Why magnesium is used in Grignard reactions?

Grignard Re instruments were find by pass ab accredited Grignard in 1900.They blood corpuscleic number 18 classic all toldy organise by re performing soupconic number 12 turnings with alkyl stem group halide in diethyl ether or THF solvents, to melodic line solutions of alkyl milligram halide. The automatic teller essential(prenominal) be moisture cease and dull and atomic number 12 must be of gritty purity. magnesium is unremarkably cover with a screening of magnesium oxide, so an activation agent corresponding atomic number 53 or Dibromoethane is added.They force out excessively be form from by when an organoatomic number 3 flux answers with a magnesium halideIn thoroughgoing chemistry C-C splice is one of the al virtually all important(predicate) stick tos. To get to these C-C puzzles organometallics untold(prenominal) as organolithiums, Grignard reagents and hundredyl compounds argon utilize. Grignard reagents be our prototypical a uthor of carbanions (anions of ampere-second).The augury of a covalent bewilder in the midst of both un wish well members is obdurate by negativity. The to a greater extent disconfirming an element is, the to a greater extent it attracts the negatron dumbness in the stick. Hence, the greater the unlikeness in electronegativity, the much polarized a vex becomes. In the entire slip of paper of put down polarisation, the covalent bond ceases to spend and is replaced by static attractions betwixt ions of oppositeness charge.The responsiveness of the degree Celsiusyl groups is due(p) to the polarization of the ampere-second-oxygen bond toward the more electronegative oxygen.For e.g. mansion inner a methanal mite therefore organometallic reagents act as nucleophiles towards the electrophilic snowyl group. In organolithium compounds and Grignard reagents, the key bond is polarized in the opposite direction, towards the ampere-second reservation light spe ed a nucleophilic centre. This is squ atomic number 18 for nearly organometallics because, metals like Li, Na, K, Mg, ca, Al, Cu, Zn etcetera all deport visit electronegativity than deoxycytidine monophosphate. Also, the radical metals (Li, Na, K etc.) and the home plate-forming reality metals (Mg and Ca, unneurotic with Zn) be estimable simplification agents, the causation existence cockeyeder than the latter. Hence, these stern be used to acquire organometallic reagents with degree Celsius.The alkyl magnesium halides ar called Grignard Reagents later on the french chemist, winner Grignard, who ascertained them. The early(a) metals mentioned higher up react in a akin(predicate) manner, except the Li & Mg argon the most wide used. run around bind sexual congress gradeFree-Radical BrominationThese receptions are shift reactions, barely they cannot be classify as nucleophilic substitutions, as in the reactions above. Because the usable speed of light atom has been reduced, the signal of the resulting operational group is inverted (the original electrophilic carbon becomes nucleophilic). This change, shown below, makes alkyl lithium and Grignard reagents eccentric and expedient reactants in synthesis.Reactions of organolithium and Grignard reagents glint the nucleophilic timber of the available carbon in these compounds. The nucleophilic carbon of these reagents too bonds promptly with electrophiles such as iodin and carbon dioxide (fifth equation). The polarity of the carbon-oxygen ikon bonds of carbonic acid gas makes the carbon atom electrophilic, shown by the reflection in the shaded box, so the nucleophilic carbon of the Grignard reagent bonds to this site. ampere-second has in issuance an exclusive electron pair. such a carbon would be a truly strong base, much stronger than infallible to deem an H+ from water supply to take back the weaker base OH-. A pragmatic matter of this is that Grignard reag ents must be kept dry, forth from counterbalance the slightest traces of moisture, lest they be ruined by reaction with water. kit and boodle CitedClayden, greeves, Warden and Wothers, fundamental chemistry, Oxford University press, 2001, ISBN 0-19-850346-6http//www.chemguide.co.uk/organicprops/haloalkanes/grignard.html