Physicochemical Properties

N-Methylbenzamide (CAS 613-93-4) is a secondary amide formed by N-methylation of benzamide. Its molecular formula is C₈H₉NO with a molecular weight of 135.17 g/mol. The compound presents as a white to off-white crystalline solid under ambient conditions.

The amide bond in N-Methylbenzamide exhibits partial double-bond character due to resonance delocalization between the nitrogen lone pair and the carbonyl π system, restricting rotation around the C–N bond. This resonance stabilization renders the amide relatively resistant to hydrolysis under neutral aqueous conditions compared with esters or acid chlorides.

N-Methylbenzamide is soluble in a wide range of polar aprotic and protic organic solvents including dichloromethane, ethanol, acetone, and dimethylformamide, while showing only limited solubility in water. The compound is stable under standard laboratory storage conditions when kept away from moisture, strong acids, strong bases, and oxidizing agents.

Note: Exact melting point values should be confirmed against the Certificate of Analysis (CoA) provided with each lot.

Synthesis and Preparation

N-Methylbenzamide is most commonly prepared by the reaction of benzoyl chloride with methylamine (as a free base or hydrochloride salt in the presence of a base such as triethylamine). This acylation proceeds under mild conditions and typically affords the product in high yield after aqueous workup and recrystallization.

Alternative synthetic routes include:

• Direct amidation of benzoic acid with methylamine using coupling reagents (e.g., DCC, EDC) or thermally under forcing conditions.
• Transamidation of methyl benzoate with methylamine, although this route generally requires elevated temperatures or catalytic activation.
• Reduction of N-methyl benzonitrile oxide intermediates — a less common laboratory route.

For research applications requiring high purity, procurement of a commercially certified reagent-grade material (such as Aladdin Scientific SKU N304144) is recommended to ensure reproducible results and avoid purification artifacts that can confound sensitive catalytic or analytical experiments.

Applications in Organic Synthesis and Catalysis

N-Methylbenzamide is a valuable compound across several research domains:

1. Directing Group in C–H Functionalization

One of the most significant contemporary uses of N-Methylbenzamide is as a substrate and directing group in transition-metal-catalyzed ortho C–H functionalization. The amide NH (or its deprotonated form in certain catalytic cycles) can coordinate to metals such as palladium, rhodium, ruthenium, or cobalt, directing electrophilic or oxidative metalation to the ortho position of the phenyl ring. This strategy enables the selective introduction of aryl, alkenyl, alkyl, or heteroatom-containing groups without pre-functionalization of the ring.

2. Model Substrate in Mechanistic Studies

Due to its structural simplicity, N-Methylbenzamide is widely employed as a model substrate for benchmarking new catalytic systems, studying reaction kinetics, and elucidating mechanisms of amide-directed metalation.

3. Synthetic Intermediate

N-Methylbenzamide serves as a building block for the preparation of more complex N-substituted benzamide derivatives, pharmaceutical intermediates, and agrochemical compounds. Its amide carbonyl can undergo further transformations including reduction to the corresponding amine, condensation reactions, or incorporation into heterocyclic scaffolds.

4. Reference Standard in Analytical Chemistry

High-purity N-Methylbenzamide is used as a reference standard in HPLC method development, mass spectrometry calibration, and NMR spectroscopy.

Handling, Safety, and Storage Guidelines

While N-Methylbenzamide is not classified as acutely highly toxic, standard laboratory safety practices must be observed when handling this compound:

• Personal Protective Equipment (PPE): Wear appropriate lab coat, nitrile gloves, and safety glasses. Work in a well-ventilated area or fume hood when handling powders to avoid inhalation of dust.
• Skin and Eye Contact: Avoid prolonged skin contact. In case of contact, wash thoroughly with soap and water. Flush eyes with copious water if contact occurs and seek medical attention if irritation persists.
• Storage: Store in a tightly closed container at room temperature, away from moisture, heat sources, strong acids, strong bases, and oxidizing agents. Keep away from incompatible materials.
• Disposal: Dispose of in accordance with local, regional, and national regulations for organic chemical waste. Do not dispose of down the drain.

Always consult the Safety Data Sheet (SDS) provided by Aladdin Scientific for complete hazard information before use.

Selecting the Right Grade for Your Research

The purity and specification of N-Methylbenzamide can significantly affect experimental outcomes, particularly in catalysis, spectroscopic reference, and pharmaceutical intermediate applications. Key considerations when selecting a grade include:

• Purity (%): For sensitive catalytic or analytical applications, reagent-grade material with purity ≥98% (as confirmed by HPLC or GC) is recommended. Aladdin Scientific N304144 is offered as a research-grade reagent; consult the product page or CoA for the current certified purity value.
• Lot-to-Lot Consistency: Request CoA data for each lot to verify consistency of purity, melting point, and spectroscopic identity (IR, NMR).
• Packaging: Available in multiple pack sizes to suit both small-scale discovery research and larger preparative needs. Contact Aladdin Scientific for bulk pricing and custom packaging inquiries.
• Certificates: Ensure the supplier provides a full CoA, SDS, and, where required, country-of-origin documentation for regulatory compliance.