77
CATALYSIS I. THE HYDROFORMYLATION REACTION
CATALYSIS I. THE HYDROFORMYLATION REACTION
THE HYDROFORMYLATION REACTION Oldest process still in use Responsible for the production of
materials from a homogeneous catalyzed reaction
100% atom recovery
THE HYDROFORMYLATION REACTION
R R H
O R
H O"normal"linear product
"iso"branched product
catH2 CO++ +
Fig. 7.1. The hydroformylation reaction
HYDROFORMYLATION THERMODYNAMICS
H2 + CH3CH=CH2 + CO CH3CH2CH2C(O)H G 63 -138 -117 (l) = -42 kJ.mol-1 H 21 -109 -238 = -150 kJ.mol-1
H2 + CH3CH=CH2 CH3CH2CH3
G 63 -25 = -88 kJ.mol-1
H 21-105 = -126 kJ.mol-1
COBALT CATALYZED HYDROFORMYLATION REACTION
A prototype homogeneous metal catalysis
- precatalyst to an active complex- steps involving organometallic
reactions- 16 e to 18 e transition steps- possible geometries of
intermediates
STEP a
- Formation of the catalytically active species (16 e) from HCo(CO)4
- HCo(CO)4 from Co2(CO)8 + synthesis gas (CO + H2)
Reaction conditions:(200 – 300 bar, 120-170oC)
STEP aPreferred geometry of the intermediate: (based on calculations)
STEP b
binding of the alkene to the active catalyst - forms 18 e complex
STEP bTheoritical calculations indicate a slightly stable 4 (less steric hindrance). Structure 5 has the requisite coplanar geometry for Co, H, and the double bond C atoms)
STEP c1,2 alky insertion - reversible
-elimination is highly possible but
high CO partial pressure will
stabilize the 18 e- complex
STEP c
initial 16e complex18 e complexes upon CO addition
Step d
CO insertion (1,2 alkyl migration)
STEP d
18e 16e
STEP eoxidative addition (H2) –reductive elimination (product) sequence.
STEP e
8. Hydroformylation A comment about metal-ligand ratio
Consider the following exercise. The catalytically active complex is involved in the following equilibrium:
L + HM(CO) LHM(L) + CO The selective and fast catalyst species we want is HM(L) and we have determined that at a certain pressure we need a twenty-fold excess of L in order to have 95 % of M in the M(L) state. The concentration of M = 10-3 molar. Suppose we want to reduce the concentration of M to 10-5. What should we do with the concentration of L (at constant pressure of CO). What ratio L/M should one choose? What happens if the ratio is kept at 20?(calculate the equilibrium constant from the first example and then calculate the required concentration of L at M = 10-5 molar)
HYDROFORMYLATIONRHODIUM CATALYSTS, MONODENTATES
tppms "bulky" phosphite UCC ligand
O
OP O
OP
OO
R
R
R
P
SO3Na
P
tpp
Hydroformylation Hydroformylation with rhodium phosphite/phosphines
O
O
+
Results of rhodium catalysed hydroformylation with various ligands
L4RhH
Linearity 40-96% depending on L
L4RhH8% linear if L=
62% linear if L=
P(OEt)3
P(OCH2CF3)3
O
L4RhH
BASF, L=PPh3
700 bar, 120 °C
L= bulky phosphite,
10 bar, 80 °C
L4RhH<25 m/m/h
4000 m/m/h
L= PPh3
L= bulky phosphite
HydroformylationRhodium catalysts for propene
Rh/triphenylphosphine: linearity 60 to 96 %
Union Carbide Corporation, now Dow Chemicals 30 bar, at 120 °C, at high phosphine concentrations linearity 92%. 300 mol.mol-1(Rh).h-1.
Low ligand concentrations, 10-20 mM, 1 mM Rh10-20 bar and 90 °Clow linearities (70%), 5-10,000 mol.mol-1(Rh).h-1.
