Waiting or Heating

So I have had a reaction going these past few days. Going, in a word, slowly.

This should be a quandry familiar to many in the synthesis field. Do I try to speed it up so I can get on with it or do I let nature take its course? Sure, I have other things I can be getting on with, but I set this reaction up in order to get to the desired product, so at some point I have to decide that it has done what it is going to do. If I want that point to come sooner, then the obvious answer is to heat it up, perhaps a little at first, then a little more, until you are reduced to stripping it down and redissolving it in something that boils at a higher temperature.

When that works, it is great, of course, and some reactions really do need some pushing to go in a reasonable time-frame. But there are dangers in that a higher temperature might give rise to more by-products or even decomposition of the desired material. So it has to be carefully considered.

Many times it is a question of context. If this is a final step and the overall yield does not really matter as long as I get enough to test, then I am more likely to heat it up, get what I can quickly and move along. But if this is an intermediate that needs to get me through several more steps then the possibly pitfalls of heating it up need to be pondered. One of the things that always feeds into my thinking here is an apochryphal story from grad school in which an industry chemist had come back to do his Ph.D. and completed his degree in double-quick time thanks to a willingness to heat things that weren’t working at room temperature.

As it happens for the current chemistry, the potential for side-reaction is significant and by-products are very likely. So an extra day at room temperature does not seem like such a great price to pay. And like I say, I have some other things to be doing.

Then again, maybe I could put it in the microwave?


2 comments on “Waiting or Heating

  1. Chemjobber says:

    Got an LC/MS? Might help your decision-making process…

  2. You have a real conundrum there.


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