Some Common Drying Agents

In all endeavors, remember that water is the enemy.  It will not discriminate.  It will destroy.  Fight to the finish my friends and remove the invader before it does harm.

And be sure to check the humidity before any reaction!!!

Agent
Useful Solvents
Incompatibilities
Phosphorus pentoxide
Hydrocarbons, acids, anhydrides, ethers, halohydrocarbons
Amines, Alcohols 
PREDRY!!!!!
CaH
Alcohols > C4, hydrocarbons, ethers, amines, esters
Carbonyl compounds
Na
Hydrocarbons, aryl halides, ethers
halogens
LAH
Hydrocarbons and ethers
Everything else
BaO, CaO
Alcohols and amines
Base sensitive compounds
Molecular sieves (3A)
Everything
Must Predry!!!
Alkali hydroxides
Amines
 
CaCl2
Hydrocarbons and alkyl halides
 
Silica Gel, Alumina
Hydrocarbons
 
Mg SO4, NaSO4, CaSO4
General
 
 K2CO3
Alcohols, esters, nitriles, ketones
 

Please note that this is just a generalized list.  I am providing this based upon my knowledge and information found in the following reference:

Gordon, A. J. and Ford, R. A. (1972) The Chemistís Companion, John Wiley & Sons, New York, pp 445-447.

The preceding information is intended for use by experienced chemists only.  If you are not famialiar with the reagents listed, do not attempt to use this information.