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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 ...
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 ...
Grignard reagents can be used in place of organolithium compounds. Gilman also investigated the dialkylcuprates. These are obtained by combining two equivalent of RLi with Cu(I) salts. Alternatively, these cuprates are prepared from oligomeric neutral organocopper compounds by treatment with one equivalent of organolithium reagent.
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.
Kumada coupling reaction, M = catalyst, usually based on Ni or Pd complexes. In organic chemistry, the Kumada coupling is a type of cross coupling reaction, useful for generating carbon–carbon bonds by the reaction of a Grignard reagent and an organic halide.
The reaction mechanism [8] of the Bartoli indole synthesis is illustrated below using o-nitrotoluene (1) and propenyl Grignard (2) to form 3,7-dimethylindole (13). The mechanism of the Bartoli indole synthesis. The mechanism begins by the addition of the Grignard reagent (2) onto the nitroarene (1) to form intermediate 3.
For example, when preparing Grignard reagents, magnesium (the cheapest reagent) is often used in excess, which reacts to remove trace water, either by reacting directly with water to give magnesium hydroxide or via the in situ formation of the Grignard reagent which in turn reacts with water (e.g. R-Mg-X + H 2 O → HO-Mg-X + R-H).