N-Methylbenzamide

Chemical properties

N-methylbenzamide is an off-white crystalline solid.

The Uses of N-Methylbenzamide

N-Methylbenzamide is an important pesticide intermediate. It acts as a potent PDE10A (phosphodiesterase with a remarkable localization as the protein is abundant only in brain tissue) inhibitor.

Synthesis Reference(s)

Synthetic Communications, 7, p. 549, 1977 DOI: 10.1080/00397917709409275
Tetrahedron Letters, 30, p. 451, 1989 DOI: 10.1016/S0040-4039(00)95225-0

Air & Water Reactions

Insoluble in water.

Reactivity Profile

N-METHYLBENZAMIDE is an amide. Amides/imides react with azo and diazo compounds to generate toxic gases. Flammable gases are formed by the reaction of organic amides/imides with strong reducing agents. Amides are very weak bases (weaker than water). Imides are less basic yet and in fact react with strong bases to form salts. That is, they can react as acids. Mixing amides with dehydrating agents such as P2O5 or SOCl2 generates the corresponding nitrile. The combustion of these compounds generates mixed oxides of nitrogen (NOx).

Fire Hazard

Flash point data concerning N-METHYLBENZAMIDE are not available, however, N-METHYLBENZAMIDE is probably combustible.

Synthesis

Add benzoic acid (977 mg, 8 mmol), dry DCM (20 mL) and catalytic amount of DMF in a 100 mL round-bottom flask. Cool the reaction mixture to 0°C and stir for 5 minutes. Add (COCl)2 (0.89 mL, 1.3 equiv.) dropwise to the reaction mixture and stir at room temperature for 4 hours. Concentrate the resulting mixture under reduced pressure to obtain acid chloride. Add catalytic amount of 4-dimethylaminopyridine, dry DCM (15 mL), MeNH2 (2 (M) in THF) (5.19 mL, 1.3 equiv.) and Et3N (1.56 mL, 1.4 equiv.) to the mixture in a 100 mL round-bottom flask. Cool the reaction mixture to 0°C. Add acid chloride (1.0 equiv.) dropwise at 0°C. Stir the reaction mixture at room temperature for 12 hours. Add water (40 mL) and seperate the organic layer. Extract the aqueous layer with DCM (3 x 30 mL). Wash the combined organic layer with saturated aqueous NaHCO3 (30 mL) solution followed by water (30 mL). Dry the organic layer over Na2SO4 and concentrated under reduced pressure. Purify the crude mass by silica gel column chromatography (20% ethyl acetate in hexane as eluent) to obtain N-methylbenzamide. DOI: 10.1002/anie.202203539