solvents

[flipper]

How important are solvents? Can I just use less then is described in the procedures?

Say this one.

Post 390003

(flipper: "LSD from LSA synth qeustion", Tryptamine Chemistry) Carbodiimidazole method.
If swim want to make a batch of 1 kilogram he needs to use almost 100 liters of DMF. That's a lot of solvent.
But can swim use say 50 liters of DMF or THF or Chloroform in this reaction without effecting the yield?  

[Lilienthal]

Usually the relative amount of solvents is drastically reduced during the upscaling of a reaction. The amount depends mainly on the solubility of the reactants and the consistency of the mixture.

For upscaling one usually starts with microreactions of 10 to 100 mg under TLC control to find out the reaction conditions. After optimization one goes stepwise to larger scales thereby eliminating problems due to the larger amounts (e.g. problems with stirring , heating, cooling, and purification).

The same is true for (column) chromatography. One starts with microgram amounts on thin-layer-chromatogryphy sheets (TLC) to find out the best solvent system, and then runs stepwise larger columns under (TLC-)control of your fractions.

It's impossible to get a reaction or a purification running on the first try on a larger scale with out this initial testing!!! You would be like a blind and deaf person in a new town...

[flipper]

Thanks for your reply