Hosoi and co-workers have observed the microwave spectra of six isotopic species of (E ) and (Z ) acetaldehyde oximes or acetaloximes. For the E they determined rotational The existence of hydroxy(methylamino) carbene was demonstrated by gas-phase experiments in which one-electron reduction of radical cations was followed by neutralisation-reionisation. Thus, H 3 C -N --C(H) -OH, N-methyl-methanimidic acid, and H 3 C -NH -C -OH were established.