Organic 2 Review Problem 298

Organic 2 Review Problem 298 - MeMgI + EtXHH- MeH -J-...

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282 PRACTICAL ORGANIC CHEMISTRY with water, giving magnesium hydroxy-iodide: it will be understood that the latter dissolves in the dilute acid to give a mixture of magnesium iodide and sulphate. SYNTHETIC USE OF GRIGNARD REAGENTS. Grignard reagents can be used to synthesise a wide variety of organic compounds, and are consequently of very great value in organic chemistry: the chief reactions are summarised in the following table, in which magnesium methyl iodide (denoted as MeMgI, in order to differentiate the methyl group introduced by the reagent from any methyl groups already present in the organic compound) is used as a typical Grignard reagent. (1) Water, alcohols and hydroxy compounds generally, and also primary and secondary amines, give the hydrocarbon corresponding to the Grignard reagent, MeMgI r HOM - MeH \- Mg (OH)I MeMgI -f EtOH -- > IMeH -f- IVIg(OEt)I
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Unformatted text preview: MeMgI + EtXHH- MeH -J- Mg(NHEt)I (2) Oxygen is directly absorbed, and the product on hydrolysis gives the corresponding alcohol. MeMgI °> MeOMgI AIcOMgI -f HOH — MeOH-Mg(OH)I (3) Carbon dioxide is similarly absorbed, and gives the corresponding car boxy lie acid. MeMgI E^! MeCOOMgI MeCOOMgI -f HOH - MeCOOH T Mg(OH)I (4) Aldehydes form addition products at the double bond of the carbonyl (>C:O) group, and hydrolysis gives secondary alcohols. Thus acetaldehyde gives isopropyl alcohol: / H / H CH 3 CiO + MeMgI = CH 3 C-OMgI /H ClI 3 C-OMgI HOH -CH 3 C-OH M K (OH)1 Note. Formaldehyde is a special case. It reacts similarly, but a primary alcohol is necessarily produced. This alcohol, however, will always contain one carbon atom more than that obtained in Reaction (2). / H / H HC:O + MeMgI = HC-OMgI \VIe...
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.

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