Pulling for ketenes and imines

Mechanochemistry Expanding the range of reactive functional groups that can be generated by polymer mechanochemistry—literally pulling the chains apart by applying force—is important for creating new self-healing materials. Robb and Moore show that the Staudinger cycloaddition [the formation of a four-membered β-lactam ring from an imine (=N–R, where R is an alkyl or aryl group) and a ketene (=C=O)] could be reversed mechanically. Poly(methyl acrylate) polymers with an internal β-lactam ring were cleaved by ultrasonication in organic solvent. The highly reactive ketene was scavenged with isobutanol. J. Am. Chem. Soc. 10.1021/jacs.5b07345 (2015).