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Author: Subject: Scaling up microwave reactions
ergoamide
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[*] posted on 2-7-2007 at 00:54
Scaling up microwave reactions


I'm just wondering if anyone could give me any advice as to scaling up microwave reactions. Obviously time would need to be increased as the reaction size increased but should the time increase be proportional to the reaction size increase? Also the power of the waves emmitted, should they be increased as the reaction size increases? Any help with this would be great.

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[*] posted on 2-7-2007 at 01:38


Not enough information.



Irgendwas is ja immer
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roamingnome
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[*] posted on 2-7-2007 at 19:44


consider designing a flow reactor with a residence time in the microwave field.

if the reaction is spinning on plate it would be harder...

to find the hot spot of your microwave place marshmallows around the input wave guide... if a marshmallow is in a hot spot in will inflate quite quickly! :o

the accuracy of this method is still in question though....
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[*] posted on 3-7-2007 at 06:19


Roamingnome is right - flow reactors are often used to scale up microwave assisted reactions. It's difficult to get uniform power distribution as the reaction volume increases, unless you lower the RF frequency, going to a relatively small volume with a flowing reaction mass gets around this.

More attention must be paid to the characteristics of the chamber. Standing wave patterns, matching to the power source, and so on, can affect results.

The clay supported reactions, and other similar ones, don't always scale well. Often these are done will a few millimoles of reactants, the volume of support matter needed to product product on the scale of many grams can be impractically large' although I remember reading a paper or two on modifications to address that problem.

Doing online searches should yield some references to scaling up, plus check out the books mentioned for D/L. Off the top of my head, I can't think of any specific references, and it's too late to be digging through what I've got stored away tonight, but I'll see if I can find something tomorrow.
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