US 8242318 B2 abstract catalytic hydrogenation of a double bond notably a c u2550 c or c u2550 n double bond is carried out using a homogenous catalyst which is a complex of rhodium or other transition metal containing at least one ligand which is a nitrogenous organic base preferably the complex is phosphorus free and the ligand is a bicyclic base having formula where r 1 and r 4 are hydrocarbon chains r 1 preferably is a saturated chain of two carbon atoms and r 4 preferably is a saturated chain of three to five carbon atoms application_number US 63001309 A description in these examples all operations with air sensitive complexes were performed under an inert atmosphere of dry n 2 using standard schlenk techniques or in a glove box mbraun labmaster sp all solvents including deuterated solvents were dried and deoxygenated using sodium benzophenone and then distilled under nitrogen ir spectra were obtained using a nicolet 800 ft ir spectrometer and nmr spectra were recorded on a bruker avance 400 spectrometer 1 h at 400 1 mhz and 13 c at 100 6 mhz and spectra are reported relative to tetramethylsilane 38 1644 mg rh cod cl 2 0 0774 mmol was dissolved in ca 5 ml toluene and 0 3719 mmol dbu 56 6181 mg was then added the reaction mixture was stirred at 70 u00b0 c for 16 hours the reaction mixture was dried in vacuum and then washed with hexane the remaining solid was dried again and then dissolved in benzene by carefully layering the.