument includes a microwave cavity, preferably a closed microwave cavity, for conducting microwave assisted chemical reactions, and a source for applying microwave radiation within the cavity and to a vessel and its contents. The instrument also includes an illumination source for illuminating the vessel and its contents, as well as means for visually observing the vessel and its contents, an infrared detector for monitoring the temperature of the vessel and its contents, and means for preventing the illumination source from saturating the infrared detector, thereby enabling concurrent visual observation and infrared monitoring.

1 . A method of carrying out microwave assisted chemical reactions, the method comprising:
 placing reactants in a microwave-transparent vessel;   positioning the vessel and its contents inside a microwave cavity;   applying a continuous single mode of microwave radiation within the cavity and to the vessel and its contents;   while concurrently monitoring infrared radiation emitted from the reactants to determine the temperature of the vessel contents;   while concurrently illuminating and visually monitoring the reactants to determine the progress of a reaction; and   adjusting the microwave power in response to a monitored change in the reactants in the vessel.   
     
     
         2 . A method of carrying out microwave assisted chemical reactions according to  claim 1  wherein the step of adjusting the microwave power comprises adjusting the microwave power in response to a monitored temperature change. 
     
     
         3 . A method of carrying out microwave assisted chemical reactions according to  claim 1  wherein the step of adjusting the microwave power comprises adjusting the microwave power in response to a visually monitored change. 
     
     
         4 . A method of carrying out microwave assisted chemical reactions according to  claim 1  wherein the step of adjusting the microwave power comprises adjusting the microwave power in response to a monitored chemical change in the reactants. 
     
     
         5 . A method of carrying out microwave assisted chemical reactions according to  claim 1  wherein the step of adjusting the microwave power in response to a monitored change in the reactants in the vessel comprises adjusting the microwave power in response to a monitored, predetermined change in the reactants in the vessel. 
     
     
         6 . A method of carrying out microwave assisted chemical reactions according to  claim 1  further comprising visually recording the reaction. 
     
     
         7 . A method of carrying out microwave assisted chemical reactions according to  claim 1  wherein the step of visually monitoring the reactants to determine the progress of a reaction comprises illuminating the reaction vessel and the reactants in the reaction vessel with a visual light source. 
     
     
         8 . A method of carrying out microwave assisted chemical reactions according to  claim 1  wherein the step of illuminating and visually monitoring the reactants further comprises limiting the monitored IR wavelengths to IR wavelengths produced by the reaction. 
     
     
         9 . A method of carrying out microwave assisted chemical reactions, the method comprising:
 applying a continuous single mode of microwave radiation within a cavity and to a reaction vessel in the cavity and reactants in the reaction vessel;   intermittently monitoring infrared radiation emitted from the reaction vessel and the reactants to determine the temperature of the vessel contents; and   intermittently illuminating and visually monitoring the reactants.   
     
     
         10 . A method of carrying out microwave assisted chemical reactions according to  claim 9 , further comprising placing the reactants in a vessel and sealing the vessel prior to the step of applying the microwave radiation. 
     
     
         11 . A method of carrying out microwave assisted chemical reactions according to  claim 10  wherein the step of placing the reactants in a vessel comprises placing the reactants in a pressure-resistant vessel. 
     
     
         12 . A method of carrying out microwave assisted chemical reactions according to  claim 9  wherein the step of applying microwave radiation comprises applying microwave radiation from a source selected from the group consisting of magnetrons, klystrons, and solid state sources. 
     
     
         13 . A method of carrying out microwave assisted chemical reactions according to  claim 9  wherein the step of visually monitoring the reactants comprises illuminating the reaction vessel and the reactants using a light source that includes the visible wavelengths. 
     
     
         14 . A method of carrying out microwave assisted chemical reactions according to  claim 9  wherein the step of intermittently illuminating and visually monitoring the reactants comprises modulating a light source containing an IR component to allow intermittent visual observation and infrared temperature monitoring. 
     
     
         15 . A method of carrying out microwave assisted chemical reactions according to  claim 9  wherein the illuminating and visually monitoring step comprises illuminating the interior of a closed cavity. 
     
     
         16 . A method of carrying out microwave assisted chemical reactions according to  claim 9  wherein the illuminating and visually monitoring step comprises inserting a fiber optic light pipe into a spectroscopy port in a closed microwave cavity. 
     
     
         17 . A method of carrying out microwave assisted chemical reactions according to  claim 16  further comprising monitoring through a lens. 
     
     
         18 . A method of carrying out microwave assisted chemical reactions according to  claim 17  wherein the step of monitoring through a lens comprises monitoring through a lens on the cavity end of the fiber optic light pipe to enhance a viewing angle. 
     
     
         19 . A method of carrying out microwave assisted chemical reactions according to  claim 15  further comprising visually recording the reaction. 
     
     
         20 . A method of carrying out microwave assisted chemical reactions according to  claim 9  further comprising moderating the microwave radiation in response to an observed reaction change. 
     
     
         21 . A method of carrying out microwave assisted chemical reactions according to  claim 9  wherein the step of visually monitoring the reactants to determine the progress of a reaction comprises directing the monitored output to a spectrophotometer. 
     
     
         22 . A method of microwave assisted chemistry comprising:
 applying microwave radiation to a reaction vessel and its contents;   periodically obtaining an image of the vessel and its contents;   converting the obtained images to digital output; and   moderating the application of microwaves to the vessel and its contents based on the digital image output.   
     
     
         23 . A method according to  claim 22  further comprising periodically measuring a variable selected from the group consisting of the temperature of the vessel and its contents and the pressure within the reaction vessel and moderating the application of microwaves to the vessel and its contents based on the digital image output and at least one of the periodic measurements of temperature and pressure. 
     
     
         24 . A method according to  claim 23  comprising moderating the application of microwaves to the vessel and its contents based on the digital image output and both of the periodic measurements of temperature and pressure. 
     
     
         25 . A method according to  claim 22  comprising obtaining an image of the vessel and its contents in the visual wavelengths. 
     
     
         26 . A method according to  claim 22  comprising moderating the application of microwaves independently of any visual display of the obtained images. 
     
     
         27 . A method according to  claim 22  comprising moderating the application of microwaves without any visual display of the obtained images. 
     
     
         28 . A method of microwave assisted chemistry comprising:
 obtaining an image of compositions during the application of microwave radiation to the compositions at specific time intervals;   measuring the temperature of the compositions at the same specific time intervals as the images are obtained;   measuring the pressure generated by the compositions at the same specific time intervals as the images are obtained;   recording the microwave power applied to the compositions at the same specific time intervals as the images are obtained; and   generating a recorded matrix of the image, temperature, pressure, and power measurements at the specific time intervals.   
     
     
         29 . A method according to  claim 28  comprising obtaining images in the visual wavelengths. 
     
     
         30 . A method according to  claim 28  comprising generating the recorded matrix independently of any visual display of the obtained images. 
     
     
         31 . A method according to  claim 28  comprising generating the recorded matrix without any visual display of the obtained images.