CATALYSIS I . The HYDROFORMYLATION REACTION

transcript

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

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

Hydroformylation Hydroformylation with rhodium phosphite/phosphines

Results of rhodium catalysed hydroformylation with various ligands

Linearity 40-96% depending on L

L4RhH8% linear if L=

62% linear if L=

P(OEt)3

P(OCH2CF3)3

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

8.3. Rhodium tpp mechanism, dimers

LRhCOL

Positive effect of raising H2 pressure

8.3. Rhodium cycle

8ee 7c

8ae 7t

8. HydroformylationKinetics, overall (M=RhL3, L=any ligand, Ol=alkene)

B product

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

CH2ORh

H(O)CC2H4R

CH2 CHR

rds, type I

resting state

CH2CH2

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

CH2ORh

H(O)CC2H4R

CH2 CHR

rds, type II

resting state

CH2CH2

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

migration

PPh3PPh3

COPPh3

PPh3PPh3

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

4e 4ee

PPh3OC

HRhPPh3

PPh3PPh3

COPPh3

HRhPPh3

COPPh3

PPh3PPh3

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

de-mister

cooler

separator

off-gas

product

bleedcatalyst

regeneration

8.5. HydroformylationRhodium LPO liquid

catalyst recycle

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

SO3NaNaO3S

8.7. Hydroformylation Ruhrchemie-Rhône Poulenc process

aldehyde

alkene

syngas

exhaust

8.8. Hydroformylation one-phase, two phase

PSO3Na

NMP,org.,cat.

org.,NMP

NMP,water,cat

NMP,cat

waterextractions

extractions

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

PPh3PPh3

COPPh3

PPh3PPh3

8. Hydroformylation Mechanistic Scheme; Why Bidentates

rearrangement

CH2CH2

H(O)CC2H4R

CH2 CHR

8. Hydroformylation Novel bidentates

Eastman, 1987 Union Carbide 1997

general formula of diphosphite"BISBI"

OP(OR)2

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

PPh2PPh2

11 12 13

8. HydroformylationRhodium diphosphine catalysts

Ph2P PPh2

Ph2P PPh2 Ph2P PPh2Ph2P PPh2 PPh2PPh2

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

BINAS Hoechst/celanese Herrmann

8. Hydroformylation Novel bidentates 3

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

PPh2 PPh2

8. Hydroformylation Geometry of bidentate Xantphos/rhodium

Fig. 6.15. Bis-equatorial coordination of Xantphos

RhPh3P

Table 8.2. Hydroformylation Bite angle effects in Xantphos ligands

Hydroformylation of octene-1 (1.2 M)

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

steric hindrance

8.3. Hydroformylationdppf Electronic Ligand Effect

for R see Table 6.1.

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

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

O S XR =

IR spectra of complexes

RhH(ligand)CO (ligand = 36–41, 29)

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

8.13. Hydroformylation Linearity and isomerisation

Linear aldehyde

Branchedaldehyde

CO, H2

8.14. Hydroformylation Internal alkenes Table 8.4.

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

Bulky phosphite, q = 170°, and its rhodium hydride complex

8. Hydroformylation Novel bidentates

Eastman, 1987 Union Carbide 1997

general formula of diphosphite "BISBI"

OP(OR)2

8.18. Hydroformylation Bidentate phosphites

tButBu tBu

tButBu

P(OAr)2

8.17. Hydroformylation, diphosphites

P(OR)2O

P(OR)2

Oa b c

8.17. Hydroformylation Structure, NMR spectroscopy

P COCO

Mortreux

Donor, apical; 4 atoms in bridge, yet a-e

8. Hydroformylation Structures of dimers

orange red

CO2 + H2

P + 2 CO

8. Asymmetric Hydroformylation

CHOCHO

+CO/H2

UC-P2*

R3SiSiR3

SiR3 R3Si

R3SiSiR3

SiR3 R3Si

8a (R = Me)8b (R = Et)8c (R = tert-Bu Me2)

8.21. Asymmetric HydroformylationAtropisomerism

8.22. Asymmetric HydroformylationAtropisomerism, bisnaphthol, match-mismatch effects

R3SiSiR3

SiR3 R3Si

R3SiSiR3

SiR3 R3Si

8.23. Asymmetric Hydroformylationmatch-mismatch effectsBINAPHOS

PPh2Me

46 (R,S)-BINAPHOS

47 (R,S)

50 (R)

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)

PPh2Me

46 (R,S)-BINAPHOS

47 (R,S)

50 (R)

49a (S,R)49b (R,R)

8.23. Asymmetric Hydroformylation BINAPHOS structure, ae!

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

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CATALYSIS I . The HYDROFORMYLATION REACTION

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