Sciencemadness Discussion Board

Microwave assisted organic synthesis

feynmann - 4-5-2009 at 15:25

I would like to know if there is a low cost solution for a pressure tolerating vessel or vial to be used in a domestic microwave oven

I know the ideal solution is provided in the form of digesting bomb but 500 dollars for a teflon vessel is more than what i can afford ...
I have those pressure vessels from kimble,chemglass and ace which are rated at 150 psi and i intend to use them in reactions like condensation ,esterification and so like reactions which are not rapidly exothermic...........Is this going to work ????
I really would like someone to give me a scenario where the pressure can exceed 150 psi such that the reaction is as mentioned above (aka no exothermic reaction ...no gas byproduct ..........)



ptfe m.o.r.e.

jimwig - 4-5-2009 at 15:35

tricky name where u find?

is yoour first name richard p.?

i have heard that the teflon m.o. containers much cheaper than that - long while back maybe on Lab X ???

there are ways to building containers that will melt metal - with i think silicon carbide ???? -your applications might vary!!!

fabricating ceramic vessels with a high temp gasket might - just guessing but i have been seeking similar answers.

will monitor this thread and hopefully learn learn learn

hey what about a tube furnace through the oven - as in one side and out the other. check for leakage - a right turn and then through the proper side screening...... maybe....








feynmann - 4-5-2009 at 15:43

I am not looking actually for any mod considering the microwave ....aka drilling or any other mod
I am using it in synthesis not melting metals so silicon carbide is off topic here
I am trying to focus if the pressure vessels by kimble can suffice or not for the reactions mentioned:(

Paddywhacker - 4-5-2009 at 16:17

You mean glassware like this:-
http://www.chemglass.com/products_new/np-pressurevessels.htm...

This is an interesting subject. Please keep us informed of your findings.

feynmann - 4-5-2009 at 16:19

yes exactly as they are cheap .................I need some expert in this field to give me advice concerning this before trial

Nicodem - 4-5-2009 at 23:31

If you buy a closed cap vial, then why would you want to use microwave heating?
Besides, it seem to me you have never seen a microwave synthesis reactor as you fail to realize that it has an IR temperature sensor built in which regulates the microwave power output in relation to the reaction temperature (that, and the use of autoclave as reaction vessel, is the whole point of such an instrument, and this is why they can sell it so bloody expensive). Without temperature control, the vessel would just blow up. Hence, you can not use a confined vessel inside a domestic microwave oven (unless it is your desire to get injured). That would be like a bomb waiting to blow up, because there would be absolutely nothing to control the temperature and the pressure would just grow till the limits of the vessel. I work with a microwave synthesis reactor on nearly daily basis and I have seen a couple of vessels blow up even with all the temperature/pressure control electronics to back up safety. I can tell you these things, when they blow up, they are very violent even for 10ml vessels (luckily the heating core is shielded, while a domestic oven is not). Without power regulation the vessels blow up in matter of seconds or minutes, depending on the solvent used.
It seems to me you had this impulsive idea without investing any thought. Surprisingly, the exactly same crazy idea was already brought up: http://www.sciencemadness.org/talk/viewthread.php?tid=11613

UnintentionalChaos - 4-5-2009 at 23:44

I concur that microwave synthesis is not at all something you can throw in a regular microwave. I use a microwave reactor during undergrad. research and use very heavy-walled 5 or 10ml capacity tubes with a high temperature silicone crimped-seal. The reactor maintains a standing wave in the chamber for completely even heating. It has software that runs it, regulating temperature within a very narrow range, as well as how much power is being delivered to the microwave. Tanks of nitrogen connected to the setup are used to rapidly cool the reaction tube if need be and to adjust it during the actual reaction. The research has been on running solvent-free reactions, so pressure is less of a concern, but I can see how easily things would get hairy with solvents.

[Edited on 5-5-09 by UnintentionalChaos]

feynmann - 5-5-2009 at 00:15

Well I know well commercial reactors (CEM,biotage ,milestone and parr) and I have pretty good knowledge about the temp control using pyrometer......fiber optic....and ir sensors.

