ReidN_PhD_Defense

Kinetic Analysis of Thiol Oxidations to
Study the Effects of Perfluorinated
Groups on Metal Phthalocyanines
Nellone E. Reid
Advisor: Professor Robert Barat
Ph.D. Dissertation Defense – April 14, 2014
New Jersey Institute of Technology
Otto H.York Department of Chemical, Biological, and Pharmaceutical
Engineering

Outline
 Inspiration for Novel Phthalocyanine (Pc) Catalysts
 Derivation of Biologically Inspired Catalytic Models
 Experimental System
 Experimental Results
 Correlation of Kinetic Parameters to Phthalocyanine Structure
 Supplementary Catalytic Experiments
 Summary & Conclusions

Mercaptan Oxidation
• Auto oxidation of thiols (mercaptans)
• Catalyzed by cobalt phthalocyanines
• Removal of mercaptans from natural
hydrocarbons
• Industry adapts their own versions of
oxidation process
• MerifiningTM- Merichem
• UOP Merox™ LPGTreating
Process

Effects of Fluorinated Substituents
• Auto oxidation of thiols (mercaptans) practiced industrially with PcM’s similar to H16PcCo
• MERcaptan OXidation (MEROX) process: thiols from gasoline removed as disulfides. Low-S
fuels = less acid rain
• Overall reaction: 4 RSH + O2  2 RSSR + 2 H2O
H16PcCo
Source: Braun, 1907
• Inexpensive, ease of synthesis, chemically and
thermally stable
• Catalytic oxidation of organic substrates at the
metal center
• Problematic for aerobic oxidations
• Want to modify structure to be able to resist
degradation via nucleophillic, electrophillic, and
radical attacks

F16PcCo
Source: Bedioui, 1993
• Replace H atoms with F atoms
• Pros: Enhances Pc Stability to electrophillic
degradation
• Cons: Favors nucleophillic susceptibility; promotes
aggregation
• Increase in steric hindrance around catalyst should
protect aromatic fluorine groups from attack

F64PcCo
Source: Gorun, 2002
• Selectively replace F atoms with alkyl groups, esp.
perfluorinated groups
• Result is a more robust molecule
• Resists degradation via nucleophillic, electrophillic
and radical attacks
• Concerns: steric hindrance, excessive electron
withdrawing
Rf = C3F7 =

Steric Hindrance
Bulky fluorinated groups surrounding metal center of catalyst might hinder rate of RS-
substrate binding, while also accelerating product expulsion
Lewis Acidity
Fluorinated groups cause metal center to become electron deficient, thereby strengthening RS-
substrate and electron binding to the metal center
F16PcCoH16PcCo F64PcCo
Rf = C3F7 =

Goal of the Project
 Understand advantage of fine-tuning steric and electronic
properties of catalysts
 Quantitative and qualitative study to provide insight into the
relationship between modified Pc structure and design limitations
◦ Minimize effects caused by mass transfer
◦ Relevance of hydrogen peroxide in rate of mercaptan
consumption
◦ Confirm best fit model and value of rate and equilibrium
constants
◦ Correlate structure of Pc catalyst with rate and equilibrium
constants
◦ Location of radical coupling
◦ Study effects of substrate size on kinetics

Total Oxidation Mechanism
Via H2O2 (rb)
2RSH + H2O2 ⇔ 2H2O + RSSR
Via O2 (ra)
2RSH + O2 ⇔H2O2 + RSSR
Total Stochiometry
4RSH + O2 ⇔ 2H2O + 2RSSR
Non-Catalytic
Catalytic
−
d[RSH]
dt
≈ ra + rb
2RSH
2RSH

Overall Stoichiometry: 4RSH + O2  2RSSR +2H2O
Simultaneous Mechanisms:
Source: Giles, 1986
AerobicThiol Oxidation by Series /
Parallel Reactions
Non-Pc Hydroxide-Catalyzed (via O2)
1. 2RSH + 2OH-  2RS-+ 2H2O
2. RS- + O2  RSO2
-
3. RS- + RSO2
-  RSSR+ O2
2-
4. O2
2- + 2H2O  H2O2 + 2OH-
5. 2RS•   RSSR
VS.
Non-Catalytic (via H2O2)
1. 2RSH + 2OH-  2RS- + 2H2O
2. RS- + H2O2  RSOH + OH-
(slow)
3. RS- + RSOH  RSSR +OH
Pc-Catalyzed (via O2)
…Depends on Choice of
Rate-Determining Step and
PcM Catalytic Mechanism…
−rnonPcI ≈ 4kapp [RSH]
2
][4 RSHkr appnonPcII ≈−
]][[2 222222
RSHOHkr OHOH ≈−
FOCUS OF THIS STUDY
IS UNDERSTANDING
HOW THE STRUCTURE
OF PC-CATALYST
AFFECTS THE PC-
CATALYZED
MECHANISM

Total Oxidation Mechanism
 Determine ra, by assuming a rate-determining step for
the mechanism of interest
 Use ra and rb to solve for estimated [H2O2], assuming
PSSH
 Knowing [H2O2], solve for rb
 Plug values of ra and rb into total rate of thiol
consumption equation
Via H2O2 (rb)
2RSH + H2O2 ⇔ 2H2O + RSSR
Via O2 (ra)
2RSH + O2 ⇔H2O2 + RSSR
Total Stochiometry
4RSH + O2 ⇔ 2H2O + 2RSSR
Non-Catalytic
Catalytic
−
d[RSH]
dt
≈ ra + rb
2RSH
2RSH
Non-catalytic Case (via O2)
Pure H2O2-induced
Rate of change of H2O2 concentration
][2 RSHkr appa ≈−
]][[2 2222
RSHOHkr OHb ≈−
ba rr
dt
OHd
−≈
][ 22