Rhodium TPP mechanism 1
3c
2ae
3t
12ee
HRh
CO
COL
LHRh
L
COOC
LH
Rh
COL
L
L
HRh
COLL
HRh
LLOC
COCOL
8.3. Rhodium tpp mechanism, dimers
3c
2ae
3t
19
2ee
HRh
CO
COL
LRhCOL
LRh
COL
CO
C
CO
OHRh
L
COOC
LH
Rh
COL
L
L
H
Rh
COLL
H
Rh
LLOC
COCOL
H2
Positive effect of raising H2 pressure
8.3. Rhodium cycle
8ee 7c
6ae
4ee
5c
3c
2ae
5t
4ae
3t
1
8ae 7t
6ee
2ee
HRh
CO
COL
L
CRh
CO
LL
O CH2
CH3
CH
O CH2
CH3
CRh
L
L
O CH2
CH3
OCOC
HRh
L
COOC
LH
Rh
COL
L
L
HRh
COLL
HRh
LOC
L
CH2Rh
COLL
CH3
CH2
Rh
COCO
L
L
CH3
HRh
LLOC
CH2
Rh
LCO
OC
L
CH3
CO
C2H4
COL
CO
H2
CO
8. HydroformylationKinetics, overall (M=RhL3, L=any ligand, Ol=alkene)
F
F
E
D
C
B
B product
G
F
E
D
C
BA
k7
k6
k5
k4
k3
k2
k-6
k-5
k-4
k-3
k-2
k-1
k1
MH + HC(O)R MC(O)R + H2
MC(O)R(CO)MC(O)R + CO
MC(O)RMR(CO)
MR(CO)MR + CO
MRMH(Ol)
MH(Ol)MH + Ol
MH + COMH(CO)
Scheme 6.1. Hydroformylation
HydroformylationKinetics, resting state, type I
CO
Rh
CO
COL
L
RCH2
CH2ORh
H
CO
L
L
Rh
H
CO
COL
L
H(O)CC2H4R
H2
2 CO
CO
CH2 CHR
CH2
CHR
- CO
rds, type I
resting state
Rh
CO
L
L
CH2CH2
R
8. HydroformylationKinetics, rate equation, type I
equation d'Oro v = k [C3H6]0.54[PPh3]-0.7[Rh]1
(conditions 90-110°C, 1-25 bar CO, 1-45 bar H2, PPh3/Rh ratio 300:1 to 7:1)
v = k1k2k3[Rh][C3H6]
k1k2[C3H6] + k1(k-2 + k3) + k-1(k-2 + k3)[L]
v = kA [Rh] [C3H6]
kB + kC[CO]“type I kinetics”
8.2.2. HydroformylationKinetics, resting state, type II
CO
Rh
CO
L
L
RCH2
CH2ORh
H
CO
L
L
Rh
H
CO
COL
L
H(O)CC2H4R
H2
CO
CO
CH2 CHR
CH2
CHR
- CO
rds, type II
resting state
Rh
CO
OCL
L
CH2CH2
R
Rh
CO
COL
L
RCH2
CH2O
CO
8. HydroformylationKinetics, rate equation, type II
°conditions:75 CH2 33-126 barCO 40-170 bar
[H2] [RhH(CO)4] [CO]
rate expression Marko' v = k
rate equation Garland v = k [RC(O)Rh(CO)4]1[CO]-1.1[H2]1[3,3-DMB]0.1
v = k-6k7[Rh][H2]
k-6 + k6[CO] + k7[H2]
“type II kinetics”
8.2.2. Rhodium tpp cycle, type I kineticselectronic effects
][]][[)(
LBRhalkeneAItypeRate
8ee
7c
6ae
4ee
5c
3c
2ae
5t
4ae
3t
8ae
7t
6ee
2ee
CH
O CH2
CH3
CRh
L
L
O CH2
CH3
OCOC
C2H4
CO
CO
H2
CO
migration
migration
H
Rh
CO
PPh3PPh3
H
Rh
CO
COPPh3
H
Rh
PPh3
COPPh3
H
Rh
PPh3
COOC
H
Rh
CO
COPPh3
PPh3H
Rh
CO
PPh3PPh3
PPh3H
