Organic Building Blocks Derived From Carbon Dioxide

Nickeisha StephensonStahl and Gellman groupsOctober 25th 2007

2

The Carbon Cycle

http://www.eo.ucar.edu/kids/green/images/carboncycle_sm.jpgLiu, C-J., Mallison, R.G., Aresta, M., Utilization of Greenhouse gases, ACS Symposium Series, 2003

Since the pre industrial era CO2 levels have risen from 270 ppm-380 ppm

3

Where is our excess CO2 coming from

Transportation26%

Electrical Energy Production

36%

Industries24%

HeatingCivil Industrial

14%

Liu, C-J., Mallison, R.G., Aresta, M., Utilization of Greenhouse gases, ACS Symposium Series, 2003

4

Industrial Sources of Carbon

Fossil raw materials

mineral oil, natural gas, coal

3

Basic products and intermediates

CO, methanol, arenes,ethylene oxide, etc.

300

End Products

plastics, fertilizers, plant protection agents,pharmaceuticals, etc.

30000

CO2

Organics

Chemical Products

Recycle

1013 tons of carbon finite resource

Atmosphere – 1014 tons carbon

Carbonates -1016 Tons carbon

5

Closing the Cycle

CO2 Capture

6

CO2 usage industrially

Liu, C-J., Mallison, R.G., Aresta, M., Utilization of Greenhouse gases, ACS Symposium Series, 2003

7

Carbon Dioxide Produced Anually

26,100 Mt

CO2 ChemicallyTransformed Annually

120Mt

Large Available Carbon Feedstock

Liu, C-J., Mallison, R.G., Aresta, M., Utilization of Greenhouse gases, ACS Symposium Series, 2003

8

Carbon Dioxide Thermodynamics

C (s) + H2 (g) CH4 (g)

C (s) + 2H2 (g) CH3OH (l)+ 1/2 O2 (g)

C (s) + 1/2 O2 (g) CO (g)

C (s) + O2 (g) CO2 (g)

Free Energy Of FormationCarbon Species

-50.75

-166.10

-137.15

-394.01

GfkJ mol-1

CO2 is carbon in its most oxidized form

Liu, C-J., Mallison, R.G., Aresta, M., Utilization of Greenhouse gases, ACS Symposium Series, 2003

9

In Other Words

CO2

En

erg

y

Chemicalproducts

In order to make CO2 into a useful compound, energy needs to be supplied to reduce the oxidized species

Sources of Energy for CO2 Activation

1) Chemical

2) Photochemical

3) Electrochemical

4) Biological

Sakakura, T. Choi J-C., Yasuda, H.Chem. Rev. 2007, 107, 2365-2387

10

MO Diagram CO2

C OO+ --

[M] C

O

O

1. Salahub, D.R. and Russo, N., Metal Ligand Interactions: From atom Clusters, to surfaces, 1991; p 175-197

11

Some Not So Unfamiliar Reactions Of Carbon Dioxide

" Anhydrous Carbonic Acid"

MgBr+ CO2

OMgBr

O

NHR

R CO2 RN ONa

O

R

ONa

ONa

O

+

CO2+OHNaOH

Ether

Na metal

Liu, C-J., Mallison, R.G., Aresta, M., Utilization of Greenhouse gases, ACS Symposium Series, 2003

12

Basic CO2 Insertion Mechanism

CO2

Ln[M]

ECO

O

E

OLn[M]E

Ln[M]

E

O

C

O

OLnM

E = C, O, H,Elimination

Product

13

CO2

M-H

M-OM-C

C OH

OH OH

O H NMe2

OH O

OMe

O O

ORR

OO

R O

x

O O

O

R

14

Insertion into an M-C Bond

CO2

M-H

M-OM-C

C OH

OH OH

O H NMe2

OH O

OMe

O O

ORR

OO

R O

x

O O

O

R

15

Relative Rates of Insertion

RhPh3P

Ph3P PPh3 CO2 RhPh3P

Ph3P PPh3

OO

RhMe3P

Me3P PMe3CO2 Rh

Me3P

Me3P PMe3

OO

Vs.