Catalytic Mechanism A: Coupling of RS
•
to form disulfide occurs in solution
Elementary Steps
i. 2RSH + 2OH-  2RS- + 2H2O
ii. RS-
+ PcCo(II)RS-
…PcCo(II)
iii. RS
-
…PcCo(II)RS
…PcCo(I)
iv. RS
…PcCo(I)+O2RS
…PcCo(I)…O2
v. RS
…PcCo(I)…O2RS
…PcCo(II)…O2
-
vi. RS
…PcCo(II)…O2
-
RS
+PcCo(II)…O2
-
Above steps repeated
R-S• O2
2-
i. 2RSH + 2OH- 2RS- + 2H2O
Cytochrome P-450
Source: Parton, 1994

Catalytic Mechanism A: Coupling of RS
•
to form disulfide occurs in solution
Elementary Steps
i. 2RSH + 2OH-  2RS- + 2H2O
ii. RS-
+ PcCo(II)RS-
…PcCo(II)
iii. RS
-
…PcCo(II)RS
…PcCo(I)
iv. RS
…PcCo(I)+O2RS
…PcCo(I)…O2
v. RS
…PcCo(I)…O2RS
…PcCo(II)…O2
-
vi. RS
…PcCo(II)…O2
-
RS
+PcCo(II)…O2
-
Above steps repeated
R-S• O2
2-
i. 2RSH + 2OH- 2RS- + 2H2O
CoPTS
2
RS-
R-S
O2
-
R-S
O2
-
3 4
R-S
O2
1. 2RSH + 2OH- 2RS- + 2H2O
Catalytic Models
Model I: assumes substrate binding and reduction
of Co(II) center (step 2) is the r.d.s.
Model II: assumes electron transfer from metal
center to coordinated to O2 (step 3) is the
r.d.s.
Model III: assumes RS
•
thiyl radical expulsion
from catalyst cavity (step 4) is the r.d.s.
(takes same form as model II, with different
parameter definitions)
−rI ≈ 4αI [RSH]
−rII ≈
4αII [RSH]
1+ βII [RSH]
][1
][4
RSH
RSH
r
III
III
III
β
α
+
≈−

Catalytic Models
Model IV: assumes substrate binding and
reduction of Co(II) center (step 2) is the r.d.s.
ModelV: assumes electron transfer from metal
center to coordinated to O2 (step 3) is the
r.d.s. (takes same form as model IV, with
different parameter definitions)
ModelVI: assumes 2nd substrate binding and
reduction of Co(II) center (step 4) is the r.d.s.
][]/[1
][4
RSHRSH
RSH
r
IVIV
IV
IV
γβ
α
++
≈−
][1
][4 2
RSH
RSH
r
VI
VI
VI
β
α
+
≈−
][]/[1
][4
RSHRSH
RSH
r
VV
V
V
γβ
α
++
≈−
Catalytic Mechanism B: Coupling of RS
•
to form disulfide occurs in catalyst cavity

Catalytic Mechanism B: Coupling of RS
•
to form disulfide occurs in catalyst cavity
Catalytic Models
ModelVII: assumes electron transfer from Co(I) to
coord O2
-
(step 5) is the r.d.s.
ModelVIII: assumes RSSR product expulsion from
the catalyst cavity (step 6) is the r.d.s. (takes
same form as modelVII, with different
parameter definitions)
2
2
][][1
][4
RSHRSH
RSH
r
VIIVII
VII
VII
γβ
α
++
≈−
2
2
][][1
][4
RSHRSH
RSH
r
VIIIVIII
VIII
VIII
γβ
α
++
≈−

Experimental Set-up
Thiol oxidations conducted
at standard conditions
HP Gas Chromatograph
5890
Flame ionization detector.
A: 100 ml glass vessel
B: Baffle
C: Open port used for
injection and extraction
D: Temperature Probe
E: Pressure Transducer
F: Injector/Extraction valve
G: Needle valve
H: Gas inlet valve
I: Magnetic Stirrer

Experimental Mechanism
1. Thiolate (RS-) binds to
catalyst
2. Dissolved oxygen binds
to catalyst
3. Partial pressure of
oxygen in solution
(Po2*) directly
proportional to O2
available for oxidation
4. Gaseous O2 transported
into solution
RS-
Cat.
O2
PO2
*
PO2
1
2
4
3
RS-
O2
2a1a
1a. Thiolate (RS-) binds to
O2 in solution without
assistance of catalyst
2a. Partial pressure of
oxygen in solution
(Po2*) directly
proportional to O2
available for oxidation
catalyst