Rh
PPh3
COOC
PPh3
ee ae
linear aldehyde mixed aldehydes
*
8.4. Rhodium complex isomers for regioselective propene hf
8.4. Rhodium complex isomers; regioselectivity
4ae 4a
3t 3c10c 10t
1 2ee 2ae
linear aldehyde mixed aldehydes
4e 4ee
HRh
PPh3OC
OCH
Rh
PPh3OC
PPh3H
Rh
COOC
PPh3H
RhCO
PPh3
PPh3
HRhPPh3
COOC
PPh3H
RhCO
PPh3PPh3
PPh3H
RhCO
COPPh3
PPh3
HRhPPh3
COOC
HRhPPh3
COPPh3
HRhCO
COPPh3
HRhCO
PPh3PPh3
PPh3
8. Steric effects for regioselective hfTable 8.1. Hydroformylation of methyl-substituted 1-alkenes Alkene Rate, mol.mol-1.h-1 Linearity, %
1-pentene 11,300 78.44-Me-1-pentene 9,300 78.04,4-Me2-1-pentene 5,300 85.03-Me-1-pentene 9,600 91.03,3-Me2-1-pentene 7,600 99.0 Conditions: 90 °C, p(CO/H2) = 20 bar, [Rh]=0.5 mM, [PPh3]=5 mM, [alkene]=0.5 M,initial rates at <20% conversion, no isomerization was observed [18].
8. HydroformylationRhodium LPO stripping
reactor
propene, CO, H2
propene, CO, H2
de-mister
cooler
separator
off-gas
product
bleedcatalyst
regeneration
8.5. HydroformylationRhodium LPO liquid
catalyst recycle
propene, CO, H2
propene, CO, H2
reactor
cooler
separator
off-gas
product
bleedcatalyst
regeneration
8.6. HydroformylationRhodium tppts
Ruhrchemie-Rhone Poulenc 1986Propene and 1-buteneSame chemistry as tpp
P
SO3NaNaO3S
SO3Na
8.7. Hydroformylation Ruhrchemie-Rhône Poulenc process
aldehyde
alkene
syngas
water
syngas
exhaust
steam
8.8. Hydroformylation one-phase, two phase
SO3Na
PPh2
tppms
PSO3Na
DPBS
NMP,org.,cat.
water
org.,NMP
NMP,water,cat
NMP,cat
waterextractions
extractions
dist.
NMP
product
alkene
8.7. Hydroformylation Summary of hydroformylation catalysts
Catalyst Co Co/phosphine Rh/phosphine Pd/phosphine Pressure, bar 200 70 30 60Temperature, °C 140 170 120 100
Substrate C3 C3 C3,4
internal C10+ terminal allProduct aldehyde alcohol aldehyde aldehydeLinearity, % 60‑70 70‑90 70‑95 70-95Alkane by‑product, %2 10‑15 0 ?Corrosion + + ‑ ?Metal deposition + + ‑ -Heavy ends + + ‑ ?Catalyst costs (Co=1) 1 10 1000 500
8. HydroformylationRhodium catalyst isomers for propene
H
Rh
CO
PPh3PPh3
H
Rh
CO
COPPh3
H
Rh
PPh3
COPPh3
H
Rh
PPh3
COOC
H
Rh
CO
COPPh3
PPh3H
Rh
CO
PPh3PPh3
