New Antisolvents for Swish Purification

Swish purification and concentrates of impurities made using swish TLC could usefully be studied using constant boiling azeotropic mixtures which are predominantly either water or hydrocarbons but contain small amounts of other solvents which could provide a useful boost to the overall solvency. Hydrotropes with an appropriately controlled amount of organic ingredients to increase organic solubility could be used in the same way for swishing. 

Examples of azeotropes that might be expected to only dissolve small amounts of many organics might be:

97.0% water; 3.0% acetic acid azeotrope bp 76.6 C

91.0% water; 9.0% Benzyl alcohol azeotrope bp 99.9ºC

95.5% hexane; 4.5% allyl alcohol azeotrope bp 65.5ºC

97% hexane 3% 1-butanol azeotrope bp 67.0ºC

94.5% carbon tetrachloride; 5.5% isobutanol bp 75.8 C

96.0% hexane; 4.0% propanol bp 65.7 C

90.0% water ;10.0% 1-octane bp 99.4 C

These constant boiling mixtures are selected because each one is either predominantly water, a hydrocarbon or carbon tetrachloride. They should be tested for their usefulness for swishing. None of these separate into two phases on standing at room temperature.

Another class of anti-solvents that might be tested for use in swishing are hydrotropes. Aqueous solutions of such compounds as 

aromatic sulfonate salts

aromatic sulfonic acids

salts of benzoic acid and substituted benzoic acid

glycols

urea

4-isopropylbenzenesulfonic acid calcium salt

2,4-dimethylbenzenesulfonic acid sodium salt 40%

p-toluenesulfonate sodium

ethylene glycol monobutyl ether O-sulfonate potassium

potassium saliscylic acid

Each made up at an appropriate concentration to only dissolve a small amount of sample.

Calcium bromide dihydrate to Precipitate Neutral Organic Intermediates in Chemical reaction Routes

In the Kilomentor blog article titled Inorganic Non-Stoichiometric Metal Salt Complexes as a Useful Method for Purifying Neutral Organic Compounds solid complexes were obtained by mixing a 15% by weight solution of calcium bromide dihydrate in amyl methyl ketone and a solution containing an organic mixture that contained steroidal ketones also in amyl methyl ketone. These solid complexes could be decomposed to yield these steroids in a highly concentrated isolate.

These are from the experimental examples of the patent, not from the claims. This is important because claims are based on extrapolations which are often overly optimistic. What these examples are promising is that any large organic molecule containing functionality, even different from alcohol (here ketone), might be precipitated as an insoluble complex from a solution in a low molecular weight ketone using a solution of calcium bromide dihydrate!

The question this begs is what range of larger neutral organic molecules can be isolated/concentrated using such reagents? Finding simple, inexpensive, rugged means to isolate neutral intermediates in chemical reaction sequences would be publication worthy, while the chemical skill to execute the experimentation would not be demanding.