I am asking about improvised things like knowing the behavior of the solvent and then be able to use microwave intermittently 1 min intervals or something at moderate power without explosion

I have successfully carried out some reactions in open vessel like anilines sulfonation and there are many so like reactions carried out in the literature but as u said many of them were carried out using clays ,silica,alumina (solvent free) .

A highly improvised approach was to use glass block over an open vessel (somehow heavy one and put cardice over it and monitor ur reaction ........when it melts pause the oven and put some other pieces (used in the papers attached below)

I uploaded many papers from journal of chemical education which was carried out successfully in our lab
http://rapidshare.com/files/229338397/microwave.rar

1. Microwave-Assisted Organic Synthesis in the Organic Teaching Lab: A Simple, Greener Wittig Reaction
Martin, Eric; Kellen-Yuen, Cynthia 2007, 84, 2004
Abstract Full text
2. A Knoevenagel Initiated Annulation Reaction Using Room Temperature or Microwave Conditions
Cook, A. Gilbert 2007, 84, 1477
Abstract Full text
3. Microwave-Mediated Synthesis of Lophine: Developing a Mechanism To Explain a Product
Crouch, R. David; Howard, Jessica L.; Zile, Jennifer L.; Barker, Kathryn H. 2006, 83, 1658
Abstract Full text
4. Microwave-Assisted Heterocyclic Chemistry
Coleman, William F. 2006, 83, 621
Abstract Full text
5. A Greener Approach to Aspirin Synthesis Using Microwave Irradiation
Montes, Ingrid; Sanabria, David; García,, Marilyn; Castro, Joaudimir; Fajardo, Johanna 2006, 83, 628
Abstract Full text
6. Microwave-Assisted Heterocyclic Chemistry for Undergraduate Organic Laboratory
Musiol, Robert; Tyman-Szram, Bozena; Polanski, Jaroslaw 2006, 83, 632
Abstract Full text
7. Incorporation of Microwave Synthesis into the Undergraduate Organic Laboratory
Katritzky, Alan R.; Cai, Chunming; Collins, Meghan D.; Scriven, Eric F. V.;Singh, Sandeep K.; Barnhardt, E. Keller 2006, 83, 634
Abstract Full text
8. Microwave-Induced Chain Transfer Polymerization of a Stimuli-Responsive Polymer and Determination of Its Critical Solution Temperature
Fischer, F.; Freitag, R. 2006, 83, 447
Abstract Full text
9. Microwave-Assisted Synthesis of a Natural Insecticide on Basic Montmorillonite K10 Clay. Green Chemistry in the Undergraduate Organic Laboratory
Dintzner, Matthew R.; Wucka, Paul R.; Lyons, Thomas W. 2006, 83, 270
Abstract Full text
10. A Microwave-Assisted Reduction of Cyclohexanone Using Solid-State-Supported Sodium Borohydride
White, Lori L.; Kittredge, Kevin W.

and many others found in this search
http://search.jce.divched.org/JCEIndex/FMPro?-db=jceindex.fp...


[Edited on 5-5-2009 by feynmann]

marksev1 - 5-5-2009 at 12:39

Here is one example of a solvent-free reaction www.scilet.com/chemistry/JCR%20sample%20paper.doc , which they made in a domestic oven.

Also one problem would be how to modify the microwave generator to modulate frequency of the microwaves, since some reactions give better yields at different frequencys. Domestic microwaves ovens operate with a frequency of 2.45 GHz, but how to modulate this generator it would require some electronics know-how probably.

roamingnome - 5-5-2009 at 17:47

Since research level M.O.R.E chemistry lends itself to smaller substrate amounts because of even heating issues,
ive had frugal success with double vessel approaches. A PC or PET outer vessel containing a smaller inner vessel with inner core graphite sensitizer ( which is part of the reaction mix in my studies).

Test a blank matrix for its failure point which is contained by the outer vessel.