PPh3H
Rh
PPh3
COOC
PPh3
ee ae
linear aldehyde mixed aldehydes
*
8. Hydroformylation Mechanistic Scheme; Why Bidentates
CO
rearrangement
Rh
CO
COL
L
RCH2
CH2O
Rh
CO
COL
L
Rh
H
CO
L
L
Rh
H
CO
COL
L
Rh
H
CO
LL
L
CH2CH2
R
CO L
H(O)CC2H4R
H2
CO
CO
CO
CH2 CHR
CH2
CHR
- CO
8. Hydroformylation Novel bidentates
Eastman, 1987 Union Carbide 1997
general formula of diphosphite"BISBI"
OP(OR)2
OP(OR)2
tBu
tBu
PPh2
PPh2
8.9. Table 8.1. Hydroformylation; Novel bidentatesLigand Bite angle
Rate m.m–1.h–1
Ratio l:b
12 126 2550 2.6–4.3BISBI, 11 113/120 3650 25
13 107 3200 4.4–12DIOP [also 56] 102 3250 4.0–8.5dppf [also 33] 99 3800 3.6–5
dppp 91 600 0.8–2.6dppe 85 2.1PPh3
a 6000 2.4
PPh2
PPh2
PPh2
PPh2
PPh2PPh2
11 12 13
8. HydroformylationRhodium diphosphine catalysts
Ph2P PPh2
OO
Ph2P PPh2 Ph2P PPh2Ph2P PPh2 PPh2PPh2
Fe
BISBI DIOP dppf dppe
Bite angle 113 107 102 99 85
l/b ratio 66 12 8.5 2.4
Devon, 1987, Casey, 1992 13 4-5Consiglio, 1973 Unruh, 1982
8. Hydroformylation Novel bidentates 2
PAr2
PAr2
SO3Na
SO3Na
NaO3S
NaO3S
BINAS Hoechst/celanese Herrmann
Ar =
SO3Na
8. Hydroformylation Novel bidentates 3
O
PPh2PPh2
(patent to Shell, 1987)
Linear/ branched = 10
8.10. Hydroformylation Bite angles in Xantphos ligands
DPEphos (35) 102° Benzoxantphos (34) 120.6° R = H, Nixantphos (32) 114.1° R = Bn, Benzylnixantphos (33) 114.2
Isopropxantphos (31) 113.2° Xantphos (30) 111.4° Thixantphos (29) 109.6°
Sixantphos (28) 108.5° Phosxantphos (27) 107.9°Homoxantphos (26) 102.0°
OPPh2 PPh2
O
S
PPh2 PPh2
O
PPh2 PPh2
O
Si
PPh2 PPh2
O
PPh2 PPh2
O
PPh2 PPh2
O
P
PPh2 PPh2
O
NR
PPh2 PPh2
O
PPh2 PPh2
8. Hydroformylation Geometry of bidentate Xantphos/rhodium
Fig. 6.15. Bis-equatorial coordination of Xantphos
H
RhC
CP
P O
O
O
H
RhPh3P
CP
P
O
O
Table 8.2. Hydroformylation Bite angle effects in Xantphos ligands
Hydroformylation of octene-1 (1.2 M)
H
RhOC
C
PR2
PR2
O
O X R =
X n l/b H, H 102 7PPh 105 18SiMe2 109 34S 111 41C=CMe2 112 50
8. Hydroformylation Bite angle effects, steric hindrance
4ae
RH
Rh
PP
OC
4ee
H
Rh
COP
PR
RRhP
P
COH
HRh
P
P
CO
R
steric hindrance
8.3. Hydroformylationdppf Electronic Ligand Effect
for R see Table 6.1.