PMe3 > PPh3

Increasing the basicity of the phosphine ligand, increases electron density on the metal, allowing for faster CO2 insertion

Kolomnikov, I.S., Gusev, A.O., Belopotapova, Grigoryan, M.Kh., Lysyak, T.V., Struchkov, Yu. T., Volpin, M.E J. Organometallic Chem., 1974, 69, C10-C12

16

RhMe3P

Me3P PMe3

CH3

CO2 RhMe3P

Me3P PMe3

OCH3

O

RhMe3P

Me3P PMe3CO2 Rh

Me3P

Me3P PMe3

OO

Vs.

Me > Ph

Decreasing electron withdrawing ability of R group, increases electron density at the metal center, thereby increasing CO2 insertion

Darensbourg, D., Grötsch, G., Wiegreff, P., Rheingold, A, Inorg. Chem., 1987, 26, 3827-3830

17

Benzoic Acid and Methyl Benzoate Formation

RhPh3P

Ph3P PPh3

OO

mineral acid OH

O

RhPh3P

Ph3P PPh3

OO BF3-MeOH, O

OMe

Reaction not catalytic

Kolomnikov, I.S., Gusev, A.O., Belopotapova, Grigoryan, M.Kh., Lysyak, T.V., Struchkov, Yu. T., Volpin, M.E J. Organometallic Chem., 1974, 69, C10-C12

18

Catalytic Formation of Benzoic Acids

Ar BO

O

CO2 (1 atm)

3 mol% [Rh(OH)(cod)]27 mol% dppp,3 eq. CsF

dioxane, 60ºCAr O

O

BO

O

OH

O

90%

OH

O

MeO 95%

OH

O

F3C 76%

OH

O

NH

O

O

88%

S

OHO

64%OH

O

CN63%

P P

dppp

Ukai, K., Aoki, M., Takaya, J., Iwasawa, N., J. Am. Chem. Soc. 2006, 128, 8706-8707

19

LnRh Ar

LnRh(I)

ArB(OR)2

Transmetalation

CO2Insertion

LnRhO Ar

O

ArB(OR)2 Ar O

O

BO

OTransmetalation

Ukai, K., Aoki, M., Takaya, J., Iwasawa, N., J. Am. Chem. Soc. 2006, 128, 8706-8707

20

Insertion Into M-O bonds

CO2

M-H

M-OM-C

C OH

OH OH

O H NMe2

OH O

OMe

O O

ORR

OO

R O

x

O O

O

R

21

Organic CarbonatesLinear

O O

OMeMe

Polycarbonate Synthesis

Solvent

Fuel Additive

Carbonylating and Alkylating agent

Cyclic

O O

O

Me

High boiling solvents

Reactive intermediates

Cosmetics

Antifreeze

http://img.alibaba.com/photo/50047975/Dimethyl_Carbonate.jpg

Electronics

Optical media

Sheeting

Water Bottles

2.7 million tons produced annually

OCH3

CH3

O

O

n

Polymer

22

Organic Carbonate Production

OCH3H3CO

O

2MeOH + Cl Cl

O+ 2NaOH + NaCl H2O+

2MeOH + 1/2O2 + COOCH3H3CO

O+ H2O

CuCl

Dimethyl Carbonate

Cyclic Carbonates

O O

O

+ Cl Cl

O+ 2 HClHO OH

Polymeric Carbonates

Cl Cl

OCH3H3C

HO OH

+

NaOH

CatalystO

CH3

CH3

O

O

nLexan

Tundo, P., Selva, M. Acc. Chem. Res. 2002, 35, 706-716ukuoka, S., Kawamura, M., Komiya, K., Tojo M., Hachiya, H., Hasegawa, K., Aminaka, M., Hirosige O., Fukawa, Konno, S Green Chemistry, 2003, 5, 497-507

