Allyl Methyl Carbonate: Properties, Uses & FAQs

Allyl Methyl Carbonate is a versatile bifunctional carbonate ester reagent widely employed in organic synthesis, particularly as an allylating agent in palladium-catalyzed reactions and as a source of allyl and methoxycarbonyl functionality.

Chemical Name

Allyl Methyl Carbonate (Methyl Allyl Carbonate)

Molecular Formula

C5H8O3

Molecular Weight

116.12 g/mol

CAS Number

35466-83-2

Key Application

Palladium-catalyzed allylic substitution and allylation reactions in organic synthesis

Functional Groups

Allyl ester (vinyl methylene) and carbonate linkage

SKU

A136273

What Is Allyl Methyl Carbonate and What Are Its Key Properties?

Allyl Methyl Carbonate (AMC), CAS 35466-83-2, is a simple mixed carbonate ester with the molecular formula C₅H₈O₃ and a molecular weight of approximately 116.12 g/mol. Its structure consists of an allyl group (CH₂=CH–CH₂–) and a methyl group connected through a carbonate (–OC(O)O–) bridge.

At room temperature, Allyl Methyl Carbonate is a colorless to pale-yellow liquid with a characteristic ester-like odor. It is miscible with common organic solvents such as tetrahydrofuran (THF), dichloromethane, acetonitrile, and dimethylformamide (DMF), while showing limited miscibility with water.

The molecule possesses two electrophilic sites that can be exploited selectively under different reaction conditions, making it a uniquely bifunctional synthetic building block. The allyl portion is susceptible to oxidative addition with palladium(0) catalysts, whereas the methyl carbonate moiety can serve as a leaving group or a source of CO₂ and methanol under appropriate conditions.

What Are the Main Applications of Allyl Methyl Carbonate in Organic Synthesis?

The most prominent application of Allyl Methyl Carbonate is as an allylating agent in palladium(0)-catalyzed allylic substitution reactions, commonly referred to as Tsuji–Trost-type reactions. In these transformations, the Pd(0) complex undergoes oxidative addition into the allylic C–O bond, generating a π-allyl palladium complex. This electrophilic intermediate can then react with a wide range of carbon, nitrogen, oxygen, and sulfur nucleophiles to furnish allylated products with high regio- and stereoselectivity when chiral ligands are employed.

Allyl Methyl Carbonate is particularly favored over allyl acetate or allyl halides in many protocols because the methyl carbonate anion released upon oxidative addition is basic and non-coordinating. This basicity can deprotonate pronucleophiles in situ (e.g., malonates, β-ketoesters), eliminating the need for an external base and thereby simplifying reaction conditions and improving functional-group compatibility.

Beyond Pd-catalysis, AMC has been investigated as a monomer or co-monomer in polymer chemistry and as a reagent for the introduction of allyl protecting groups onto hydroxyl and amino functional groups, useful in peptide and carbohydrate chemistry.

How Should Allyl Methyl Carbonate Be Handled and Stored Safely?

As with most low-molecular-weight ester reagents, Allyl Methyl Carbonate should be handled with appropriate personal protective equipment (PPE), including chemical-resistant gloves, safety glasses, and a laboratory coat. Operations involving larger quantities or prolonged exposure should be conducted in a well-ventilated fume hood to avoid inhalation of vapors.

For storage, AMC should be kept in a tightly sealed container away from heat, open flames, and strong oxidizing agents, as the allyl double bond renders the compound flammable. Storage at room temperature or under refrigeration (2–8 °C) in a cool, dry, well-ventilated area is recommended to maintain purity and stability over time. Contact with strong acids, bases, or oxidants should be avoided.

In the event of skin or eye contact, the affected area should be flushed immediately with copious amounts of water, and medical advice should be sought. Consult the Safety Data Sheet (SDS) provided by Aladdin Scientific for complete hazard information, first-aid measures, and disposal guidance before use.

What Reaction Conditions Are Typically Used with Allyl Methyl Carbonate?

In palladium-catalyzed allylic alkylation reactions, Allyl Methyl Carbonate is typically used with a Pd(0) source such as Pd₂(dba)₃ or Pd(PPh₃)₄, or a Pd(II) precatalyst that is reduced in situ to Pd(0). Phosphine ligands (e.g., PPh₃, BINAP, or chiral bisphosphines such as DPPE or Trost's DPPBA-based ligands) are commonly employed to modulate reactivity and enantioselectivity.

