Chemical model abundances of CH₃CN (black) and CH₃NC (green) for the warm-up stage of a hot core type model where the main destruction pathway for CH₃ NC (H+CH₃NC) has been disabled. Solid lines denote gas-phase abundances, while dashed lines indicate grain-surface abundances. The top panel shows the model with a final collapse density of n_H = 1.6 × 10⁷ cm⁻³ and the bottom panel shows the model with a final collapse density of n_H = 6 × 10¹⁰ cm⁻³.