S1 Supporting Information Mechanism of Pd(OAc) - Shannon S. Stahl
Supporting Information Mechanism of Pd(OAc)2/DMSO-Catalyzed Aerobic Alcohol Oxidation: MassTransfer-Limitation Effects, Catalyst Decomposition Pathways Bradley A. Steinhoff and Shannon S. Stahl* Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706
40 35 30 25 20 15 10 5 0
Initial Rate (µmol O2/min)
Initial Rate (µmol O2/min)
0.5 mol% (2.5 mM) Pd(OAc)2
data mass transport limit with 1 SD error, extrapolated
0
200
(A)
400 600 800 O2 Pressure (Torr)
1000
35 30 25 20 15 10 5 0
(B)
0
0.2 0.4 0.6 0.8 [1-Phenylethanol] (M)
1
(C)
Initial Rate (µmol O2/min)
Initial Rate (µmol O2/min)
5 mol% (25 mM) Pd(OAc)2 160 120 80 40 0
0
500
1000 1500 2000 O2 Pressure (Torr)
2500
(D)
70 60 50 40 30 20 10
0
0
0.2 0.4 0.6 0.8 [1-Phenylethanol] (M)
1
Figure S1. Dependence of the initial rate on oxygen pressure and alcohol concentration at both low and high catalyst loadings. Conditions: (A) 2.5 mM Pd(OAc)2, 150-990 Torr O2, 0.52 M 1-phenylethanol, 2 mL DMSO, 80 °C, in 25.4 mm OD tube. (B) 2.5 mM Pd(OAc)2, 730 Torr O2, 0.10-0.83 M 1-phenylethanol, 2 mL DMSO, 80 °C, in 25.4 mm OD tube, data fit to a hyperbolic curve. (C) 25.2 mM Pd(OAc)2, 730-2070 Torr O2, 0.83 M 1-phenylethanol, 2 mL DMSO, 80 °C, in 25.4 mm OD tube. Rates normalized to 1 atm. (D) 25.2 mM Pd(OAc)2, 730 Torr O2, 0.21-0.83 M 1-phenylethanol, 2 mL DMSO, 80 °C, in 25.4 mm OD tube. Rates normalized to 1 atm.
S1
[2,5-Dimethoxybenzyl Alcohol] (M)
Table S1. Initial rates from Figure 7. Initial O2 Pressure Initial rate (Torr/sec) 542 Torr 24.8 728 Torr 26.1 ± 2.8 992 Torr 28.5
[Pd] = 5 mM
0.6
no decomposition (eq 13) unimolecular (eq 17) bimolecular (eq 21)
0.5 0.4 0.3 0.2 0.1 0
0
40
80 120 Time (min)
160
[2,5-Dimethoxybenzyl Alcohol] (M)
Figure S2. Representative time-course of the oxidation of 1 with 5 mM Pd(OAc)2. Conditions: 5 mM Pd(OAc)2, 730 Torr O2, 0.52 M 2,5-dimethoxybenzyl alcohol, 2 mL DMSO, 80 °C, in 25.4 mm OD tube. Initial and final time-points were used to fit the time-courses to either a unimolecular decomposition equation (eq 17) or a bimolecular decomposition equation (eq 21). Only initial time-points were used to fit the time-course to an equation without a decomposition term (eq 13).
[Pd] = 10 mM
0.6
no decomposition (eq 13) unimolecular (eq 17) bimolecular (eq 21)
0.5 0.4 0.3 0.2 0.1 0
0
10
20
30 40 Time (min)
50
60
Figure S3. Representative time-course of the oxidation of 1 with 10 mM Pd(OAc)2. Conditions: 10 mM Pd(OAc)2, 730 Torr O2, 0.52 M 2,5-dimethoxybenzyl alcohol, 2 mL DMSO, 80 °C, in 25.4 mm OD tube. Initial and final time-points were used to fit the timecourses to either a unimolecular decomposition equation (eq 17) or a bimolecular decomposition equation (eq 21). Only initial time-points were used to fit the time-course to an equation without a decomposition term (eq 13).