GC and Methodology Precision
0
200
400
600
800
1000
0 2 4 6 8
PEAKAREA
TIME (minutes)
0
5
10
15
20
25
30
35
40
45
0.00 1.00 2.00 3.00 4.00
2-METOTALCONVERSION(%)
TIME (h)
F16PcCo_5%O2_Run1
F16PcCo_5%O2_Run2
F16PcCo_5%O2_Run3
Peak 1 Peak 2 Peak 3 Average (%)
Stand
Dev.
% RSD
7.08 6.92 7.23 7.06 +/- 0.13 +/- 1.84
Conv. 1
(%)
Conv. 2
(%)
Conv. 3
(%)
Average
(%)
Stand
Dev.
% RSD
23.0 21.0 20.0 21.3 +/- 1.53 +/- 7.16
Repeated injection of 71mmol/L of 2-ME
Repeated experiments of F16PcCo catalyzed
oxidation of 2-ME under 5% gaseous O2

Preliminary Mass Transfer Tests
0
10
20
30
40
50
60
70
80
90
100
0.00 0.50 1.00 1.50 2.00 2.50
2-MECONVERSION(%)
TIME (h)
RPM=450 RPM=1350 RPM=1800

y = 0.004x + 0.234
R² = 0.998
0
1
1
2
2
3
3
0 100 200 300 400 500 600 700
(pO2/r0)x103(L-h-atm/mmol)
1/EFFECTIVE CATALYST CONCENTRATION (L/mmol)
0
500
1000
1500
2000
2500
3000
0 0.01 0.02 0.03 0.04
INITIALRATES(mmol/L-h)
EFFECTIVE CATALYST CONCENTRATION (mmol/L)
MassTransfer: Gas phase
oxygen must transfer in to
the bulk liquid phase
where reaction occurs
RATE =
kR km[Cat]eff
kR [Cat]eff + km
RATE−1
=
1
km
+
1
kR [Cat]eff
km = 4270 mmol/L-h-atm
F16PcCo Catalyzed Oxidation in
Pure Oxygen
intercept
Mass transfer threshold

0
10
20
30
40
50
60
70
80
90
100
0.00 1.00 2.00 3.00 4.00 5.00 6.00
2-MECONVERSION(%)
TIME (h)
NaOH_Exp.
NaOH_1st Order Model
NaOH_2nd Order Model
vs
Hydroxide-Induced (non-Pc) 2-ME
Oxidation
Parameter Definitions
K1: Thiolate production; K2/k2: Coupling of RS- to dissolved O2; k3: Coupling of 2nd RS- to sulfoxide
(RSO2
-
)
2
2 ]][[4
][
RSHOk
dt
RSHd
app−=−
][
][
2
12
OH
OHKk
kapp
−
=
2 2
3 2 1
2
2
[ ]
[ ]
app
k K K OH
k
H O
−
=
2
[ ]
4 [ ][ ]app
d RSH
k O RSH
dt
− =
Hydroxide-Catalyzed (via O2)
1. 2RSH + 2OH-  2RS-+ 2H2O
2. RS- + O2  RSO2
-
3. RS- + RSO2
-  RSSR+ O2
2-
4. O2
2- + 2H2O  H2O2 + 2OH-
5. 2RS•   RSSR

Oxidation
K1: Thiolate production; k2: Coupling of RS- to dissolved O2
][
][
2
12
OH
OHKk
kapp
−
=
2
[ ]
4 [ ][ ]app
d RSH
k O RSH
dt
− =
0
10
20
30
40
50
60
70
80
90
100
0.00 2.00 4.00 6.00
2-MECONVERSION(%)
TIME (h)
2.58 mmole/L NaOH_Exp.
2.58 mmole/L NaOH_Model
NaOH
(mmol/L)
kapp (liter/mmole-hr)
1.65 4.70E-03
2.58 6.50E-03
5.17 1.20E-02

Oxidation
0
10
20
30
40
50
60
70
80
90
100
0.00 2.00 4.00 6.00
2-MECONVERSION(%)
TIME (h)
Peroxide Induced_Exp.
Peroxide Induced_Model
NaOH
(mmol/L)
1.65 4.70E-03
2.58 6.50E-03
5.17 1.20E-02
]][[2 222222
RSHOHkr OHOH ≈−
kH2O2 = 0.52 liter/mmole-hr
][
][
2
12
OH
OHKk
kapp
−
=

Oxidation
y = 0.002x
R² = 0.989
0.0E+00
2.0E-03
4.0E-03
6.0E-03
8.0E-03
1.0E-02
1.2E-02
1.4E-02
0 1 2 3 4 5 6
kapp(L/mmol-h)
NaOH (mmol/L)
kapp
Linear (kapp)
NaOH
(mmol/L)
1.65 4.70E-03
2.58 6.50E-03
5.17 1.20E-02
K1=10-9.643/10-15.7=1.14x106
k2=1.93x10-6 liter/mmole-hr
]][[2 222222
RSHOHkr OHOH ≈−
][
][
2
12
OH
OHKk
kapp
−
=
PAPER ACCEPTER BY CHEMICAL
ENGINEERING COMMUNICATIONS,
MARCH 2014

0
10
20
30
40
50
60
70
80
90
100
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
2--MECONVERSION(%)
TIME (h)
H16PcCo_PureO2 F16PcCo_PureO2
F64PcCo_PureO2
Experimental Data
CATALYST H16PcCo F16PcCo F64PcCo
fm 0.85 0.30 0.80
(Loas, 2012)
Order of increasing rate of reaction:
F16PcCo<H16PcCo<F64PcCo

