Illustrative behaviour of abundances of O-bearing COMs (blue) and N-bearing molecules (pink, including cyanopolyynes and cyanides) in Sgr B2 (N1) in (1) the pre-shock gas (here represented by N1S) and (2) the post-shock gas (N1SE1:OF) in comparison to (3) G+0.693–0.027. Involved physical processes or chemical reactions are discussed in detail in Sects. 4.3–4.5; key points are provided below the figure. Boxes filled with colours indicate detections while empty ones represent upper limits. Dashed boxes enclose molecules with similar abundances (within an order of magnitude).