Fe
R
R
P
R
Rh
R
P
Fig. 6.11. Ferrocene-derived diphosphine
Hydroformylation with substituted aryl phosphines Fe[C5H4P(C6H4R)2]2 Ar=
i-value (Ar) linearity relative rate isomerization % % 2-hexene Ph 4.3 84 7.2 4 p-Cl-C6H4 5.6 87 9.3 5 m-F-C6H4 6.0 89 13.7 5 p-CF3-C6H4 6.3 92 13.8 6 (conditions 110°C, 8 bar CO/H2 = 1:1, 1-hexene, (Unruh and Christenson [14]),
8. Hydroformylation & NMR Electronic effects in Xantphos ligands
X = -Rh JH-Rh JP-Rh JP-H rate isom % l/b
H
RhOC
C
PR2
PR2
O
O S XR =
CF3 850 4.4 135 3.6 158 7 89 Cl 840 5.9 132 8.4 68 7 68 H 6.6 128 15 107 5 50 F 835 6.3 131 11 75 6 52 Me 831 7.3 126 18 78 5 44 MeO 825 7.3 125 21 45 6 37
NMe2 814 8.8 122 28 29 5 45
8.12. Hydroformylation Electronic effects in Xantphos ligands
H
RhOC
C
PR2
PR2
O
O S XR =
IR spectra of complexes
RhH(ligand)CO (ligand = 36–41, 29)
1
23
4
36
37
38
29
39
40
41
2100 2000 1900 cm-1
8.12. HydroformylationIR of RhH(xant)(CO)2
IR frequencies of complexes RhH(diphosphine)(CO)2
Substituent R i-Value CO eq-ap (cm–1) CO eq-eq (cm–1)
N(CH3)2 1.7 2027, 1960 (50%) 1983, 1935 (50%)
OCH3 3.4 2034, 1966 1990, 1942
H 4.3 2037, 1972 1994, 1946
F 5.0 2041, 1975 1997, 1950
Cl 5.6 2042, 1977 1999, 1952
CF3 6.4 2046, 1982 (90%) 2004, 1957 (10%)
CO-eq-eqCO-eq-ap
Ar = R
S
O P
P
H
RhCO
COAr2
Ar2
H
RhOC
COP
PO S
Ar2
Ar2
8.13. Hydroformylation Linearity and isomerisation
RhLn
RhLn
Linear aldehyde
Branchedaldehyde
CO, H2
CO, H2
LnRhH
8.14. Hydroformylation Internal alkenes Table 8.4.
OPP
OPP
OO
31 32
Ligand Substrate l:b ratiob % linear ald
t.o.fc.
PPh3 2-octene 0.9 46 39
31 9.5 90 65
32 9.2 90 112
PPh3 4-octene 0.3 23 2
31 6.1 86 15
32 4.4 81 20
120 °C 2 bar
Table 8.5. Hydroformylation rhodium monophosphite
Ligand R3PR=
‑value q‑value linearity of product %
n-Bu 4 132 71n-BuO 20 109 81Ph 13 145 82PhO 29 128 862,6-Me2C6H3O 28 190 474-Cl-C6H4O 33 128 93CF3CH2O 39 115 96(CF3)2CHO 51 135 55
8.15. Hydroformylation Hydroformylation with rhodium bulky phosphite
O POO
Bulky phosphite, q = 170°, and its rhodium hydride complex
Rh
H
CO
LCOCO
= L
8. Hydroformylation Novel bidentates
Eastman, 1987 Union Carbide 1997
general formula of diphosphite "BISBI"
OP(OR)2
OP(OR)2
tBu
tBu
PPh2
PPh2
8.18. Hydroformylation Bidentate phosphites
O
O
P
P
O
O
O
O
tBu
tBu
tBu
tButBu tBu
tButBu
OO
P(OAr)2
P(OAr)2
CO2Me
CO2Me
42
Ar =
41
8.17. Hydroformylation, diphosphites
H
RhC
C
O
O tBu
tBu
P(OR)2O
P(OR)2
O
H
RhC
PP
OC
OH
RhC
CP
PO
O
O
O
O
Oa b c
8.17. Hydroformylation Structure, NMR spectroscopy
