Metal-Free Catalytic Hydrogenation

In their Communication the authors stated that “non-transition-metal catalysts for hydrogenation reactions are all but unknown.” However, it should be noted that non-transition-metal systems have been shown to effect hydrogenation under more forcing conditions. For example, DeWitt, Ramp, and Trapasso demonstrated hydrogenation with iPr₃B under 67 atm (1000 psi) H₂ at 220 ^oC.¹ Similarly, Haenel and co-workers² among others³ showed hydrogenation of coal under almost 148 atm (15 MPa) H₂ and at 280–350 °C using BI₃ or alkyl boranes. As well, superacid systems have also been shown to effect hydrogenation of alkenes at H₂ pressures of at least 35 atm.⁴