Grignard Reagents
Grignard Reagents - Related Videos
07:20
Grignard Reaction
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2023
Source: Vy M. Dong and Faben Cruz, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate how to properly carry out a Grignard reaction. The formation of an organometallic reagent will be demonstrated by synthesizing a Grignard reagent with magnesium and an alkyl halide. To demonstrate a common use of a Grignard reagent, a nucleophilic attack onto a carbonyl will be performed to generate a secondary alcohol by forming a new C-C bond.
01:13
Preparation of Carboxylic Acids: Carboxylation of Grignard Reagents
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2025
Carboxylic acids can be prepared by the carboxylation of Grignard reagents (RMgX). This method is convenient for converting alkyl (primary, secondary or tertiary), vinyl, benzyl, and aryl halides to carboxylic acids with one additional carbon than the starting RMgX. The carboxylation mechanism involves two steps. In the first step, the nucleophilic attack of the Grignard reagent on the electrophilic site of the carbon dioxide generates the magnesium salt of the carboxylate ion. In the...
10:17
Preparing Anhydrous Reagents and Equipment
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2023
Source: Laboratory of Dr. Dana Lashley - College of William and Mary Demonstrated by: Timothy Beck and Lucas Arney Many reactions in organic chemistry are moisture-sensitive and must be carried out under careful exclusion of water. In these cases the reagents have a high affinity to react with water from the atmosphere and if left exposed the desired reaction will not take place or give poor yields, because the reactants are chemically altered. In order to prevent undesired reactions with H2O...
01:08
Esters to Alcohols: Grignard Reaction
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2025
The reaction of an ester with a Grignard reagent, followed by hydrolysis of the magnesium alkoxide salt in aqueous acid, yields a tertiary alcohol. In the case of formate esters, secondary alcohols are formed. The reaction requires two equivalents of the Grignard reagent and introduces two identical alkyl groups, derived from the Grignard reagent, bonded to the hydroxyl-bearing carbon of the alcohol. The reaction follows the typical nucleophilic acyl substitution mechanism. The Grignard...
00:57
Nitriles to Ketones: Grignard Reaction
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2025
Organomagnesium halides, commonly known as Grignard reagents, convert nitriles to ketones and proceed through a nucleophilic acyl substitution. Nitriles react with a Grignard reagent, followed by an aqueous acid, to yield ketones. The reaction introduces a new carbon–carbon bond. The alkyl–magnesium bond in the Grignard reagent is highly polar, so the alkyl carbon develops a carbanionic character and acts as a nucleophile. The mechanism begins with a nucleophilic attack by the Grignard reagent...
FAQs
The polarized carbon-magnesium bond gives the carbon end nucleophilic character, allowing it to attack an electrophilic carbon in an aldehyde or ketone. This interaction creates a new carbon-carbon bond before aqueous workup. Consequently, the reagent changes the carbon framework rather than merely modifying an existing functional group.
Aldehydes and ketones contain electrophilic carbon centers that can be attacked by the carbon portion of a Grignard reagent. This bond-forming step is followed by aqueous workup, which commonly converts the resulting reaction product into an alcohol. Selecting one of these carbonyl compounds therefore supports predictable carbon-skeleton construction.
Moisture protonates and destroys a Grignard reagent, removing its ability to act as a carbon nucleophile. For that reason, preparation and reaction conditions use anhydrous ether, meaning ether with water excluded. Maintaining this dry environment preserves the reagent long enough for it to react with the intended electrophile.
The starting halide can be alkyl, aryl, or vinyl, so its organic group supplies the carbon fragment carried into the bond-forming reaction. When that reagent attacks an aldehyde or ketone, the selected fragment becomes part of the expanded carbon skeleton. This makes halide choice central to planning the desired molecular structure.
A typical sequence begins by reacting an alkyl, aryl, or vinyl halide with magnesium metal in anhydrous ether. The resulting reagent is then brought into contact with an aldehyde or ketone so its carbon nucleophile can form a new carbon-carbon bond. An aqueous workup follows to produce the commonly observed alcohol product.
Aqueous workup is the finishing stage after the carbon nucleophile has reacted with an aldehyde or ketone. It converts the reaction-derived product into an alcohol, allowing the chemist to isolate the commonly observed functional-group outcome. Because the workup follows carbon-carbon bond formation, it reveals the final structure without replacing that new bond.
Grignard reagents are useful when a synthesis requires carbon-carbon bond formation accompanied by a commonly observed alcohol product after workup. Their application extends beyond individual teaching reactions to the preparation of pharmaceuticals, natural products, and other complex organic molecules. In chemistry, they provide a way to connect selected carbon fragments during multistep molecular construction.