Supporting Information. In-Situ Spectroscopic Investigation of the Cobalt-Catalyzed Oxidation of Lignin Model Compounds in Ionic Liquids

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1 Supporting Information In-Situ Spectroscopic Investigation of the Cobalt-Catalyzed xidation of Lignin Model Compounds in Ionic Liquids Joseph Zakzeski, Pieter C. A. Bruijnincx, and Bert M. Weckhuysen* [a] [a] Dr. J. Zakzeski, Dr. P. C. A. Bruijnincx, Prof. dr. ir. B. M. Weckhuysen Inorganic Chemistry and Catalysis group Debye Institute for Nanomaterials Science Utrecht University Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands Fax: ( ) 1

2 Table of Contents: Figure S1: Schematic depiction of the ATR-IR apparatus. Figure S2: ATR-IR spectra of [EMIM][DEP]. Table S1: IR and Raman bands of [EMIM][DEP] and their vibrational assignments. Table S2: IR and Raman bands of [EMIM][MeS 3 ] and their vibrational assignments. Figure S3: Raman spectra of [EMIM][DEP]. Figure S4: ATR-IR spectra of [EMIM][DEP]/H. Figure S5: Raman spectra of [EMIM][DEP]/H. Figure S6: UV-vis spectra of [EMIM][DEP]/H. Figure S7: ATR-IR spectra of Co/[EMIM][DEP]. Figure S8: Raman spectra of Co/[EMIM][DEP]. Figure S9: UV-vis spectra of Co/[EMIM][DEP]. Figure S10: ATR-IR spectra of [EMIM][MeS 3 ]. Figure S11: Raman spectra of [EMIM][MeS 3 ]. Figure S12: ATR-IR spectra of [EMIM][MeS 3 ]/H. Figure S13: Raman spectra of [EMIM][MeS 3 ]/H. Figure S14: UV-vis spectra of [EMIM][MeS 3 ]/H. Figure S15: ATR-IR spectra of Co/[EMIM][MeS 3 ]. Figure S16: Raman spectra of Co/[EMIM][MeS 3 ]. Figure S17: UV-vis spectra of Co/[EMIM][MeS 3 ]. Figure S18: Mass spectra of a) veratraldehyde and b) veratraldehyde produced via Co/[EMIM][DEP]/H catalyzed veratryl alcohol oxidation using Figure S19: Reproduction of Figure 1 using 18 2 as the oxidant. 2

3 Figure S20. Vibrational intensities associated with 16 (1683 cm -1 ) and 18 (1657 cm -1 ) labelled veratraldehyde versus time using 18 2 as the oxidant. Figure S21: In-situ IR spectrum of Co/[EMIM][DEP]/H catalyzed veratryl alcohol oxidation using 18 2 for comparison with Figure 2. Vibrations associated with cobalt complexes are marked with arrows. Scheme S1: Proposed catalytic mechanism depicting the exemplary oxidation of veratryl alchol to veratraldehyde in the ionic liquid [EMIM][DEP] using 18 2 as the oxidant. Supporting Information References 3

4 Pressure Transducer Gas inlet/ Sampling valve Magnetic driver Pressure Gauge Thermocouple Gas vent Clamp Heater Insulation Co/[EMIM][DEP]/ H/Substrate Diamond probe ZnSe crystal To detector Figure S1: Schematic depiction of the ATR-IR apparatus. Table S1. IR and Raman bands of [EMIM][DEP] and their vibrational assignments Asym = 1568 antisymmetric, C=C sym str = symmetric, str = stretch, ip = inplane, op = out-of-plane, sh = shoulder C=N str Infrared Relative Raman Vibrational assignment (cm ) Intensity 15sh (cm ) Ring ip asym str, CH3(N) str Ring CCH HCCH HCH asym str bend, CH 3 (N) HCH sym bend Ring HCCH sym str Ring ip asym str, CH 2(N) bend CH 3(N) HCH asym str Ring ip sym str, CH 2 (N) str CH 2 HCH asym str P= str Terminal CH 3 HCH asym str Ring ip asym str, CC str, (N)CH 2 and Terminal (N)CH 3CN CHstr 3 HCH sym str sh ? CC str ? P 2 sym str ? Ring sym str, CH 3 (N) str, CH 2 (N) str ? P--C vibration 4

