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Synthesis of an amide with work-up step in red. A concentrated solution of sodium bicarbonate is added to the reaction mixture. This will promote the migration of impurities and byproducts to the aqueous layer and leave the product in the dichloromethane (organic layer). The aqueous and organic layers are allowed to separate.
The mechanism of the reaction involves two steps. The first step is a nucleophilic addition to the nitrile with the aid of a polarizing Lewis acid, forming an imine, which is later hydrolyzed during the aqueous workup to yield the final aryl ketone. Hoesch reaction mechanism
This reductive coupling can be viewed as involving two steps. First is the formation of a pinacolate (1,2- diolate ) complex, a step which is equivalent to the pinacol coupling reaction . The second step is the deoxygenation of the pinacolate, which yields the alkene , this second step exploits the oxophilicity of titanium.
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 ]
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.
The Corey–House synthesis (also called the Corey–Posner–Whitesides–House reaction and other permutations) is an organic reaction that involves the reaction of a lithium diorganylcuprate with an organic halide or pseudohalide (′) to form a new alkane, as well as an ill-defined organocopper species and lithium (pseudo)halide as byproducts.
For example, nonylmagnesium bromide reacts with methyl p-chlorobenzoate to give p-nonylbenzoic acid, in the presence of Tris(acetylacetonato)iron(III) (Fe(acac) 3), after workup with NaOH to hydrolyze the ester, shown as follows. Without the Fe(acac) 3, the Grignard reagent would attack the ester group over the aryl halide. [21]
The product is isolated upon acidic workup. Subsequent mechanistic studies have shown that the subjection of independently prepared ortho- nitroso benzamide and azoketone intermediates to von Richter reaction conditions afforded the expected product, lending further support to this proposal.