Just a quick link: Over at the chem blog there is a post about doing reactions in a rotovap, increasing reaction speed caused by evaporation of solvents. Kyle posts a creative way to hack his lab’s rotovap for this.
The original article on this new method (hey, it is actually a 21st century preparatory synthetic method!) was published in Chem. Commun. 2006, 4729-4731, doi:10.1039/b609567d by Orita, Miwa and Otera.
Snippet from the abstract:
Several types of organic reactions were accelerated by immediate evaporation of solvents because of remarkable enhancement of molecule-to-molecule contacts between reactants.
Nice to know people actually find out about this during workup — not during the experiment planning phase, where chemists should at least think about stuff like concentrations… And, I have to say it, a remarkable way of euphemizing concentration effects.
In industry that is called process intensification.
One of the first questions is:
Do we really need a solvent?
Then: What is the benefit of wasting half of the vessel volume with an inert compound we have to take care of in workup, increasing cost?
If it was that easy.
We all know about reaction heat/transfer, viscosity, and solid reactants
Of course in practise it is a little more involved. However even solid reactants do melt most of the time and in many case one of the reactants can very well be used as solvent for the other components.
On a lab perspective this is ingenious as he has found a mild way to afford intimate and thorough mixing.