0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
0.00 0.20 0.40 0.60 0.80 1.00 1.20
2-MECONVERSION(%)
TIME (h)
F64PcCo_Adjusted F16PcCo_Adjusted
H16PcCo_Adjusted
Experimental Data
CATALYST H16PcCo F16PcCo F64PcCo
fm 0.85 0.30 0.80
(Loas, 2012)
Order of increasing rate of reaction:
H16PcCo<F16PcCo<F64PcCo

0
10
20
30
40
50
60
70
80
90
100
0.00 0.20 0.40 0.60 0.80 1.00 1.20
2-MECONVERSION(%)
TIME (h)
H2O2_Hypothetical F64PcCo_Adjusted
F16PcCo_Adjusted H16PcCo_Adjusted
H2O2-Induced Reaction
]][[2 222222
RSHOHkr OHOH ≈−
[H2O2]= [O2] = 8.02 mmol/L
Henry’s Law

Varying dependencies on dissolved O2
concentration
Model IV-VIII:
Provide more complex dependencies
on [O2]
Expanded Kinetic Models
][])/[]][[(4 212 RSHOHCatOHKkr
I
TI
α
−
≈−
][])/[][(1
][])/[]][][[(4
212
22123
RSHOHOHKK
RSHOHCatOOHKKk
r
II
II
T
II
β
α
−
−
+
≈−
][])/[])[1]([(1
][])/[]][][[(4
22312
221234
RSHOHOKOHKK
RSHOHCatOOHKKKk
r
III
IIIa
T
III
β
++
≈− −
−
Model I:
Model II:
Model III:

H16PcCo Reaction Kinetics (2-ME)
0
10
20
30
40
50
60
70
80
90
100
0 0.5 1 1.5
2-MECONVERSION(%)
TIME' (h)
H16PcCo_5%O2 (EXP.)
H16PcCo_21%O2 (EXP.)
• No significant dependence on
gaseous O2 composition
• At high O2 composition there
is a slight decrease in
reaction rate
• Degradation may be
present!!!

H16PcCo Reaction Kinetics (2-ME)
0
10
20
30
40
50
60
70
80
90
100
0 0.5 1 1.5
2-MECONVERSION(%)
TIME' (h)
H16PcCo_5%O2 (EXP.)
H16PcCo_5%O2 MODEL I
K1: Thiolate production; k2: Substrate binding and reduction of Co(II) metal center
I
TI
α
−
≈−
Model I: Provides best fit for
H16PcCo catalyzed oxidation
of 2-ME
• Substrate binding and
reduction of Co(II) to
Co(I) is rate determining
• Least Lewis acidic
H16PcCo molecule has
difficulty attracting
basic substrate
• k2= 0.0071 L/mmmol-h
H16PcCo 5% O2 21% O2 100% O2
αI 0.22 0.22 0.17

Model II/III:
Provides best fit for
F16PcCo catalyzed
oxidation of 2-ME
F16PcCo Reaction Kinetics (2-ME)
vs][])/[][(1
][])/[]][][[(4
212
22123
RSHOHOHKK
RSHOHCatOOHKKk
r
II
II
T
II
β
α
−
−
+
≈−
][])/[])[1]([(1
][])/[]][][[(4
22312
221234
RSHOHOKOHKK
RSHOHCatOOHKKKk
r
III
IIIa
T
III
β
++
≈− −
−
K1: Thiolate production; K2: Substrate binding and reduction of Co(II) metal center; K3: Electron transfer
from metal center to coordinated oxygen; k4: Radical/product expulsion from catalyst into solution
0
10
20
30
40
50
60
70
80
90
0.00 0.50 1.00 1.50
2-MECONVERSION(%)
TIME' (h)
F16PcCo_5%O2 (EXP.)
F16PcCo_5%O2 MODEL II/III
F16PcCo_21%O2 (EXP.)

][1
][
][4 23
2340
OK
OKk
Cat
r
T
III
+
≈
−
y-intercept = 0 y-intercept = 1/k4
][
][4
23
0
Ok
Cat
r
T
II
≈
−
][
1][4
230
Okr
Cat
II
T
≈−
4234
1
][
1][4
0
kOKkr
Cat
III
T
+≈−
Catalyst Initial Rates
Model II Model III
ASSUMING THIOL
CONCENTRATION IS
LARGE EARLY IN THE
REACTION, β[RSH]>>1
][])/[][(1
][])/[]][][[(4
212
22123
RSHOHOHKK
RSHOHCatOOHKKk
r
II
II
T
II
β
α
−
−
+
≈−
][])/[])[1]([(1
][])/[]][][[(4
22312
221234
RSHOHOKOHKK
RSHOHCatOOHKKKk
r
III
IIIa
T
III
β
++
≈− −
−

vs][])/[][(1
][])/[]][][[(4
212
22123
RSHOHOHKK
RSHOHCatOOHKKk
r
II
II
T
II
β
α
−
−
+
≈−
][])/[])[1]([(1
][])/[]][][[(4
22312
221234
RSHOHOKOHKK
RSHOHCatOOHKKKk
r
III
IIIa
T
III
β
++
≈− −
−
402340
1
][
1][4
kOkkr
Cat
III
T
+≈−
R² = 0.999
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.00 0.50 1.00 1.50 2.00 2.50 3.00
-4000*[Cat]T/r0(h)
1/[O2] (L/mmol)
F16PcCo
• Initial rate analysis needed
to discern between model
II and III
• More Lewis acidity
increases oxidative ability
(substrate binding) of
F16PcCo molecule
• Expulsion of thiyl radical
from catalyst cavity is rate
determining