O
Me
N
P COCO
H
P
Rh
MePh
PhPh
PhPh
Mortreux
Donor, apical; 4 atoms in bridge, yet a-e
8. Hydroformylation Structures of dimers
ba
P Rh
CO
P
Rh
O
OP
CO
P
PRh
PRh
P
P
O
O
orange red
P Rh
H
PCO
CO2 + H2
P Rh
CO
P
Rh
O
OP
CO
P + 2 CO
8. Asymmetric Hydroformylation
CHOCHO
+CO/H2
[Rh]
O
OP
O O
O
OP
RRBu
BuBu
Bu
R
RR
R
2 2
2
11
2
t
tt
t
UC-P2*
OO
OP O
O
OP
R3SiSiR3
SiR3 R3Si
OO
OP O
O
OP
R3SiSiR3
SiR3 R3Si
8a (R = Me)8b (R = Et)8c (R = tert-Bu Me2)
9a (R = Me)9b (R = Et)9c (R = tert-Bu Me2)
8.21. Asymmetric HydroformylationAtropisomerism
O O
POO
P
8.22. Asymmetric HydroformylationAtropisomerism, bisnaphthol, match-mismatch effects
OO
OP O
O
OP
R3SiSiR3
SiR3 R3Si
OO
OP O
O
OP
R3SiSiR3
SiR3 R3Si
44a (R = Me)44b (R = Et)44c (R = tert-Bu Me2)
45a (R = Me)45b (R = Et)45c (R = tert-Bu Me2)
8.23. Asymmetric Hydroformylationmatch-mismatch effectsBINAPHOS
O P O
O
PPh2
O P O
O
PPh2
PPh2
O P O
O
O P O
O
P
Me
Me
ClMe
PPh2Me
Cl
O P O
O
46 (R,S)-BINAPHOS
48(R)
47 (R,S)
50 (R)
2
49a (S,R)49b (R,R)
8.23. Asymmetric Hydroformylationmatch-mismatch effectsBINAPHOS
Ligand % e.e.
46 (S,R) 94 (S)
46 (R,R) 25 (R)
47 (R,S) 85 (R)
48 (R,--) 83 (R)
49 (S,R) 94 (S)
49 (R,R) 16 (R)
50 (--,R) 69 (S)
O P O
O
PPh2
O P O
O
PPh2
PPh2
O P O
O
O P O
O
P
Me
Me
ClMe
PPh2Me
Cl
O P O
O
46 (R,S)-BINAPHOS
48(R)
47 (R,S)
50 (R)
2
49a (S,R)49b (R,R)
8.23. Asymmetric Hydroformylation BINAPHOS structure, ae!
O P O
O
RhCO
CO
H
PPh2
JP-H
JP-Rh
JP-P
Exam IIIMarch 7, Wed 6-7:30
Comprehensive Final Exam, March 21 Wed. 7:30 -9:30 CTC 102
Write solubility product expressions for the followingcompounds.Ba3(PO4)2 PbI2FePO4 Ag2S
Calculating Ksp from solubility dataThe solubility of silver dichromate, Ag2Cr2O7, (molar mass = 431.8 g/mol) in water is 1.59 g/L. Calculate Ksp.
Calculating KspThe pH of a saturated solution of magnesium hydroxide (milk of magnesia) was found to be 10.52. From this, find Ksp for magnesium hydroxide.
Solubility from KspWhat is the solubility of magnesium hydroxide in a solution buffered at pH 8.80? Ksp Mg(OH)2 = 6.3 x 10-10
Common ionWhat is the solubility (in grams per liter) of strontium sulfate, SrSO4 (molar mass = 183.69), in 0.23 M sodium sulfate, Na2SO4? Ksp = 3.2 x 10-7
A 0.150-L solution of 2.4 x 10-5M MgCl2 is mixed with 0.050 L of 4.0 x10-3 M NaOH. Calculate Qc for the dissolution of Mg(OH)2. No precipitate has formed. Is the solution supersaturated, saturated, or unsaturated? Ksp Mg(OH)2 = 5.2 x 10-24
PRECIPITATE?
