Question

There are many steps for the extraction and isolation of the final product from the distillate. There are three solutions that you will be working with in the extraction process: 1.) Dichloromethane. 2.) 2M NaOH. 3.) 6M HCl. Please explain the purpose for each of these solutions in the workup process. (Hint: Think acid/base chemistry)

Answer 1

In the extraction and isolation of final product from the disllate, the role of dichloromethane , 2M NaOH and 6M HCl are as

1) Dichloromethane-

It is a solvent used in the extraction and purification of compound. The distillate is dissolved in the dichloromethane and successively treated with 2N NaOH and 6M HCl in case of acid compound purification while it is treated with successively treated with 6M HCl   and 2N NaOH in case of basic comppound purification. In the dichloromethane solvent, the impurities are trapped and the acid or base compound is dissolved in water.

2) 2N NaOH

If distillate obtained is acidic compound, it is treated with 2N NaOH which forms sodium salt and is dissolved in water while other impurities which are not forming sodium salt are dissolved in the dichloromethane and separated by aqueous layer separation.

3) 6M HCl

In the above aqueous layer, compound is present in the form of sodium salt. This aqeous layer is treated with 6M HCl solution in which the sodium salt of compound is converted into acid and is extracted with dichloromethane. After distillation of dichloromethane solvent, the pure acid compound is obtained.