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Grignard reagents or Grignard compounds are chemical compounds with the general formula R−Mg−X, where X is a halogen and R is an organic group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride Cl−Mg−CH 3 and phenylmagnesium bromide (C 6 H 5)−Mg−Br. They are a subclass of the organomagnesium compounds.
A solution of a carbonyl compound is added to a Grignard reagent. (See gallery) An example of a Grignard reaction (R 2 or R 3 could be hydrogen). The Grignard reaction (French:) is an organometallic chemical reaction in which, according to the classical definition, carbon alkyl, allyl, vinyl, or aryl magnesium halides (Grignard reagent) are added to the carbonyl groups of either an aldehyde or ...
Examples of Grignard reagents are phenylmagnesium bromide and ethylmagnesium bromide. These simplified formulas are deceptive: Grignard reagents generally exist as dietherates, RMgX(ether)2. As such they obey the octet rule. Grignard reagents participate in the Schlenk equilibrium. Exploiting this reaction is a way to generate dimethylmagnesium.
Synthesis is analogous to other saturated alkyl Grignard reagents. A solution of 1-bromopropane in ether - typically diethyl ether or tetrahydrofuran - is treated with magnesium, which inserts itself into the organohalogen bond. As both the magnesium metal and the product are sensitive to water, the reaction must take place in anhydrous ...
The addition of Grignard reagents to alkynes is facilitated by a catalytic amount of copper halide. Transmetalation to copper and carbocupration are followed by transmetalation of the product alkene back to magnesium. The addition is syn unless a coordinating group is nearby in the substrate, in which case the addition becomes anti and yields ...
The reaction typically is carried out in tetrahydrofuran or diethyl ether as solvent. Such ethereal solvents are convenient because these are typical solvents for generating the Grignard reagent. [2] Due to the high reactivity of the Grignard reagent, Kumada couplings have limited functional group tolerance which can be problematic in large ...
The first step of the Bouveault aldehyde synthesis is the formation of the Grignard reagent. Upon addition of a N , N -disubstituted formamide (such as dimethylformamide ) a hemiaminal is formed, which can easily be hydrolyzed into the desired aldehyde.
As with most Grignard reagents, methylmagnesium chloride is highly solvated by ether solvents via coordination from two oxygen atoms to give a tetrahedrally bonded magnesium center. Like methyllithium, it is the synthetic equivalent to the methyl carbanion synthon. It reacts with water and other protic reagents to give methane, e.g.,: