2 Cl 2 were used as a solvent, caffeine would favor dissolving in the later solvent by a factor of 8.2 to 1. This transfer is not easy, and you should expect to have some of the CH 2 Cl 2 solution run out of your transfer pipet at the wrong time. The problem is that CH 2 Cl 2 vapors are warmed by your hand even while it is inside the pipet and expand, forcing the liquid to dribble out of the pipet. With some practice you can counteract this by constantly sucking air into the pipet. In any case, nothing is lost if the CH 2 Cl 2 dribbles back into the centrifuge tube.
Caffeine normally sublimes before it melts.
Thus the melting point capillary must be sealed. Mayo et al. Cleveland, OH, 1960-present. Aldrich Chemical Co. Milwaukee WI 1970-present.