A Perfect Reaction (see all): Your reactant is commercially available. The reagents you need are cheap, and you have as much as you need in the lab already. You know exactly how long the reaction will take. You know the appropriate reaction scale to carry out (even better, that scale involves 0.2- 1.0 g of reactant). You will not need to leave the lab before the reaction is complete. The product is going to be stable and able to be stored indefinitely.
A Nightmare Scenario (see all): It's 9 PM. None of your glassware is clean. You can't decide what scale to run it on and you don't have any of the reagents.
Step by Step (usually days ahead of time):
Decide on a scale for your reaction. The following factors will influence your decision.
Have you run the reaction before? On what scale?
How precious is the reactant?
Will you need the reactant for any other experiments?
When a reaction is new to you,
one millimole is often a good starting point, if reactant is not limiting.
If reactant is precious, it can be divided into three or four portions,
or if you are comfortable on small scale, 10 mg is usually the most useful choice.
If you have run the reaction before, you may choose to run a larger scale reaction.
It is best to scale up by no more than 3-4 times the previous experiment, in case the
reaction begins to lose efficiency.
If you need a lot of the product compound, have experience with similar procedures,
or feel sure of success (based on the literature, for example), you might start with
one or even five grams of reactant.
Calculate your reactant and reagent quantities.
Locate or order the chemicals needed, and find out if additional purification will be necessary.
Predict how long the reaction will take to set up, run, and work up.
Plan a time to begin the experiment such that you can stay with it and monitor it until
It has gone to completion and you have worked it up OR
It has been stirring at a constant temperature for one hour and is less than 25% complete.