0
10
20
30
40
50
60
70
80
90
100
0.0 0.5 1.0 1.5 2.0 2.5 3.0
2-MECONVERSION(%)
TIME' (h)
F64PcCo_5%O2 (EXP.)
Model II/III:
F64PcCo catalyzed
oxidation of 2-ME
vs][])/[][(1
][])/[]][][[(4
212
22123
RSHOHOHKK
RSHOHCatOOHKKk
r
II
II
T
II
β
α
−
−
+
≈−
][])/[])[1]([(1
][])/[]][][[(4
22312
221234
RSHOHOKOHKK
RSHOHCatOOHKKKk
r
III
IIIa
T
III
β
++
≈− −
−

R² = 0.995
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50
-4000*[Cat]T/r0(h)
1/[O2] (L/mmol)
F64PcCo
vs][])/[][(1
][])/[]][][[(4
212
22123
RSHOHOHKK
RSHOHCatOOHKKk
r
II
II
T
II
β
α
−
−
+
≈−
][])/[])[1]([(1
][])/[]][][[(4
22312
221234
RSHOHOKOHKK
RSHOHCatOOHKKKk
r
III
IIIa
T
III
β
++
≈− −
−
402340
1
][
1][4
kOkkr
Cat
III
T
+≈−
to discern between model
II and III
• More Lewis acidity
increases oxidative ability
(substrate binding) of
F64PcCo molecule
determining

K1:Thiolate production
K2 or k2: Substrate binding and
reduction of Co(II) metal center
K3 or k3: Electron transfer from
metal center to coordinated oxygen
k4: Radical/product expulsion from
catalyst into solution
Model I:
Model II:
Model III:
Expanded Kinetic Models
I
TI
α
−
≈−
][])/[][(1
][])/[]][][[(4
212
22123
RSHOHOHKK
RSHOHCatOOHKKk
r
II
II
T
II
β
α
−
−
+
≈−
Catalyst Best Fit Model
H16PcCo Model I
F16PcCo Model III
F64PcCo Model III
][])/[])[1]([(1
][])/[]][][[(4
22312
221234
RSHOHOKOHKK
RSHOHCatOOHKKKk
r
III
IIIa
T
III
β
++
≈− −
−

Correlation of Kinetic Parameters
to Phthalocyanine Structure
Lewis Acidity
 Fluorinated groups cause metal
center to become electron deficient,
thereby strengthening RS- substrate
binding (k2 or K2) and decelerating
electron transfer from the metal
center to coordinated O2 (k3 or K3)
 H16PcCo < F16PcCo < F64PcCo
Steric Hindrance
 Bulky fluorinated groups surrounding
metal center of catalyst might hinder
rate of RS- substrate binding (k2 or
K2), while also accelerating product
expulsion (k4)
 H16PcCo ≈ F16PcCo << F64PcCo
][4 RSHr II α≈−
][1
][4
RSH
RSH
r
III
III
III
β
α
+
≈−
-rI k2(L/mmol-h)
H16PcCo 0.0071
-rIII K2(L/mmol) K3(L/mmol) k4(1/h)
F16PcCo 8.00E-07 1.19 8060
F64PcCo 3.46E-06 0.19 17,470

Mass Transfer Resistance
IIIMT rr −≈−
][])/[])[1]([(1
][])/[]][][[(4
)][(
22312
221234
22
RSHOHOKOHKK
RSHOHCatOOHKKKk
HOpk
III
IIIa
T
Om
β
++
≈− −
−
 Mass transfer is tested once again by
comparing a calculated dissolved O2
concentration to that predicted by
Henry’s Law
 Kinetic parameters found using
initial rates were used in calculation
 Calculated [O2]~Henry’s Law [O2]
F16PcCo 8.00E-07 1.19 8060
F64PcCo 3.46E-06 0.19 17,470
K1=10-9.643/10-15.7=1.14x106

0
10
20
30
40
50
60
70
80
90
100
0.00 0.50 1.00 1.50
2-MECONVERSION(%)
TIME' (h)
F64PcCo_5% Oxygen_Exp.
F64PcCo_5% Oxygen_Model
Henry’s Law
F16PcCo 8.00E-07 1.19 8060
F64PcCo 3.46E-06 0.19 17,470
K1=10-9.643/10-15.7=1.14x106

0
10
20
30
40
50
60
70
80
90
100
0.00 0.50 1.00 1.50
2-MECONVERSION(%)
TIME' (h)
Henry’s Law
F16PcCo 8.00E-07 1.19 8060
F64PcCo 3.46E-06 0.19 17,470
K1=10-9.643/10-15.7=1.14x106

0
10
20
30
40
50
60
70
80
90
100
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70
2-MECONVERSION(%)
TIME' (h)
Henry’s Law
F16PcCo 8.00E-07 1.19 8060
F64PcCo 3.46E-06 0.19 17,470
K1=10-9.643/10-15.7=1.14x106

Consequence of ChangingThiol
Structure
More
acidic Larger
More
Reactive
pKa:
9.646.45
2-ME
4-FBT
Steric Hindrance
The rate of substrate binding may decrease with increasing steric bulkiness because of
difficulty to reach the metal center.
Thiyl radical expulsion may increase as steric bulkiness increases because the additional
fluorine atoms might quicken the ejection of these radicals once formed
Acidity
Less basic molecule may decrease the rate of substrate binding