S2
[2,5-Dimethoxybenzyl Alcohol] (M)
[Pd] = 12.5 mM
0.6
no decomposition (eq 13) unimolecular (eq 17) bimolecular (eq 21)
0.5 0.4 0.3 0.2 0.1 0
0
40
80 120 Time (min)
160
Figure S4. Representative time-course of the oxidation of 1 with 12.5 mM Pd(OAc)2. Conditions: 12.5 mM Pd(OAc)2, 730 Torr O2, 0.52 M 2,5-dimethoxybenzyl alcohol, 2 mL DMSO, 80 °C, in 25.4 mm OD tube. Initial and final time-points were used to fit the timecourses to either a unimolecular decomposition equation (eq 17) or a bimolecular decomposition equation (eq 21). Only initial time-points were used to fit the time-course to an equation without a decomposition term (eq 13). Table S2. Selected rate constants determined from the time-course fits. Entry Figure Alcohol [Pd(OAc)2] (mM) ki (M-1 min-1) kuni (min-1) kbi (M-1 min-1) 1 8A 1 2.5 13.0 0.081 -2 S2 1 5 10.2 0.074 -3 8C 1 15 7.7 -18.8 4 8D 1 25 3.3 -4.9 5 9A 2 2.5 21.3 0.17 -6 9B 2 5 23.4 0.14 -7 9C 2 10 9.3 0.040 -8 9D 2 25 4.1 -2.5 Note: Detailed interpretation and/or comparison of the absolute magnitudes of these rate constants is not warranted because of the complexities introduced by the different reaction conditions. For example, the reactions associated with entries 3, 4, 7 and 8 were performed under conditions that are close to or subject to mass-transport-limiting conditions. In such cases, significant quantities of Pd will decompose at early stages of the reaction (i.e., within the first minute), thereby rapidly reducing the concentration of "active Pd" until the reaction is no longer mass-transport-limited. The full-time-course fit does not account for this portion of rapidly-decomposed Pd, and thus will yield an artificially low ki.
S3
730.0 y = 728.51 - 11.33x R= 0.98384
pO
2
720.0 710.0 700.0 690.0 680.0
0
1
2
3
Time (min)
4
5
Figure S5. Representative time-course data and initial-rate data fitting used in the preparation of initial rate kinetic plots (e.g., Figures 1, 2, 3 and 6).
S4
40 35 30 25 20 15 10 5 0
Initial Rate (µmol O2/min)
Initial Rate (µmol O2/min)
0.5 mol% (2.5 mM) Pd(OAc)2
data mass transport limit with 1 SD error, extrapolated
0
200
(A)
400 600 800 O2 Pressure (Torr)
1000
35 30 25 20 15 10 5 0
(B)
0
0.2 0.4 0.6 0.8 [1-Phenylethanol] (M)
1
(C)
Initial Rate (µmol O2/min)
Initial Rate (µmol O2/min)
5 mol% (25 mM) Pd(OAc)2 160 120 80 40 0
0
500
1000 1500 2000 O2 Pressure (Torr)
2500
(D)
70 60 50 40 30 20 10
0
0
0.2 0.4 0.6 0.8 [1-Phenylethanol] (M)
1
Figure S1. Dependence of the initial rate on oxygen pressure and alcohol concentration at both low and high catalyst loadings. Conditions: (A) 2.5 mM Pd(OAc)2, 150-990 Torr O2, 0.52 M 1-phenylethanol, 2 mL DMSO, 80 °C, in 25.4 mm OD tube. (B) 2.5 mM Pd(OAc)2, 730 Torr O2, 0.10-0.83 M 1-phenylethanol, 2 mL DMSO, 80 °C, in 25.4 mm OD tube, data fit to a hyperbolic curve. (C) 25.2 mM Pd(OAc)2, 730-2070 Torr O2, 0.83 M 1-phenylethanol, 2 mL DMSO, 80 °C, in 25.4 mm OD tube. Rates normalized to 1 atm. (D) 25.2 mM Pd(OAc)2, 730 Torr O2, 0.21-0.83 M 1-phenylethanol, 2 mL DMSO, 80 °C, in 25.4 mm OD tube. Rates normalized to 1 atm.