Catalyst loadings typically range from 1–10 mol% Pd, and reactions are generally performed in polar aprotic solvents such as THF, DMF, acetonitrile, or dichloromethane at temperatures ranging from room temperature to approximately 80 °C, depending on the substrate and nucleophile.

Because the methyl carbonate leaving group is self-basic, many reactions with stabilized carbon nucleophiles (e.g., malonates) can proceed without addition of an external base. However, for harder or less-acidic nucleophiles, mild exogenous bases such as triethylamine or K₂CO₃ may be required. Reaction monitoring by thin-layer chromatography (TLC) or GC is routine.

Quality, Purity, and Specification Considerations for Research Use

For reproducible research results, the purity of Allyl Methyl Carbonate is a critical parameter. Impurities such as allyl alcohol, methanol, diallyl carbonate, or dimethyl carbonate can arise from synthesis or decomposition and may act as catalyst poisons or competing nucleophiles, adversely affecting reaction outcomes.

Aladdin Scientific offers Allyl Methyl Carbonate (SKU: A136273) for research applications. Researchers should consult the Certificate of Analysis (CoA) accompanying each lot to verify purity (typically assessed by GC), identity (confirmed by NMR or IR spectroscopy), and water content. For sensitive catalytic reactions, redistillation or passage through activated molecular sieves may be advisable to remove trace moisture.

When comparing reagent grades from different suppliers, researchers should pay attention to the analytical method used for purity determination, as GC purity and HPLC purity can differ. Aladdin Scientific's technical support team can provide lot-specific CoA documents and additional specification information upon request.

Frequently asked questions

Why is Allyl Methyl Carbonate preferred over allyl acetate in Pd-catalyzed reactions?

The methyl carbonate anion generated upon oxidative addition of Allyl Methyl Carbonate to Pd(0) is a stronger, non-coordinating base compared to the acetate anion from allyl acetate. This allows it to deprotonate pronucleophiles such as malonates in situ, eliminating the need for an external base and improving functional-group tolerance and reaction reproducibility.

Can Allyl Methyl Carbonate be used as an allyl protecting group reagent for alcohols and amines?

Yes, Allyl Methyl Carbonate can serve as an allylating agent for the protection of hydroxyl and amino groups, introducing allyl carbamate (Alloc) or allyl ether protecting groups that are orthogonal to many commonly used protecting groups. These protecting groups can subsequently be removed under mild Pd(0)-catalyzed conditions, making them valuable in multistep synthesis strategies including peptide and carbohydrate chemistry.

What is the typical catalyst system used with Allyl Methyl Carbonate for allylic alkylation?

The most commonly employed catalyst systems consist of a Pd(0) complex such as Pd(PPh3)4 or a combination of Pd2(dba)3 with a phosphine ligand. For asymmetric allylic alkylation, chiral bisphosphine ligands are used to achieve enantioselectivity. Catalyst loadings typically range from 1 to 10 mol% relative to the substrate.

How should Allyl Methyl Carbonate be stored to maintain stability?

Allyl Methyl Carbonate should be stored in a tightly sealed container in a cool, dry, and well-ventilated location away from heat sources and open flames. Refrigeration at 2–8 °C is recommended for long-term storage. It should be kept away from strong acids, bases, and oxidizing agents to prevent decomposition or polymerization of the allyl group.

Is Allyl Methyl Carbonate water-sensitive or air-sensitive?

Allyl Methyl Carbonate is not highly sensitive to moisture or air under normal storage conditions, unlike many organometallic reagents. However, for use in sensitive catalytic reactions, it is advisable to use freshly dried material or material stored over molecular sieves to minimize trace moisture, which can interfere with metal catalysts or hydrolyze the carbonate ester linkage over time.

References

1. Tsuji, J. Palladium Reagents and Catalysts: New Perspectives for the 21st Century. Wiley, 2004. (General reference for Pd-catalyzed allylic substitution using allyl carbonates.)
2. Trost, B. M.; Van Vranken, D. L. Asymmetric Transition Metal-Catalyzed Allylic Alkylations. Chemical Reviews, 1996, 96(1), 395–422. doi:10.1021/cr9409804
3. Aladdin Scientific Certificate of Analysis, Allyl Methyl Carbonate, SKU A136273. (Lot-specific purity and specification data.)

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