0
10
20
30
40
50
60
70
80
90
100
0.00 0.50 1.00 1.50 2.00 2.50
4-FBTCONVERSION(%)
TIME (h)
4-FBT: NonPc Experimental
1st Order Fit
2nd Order Fit
vs
Hydroxide-Induced (non-Pc) 4-FBT
Oxidation
2
2 ]][[4
][
RSHOk
dt
RSHd
app−=−
][
][
2
12
OH
OHKk
kapp
−
=
2 2
3 2 1
2
2
[ ]
[ ]
app
k K K OH
k
H O
−
=
2
[ ]
4 [ ][ ]app
d RSH
k O RSH
dt
− =
Thiol kapp
2-ME 6.50E-03
4-FBT 2.24E-02
K1=10-6.45/10-15.7=1.45x109
2-ME

0
10
20
30
40
50
60
70
80
90
100
0 0.5 1 1.5 2
THIOLCONVERSION(%)
TIME' (h)
H16PcCo_5% O2_4-FBT
H16PcCo_21% O2_4-FBT
H16PcCo_100% O2_4-FBT
H16PcCo_5%O2_2ME
H16PcCo_21%O2_2ME
H16PcCo_100%O2_2ME
H16PcCo Reaction Kinetics (4-FBT)
• Degradation is apparent in
the more aggressive
thiolate
• Extent of conversion
decreases as gaseous O2
composition increases
• In O2 rich solutions, 4-FBT
more readily converts into
the active thiolate
• High concentration of
electrophilic thiolate
attacks C-H bonds
surrounding H16PcCo
catalyst -

0
10
20
30
40
50
60
70
80
90
100
0.00 0.20 0.40 0.60 0.80 1.00
4-FBTCONVERSION(%)
TIME' (h)
F16PcCo_5% O2_Exp.
F16PcCo_5% O2_Model
F16PcCo_21% O2_Exp.
F16PcCo_21% O2_Model
F16PcCo_100% O2_Exp.
Model II/III:
F16PcCo catalyzed
oxidation of 4-FBT
F16PcCo Reaction Kinetics (4-FBT)
vs][])/[][(1
][])/[]][][[(4
212
22123
RSHOHOHKK
RSHOHCatOOHKKk
r
II
II
T
II
β
α
−
−
+
≈−
][])/[])[1]([(1
][])/[]][][[(4
22312
221234
RSHOHOKOHKK
RSHOHCatOOHKKKk
r
III
IIIa
T
III
β
++
≈− −
−

0
10
20
30
40
50
60
70
80
90
100
0.00 0.50 1.00 1.50
4-FBTCONVERSION(%)
TIME' (h)
F64PcCo_5% O2_Exp.
F64PcCo_21% O2_Exp.
F64PcCo_100% O2_Exp.
F64PcCo_5% O2_Model
Model II/III:
F64PcCo catalyzed
oxidation of 4-FBT
F64PcCo Reaction Kinetics (4-FBT)
vs][])/[][(1
][])/[]][][[(4
212
22123
RSHOHOHKK
RSHOHCatOOHKKk
r
II
II
T
II
β
α
−
−
+
≈−
][])/[])[1]([(1
][])/[]][][[(4
22312
221234
RSHOHOKOHKK
RSHOHCatOOHKKKk
r
III
IIIa
T
III
β
++
≈− −
−

R² = 0.998
R² = 0.982
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 0.50 1.00 1.50 2.00 2.50 3.00
-4000*[Cat]T/r0(h)
1/[O2] (L/mmol)
F16PcCo
F64PcCo
vs][])/[][(1
][])/[]][][[(4
212
22123
RSHOHOHKK
RSHOHCatOOHKKk
r
II
II
T
II
β
α
−
−
+
≈−
][])/[])[1]([(1
][])/[]][][[(4
22312
221234
RSHOHOKOHKK
RSHOHCatOOHKKKk
r
III
IIIa
T
III
β
++
≈− −
−
F16PcCo & F64PcCo Reaction
Kinetics (4-FBT)
402340
1
][
1][4
kOkkr
Cat
III
T
+≈−
to discern between model II
and III
determining
• Fluorine groups serve to
protect catalyst from
degradation pathways

Catalyst/Thiol K2 (L/mmol) K3 (L/mmol) k4 (1/h)
F16PcCo/2-ME 8.00E-07 1.19 8.00E+03
F64PcCo/2-ME 3.46E-06 0.19 1.73E+04
F16PcCo/4-FBT 8.63E-10 0.76 9.93E+03
F64PcCo/4-FBT 6.95E-10 0.29 1.83E+04
 Substrate binding and electron transfer to metal center (K2)
◦ Lewis acidity important for 2-ME oxidations
◦ Steric bulkiness important for 4-FBT oxidations
◦ Less basic 4-FBT has more difficulty binding and transferring
electron to metal center
F16PcCo F64PcCo

F16PcCo/2-ME 8.00E-07 1.19 8.00E+03
F64PcCo/2-ME 3.46E-06 0.19 1.73E+04
F16PcCo/4-FBT 8.63E-10 0.76 9.93E+03
F64PcCo/4-FBT 6.95E-10 0.29 1.83E+04
 Electron transfer from metal center to coordinated O2 (K3)
◦ More Lewis acidic molecule (F64PcCo) yields lower K3 values
despite selected thiol
◦ Electron transfer from metal center to coordinated O2 is an
internal issue
◦ Choice of thiol has little relevance
F16PcCo F64PcCo

