N-Alkylpiperidines with alkyl fragment length from C1 to Cl5 were synthesized by the reaction of CO + H2 + piperidine. The molecular mass distribution of the N-alkylpiperidines has two different distribution parameters α. Thus, α=0.45±0.03 for C1-C5 alkyl fragments, while α=0.65±0.02 for C6-C15. Piperidine was found to act as a modifier reagent and chemical trap for the intermediates in the synthesis reaction.