23

Phosgene

O2 + 2C 800ºC 2 CO

NaCl + H2Oelectricity

Cl2+

NaOH

Cl Cl

O

Property COCOCl2 CO2

MAK value 30 ppm0.1 ppm 5000 ppm

Toxicity concern

greater affiniyfor hemoglobinthan O2

producesHCl in lungs

asphyxiationconcerns

LC50 2444 ppm110 ppm 100,000 ppm

Storagegas bottles or tanks

kilogram quantities.to be avoided

gas bottles or tanks

MAK = maximum allowable concentration in the work place

LC50 = Concentration lethal to kill 50% of a population

Used as a chemicalweapon during WWI

Leitner, W. Angew. Chem. Int. Ed. Engl. 1995, 34, 2207-2221

24

Dimethyl Carbonate: Phosgene Substitute

O

OCH3

O

CH3

Nu- Nu

OCH3

O+ CH3O-

Carboxymethylation: T~ 90ºC

O

OCH3

O

CH3Nu-

NuCH3 + CH3OCOO-

Methylation: T>120ºC

2MeOH + CO2 OCH3H3CO

O

+ H2O

But…

2MeOH + CO2 OCH3H3CO

O

+ H2O

Tundo, P., Selva, M Acc. Chem. Res. 2002, 35, 706-716Choi, J-C., He, L-N., Yasuda, H., Sakaura, T, Green Chemistry, 2002, 4, 230-234

25

Overcoming Thermodynamics

Adding drying agents to remove water

- Na(SO4)4, MgSO4, dicyclohexylcarbodiimide, PPh3 and molecular sieves did not help reaction

Dehydrating methanol, to eliminate the production of water

MeOH + OCH3H3CO

O

CO2

cat. Bu2Sn(OMe)2

180ºC, 24 h,drying agent

+ H2O

88% yield

Me Me

OMeMeO+

OCH3H3CO

OCO2

cat. Bu2Sn(OMe)2

MeOH, 180ºC, 24 h+

Me Me

O

Choi, J-C., He, L-N., Yasuda, H., Sakaura, T, Green Chemistry, 2002, 4, 230-234

26

Redesigning the experimental set up

MeOH + OCH3H3CO

O

CO2

cat. Bu2Sn(OMe)2180ºC, 24 h, 3A MS

46% yield

Choi, J-C., He, L-N., Yasuda, H., Sakaura, T, Green Chemistry, 2002, 4, 230-234

27

Polycarbonates and Cyclic Carbonates From CO2 and Epoxides

O

R+ CO2

CatalystO

O

R O

n+

O O

O

R

28

Heterogeneous Systems

O

H3C+ CO2 O

O

CH3 O

x

Catalyst

Catalyst System p(CO2) [atm] T [ºC] Time [h]

ZnEt2 / H2O 20-50 80 48(Inoue, 1969)

% Carbonate linkage

88

TOF [h-1]

0.12

Zn(OH)2 /

HO

O

OH

O30 60 40

(Hattori, 1981)

881.1

ZnO /

HO

O

OH

O25 60 40 >99

(Ree, 1999)

3.4

Ree. M, Bae, J.Y., Jung, J.H., Shin, T.J J. Polym. Sci. Part A 1999, 37, 1863-1876

29

Zinc Glutarate Catalysis

Ree, J. Cat 2003, 218, 386

Darensburg, Chem Rev. 2007, 107, 2388

ZnRO

RO

OR

OP

O

H3C

ZnRO

RO

OR

O

O C

CH3

P

ZnRO

RO

OR

O

CH3

OP

CO2

ZnRO

RO

OR

O

CH3

OP

CO

O

ZnRO

RO

OR

O

O CO

CH3

OP

ZnRO

RO

OR

O O

O CH3O

P

30

Salen complexes for polymerization

tBu O

N N

tBu

O

tBu

tBuCrCl

Reaction shows a first order dependence on catalyst

O

+ .04% cat,80ºC, 24h

60 atm

O O

On

99% carbonate linkageCO2

TOF [h-1]

