Chemical Forums

Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Messi on November 13, 2012, 10:57:19 AM

Title: Stirring
Post by: Messi on November 13, 2012, 10:57:19 AM

Hi guys,

Just wondering if letting a reaction stir for one hour vs two hours and a half makes a big difference!? I can't get back to my reaction within the hour, so I was going to let it stir for two hours and a half instead? No big deal, or a big uh-oh is necessary?

Thanks!

Title: Re: Stirring
Post by: discodermolide on November 13, 2012, 11:03:26 AM

It really depends upon what you are doing. Stirring is a very complex thing. Prolonged stirring can alter the crystal morphology of a compound. To violent stirring can chop up crystals so that you cannot filter them, By choosing the wrong stirrer your mixing may not be good enough, etc.
In your case, if your reaction starting materials and products are stable extending the stirring time should not matter too much. I have experienced epimerisation by stirring for too long, but I was lazy and left the reaction while I had lunch, I should have managed my time better.

Title: Re: Stirring
Post by: curiouscat on November 13, 2012, 01:21:11 PM

What's your reaction?  Side products might be an issue. It's too generic a question.

Say A->B->C

If you want B; stirring too long's obviously bad.

Title: Re: Stirring
Post by: Messi on November 13, 2012, 04:16:40 PM

Ok, nice! Thanks!

I decided to run my reaction a little longer and nothing "too crazy" happened ;)