Top row a: column densities of complex organic molecules and two simpler ones detected in diffuse clouds in the GC and in the Scutum arm compared to the column densities in the z = 0.89 spiral galaxy in front of PKS 1830-211, the Horsehead PDR, the hot core Sgr B2(N2), and the protostellar envelope of NGC 1333-IRAS 2A (see references in Sect. 3). The column densities of H i and H₂ in the diffuse clouds are shown in the panels of methanol (Winkel et al. 2017). The values for H i, H₂, the hot core, and the protostellar envelope are scaled by the factor given in parentheses. Bottom row b: abundances relative to CH₃OH. The black crosses show the ratios for the translucent cloud CB24 (Turner 1998; Turner et al. 1998, 1999). The arrows indicate upper limits.