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Q: What are the principal advantages of microwave-assisted organic synthesis over traditional methods?
A: One important advantage, which led to the initial adoption of microwave-enhanced chemistry, is simply the speed with which synthetic reactions can be performed. While advances in the analysis of synthetic compounds—for example, fast, fully automated equipment for performing HPLC—have shortened the overall synthetic process, there is still a bottleneck in the area of the chemical reactions themselves. Reactions that would take days with conventional methods can be completed in minutes in the microwave, eliminating that bottleneck.
Q: How do the products generated by microwave synthesis compare to the products of traditional methods?
A: Microwave-enhanced synthesis actually generates larger yields and purer products than conventional techniques. Hot plates and oil baths, for example, heat the reaction mixture from the outside in, creating a hot vessel surface that can be the site of undesirable side reactions. Microwave energy, however, heats the entire sample at once, eliminating "hot spots" and reducing reaction times, all of which results in larger, purer yields.
Q: How easily can microwave synthetic reactions be converted from small-scale to larger volumes?
A: Experienced synthetic chemists, particularly in the pharmaceutical industry, have come to recognize the ease of scalability associated with microwave methods as a principal benefit—just as important as the speed of reactions. With traditional methods, a great deal of time-consuming thought and experimentation are required to convert milligram-scale reactions to larger volumes. However, in the microwave, the same conditions that worked at the smallest scale will work at a much larger scale, to generate a proportional yield of equal purity. The work that goes into optimizing a reaction needs to be performed only once.
For more information on this topic, see Dr. C. Oliver Kappe's article Back to the Roots, and Dr. Alex Rabinovich's article on The Scale-Up of Microwave-Assisted Organic Reactions.
Q: Flexible scale-up of reactions is essential to my work. What range of volumes will your microwave platform allow me to process?
A: There is no gap in the range of volumes that you can handle with our platform, from 250 μL to 1.2 liters in the MicroSynth, to 6 liters per hour in the continuous flow system. The MicroSYNTH Labstation is a modular system, and the available modules provide a comfortable overlap in range, to ensure effortless scalability. In addition, all four areas of work have the option for parallel processing.
Q: How safe are Milestone's labstations?
A: Safety Officers worldwide encourage their chemists to use Milestone technology. The MicroSynth is the safest microwave system on the market at this moment because of:
- rugged, all-stainless-steel construction
- built-in fiber-optic temperature sensors to measure the reaction temperature directly, and stop the system instantly in case of an exothermic reaction
- a patented safety spring in each reaction vessel, which releases excess pressure and then closes again, with no loss of sample and no "cloud" of solvent
In addition, the unit has been tested and survived with exploding vessels. It is the only system on the market that will stay closed in case of an explosion, due to its unique, patented, spring-mounted door design.
Q: What is the difference between a monomode and a multimode system?
A: In a small monomode system, microwaves are focused through a wave guide on the reaction vessel. You can run one sample at a time, and in general, only small volumes are used.
In a multimode system, microwaves are distributed homogeneously throughout the entire cavity by means of a mode stirrer. As a result, you can use a wide variety of reactors or well plates, and can process multiple samples simultaneously or explore larger reaction volumes. Another major advantage of a multimode system is that by using a button or stir bar made of WeflonTM (a carbon-filled polymer), you can even use non-polar (i.e., microwave-transparent) solvents such as 1,4-Dioxane, THF, Toluene, etc.—so you do not have to alter your existing chemistry.
If you have a question that has not been answered, feel free to send us an inquiry.
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