5 CC str sh 939 P--C vibration CCH bend sh 785 P--C sym str Ring HCCH asym bend Ring HCCH sym bend sh 704 Ring ip bend, CH 3(N) bend, CH 2(N) bend Ring op asym bend 600 Ring ip sym bend cm -1 is assigned to this mode. With [EMIM][DEP], the diethylphosphate anion also has several vibrational modes that were detected by infrared spectroscopy. The stretching vibration of the P= group is reported to be strong and in the region of cm -1 and therefore the strong vibration at 1243 cm -1 is assigned to this functional group. 1 The assignment is also in agreement with previous studies of the diethylphosphate anion. 2 - The symmetric P 2 stretch appears at 1082 cm -1. P--C vibrations give very strong bands between cm -1 with another additional strong band typically between 985 and 940 cm The very strong bands at 1049 cm -1 and 933 cm -1 are thus assigned to the P--C asymmetric stretching vibration. The symmetric P--C vibrations also typically exhibit strong bands between cm -1, 1 so the band at 776 5

6 Table S2. IR and Raman bands of [EMIM][MeS 3 ] and their vibrational assignments. Asym = antisymmetric, sym = symmetric, str = stretch, ip = inplane, op = out-of-plane, sh = shoulder. Table S2 (continued). IR and Raman bands of [EMIM][MeS 3 ] and their vibrational assignments. Asym = antisymmetric, sym = symmetric, str = stretch, ip = in-plane, op = out-of-plane, sh = shoulder. Infrared (cm -1 ) Relative Intensity Raman (cm -1 ) Vibrational assignment Infrared (cm -1 ) Relative Intensity Raman (cm -1 ) Vibrational assignment 3161 Ring HCCH asym str Ring HCCH sym str CH3(N) HCH asym str sh SCH 3 asym astr SCH 3 sym str CH2HCH asym str Terminal CH3 HCH asym str Terminal CH 3 HCH sym str ? 2760? ? C=N str Ring ip asym str, CH 3 (C) str CCH HCH asym bend, CH3(N) HCH sym bend S2 asym str or CH3 asym deform Ring ip asym str, CH 2 (N) bend Ring ip sym str, CH 2 (N) and CH 3 (N) str Ring ip sym str, CH2(N) str sh CH3 sym deform 1256 S 2 - asym str S 2 - sym str Ring ip asym str, CC str, (N)CH2 and (N)CH3CN str CC str S str S str CCH bend CS str Ring HCCH sym bend Ring op asym bend 599 Ring ip sym bend 553 S 3 sym bend 527 S3 asym bend Several of the vibrational characteristics of the [EMIM] + cation in [EMIM][MeS 3 ] resembled that of [EMIM][DEP] with some exceptions. The CH 3 (N) HCH asymmetric stretch for [EMIM][MeS 3 ] appeared at 3094 cm -1 relative to 3046 cm -1 for [EMIM][DEP] because of reduced influence from the less basic [MeS 3 ] - anion relative to [DEP] -. In previous studies of methanesulfonic vibrations, the S 2 asymmetric and symmetric stretching modes appear in the regions cm -1 and cm -1, respectively 3, 4, so the vibration observed at 1426 cm -1 is assigned to the S 2 asymmetric stretch and 1198 cm -1 to the symmetric stretch in [MeS 3 ] -. The shoulder at 1310 cm -1 is assigned to the CH 3 symmetric deformation of MeS 3. 3, 4 Increasing the temperature from to resulted in a shift of the SCH 3 rocking mode to 1030 cm -1 and the CS stretch to 750 cm sh SH bend 1092 S 2 - sym str sh 1041 SCH 3 rocking 1024 S3 sym str 6

7 Figure S2: In-Situ ATR-IR spectra of [EMIM][DEP] measured at ( ), ( ), ( ), ( ), ( ), ( ), and ( ) Figure S3: In-Situ Raman spectra of [EMIM][DEP] measured at ( ), ( ), ( ), ( ), ( ), ( ), and ( ). 7

8 Figure S4: In-Situ ATR-IR spectra of [EMIM][DEP]/H measured at ( ), ( ), ( ), ( ), ( ), ( ), and ( ) Figure S5: In-Situ Raman spectra of [EMIM][DEP]/H measured at ( ), ( ), ( ), ( ), ( ), ( ), and ( ). 8

9 wavelength (nm) Figure S6: In-Situ UV-vis spectra of [EMIM][DEP]/H measured at ( ), ( ), ( ), ( ), ( ), ( ), and ( ) Figure S7: In-Situ ATR-IR spectra of Co/[EMIM][DEP] measured at ( ), ( ), ( ), ( ), ( ), ( ), and ( ). 9