Or just blow up the inner vessel to mark the end of reaction and wash and work up from the outer vessel.

after checking on teflon round stock price engineer for disposable failure

napoleon9 - 10-6-2011 at 08:45

Quote: Originally posted by feynmann  
Well I know well commercial reactors (CEM,biotage ,milestone and parr) and I have pretty good knowledge about the temp control using pyrometer......fiber optic....and ir sensors.

I am asking about improvised things like knowing the behavior of the solvent and then be able to use microwave intermittently 1 min intervals or something at moderate power without explosion

I have successfully carried out some reactions in open vessel like anilines sulfonation and there are many so like reactions carried out in the literature but as u said many of them were carried out using clays ,silica,alumina (solvent free) .

A highly improvised approach was to use glass block over an open vessel (somehow heavy one and put cardice over it and monitor ur reaction ........when it melts pause the oven and put some other pieces (used in the papers attached below)

I uploaded many papers from journal of chemical education which was carried out successfully in our lab
http://rapidshare.com/files/229338397/microwave.rar

1. Microwave-Assisted Organic Synthesis in the Organic Teaching Lab: A Simple, Greener Wittig Reaction
Martin, Eric; Kellen-Yuen, Cynthia 2007, 84, 2004
Abstract Full text
2. A Knoevenagel Initiated Annulation Reaction Using Room Temperature or Microwave Conditions
Cook, A. Gilbert 2007, 84, 1477
Abstract Full text
3. Microwave-Mediated Synthesis of Lophine: Developing a Mechanism To Explain a Product
Crouch, R. David; Howard, Jessica L.; Zile, Jennifer L.; Barker, Kathryn H. 2006, 83, 1658
Abstract Full text
4. Microwave-Assisted Heterocyclic Chemistry
Coleman, William F. 2006, 83, 621
Abstract Full text
5. A Greener Approach to Aspirin Synthesis Using Microwave Irradiation
Montes, Ingrid; Sanabria, David; García,, Marilyn; Castro, Joaudimir; Fajardo, Johanna 2006, 83, 628
Abstract Full text
6. Microwave-Assisted Heterocyclic Chemistry for Undergraduate Organic Laboratory
Musiol, Robert; Tyman-Szram, Bozena; Polanski, Jaroslaw 2006, 83, 632
Abstract Full text
7. Incorporation of Microwave Synthesis into the Undergraduate Organic Laboratory
Katritzky, Alan R.; Cai, Chunming; Collins, Meghan D.; Scriven, Eric F. V.;Singh, Sandeep K.; Barnhardt, E. Keller 2006, 83, 634
Abstract Full text
8. Microwave-Induced Chain Transfer Polymerization of a Stimuli-Responsive Polymer and Determination of Its Critical Solution Temperature
Fischer, F.; Freitag, R. 2006, 83, 447
Abstract Full text
9. Microwave-Assisted Synthesis of a Natural Insecticide on Basic Montmorillonite K10 Clay. Green Chemistry in the Undergraduate Organic Laboratory
Dintzner, Matthew R.; Wucka, Paul R.; Lyons, Thomas W. 2006, 83, 270
Abstract Full text
10. A Microwave-Assisted Reduction of Cyclohexanone Using Solid-State-Supported Sodium Borohydride
White, Lori L.; Kittredge, Kevin W.

and many others found in this search
http://search.jce.divched.org/JCEIndex/FMPro?-db=jceindex.fp...


[Edited on 5-5-2009 by feynmann]


please reupload it. Because this link was disconnect.
http://rapidshare.com/files/229338397/microwave.rar

I like subject "microwave in synthesis".
thanks

azo - 10-6-2011 at 15:11

If you are going to use a domestic microwave make sure you disconnect the door switch for ovious reasons.

regards azo

Panache - 15-6-2011 at 16:39

Quote: Originally posted by azo  
If you are going to use a domestic microwave make sure you disconnect the door switch for ovious reasons.

regards azo


um which are?? i would propose the opposite, make sure you don't disconnect the door switch.

azo - 16-6-2011 at 02:34

Ok then evaperate down some methanol and open the door all the time and find out:D