F16PcCo/2-ME 8.00E-07 1.19 8.00E+03
F64PcCo/2-ME 3.46E-06 0.19 1.73E+04
F16PcCo/4-FBT 8.63E-10 0.76 9.93E+03
F64PcCo/4-FBT 6.95E-10 0.29 1.83E+04
 Expulsion of Thiyl radical from Catalyst Cavity (k4)
◦ Established as the rate-determining step for F16PcCo & F64PcCo
oxidations of 2-ME and 4-FBT
◦ Greater steric bulkiness causes an increase in expulsion rate in terms
of catalyst and thiol structure
◦ Steric bulkiness has a larger effect on thiol oxidations than Lewis
acidity
F16PcCo F64PcCo

Model I: H16PcCo
NaOH Dependent Reactions?
I
TI
α
−
≈−
0
10
20
30
40
50
60
70
80
90
100
0.00 0.20 0.40 0.60 0.80 1.00 1.20
2-MECONVERSION(%0
TIME' (h)
H16PcCo_1.65mmol/L NaOH
H16PcCo_2.58mmol/L NaOH
 Minimal change in data
cause by stability issues
◦ More NaOH increases
[RS-] due to K1 acid/base
reaction
◦ Increase likelihood of
electrophilic substitution
◦ Increase in NaOH
accelerates the reaction
rate according to the
model yet invokes
deactivation causing a
decrease in effective
catalyst concentration

0
10
20
30
40
50
60
70
80
90
100
0.00 0.10 0.20 0.30 0.40 0.50
2-MECONVERSION(%)
TIME' (h)
F16PcCo_1.65mmol/L NaOH
Model III: F16PcCo
][])/[])[1]([(1
][])/[]][][[(4
22312
221234
RSHOHOKOHKK
RSHOHCatOOHKKKk
r
III
IIIa
T
III
β
++
≈− −
−
describe by rate model
◦ NaOH exists in both
numerator and
denominator
◦ Dependence on NaOH
cancels out
◦ Supports assumption using
initial rate data
(β[RSH]>>1)

0
10
20
30
40
50
60
70
80
90
100
0.00 0.10 0.20 0.30 0.40 0.50 0.60
2-MECONVERSION(%)
TIME (h)
Model III: F64PcCo
][])/[])[1]([(1
][])/[]][][[(4
22312
221234
RSHOHOKOHKK
RSHOHCatOOHKKKk
r
III
IIIa
T
III
β
++
≈− −
−
numerator and
denominator
cancels out
initial rate data
(β[RSH]>>1)

0
50
100
150
200
250
300
0 50 100 150
-rIII(mmol/L-h)
2-ME CONCENTRATION (mmol/L)
[OH-] = 1 mmol/L [OH-] = 2 mmol/L
[OH-] = 5 mmol/L
Model III: F16PcCo
][])/[])[1]([(1
][])/[]][][[(4
22312
221234
RSHOHOKOHKK
RSHOHCatOOHKKKk
r
III
IIIa
T
III
β
++
≈− −
−
numerator and
denominator
cancels out
initial rate data
(β[RSH]>>1)

0
50
100
150
200
250
300
350
400
0 50 100 150
-rIII(mmol/L-h)
[RSH] (mmol/L)
[OH-] = 5 mmol/L
Model III: F64PcCo
][])/[])[1]([(1
][])/[]][][[(4
22312
221234
RSHOHOKOHKK
RSHOHCatOOHKKKk
r
III
IIIa
T
III
β
++
≈− −
−
numerator and
denominator
cancels out
initial rate data
(β[RSH]>>1)

Stability of Pc-Catalysts
0
10
20
30
40
50
60
70
80
90
100
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40
2-MECONVERSION(%)
TIME' (h)
H16PcCo_Baseline
H16PcCo_Reloaded
0
10
20
30
40
50
60
70
80
90
100
0.00 0.10 0.20 0.30 0.40 0.50 0.60
2-MECONVERSION(%)
TIME (h)
F64PcCo_Baseline F64PcCo_Reloaded
Baseline experiment ran under
standard conditions
At completion of baseline
experiment ([RSH]~0) 7.2mmol of
thiol added to solution in order to
reach initial baseline concentration
Catalyst TON TOF
H16PcCo 14600 2.93
F64PcCo 17850 5.51

Disulfide Dependent Reactions?
0
10
20
30
40
50
60
70
80
90
100
0.00 0.20 0.40 0.60 0.80 1.00
2-MECONVERSION(%)
TIME' (h)
H16PcCo_Baseline
H16PcCo_Disulfide Added
• Addition of disulfide to
initial reaction mixture
has no appreciable effect
on rates of thiol
oxidation
• No inhibition by disulfide
(RSSR) once product is
formed
• Supports elimination of
mechanism B models
(claims disulfide is
formed in catalyst cavity)

0
10
20
30
40
50
60
70
80
90
100
0.00 0.10 0.20 0.30 0.40 0.50 0.60
2-MECONVERSION(%)
TIME' (h)
F16PcCo_Baseline
F16PcCo_Disulfide Added
on rates of thiol
oxidation
formed
mechanism B models

