Aspects of Homogeneous Hydrogenation from Industrial Research

Alkali Metal (Li, Na, K, Rb, Cs) Mediation in Magnesium Hexamethyldisilazide [Mg(HMDS)2] Catalysed Transfer Hydrogenation of Alkenes

“…Homogeneous hydrogenation is a synthetic procedure of fundamental importance to the chemical industry as well as being one of the most extensively studied reactions in homogeneous catalysis [1–3] . Classic compounds such as the Wilkinson catalyst or the asymmetric hydrogenation catalysts from Noyori or Knowles exhibit excellent performance under mild conditions alongside high selectivity and good functional group tolerance [4–6] .…”

“…Homogeneous hydrogenation is a synthetic procedure of fundamental importance to the chemical industry as well as being one of the most extensively studied reactions in homogeneous catalysis. [1][2][3] Classic compounds such as the Wilkinson catalyst or the asymmetric hydrogenation catalysts from Noyori or Knowles exhibit excellent performance under mild conditions alongside high selectivity and good functional group tolerance. [4][5][6] Besides the aforementioned benefits these catalysts are centred on late transition metals and the growing awareness of their toxicity and high costs has prompted chemists to seek to develop alternatives.…”

“…Heating to 75°C immediately produced strong gas evolution. 1 H NMR spectroscopy revealed that hydrogen was developed and only 36 % of styrene was converted after 3 hours, although the majority of CHD was consumed. This modest yield is due to known competing side reactions (Scheme 2, eqn.…”

“…[a] x = catalyst loading; [Substrate] = 0.4 mmol (for x = 10 and 5) and 0.5 mmol (for x = 1) in C 6 D 6 , T = 75°C. Reaction time for essentially full conversion (> 98 %) have been determined by1 H NMR spectroscopy via recording a spectrum during the catalysis every 5 minutes. For slower reaction rates the conversion and yield were determined after 16 hours.…”