Organomagnesiums, 154.

Organohthium and organomagnesium compounds find their chief use m the prepa ration of alcohols by reaction with aldehydes and ketones Before discussing these reac tions let us first examine the reactions of these organometallic compounds with proton donors... 

Organohthium and organomagnesium compounds are stable species when prepared m suitable solvents such as diethyl ether They are strongly basic however and react instantly with proton donors even as weakly acidic as water and alcohols A proton is transferred from the hydroxyl group to the negatively polarized carbon of the organometallic compound to form a hydrocarbon... 

The carbon-metal bonds of organolithium and organomagnesium compounds have appreciable carbamomc character Carbanions rank among the strongest bases that we 11 see m this text Their conjugate acids are hydrocarbons—very weak acids indeed The equilibrium constants for ionization of hydrocarbons are much smaller than the s for water and alcohols thus hydrocarbons have much larger pA s... 

Victor Grignard was led to study organomagnesium compounds because of ear her work he performed with organic derivatives of zinc... 

Grignard reagent (Section 14 4) An organomagnesium com pound of the type RMgX formed by the reaction of magne Slum with an alkyl or aryl halide... 

With two equivalents of an organomagnesium hahde, a Gtignard reagent is formed, capable of use in further syntheses (35,36). Cuprous salts cataly2e oxidative dimerization of propargyl alcohol to 2,4-hexadiyne-l,6-diol [3031-68-3] (37). 

The term Grignard reaction refers to both the preparation of a class of organomagnesium haUde compounds and their subsequent reaction with a wide variety of organic and inorganic substrates. As such it has had a wide and profound influence on synthetic chemistry since its first elucidation by Victor Grignard at the beginning of the twentieth century. 

Magnesium methylate is used as a drying agent for alcohols and other organic solvents and as an intermediate in various manufacturing processes, eg, for organomagnesium compounds (79), orthocarbonic esters (80), and for oxide coatings. 

Magnesium ethylate is used as a drying agent for organic solvents, as an intermediate for the manufacture of organomagnesium and other organic products, as catalyst in the Tishchenko (85) and other reactions (86—91), in the condensation of esters (92), in alkylation reactions, and in polymeri2ations (84,91). 

Organomagnesium reagent capable of reacting with active H compounds or in additions to C X... 

Organolithium and organomagnesium reagents are highly reactive toward most carbonyl compounds. With aldehydes and ketones, the tetrahedral adduct is stable, and alcohols are isolated after protonation of the adduct, which is an alkoxide ion. 

In earlier studies [f J], it was shown that pentafluorobenzene has an acidic aryl hydrogen capable of metalation by organolithium or organomagnesium compounds to yield perfluorophenylorganometallic compounds... 

Anhydrous diethyl ether is the customary solvent used when preparing organomagnesium compounds. Sometimes the reaction does not begin readily, but once started, it is exothermic and maintains the temperature of the reaction mixture at the boiling point of diethyl ether (35°C). 

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