Hydrogenation of Biodiesel Catalysed by Pyrazolyl Nickel(II) and Palladium(II) Complexes

Biodiesel from renewable sources offers an attractive alternative to conventional diesel fuel and partial hydrogenation of free-fatty acid methyl esters (FAME) is one way to improve this renewable fuel. We...

The diagnostic peak at 3.62 ppm in the Fig. S1 corresponds to the methoxy protons (-OCH 3 ) of the substrate, methyl linoleate.The substrate's peaks around 2.01 ppm, 2.73 ppm, and 5.31 ppm are due to allylic, bis-allylic and olefinic protons, respectively.Sharp singlet signal at 1.26 ppm represents methylene protons of the carbon chain, whilst the triplet resonating at 0.85 ppm is due to the terminal methyl protons.The triplet around 2.27 ppm corresponds to the methylene protons that are adjacent to the carbonyl group (Fig. S1).Fig. S3 1 H NMR spectrum of products from the hydrogenation of methyl linoleate (ML) using complex 6 showing the distribution of the products of MO and MS.2.5 µmol (0.83 mol%) of the catalyst; 0.3 mmol of methyl linoleate; 5 mL of methanol; 50 °C; 5 bar, 0.5 h.

Fig. SI-4
1 H NMR spectrum of products from the hydrogenation of methyl linoleate (ML) using complex 4 showing the distribution of the products of MO and MS.29% conversion; 2.5 µmol (0.83 mol%) of the catalyst; 0.3 mmol of methyl linoleate; 5 mL of methanol; 50 °C; 5 bar, 0.5 h.

Fig. S5
1 H NMR spectrum of products from the hydrogenation of methyl linoleate (ML) using complex 4 showing the distribution of the products of MO and MS.52% conversion; 2.5 µmol (0.83 mol%) of the catalyst; 0.3 mmol of methyl linoleate; 5 mL of methanol; 50 °C; 5 bar, 1 h.

Fig. S6
1 H NMR spectrum of products from the hydrogenation of methyl linoleate (ML) using complex 1 showing the distribution of the products of MO and MS.35% conversion; 2.5 µmol (0.83 mol%) of the catalyst; 0.3 mmol of methyl linoleate; 5 mL of methanol; 50 °C; 5 bar, 0.5 h.

Fig. S7
1 H NMR spectrum of products from the hydrogenation of methyl linoleate(ML) using complex 1 showing the distribution of the products of MO and MS.38% conversion; 2.5 µmol (0.83 mol%) of the catalyst; 0.3 mmol of methyl linoleate; 5 mL of methanol; 50 °C; 5 bar, 1 h.

Fig. S9
1 H NMR spectrum of products from the hydrogenation of methyl linoleate using complex 2 showing the distribution of the products of the MO and MS at 1 h; 2.5 µmol (0.83 mol%) of the catalyst; 0.3 mmol of methyl linoleate; 5 mL of methanol; 50 °C; 5 bar.34% conversions; 66% selectivity towards MO;17% selectivity towards MS.Fig. S10 1 H NMR spectrum of products from the hydrogenation of methyl linoleate using complex 2 showing the distribution of the products of MO and MS at 2 h; 2.5 µmol (0.83 mol%) of the catalyst; 0.3 mmol of methyl linoleate; 5 mL of methanol; 50 °C; 5 bar.46% conversions; 54% selectivity towards MO;16% selectivity towards MS.Fig. S11 1 H NMR spectrum of products from the hydrogenation of methyl linoleate using complex 6 showing the distribution of the products of MO and MS at 2 h; 2.5 µmol (0.83 mol%) of the catalyst; 0.3 mmol of methyl linoleate; 5 mL of methanol; 50 °C; 5 bar.70% conversions; 30% selectivity towards MO; 38% selectivity towards MS.Fig. S12 1 H NMR spectrum of a time-dependent study of % conversion of ML and selectivity towards MO with complex 6. 2.5 µmol (0.83 mol%) of the catalyst; 0.3 mmol of methyl linoleate; 5 mL of methanol; 50 °C; 5 bar.

Fig. S13
The chromatogram showing the distribution of the products of MO and MS for the hydrogenation of methyl linoleate (ML) using complex 6.Fig. S14 1 H NMR spectrum of products from the hydrogenation of methyl linoleate using complex 3 showing the distribution of the products of MO and MS at 1 h; 2.5 µmol (0.83 mol%) of the catalyst; 0.3 mmol of methyl linoleate; 5 mL of methanol; 50 °C; 5 bar.40% conversions; 61% selectivity towards MO; 8% selectivity towards MS.

Fig. S15
1 H NMR spectrum of products from the hydrogenation of methyl linoleate using complex 3 showing the distribution of the product of MO and MS at 2 h; 2.5 µmol (0.83 mol%) of the catalyst; 0.3 mmol of methyl linoleate; 5 mL of methanol; 50 °C; 5 bar.75% conversions; 25% selectivity towards MO; 44% selectivity towards MS.Fig. S16 The mass spectrum showing the presence of ML when it is not fully hydrogenated with pyrazolyl nickel(II) and palladium(II) complexes.

Fig. S17
Fig. S17 The mass spectrum showing the intermediate (MO) when methyl linoleate (ML) is partially hydrogenated.

Fig. S18
Fig. S18The mass spectrum confirming the presence of methyl stearate (MS) when methyl linoleate is fully hydrogenated.

Fig. S19 1
Fig.S191 H NMR spectrum of products from the hydrogenation of methyl linoleate using complex 6 showing the distribution of the product of MO and MS at 1 h; 2.5 µmol (0.83 mol%) of the catalyst; 0.3 mmol of methyl linoleate; 5 mL of methanol; 70 °C; 5 bar.36% conversions; 64% selectivity towards MO; 17% selectivity towards MS.

Fig. S20 1 H
Fig.S201 H NMR spectrum of products from the hydrogenation of methyl linoleate (ML) using complex 6 showing the distribution of the products of MO and MS.2.5 µmol (0.83 mol%) of the catalyst; 0.5 mg of Hg; 0.3 mmol of methyl linoleate; 5 mL of methanol; 50 °C; 5 bar, 1 h.29% conversion; 71% selectivity towards MO and 3% selectivity towards MS.

Table S1
Effect of temperature, pressure, and mercury-drop test on the hydrogenation reaction of methyl linoleate with 6 using molecular hydrogen a Entry Complex   2 a Reaction conditions: 2.5 µmol (0.83 mol%) of complex; 0.3 mmol of methyl linoleate; 5 mL of methanol; 50 °C; 5 bar ; 1 h.b Conversions were estimated by 1 H NMR spectroscopy.Each run was performed in duplicates.c mercury drop experiment; one equimolar of mercury to complex 6.      -1  ℎ -1

Table S2
Crystallographic data for complexes 5 and 6