One of the key uses of Grignard reagents is the ability to make complicated alcohols easily. (I am using the normally accepted equation ignoring the fact that the Mg(OH)Br will react further with the acid.)Īn alcohol is formed. In the first stage, the Grignard reagent adds across the carbon-oxygen double bond:ĭilute acid is then added to this to hydrolyse it. The reactions are essentially identical to the reaction with carbon dioxide - all that differs is the nature of the organic product.
It is much easier to understand what is going on by looking closely at the general case (using "R" groups rather than specific groups) - and then slotting in the various real groups as and when you need to. The reactions between the various sorts of carbonyl compounds and Grignard reagents can look quite complicated, but in fact they all react in the same way - all that changes are the groups attached to the carbon-oxygen double bond. General Reaction between Grignards and carbonyls What you end up with would be a mixture of ordinary hydrated magnesium ions, halide ions and sulfate or chloride ions - depending on which dilute acid you added. That is actually misleading because these compounds react with dilute acids. The usually quoted equation is (without the red bits):Īlmost all sources quote the formation of a basic halide such as Mg(OH)Br as the other product of the reaction. A carboxylic acid is produced with one more carbon than the original Grignard reagent. Typically, you would add dilute sulfuric acid or dilute hydrochloric acid to the solution formed by the reaction with the CO 2. Industrially, ethylene and propylene oxides readily react with carbon dioxide to give ethylene. Annual production of cyclic carbonates was estimated at 100,000 tonnes per year in 2010. The product is then hydrolyzed (reacted with water) in the presence of a dilute acid. The reaction of carbon dioxide with epoxides is a general route to the preparation of cyclic 5-membered carbonates. Dry carbon dioxide is bubbled through a solution of the Grignard reagent in ethoxyethane, made as described above. In the first, you get an addition of the Grignard reagent to the carbon dioxide. Grignard reagents react with carbon dioxide in two stages.
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