2015A&A...576A..35L

We aim to detect methylamine, CH₃NH₂, in a variety of hot cores and use it as a test for the importance of photon-induced chemistry in ice mantles and mobility of radicals. Specifically, CH₃NH₂ cannot be formed from atom addition to CO whereas other NH₂-containing molecules such as formamide, NH₂CHO, can. Submillimeter spectra of several massive hot core regions were taken with the James Clerk Maxwell Telescope (JCMT). Abundances are determined with the rotational diagram method where possible. Methylamine is not detected, giving upper limit column densities between 1.9-6.4x10¹⁶cmi^–2 for source sizes corresponding to the 100 K envelope radius. Combined with previously obtained JCMT data analysed in the same way, abundance ratios of CH₃NH₂, NH₂CHO and CH₃CN with respect to each other and to CH₃OH are determined. These ratios are compared with Sagittarius B2 observations, where all species are detected, and to hot core models. The observed ratios suggest that both methylamine and formamide are overproduced by up to an order of magnitude in hot core models. Acetonitrile is however underproduced. The proposed chemical schemes leading to these molecules are discussed and reactions that need further laboratory studies are identified. The upper limits obtained in this paper can be used to guide future observations, especially with ALMA.