(2-Methyl-2-propenyl)magnesium chloride
[CAS# 5674-01-1]

Identification

• Classification: Organic raw materials >> Organometallic compound >> Organomagnesium
• Name: (2-Methyl-2-propenyl)magnesium chloride
• Molecular Formula: C₄H₇ClMg
• Molecular Weight: 114.86
• CAS Registry Number: 5674-01-1
• EC Number: 629-369-1
• SMILES: CC(=C)[CH2-].[Mg+2].[Cl-]

Properties

• Boiling point: 65-67 ºC (Expl.)

Safety Data

• Hazard Symbols: GHS02;GHS05 Danger
• Hazard Statements: H261-H314
• Precautionary Statements: P231+P232-P260-P264-P280-P301+P330+P331-P302+P361+P354-P304+P340-P305+P354+P338-P316-P321-P363-P370+P378-P402+P404-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin corrosion	Skin Corr.	1B	H314
Substances or mixtures which in contact with water emit flammable gases	Water-react.	2	H261
Serious eye damage	Eye Dam.	1	H318
Carcinogenicity	Carc.	2	H351
Flammable liquids	Flam. Liq.	2	H225
Specific target organ toxicity - single exposure	STOT SE	3	H335

• Transport Information: UN 3399 4.3/PG 1

Discovory and Applicatios

(2-Methyl-2-propenyl)magnesium chloride, also known as isoprenylmagnesium chloride, is an organomagnesium halide reagent commonly used in organic synthesis. It is a member of the Grignard reagent family, characterized by the general formula RMgX, where R is an organic group and X is a halide. This compound is particularly valuable for its ability to introduce isoprenyl groups into a wide variety of organic molecules. It has been widely utilized in synthetic methodologies since its discovery, playing a critical role in the construction of complex natural products and functionalized organic compounds.

The preparation of (2-methyl-2-propenyl)magnesium chloride typically involves the reaction of isoprene with magnesium in the presence of a halogenating agent, such as methyl chloride, in an inert atmosphere. The resultant reagent features a reactive isoprenyl group, making it an efficient nucleophile for various carbon-carbon bond-forming reactions. It is commercially available as a solution in ethers like tetrahydrofuran (THF) or diethyl ether, which stabilize the reactive Grignard reagent.

This reagent was introduced during the expansion of Grignard chemistry, which has been a cornerstone of organic synthesis since Victor Grignard’s Nobel Prize-winning work in 1912. Grignard reagents revolutionized organic chemistry by providing a robust method for forming carbon-carbon bonds, a foundational step in building complex molecular frameworks. (2-Methyl-2-propenyl)magnesium chloride emerged as a specialized variant, addressing the need for introducing isoprenyl units into organic molecules.

One of the primary applications of (2-methyl-2-propenyl)magnesium chloride is in the synthesis of terpenoids and other naturally occurring isoprenoid compounds. These molecules, characterized by repeating isoprene units, are prevalent in essential oils, steroids, and vitamins. The reagent provides a direct and efficient route to functionalize molecules with an isoprenyl group, enabling the synthesis of precursors for natural product construction. This utility extends to the pharmaceutical industry, where terpenoids serve as intermediates or active compounds in drug development.

In addition to natural product synthesis, (2-methyl-2-propenyl)magnesium chloride is employed in coupling reactions and the preparation of allylic alcohols. It reacts with aldehydes and ketones to yield alcohols, which are valuable intermediates in the synthesis of flavors, fragrances, and fine chemicals. The reagent's compatibility with a broad range of electrophiles allows for its use in constructing diverse molecular architectures.

The reagent also finds use in the field of polymer chemistry. It has been studied as a precursor for isoprene-derived polymers and as a tool for modifying polymer backbones through functional group introduction. These modified polymers often exhibit enhanced properties such as improved elasticity, durability, or chemical resistance.

Despite its utility, the reactivity of (2-methyl-2-propenyl)magnesium chloride necessitates careful handling. Like other Grignard reagents, it is highly sensitive to moisture and air, as water or oxygen can deactivate the reagent by forming unwanted byproducts. Thus, it must be used in an inert atmosphere and under strictly anhydrous conditions.

The continued development of Grignard chemistry has cemented (2-methyl-2-propenyl)magnesium chloride as a versatile tool in modern synthetic organic chemistry. Its role in enabling the functionalization of complex molecular scaffolds underscores its significance in both academic and industrial research, particularly in pharmaceuticals, materials science, and fine chemical synthesis.