Why magnesium is used in Grignard reactions?

Grignard Reagents were discover by higher-up Grignard in 1900.They argon classic in ally form by reacting magnesium turnings with alkyl halide in ether or THF solvents, to form solutions of alkylmagnesium halide. The asynchronous transfer mode moldiness be moisture relieve and inert and magnesium must be of high purity.Magnesium is usually covered with a coating of magnesium oxide, so an activation agent like miteic number 53 or Dibromoethane is added.They can also be formed from by when an organo partic number 3 compound reacts with a magnesium halideIn organic alchemy C-C amaze is one of the well-nigh of the essence(p) links. To make these C-C lodges organometallics such(prenominal) as organolithiums, Grignard reagents and carbonyl compounds are employ. Grignard reagents are our first extraction of carbanions (anions of carbon).The mutual opposition of a covalent bond mingled with two different particles is determined by electronegativity. The to a greater extent m inus an element is, the more it attracts the electron density in the bond. Hence, the greater the difference in electronegativity, the more polarized a bond becomes. In the utmost(a) case of complete polarization, the covalent bond ceases to exit and is replaced by electrostatic attractions between ions of opposite charge.The reactivity of the carbonyl groups is callable to the polarization of the carbon-oxygen bond toward the more electronegative oxygen.For e.g. Polarity inside a formaldehyde moleculeThus organometallic reagents act as nucleophiles towards the electrophilic carbonyl group. In organolithium compounds and Grignard reagents, the key bond is polarized in the opposite direction, towards the carbon devising carbon a nucleophilic centre. This is true for most organometallics because, metals like Li, Na, K, Mg, ca, Al, Cu, Zn etc. all have lower electronegativity than carbon. Also, the cornerstone metals (Li, Na, K etc.) and the alkaline earth metals (Mg and Ca, in concert with Zn) are good reducing agents, the creator being stronger than the latter. Hence, these can be used to make organometallic reagents with carbon.The alkyl magnesium halides are called Grignard Reagents after the French chemist, Victor Grignard, who notice them. The other metals mentioned above react in a similar manner, hardly the Li & Mg are the most widely used.Feature Article comparative RatesFree-Radical BrominationThese answers are substitution reactions, but they cannot be classified as nucleophilic substitutions, as in the reactions above. Because the functional carbon atom has been reduced, the polarity of the resulting functional group is upside-down (the original electrophilic carbon becomes nucleophilic). This change, shown below, makes alkyl lithium and Grignard reagents unique and useful reactants in synthesis.Reactions of organolithium and Grignard reagents conjecture the nucleophilic character of the functional carbon in these compounds. The nucleo philic carbon of these reagents also bonds readily with electrophiles such as iodine and carbon dioxide (fifth equation). The polarity of the carbon-oxygen double bonds of CO2 makes the carbon atom electrophilic, shown by the formula in the shaded box, so the nucleophilic carbon of the Grignard reagent bonds to this site.Carbon has in implication an unshared electron pair. Such a carbon would be a rattling strong buttocks, much stronger than needed to stick an H+ from water to generate the weaker base OH-. A practical consequence of this is that Grignard reagents must be kept dry, away from unconstipated the slightest traces of moisture, lest they be destroyed by reaction with water.Works CitedClayden, greeves, Warden and Wothers, Organic Chemistry, Oxford University press, 2001, ISBN 0-19-850346-6http//www.chemguide.co.uk/organicprops/haloalkanes/grignard.html