10 Figure S8: In-Situ Raman spectra of Co/[EMIM][DEP] measured at ( ), ( ), ( ), ( ), ( ), ( ), and ( ) wavelength (nm) Figure S9: In-Situ UV-Vis spectra of Co/[EMIM][DEP] measured at ( ), ( ), ( ), ( ), ( ), ( ), and ( ). 10

11 Figure S10: In-Situ ATR-IR spectra of [EMIM][MeS 3 ] measured at ( ), ( ), ( ), ( ), ( ), ( ), and ( ) Figure S11: In-Situ Raman spectra of [EMIM][MeS 3 ] measured at ( ), ( ), ( ), ( ), ( ), ( ), and ( ). 11

12 Figure S12: In-Situ ATR-IR spectra of [EMIM][MeS 3 ]/H measured at ( ), ( ), ( ) 313 K, ( ), ( ), ( ), and ( ) Figure S13: In-Situ Raman spectra of [EMIM][MeS 3 ]/H measured at ( ), ( ), ( ) 313 K, ( ), ( ), ( ), and ( ). 12

13 wavelength (nm) Figure S14: In-Situ UV-vis spectra of [EMIM][MeS 3 ]/H measured at ( ), ( ), ( ) 313 K, ( ), ( ), ( ), and ( ) Figure S15: In-Situ ATR-IR spectra of Co/[EMIM][MeS 3 ] measured at ( ), ( ), ( ) 313 K, ( ), ( ), ( ), and ( ). 13

14 Figure S10: In-Situ Raman spectra of Co/[EMIM][MeS 3 ] measured at ( ), ( ), ( ), ( ), ( ), ( ), and ( ) wavelength (nm) Figure S17: In-Situ UV-Vis spectra of Co/[EMIM][MeS 3 ] measured at ( ), ( ), ( ) 313 K, ( ), ( ), ( ), and ( ). 14

15 a 7.5 (x1,000) 166 b (x1,000) Figure S18: Mass spectra of a) veratraldehyde and b) veratraldehyde produced via Co/[EMIM][DEP]/H catalyzed veratryl alcohol oxidation using time (h) Figure S19: Reproduction of Figure 1 using 18 2 as the oxidant. 15

16 cm cm -1 0:49:54 1:39:54 2:29:54 3:19:53 -- time (h:mm:ss) Figure S20. Vibrational intensities associated with 16 (1683 cm -1 ) and 18 (1657 cm -1 ) labelled veratraldehyde versus time using 18 2 as the oxidant. Initially, only the 16 veratraldehyde is observed. Each catalytic turnover (see Scheme S1) results in the formation of H , which disproportionates to form H This H 2 18 reacts with veratraldehyde to form a diol, and the reverse reaction results in either the formation of 16 or 18 labelled veratraldehyde. As the reaction proceeds, H 2 18 concentrations increase, which results in increased incorporation of 18 in the veratraldehyde as observed by the eventual increase in vibrational intensity at 1657 cm

17 Figure S21: In-situ IR spectrum of Co/[EMIM][DEP]/H catalyzed veratryl alcohol oxidation using 18 2 for comparison with Figure 2. Vibrations associated with cobalt complexes are marked with arrows. 17

18 H H H [EMIM][Cl] CoCl 2 A B 2[EMIM][DEP] Co II (DEP) 2 Na 16 H H / F 18 H 18 Co II (DEP) H NaDEP C [Co II (DEP)( 16 H)] 18 2 [EMIM][DEP] G [Co III (DEP)( 16 H)](DEP) H NH N H Co III (DEP) H 2 16 Co II (DEP) 1/2 H 16 2 [(Co III (DEP)( 16 H)](DEP) 1/2 [EMIM][ H] 1/2 [EMIM][ 16 H] H / E 18 2 Scheme S1: Proposed catalytic mechanism depicting the exemplary oxidation of veratryl alchol to veratraldehyde in the ionic liquid [EMIM][DEP] using 18 2 as the oxidant. The mechanism clearly indicates the mix of 16 and 18 -labelled veratraldehyde. D Supporting Information References 1 G. Socrates, Infrared and Raman characteristic group frequencies: tables and charts, Wiley, New York, L. Azéma, S. Ladame, C. Lapeyre, A. Zwick and F. Lakhdar-Ghazal, Spectrochim. Acta, Pt. A: Mol. Spectrosc., 2005, 62, M. E. Tuttolomondo, A. Navarro, T. Pena, E. L. Varetti, S. F. Parker and A. B. Altabef, J. Phys. Chem. A, 2009, 113, A. Givan, A. Loewenschuss and C. J. Nielsen, J. Mol. Struct., 2005, 748,