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separating the reaction mixture into organic and aqueous layers by liquid-liquid extraction. removal of solvents by evaporation. purification by chromatography, distillation or recrystallization. The work-up steps required for a given chemical reaction may require one or more of these manipulations.
Acid–base extraction is a subclass of liquid–liquid extractions and involves the separation of chemical species from other acidic or basic compounds. [1] It is typically performed during the work-up step following a chemical synthesis to purify crude compounds [2] and results in the product being largely free of acidic or basic impurities.
Thus, isolated yields measured after standard aqueous workup and chromatographic purification should seldom exceed 94%. [11] They called this phenomenon "yield inflation" and said that yield inflation had gradually crept upward in recent decades in chemistry literature.
Such reactions usually involve an aqueous acidic workup, though this step is rarely shown in reaction schemes. In cases where the Grignard reagent is adding to an aldehyde or a prochiral ketone, the Felkin-Anh model or Cram's Rule can usually predict which stereoisomer will be formed.
The complex is destroyed upon aqueous workup to give the desired ketone. For example, the classical synthesis of deoxybenzoin calls for 1.1 equivalents of AlCl 3 with respect to the limiting reagent, phenylacetyl chloride. [14]
Aqueous workup produce the desired aldehyde and ammonia. [15] Electrochemical methods. Benzyl nitriles can also be reduced electrochemically. [16] [17] See also
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A reaction between aqueous solutions of an acid and a base is called neutralization, producing a solution of water and a salt in which the salt separates into its component ions. If the aqueous solution is saturated with a given salt solute, any additional such salt precipitates out of the solution.