S1
[2,5-Dimethoxybenzyl Alcohol] (M)
Table S1. Initial rates from Figure 7. Initial O2 Pressure Initial rate (Torr/sec) 542 Torr 24.8 728 Torr 26.1 ± 2.8 992 Torr 28.5
[Pd] = 5 mM
0.6
no decomposition (eq 13) unimolecular (eq 17) bimolecular (eq 21)
0.5 0.4 0.3 0.2 0.1 0
0
40
80 120 Time (min)
160
[2,5-Dimethoxybenzyl Alcohol] (M)
Figure S2. Representative time-course of the oxidation of 1 with 5 mM Pd(OAc)2. Conditions: 5 mM Pd(OAc)2, 730 Torr O2, 0.52 M 2,5-dimethoxybenzyl alcohol, 2 mL DMSO, 80 °C, in 25.4 mm OD tube. Initial and final time-points were used to fit the time-courses to either a unimolecular decomposition equation (eq 17) or a bimolecular decomposition equation (eq 21). Only initial time-points were used to fit the time-course to an equation without a decomposition term (eq 13).
[Pd] = 10 mM
0.6
no decomposition (eq 13) unimolecular (eq 17) bimolecular (eq 21)
0.5 0.4 0.3 0.2 0.1 0
0
10
20
30 40 Time (min)
50
60
Figure S3. Representative time-course of the oxidation of 1 with 10 mM Pd(OAc)2. Conditions: 10 mM Pd(OAc)2, 730 Torr O2, 0.52 M 2,5-dimethoxybenzyl alcohol, 2 mL DMSO, 80 °C, in 25.4 mm OD tube. Initial and final time-points were used to fit the timecourses to either a unimolecular decomposition equation (eq 17) or a bimolecular decomposition equation (eq 21). Only initial time-points were used to fit the time-course to an equation without a decomposition term (eq 13).
S2
[2,5-Dimethoxybenzyl Alcohol] (M)
[Pd] = 12.5 mM
0.6
no decomposition (eq 13) unimolecular (eq 17) bimolecular (eq 21)
0.5 0.4 0.3 0.2 0.1 0
0
40
80 120 Time (min)
160
Figure S4. Representative time-course of the oxidation of 1 with 12.5 mM Pd(OAc)2. Conditions: 12.5 mM Pd(OAc)2, 730 Torr O2, 0.52 M 2,5-dimethoxybenzyl alcohol, 2 mL DMSO, 80 °C, in 25.4 mm OD tube. Initial and final time-points were used to fit the timecourses to either a unimolecular decomposition equation (eq 17) or a bimolecular decomposition equation (eq 21). Only initial time-points were used to fit the time-course to an equation without a decomposition term (eq 13). Table S2. Selected rate constants determined from the time-course fits. Entry Figure Alcohol [Pd(OAc)2] (mM) ki (M-1 min-1) kuni (min-1) kbi (M-1 min-1) 1 8A 1 2.5 13.0 0.081 -2 S2 1 5 10.2 0.074 -3 8C 1 15 7.7 -18.8 4 8D 1 25 3.3 -4.9 5 9A 2 2.5 21.3 0.17 -6 9B 2 5 23.4 0.14 -7 9C 2 10 9.3 0.040 -8 9D 2 25 4.1 -2.5 Note: Detailed interpretation and/or comparison of the absolute magnitudes of these rate constants is not warranted because of the complexities introduced by the different reaction conditions. For example, the reactions associated with entries 3, 4, 7 and 8 were performed under conditions that are close to or subject to mass-transport-limiting conditions. In such cases, significant quantities of Pd will decompose at early stages of the reaction (i.e., within the first minute), thereby rapidly reducing the concentration of "active Pd" until the reaction is no longer mass-transport-limited. The full-time-course fit does not account for this portion of rapidly-decomposed Pd, and thus will yield an artificially low ki.
S3
730.0 y = 728.51 - 11.33x R= 0.98384
pO
2
720.0 710.0 700.0 690.0 680.0
0
1
2
3
Time (min)
4
5
Figure S5. Representative time-course data and initial-rate data fitting used in the preparation of initial rate kinetic plots (e.g., Figures 1, 2, 3 and 6).
S4
