Issue Date: June 26, 2017
Safer, greener route to methyl nitroacetate
Methyl nitroacetate is a handy chemical building block. It can be used to produce α-amino acids, isoxazoles, and α,β-unsaturated compounds. It’s also a useful reactant in Michael additions, Mannich reactions, and cyclopropanations. But it’s expensive. One gram costs anywhere from $22 to $115, depending on the vendor. That’s probably because the process that has been used to make methyl nitroacetate for more than 40 years is dangerous. The 1976 procedure published in Organic Syntheses (DOI: 10.15227/orgsyn.055.0077) requires one to dry the highly explosive intermediate dipotassium salt of nitroacetic acid in a vacuum desiccator and then grind it with a mortar and pestle. The protocol also uses carcinogenic benzene as an extraction solvent and requires two distillations. Now, Pablo E. Guzmán, Jesse J. Sabatini, and coworkers at the U.S. Army Research Laboratory have developed a safer, more environmentally friendly way to make this ester (Org. Process Res. Dev. 2017, DOI: 10.1021/acs.oprd.7b00093). The new procedure eliminates the drying and grinding steps and uses either ethyl acetate or dichloromethane as the extraction solvent. It also requires a single distillation rather than two. “While our yield is slightly lower than the original procedure, we feel it’s quite acceptable in exchange for minimizing both the safety and environmental hazards,” Sabatini tells C&EN.
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