Grignard reagents, reaction with carbon dioxide

Carbon monoxide reacts with Grignard reagents, thongh more slowly than carbon dioxide. The initial reaction is a 1,1-addition to the carbon, resnlting in an acyhnagnesinm halide. Despite potential applications of snch species, the reaction nsnally leads to mixtnres of prodncts, and has not been developed synthetically. ... 

Section 19.11 Carboxylic acids can be prepared by the reaction of Grignard reagents with carbon dioxide. 

Oddo and Sessa claimed that 1-carboxyindole (375) was obtained on treatment of indole magnesium iodide with gaseous carbon dioxide. Majima and Kotake later reported that 3-carboxyindole (376) and not 375 was the main product obtained in this reaction improved yields of 376 were obtained when the reaction was carried out in anisole instead of ether.Subsequently, several workers have employed essentially this procedure, for the synthesis of 376. It has recently been shown, however, that both the acids 375 and 376 are formed in approximately equal amounts by the carbonation of the indole Grignard reagent (Kasparek and Hea-cook ). 

The reaction of carbon dioxide with Grignard reagents initially gives a magnesium salt of a carboxylic acid, RC02MgX ... 

The reactions of Grignard reagents with aldehydes and ketones give alcohols, reaction with acid chlorides and esters give tertiary alcohols, reaction with carbon dioxide to give carboxylic acids, reaction with nitriles give ketones, and reaction with epoxides give alcohols. 

Reaction of Grignard reagents with carbon dioxide... 

A Reaction of Grignard Reagents with Carbon Dioxide... 

Such differences in mechanisms can also be derived from the results of rate measurements (Table 1) of reactions of various Grignard reagents with benzophenone, carbon dioxide, and acetone, respectively. The reactivity series of Grignard reagents toward carbon dioxide [12] is comparable with the series for acetone [13], which led to the conclusion that both types of reactions follow the same mechanistic path a concerted mechanism. Steric requirements, therefore, are not the only parameter in the predictability of results of reactions of Grignard reagents and, in fact, are of little help when no other information on the reaction mechanism is available. 

The reactions of carbon disulfide with Grignard reagents appear to be altogether similar to the corresponding reactions of carbon dioxide. Thus, it is possible to prepare dithioacids [37-39 Eq. (27)] ... 

A Grignard reagent can also react with carbon dioxide. The product of the reaction is a carboxylic acid with one more carbon atom than the Grignard reagent has. 

Organic acids can be prepared in many ways, four of which are described here (1) oxidation of primary alcohols or aldehydes, (2) oxidation of alkyl side chains on aromatic rings, (3) reaction of Grignard reagents with carbon dioxide, and (4) hydrolysis of alkyl cyanides (nitriles). 

The reactions of Grignard reagents with different types of carbonyl groups yield a number of important functional groups. For example, reaction with formaldehyde yields 1° alcohols with higher aldehydes, 2° alcohols with ketones, 3° alcohols with esters, 3° alcohols with acyl halides, ketones with N,N-dialkylformamides, aldehydes and with carbon dioxide, carboxylic acids. 

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