Context :

Aims : We aim to detect methylamine , CH _ { 3 } NH _ { 2 } , 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 , CH _ { 3 } NH _ { 2 } can not be formed from atom addition to CO whereas other NH _ { 2 } -containing molecules such as formamide , NH _ { 2 } CHO , can .

Methods : Submillimeter spectra of several massive hot core regions were taken with the James Clerk Maxwell Telescope .
Abundances are determined with the rotational diagram method where possible .

Results : Methylamine is not detected , giving upper limit column densities between 1.9 - 6.4 \times 10 ^ { 16 } cm ^ { -2 } for source sizes corresponding to the 100 K envelope radius .
Combined with previously obtained JCMT data analyzed in the same way , abundance ratios of CH _ { 3 } NH _ { 2 } , NH _ { 2 } CHO and CH _ { 3 } CN with respect to each other and to CH _ { 3 } OH are determined .
These ratios are compared with Sagittarius B2 observations , where all species are detected , and to hot core models .

Conclusions : 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 .