5 equiv N-MeIm

7 equiv N-MeIm

0 equiv N-MeIm 28.5

88.2

0

Reaction with

N N

N-MeIm

Darensbouorg, D.J., Yarbrough, J.C.J. Am. Chem. Soc. 2002, 124, 6335-6342

O

Cr

Cl

Cr

Cl

L

ClO CrCrCl L

O

O

Cr

Cl

Cl

OCr

L

CO2

L = epoxide or N-Methylimidazole

Cl

O

OO

Cr

L

PO

OO

Cr

N

N

O

PO

OO

Cr

N

N

OO

Cr

N

N

O OP

O

Initiation

Propagation

32

Cyclic Carbonate Formation

tBu O

N N

tBu

O

tBu

tBuCrCl

Cr(III) salen

O

Cr

O OP

O

O O

OO

Cr

P+

O

R

0.07 mol% Cr(III) Salen DMAP, CH2Cl2 O O

O

R3.4 atm

+ CO2

75 - 85ºC

O O

O

H3C

O O

O

O O

O

O O

O

Cl

100% 98% 94% 99%

O O

O

100%

Paddock R.L., Nguyen, S.T, J. Am. Chem. Soc. 2001, 123, 11498-11499

33

Polycarbonate Produced from CO2, Industrially

CO2

OO O

O

O OMe

OMe

CH3OH

OH

O OPh

O

Ph

CH3H3C

HO OH

OCH3

CH3

O

O

nOHHO

H

H H

H + 1/2 O2O

H

H H

H

+ 3 O2 + H2OCO2

34

Insertion into a M-H bond

CO2

M-H

M-OM-C

C OH

OH OH

O H NMe2

OH O

OMe

O O

ORR

OO

R O

x

O O

O

R

35

Formic Acid

http://en.wikipedia.org/wiki/Image:Concrete-stave-silo.jpg, http://www.italymag.co.uk/images/bags1.jpg, http://www.osha.gov/SLTC/etools/hospital/hazards/images/latex.jpg

NR

RH H H

OH OH

O

N CHR

R HH+

heat

300,000 tons of formic acid produced annually

- Silage for animal food

- Coagulant for latex rubber

- Food additive

- Tanning and dyeing

36

Formic Acid Production

CH3OH + CO

80ºC, 45 atm NaOMe (cat.)

H O

OCH3 H2O

-CH3OHH OH

O

Current Industrial Route

Alternate Route

CO2 (g) + H2 (g) H OH

O

(l)

Cat.

One Pot Synthesis of Derivatives

H OH

OHNR2

HOR

H NR2

O

H OR

OCO2 + H2

Leitner, W., Angew Chem. Int. Engl. 1995, 34, 2207-2221

37

Unfavorable Thermodynamics

CO2(g) + H2(g)H OH

O

Gº = 32.9 kJ/mol ; Hº = -31.2 kJ/mol; Sº = -215J/(mol K)

CO2(g) + H2(g)H O-NH4

+

O

Gº = -9.5 kJ/mol ; Hº = -84.3 kJ/mol; Sº = -250J/(mol K)

+ NH3(aq)(aq)

CO2(aq) + H2(aq)

Gº = -35.4 kJ/mol ; Hº = -59.8 kJ/mol; Sº = -81J/(mol K)

NH3(aq)+H O-NH4

+

O

(aq)

Jessop, P.G., Tako, I., Noyori, R., Chem. Rev. 1995, 95, 259-272

38

Initial Catalytic System

Ru(H3C)3P

(H3C)3P H

H

P(CH3)3

P(CH3)3

CO2 + H20.1 mol cat, NEt3,H2O, C6H5, 20h

H OH

O

25 atm 25 atm TOF = 4

TOF = turn over frequency= mol HCOOH/ mol catalyst h-1

HC

O2H

Yie

ld (

mo

l/ m

ol c

at.)

Water added (mmol)

Hydrolysis rate determining step

Inoue, Y., Izumida, H., Sasaki,Y., Hashimoto, H., Chem. Lett., 1976, 863-864

39

Proposed Mechanism

L4[Ru]H2CO2

L4[Ru]H

H

CO

O

L4H[Ru]

H

O

C

O

H2O

L4[Ru]-O H

O

H OH

O L4[Ru]H(OH)

+H2

-H2O

Rate determining step

CO2 + H20.1 mol cat, NEt3,H2O, C6H5, 20h

H OH

O

25 atm 25 atm TOF = 4

Inoue, Y., Izumida, H., Sasaki,Y., Hashimoto, H., Chem. Lett., 1976, 863-864

Ru(H3C)3P

(H3C)3P H

H

P(CH3)3

P(CH3)3

40

Effects Base on Hydrogenation Reaction

Ru(H3C)3P

(H3C)3P Cl

O2CMe

P(CH3)3

P(CH3)3

CO2 + H20.3 mol cat, 5mmol base0.1 mmol MeOH, 1hr,50°C

H OH

O

20 atm 20 atm pKa =3.77

Base pKa ammonium ( H2O) Yield( mole acid/ mole base)

