You find a procedure that
worked on a system very similar to yours, and
all functional group in your molecule will be
compatible with the reaction conditions. The procedure
is described in detail by a respected research group, and has been referenced often by others.
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.
You do not make errors in your calculations,
you do not need special equipment, you have clean, dry glassware,
and you do not need to purify reactant, reagents or solvent.
Combination of reactants is simple, and goes smoothly.
The reaction is homogenous, and stirs easily. You can follow
the progress of the reaction by periodic analysis using
simple TLC or GC, and can stay with the reaction until
starting material is consumed. The reaction goes to
completion, to give one new product.
No quench is necessary.
For workup, you need only remove solvent.
TLC of your product using a common solvent system
gives an Rf of 0.3. A crude 1H NMR spectrum indicates
only your desired compound with few or no impurities.
You can easily identify an optimal method for purification.
No purification step is required, but you can filter
quickly through silica to obtain analytically pure product.
You obtain a 1H NMR spectrum of a pure compound without
solvent peaks. Each peak can be assigned to a proton of
your target compound, and the integrations are consistent
with expectations. Other spectra can be obtained without complications.
You have written an exact description of your
experiment in your notebook, and another chemist can
reproduce what you have done without further consultation,
on the first try.