I don't know how many of you are interested in the compatibilities of different drying agents as I would guess most of you already have your favorite drying agent that you use with the reactions that you've gotten down pat and therefore don't need to look any further...if it works, don't fix it :-) However there may be a few bees that aren't happy with the one they are using or just want to try a different one...so for them here is a brief compatibility chart for reference use. Hope it helps, if you've got any questions feel free to ask and I'll try to answer them correctly when I stop back...
DRYING AGENTS AND THE COMPOUNDS THEY ARE SUITABLE FOR DRYING
Alumina-->Mainly as a drying agent in a desiccator or as a column through which liquid is percolated.
Aluminium Amalgam-->Mainly used for removing traces of water from alcohols, which are distilled from it after refluxing.
Barium Oxide-->Suitable for drying organic bases.
Barium Perchlorate-->Expensive. Used in desiccators (covered with a metal guard). Unsuitable for drying solvents or organic material where contact is necessary, because of the danger of EXPLOSION.
Calcium Chloride-->Large capacity for absorption of water, giving the hexahydrate below 30°, but is fairly slow in action and not very efficient. Its main use is for preliminary drying of alkyl and aryl halides, most esters, saturated and aromatic hydrocarbons and ethers. Unsuitable for drying alcohols and amines, fatty acids, amides, amino acids, ketones, phenols, or some aldehydes and esters. Calcium chloride is suitable for drying the following gases: hydrogen, hydrogen chloride, carbon monoxide, carbon dioxide, sulfur dioxide, nitrogen, methane, oxygen, also paraffins, ethers, olefines and alkyl chlorides.
Calcium Oxide-->Suitable for alcohols and amines (but does not dry them completely). Unsuitable for acidic compounds and esters. Suitable for drying gaseous amines and ammonia.
Calcium Sulfate-->Available commercially as Drierite. It forms the hemihydrate, 2CaSO4.H2O, so that its capacity is fairly low (6.6% of its weight of water), and hence is best used on partially dried substances. It is very efficient (being comparable with phosphorus pentoxide and concentrated sulfuric acid). Suitable for most organic compounds. Solvents boiling below 100° can be dried by direct distillation from calcium sulfate.
Copper (II) Sulfate-->Suitable for esters and alcohols. Preferable to sodium sulfate in cases where solvents are sparingly soluble in water (for example, benzene or toluene).
Magnesium Amalgam-->Mainly used for removing traces of water from alcohols, which are distilled from it after refluxing.
Magnesium Perchlorate-->Expensive (Available commercially as Dehydrite).Used in desiccators. Unsuitable for drying solvents or any organic material where contact is necessary, because of the danger of EXPLOSION.
Magnesium Sulfate -->More rapid and effective than sodium sulfate. It has a large capacity, forming MgSO4.7H2O below 48°. Suitable for the preliminary drying of most organic compounds.
Phosphorus Pentoxide-->Very rapid and efficient, but difficult to handle and should only be used after the organic material has been partially dried, for example with magnesium sulfate. Suitable for acid anhydrides, alkyl and aryl halides, ethers, esters, hydrocarbons and nitriles, and for use in desiccators. Not suitable with acids, alcohols, amines or ketones, or with organic molecules from which a molecule of water can be fairly readily abstracted by an elimination reaction. Suitable for drying the following gases: hydrogen, oxygen, carbon dioxide, carbon monoxide, sulfur dioxide, nitrogen, methane, ethylene and paraffins. It is available with an indicator (cobalt salt, blue when dry and pink when wet) under the name Sicapent (from Merck).
Potassium (metal)-->Properties and applications are similar to those for sodium, and it is a correspondingly hazardous substance.
Potassium Carbonate-->Has a moderate efficiency and capacity, forming the dihydrate. Suitable for an initial drying of alcohols, bases, esters, ketones and nitriles by shaking with them, then filtering off. Also suitable for salting out water-soluble alcohols, amines and ketones. Unsuitable for acids, phenols and other acidic substances.
Potassium Hydroxide-->Solid potassium hydroxide is very rapid and efficient. Its use is limited almost entirely to the initial drying of organic bases. Alternatively, sometimes the base is shaken first with a concentrated solution of potassium hydroxide to remove most of the water present. Unsuitable for acids, aldehydes, ketones, phenols, amides and esters. Also used for drying gaseous amines and ammonia.
Silica Gel-->Granulated silica gel is a commercially available drying agent for use with gases, in desiccators, and (because of its chemical inertness) in physical instruments (pH meters, spectrometers, balances). Its drying action depends on physical adsorption, so that silica gel must be used at room temperature or below. By incorporating cobalt chloride into the material it can be made self indicating, re-drying in an oven at 110° being necessary when the color changes from blue to pink.
Sodium (metal)--> Used as a fine wire or as chips, for more completely drying ethers, saturated hydrocarbons and aromatic hydrocarbons which have been partially dried (for example with calcium chloride or magnesium sulfate). Unsuitable for acids, alcohols, alkyl halides, aldehydes, ketones, amines and esters. Reacts violently if much water is present and can cause a fire with highly flammable liquids.
Sodium Hydroxide(Red Devil Lye)-->Properties and applications are similar to those for potassium hydroxide. Sodium-potassium alloy. Used as lumps. Lower melting than sodium, so that its surface is readily renewed by shaking. Properties and applications are similar to those for sodium.
Sodium Sulfate-->Has a large capacity for absorption of water, forming the decahydrate below 33°, but drying is slow and inefficient, especially for solvents that are sparingly soluble in water. It is suitable for the preliminary drying of most types of organic compounds.
Sulfuric Acid-->Widely used in desiccators. Suitable for drying bromine, saturated hydrocarbons, alkyl and aryl halides. Also suitable for drying the following gases: hydrogen, hydrogen chloride, nitrogen, carbon dioxide, carbon monoxide, chlorine, methane and paraffins. Unsuitable for alcohols, bases, ketones or phenols. Also available with an indicator (a cobalt salt, blue when dry and pink when wet) under the name Sicacide for desiccators.