Magnesium-alkyl halide reaction

It may be mentioned that the Grignard reaction can also be applied to the production of primary alcohols by the interaction of ethylene oxide and magnesium alkyl halide. 

Reaction XLIII. (a) Formation of Esters by the action of Acid Anhydrides or of Acid Chlorides on an Alcohol in the presence of Magnesium Alkyl Halide (Grignard). (B., 39, 1738.)—This application of the Grig-nard reaction to the preparation of esters is of theoretical rather than practical interest as illustrating the wide applicability of this many-sided reaction. The steps in the synthesis will be clear from the examples given they are somewhat different from the usual phases of a Grignard reaction. 

Reaction XLIII. (b) Formation of Ethyl Esters by the Action of Ethyl Chloroformate on Magnesium Alkyl Halide in Dry Ethereal Solution (Grignard).—This is another mode of application of the Grignard reaction to the synthesis of esters. It is more direct than the previous method. 

Another method of preparing acids which is applicable in certain cases is that discovered by Grignard. It will be recalled that this investigator showed that when magnesium is added to a solution of an alkyl halide in ether or other apropriate solvent, a compound is formed which reacts readily with other substances. If the magnesium alkyl halides so prepared are treated with carbon dioxide, the gas is absorbed and an addition-product is formed, which on treatment with water yields an acid. The reactions in the case of the preparation of acetic acid are expressed by the following equations —... 

Aldehydes form addition-products with the magnesium alkyl halides, from which secondary alcohols may be obtained by decomposition with water. These reactions have been much used in the preparation of alcohols of this class. The reactions are indicated by the following equations — H H... 

Table 11.1 lists some of the reaction conditions which have given prepara-tively useful yields of 3-alkylation. Entries 1-3 are typical alkylations using a magnesium salt and an alkyl halide. Even 2,3-disubstituted indoles are alkylated at C3 under these conditions (Entry 7). Entry 5 represents a more recently developed method in which an allylic alcohol and indole react in the... 

This reaction can be used for the synthesis of hydrocarbons but it may also take place as a side-reaction during generation of a Grignard reagent from an alkyl halide and magnesium, then leading to formation of undesired side-products. 

Polarization also occurs in coupling and disproportionation reactions of Grignard reagents with alkyl halides. The vinyl protons of isobutene produced in the reaction of t-butylmagnesium chloride with t-butyl bromide show A/E polarization as do the methyl protons of isobutane (Ward et al., 1970). Similar results arise in the reaction of diethyl-magnesium with organic halides (Kasukhin et al., 1972). 

A mixture of (triisopropyl phosphito)copper(I) bromide (17.6 g, 0.05 mol) and l-bromo-2,2-diphenylethylene (9.1 g, 0.035 mol) was heated at 200°C for 1 h under a nitrogen atmosphere in a flask equipped with a Vigreaux column topped by a Dean-Stark trap. The alkyl halide produced in the reaction was collected in the trap. After cooling, the reaction mixture was poured into toluene (60 ml), and ethylenedi-amine was added (5 ml). After filtering and washing the precipitate with toluene, the combined toluene solutions were washed with 10% hydrochloric acid (10 ml) and water (10 ml), dried over magnesium... 

The preparation of a Grigncird reagent begins with magnesium metal and dry ether (in most cases, either diethyl ether or THF, tetrahydrofuran). The ether cleans the surface of the metal and takes the reagent into solution for reaction. (If either the ether or the reaction vessel contains moisture, the yield is poor.) The magnesium then reacts with either an alkyl halide or an aryl halide. The ease of reactivity decreases in the order R1 > RBr > RCl. Iodides may react too rapidly, but chlorides may react too slowly. Thus bromides are usually the best. The general reaction is... 

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