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The desired product, benzoic acid (3), is obtained by the following work-up: [2] Synthesis of benzoic acid with work-up step in red. The reaction mixture containing the Grignard reagent is allowed to warm to room temperature in a water bath to allow excess dry ice to evaporate. Any remaining Grignard reagent is quenched by the addition of water.
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
In the cited example the Lewis acid TiCl 4 is used. First, the Lewis acid activates the aldehyde component followed by carbon-carbon bond formation between the enol silane and the activated aldehyde. With the loss of a chlorosilane the compound 1 is built. The desired product, a racemate of 2 and 3, is obtained by aqueous work-up. [3]
In another example, the Nicolaou's total synthesis of Taxol uses this reaction, although coupling stops with the formation of a cis-diol, rather than an olefin. Optimized procedures employ the dimethoxyethane complex of TiCl 3 in combination with the Zn(Cu). The first porphyrin isomer, porphycene, was synthesised by McMurry coupling. [8]
4 HCrO 4 − + 3 RCH 2 OH + 16 H + + 11 H 2 O → 4 [Cr(H 2 O) 6] 3+ + 3 RCOOH. The inorganic products are green, characteristic of chromium(III) aquo complexes. [2] Like many other oxidations of alcohols by metal oxides, the reaction proceeds via the formation of a mixed chromate ester: [3] [4] These esters have the formula CrO 3 (OCH 2 R) −
2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (or DDQ) is the chemical reagent with formula C 6 Cl 2 (CN) 2 O 2. This oxidant is useful for the dehydrogenation of alcohols, [3] phenols, [4] and steroid ketones. [5] DDQ decomposes in water, but is stable in aqueous mineral acid. [6]
Thus, a stochiometric quantity of AlCl 3 is needed. 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]
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.