Ring opening of 1,2,3,4-tetrahydroquinoline and decahydroquinoline on MoS2/γ-Al2O3 and Ni-MoS2/γ-Al2O3

► Hydrodenitrogenation of decahydroquinoline and quinoline on (Ni)MoS2/γ-Al2O3. ► The C-N cleavage in tetrahydroquinoline and decahydroquinoline is the determining step. ► Dibenzothiophene and Ni accelerate the rate of that C(sp3)-N bond cleavage. ► The ring opening via Hofmann elimination occurs on acidic -SH groups and S2− ions.