0
10
20
30
40
50
60
70
80
90
100
0.00 0.10 0.20 0.30 0.40
2-MECONVERSION(%)
TIME' (h)
F64PcCo_Baseline
F64PcCo_Disulfide Added
on rates of thiol
oxidation
formed
mechanism B models

0
50
100
150
200
250
300
350
40 45 50 55 60 65 70 75
-r0(mmol/L-h)
TEMPERATURE (°F)
F16PcCo_5% O2
F16PcCo_21% O2
F16PcCo_100% O2
0
20
40
60
80
100
120
140
160
180
200
40 50 60 70 80
-r0(mmol/L-h)
TEMPERATURE (°F)
H16PcCo_5% O2
H16PcCo_21% O2
H16PcCo_100% O2
Temperature Dependent Reactions?
H16PcCo
Lower temperatures result in longer
reaction times
Longer reaction times increase
H16PcCo susceptibility to
degradation
F16PcCo
K2
(L/mmol)
K3
(L/mmol)
k4
(L/mmol)
50 oF 4.83E-08 1.37 3221
60 oF 6.50E-08 1.06 3410
70 oF 8.00E-07 1.19 8018
F16PcCo

Summary & Conclusions
 Radical-radical coupling to form disulfide occurs in solution
(outside catalyst cavity)
 Substitution of H atoms with F groups affects Lewis acidity so
severely, that it changes the rate-determining step
◦ Rate determining step for H16PcCo catalyzed oxidation of 2-
Mercaptoethanol is the binding of thiolate (RS-) substrate and
reduction of Co(II) metal center to Co(I)
◦ Rate determining step for F16PcCo and F64PcCo oxidation of
2-Mercaptoethanol is the expulsion of the RS• thiyl radical
from the catalyst molecule (Follows Michalis/Menten-like rate
form)

 Lewis acidity directly affects substrate binding (k2 or K2) and
electron transfer from Co(II) metal center to coordinated O2
(K3)
 Greater steric hindrance increases rate of RS• thiyl radical
expulsion from catalyst molecule (k4)
 Reactivity of thiol must be considered when choosing a suitable
catalyst, as stability issues may arise
 Larger thiols will hinder substrate binding (K2) while
accelerating RS• thiyl radical expulsion from catalyst molecule
(k4)
 Electron transfer from metal center to coordinated O2 is
independent of choice of thiol

 Catalytic oxidations show weak dependency on
concentration of NaOH due to stability issues (H16PcCo) or
based on model form
 Disulfide (RSSR) product does not inhibit reaction once
formed in solution
 Steps dependent on reactant attachment (K2) and product
release (k4) show temperature dependence; not intra-catalyst
electron transfer

Proposed Plan – thiol oxidation
experiments
 Perform a set of runs which considers the variation in thiol (2-
ME) oxidation rate as a function of dissolved catalyst mass
◦ Plot initial rate vs. catalyst mass
◦ Identify reaction-limited and mass-transfer-limited regimes
 Do a limited set of new experiments with 2-ME varying
reaction temperature
◦ Create Arrhenius plot of initial rate vs. temperature
◦ Look for reaction-limited and mass-transfer-limited regimes
 Repeat a thiol (2-ME) oxidation experiment using a used
reaction solution
◦ Simply spike the solution with new thiol
◦ Look for any possible loss of catalyst cavity
 Complete a limited set of new experiments with 4-FBT
◦ Test H16PcCo, F16PcCo and F64PcCo

Proposed Plan – modeling of thiol
oxidation experiments
 Show enhanced reactor set-up, with minimal mass transfer
effects
 Report kinetic data within reaction limited regime
 Present experimental data with error bars, especially if repeat
runs have been made
 Do a better job linking kinetic parameters to chemical
structure and activity of the catalysts
◦ How do they relate to degree of fluorination
◦ Emphasize novelty of F64PcCo in catalyzed thiol oxidation
◦ Provide evidence supporting SHU hypothesis that F64PcCo is a superior
catalyst
 Try to use simple, semi-quantitative means to eliminate
outright potential models derived from Mechanisms A and B
◦ Consider using initial rates from experimental data

Recommendations
 Verifying and quantifying catalyst decay
◦ Confirming degradation pathways of H16PcCo, F16PcCo
and F64PcCo (if applicable)
◦ Question why F64PcCo eventually loses activity
 Understanding the reactivity of highly sensitive
thiols, ie. 4-FBT
 Study other thiols that may be industrially
relevant
 Study thiol oxidations in aqueous solvent

Acknowledgements
 Advisor Prof. Robert B. Barat for continual guidance, patience and support
 Committee members: Prof. Basil C. Baltzis; Prof. Reginald P.T.Tomkins; Prof. Norman Loney; Prof.
Xianqin Wang; Prof. Robert Farrauto for their strong interest and efforts in the success of the project
 Prof. Sergiu Gorun as the source of F64PcCo catalyst and initial contribution and establishment of the
project
 Dr.Andreis Loas for thought-provoking discussions on the chemistry of thiols and phthalocyanines
 Mr. Hemantbhai Patel for synthesis of F64PcCo catalyst at Seton Hall University
 New Jersey Institute ofTechnology and National Science Foundation for generous financial support
 Neville and Orla Reid for instilling within me the importance of education
 Karen Joyce for constant support and settling for cheap dates so that I can pursue my degree
 Friends and family for their prayers and reassuring words of confidence

ReidN_PhD_Defense

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