N

NN

N

N

NN

N(CF2CF3)3

N(CH2CH3)3

~-15.7

5.2

8.6

10.2

12

12.3

0

0

0.10

0.09

0.92

0.02

Base must be capable ofdeprotonating and stabilizingformic acid

Munshi, P., Main, A.D., Linehan, J.C, Tai, C-C., and Jessop, P.G., J. Am. Chem. Soc.,2002, 124, 7963-7971

41

Effects of Protic Source

CO2 + H20.3 mol cat, 5mmol base0.1mmol additive, 1hr,50°C

H OH

O

20 atm 20 atm pKa =3.77

Amine AdditivepKa additiveaqueous scale

yield mole acid/ mole amine

N

N

N(CH2CH3)3

pKa =10.7

pKa = 12

H2O

MeOH

C6F5OH

HBF4

MeOH

C6F5OH

15.7

15.5

5.5

0.5

15.5

5.5

0.6

0.9

0.66

0.19

2,6-tBu2C6H3OH ~11.7 0.001

0.92

1.36

Munshi, P., Main, A.D., Linehan, J.C, Tai, C-C., and Jessop, P.G., J. Am. Chem. Soc.,2002, 124, 7963-7971

42

Putting the Pieces Together

pKa

HC

O2H

yie

ld

(mo

l p

er m

ol

NR

3)

• Effective alcohols have aqueous pKa’s below that of the protonated amine

• Alcohols may help to facilitate CO2 insertion

Munshi, P., Main, A.D., Linehan, J.C, Tai, C-C., and Jessop, P.G., J. Am. Chem. Soc.,2002, 124, 7963-7971

43

Hydrogenation of CO2

• Despite the unfavorable thermodynamics for the hydrogenation of CO2 addition of an appropriate base and alcohol helps to over come these barriers

• Another strategy in bringing about CO2 hydrogenation would be to carry out the reaction in supercritical CO2

44

Supercritical CO2

Critical point (C) CO2

Temperature = 31.0°C

Pressure = 73.75bar

http://www.chemguide.co.uk/physical/phaseeqia/pdco2.gif

45

Increased Rates Observed in ScCO2

TO

F (

h-1

)

0

96,000

480

1,400

95,000

Ru

H2((

PM

e 3) 4

)

TH

F, T

EA

, 20

5 at

m,

50oC

Ru

H2((

PM

e 3) 4

)

C6H

5, T

EA

, H2O

50

atm

, R

T

Ru

H2(

(PM

e 3) 4

)

ScC

O2, T

EA

, MeO

H, 2

05 a

tm,

50oC

Ru

Cl(

OA

c)(

(PM

e 3) 4

)

ScC

O2, T

EA

, 12

0 at

m C

O2,

C6F

5O

H, 5

0oC

CO2 (g) + H2 (g) H OH

O

(l)

Cat.

Jessop, P.G., Tako, I., Noyori, R. Nature, 1994, 368, 231-233Jessop, P.G., Hsiao, Y., Ikariya, T., Noyori, R., J. Am. Chem. Soc., 1996, 118, 344-355Munshi, P., Main, A.D., Linehan, J.C, Tai, C-C., and Jessop, P.G., J. Am. Chem. Soc., 124, 7963-7971

46

Methyl Formate

Ru(H3C)3P

(H3C)3P Cl

Cl

P(CH3)3

P(CH3)3

CO2 (g) + H2 (g)

Cat., NEt3 MeOH, 80°C

200 atm 80 atm H OMe

OTOF = 68 h-1

47

H OH

OHNR2

HOR

H NR2

O

H OR

OCO2 + H2

Formamides and Alkyl Formates

48

FormamidesAddition of amine to the formic acid reaction results in the formation of formamides

Ru(H3C)3P

(H3C)3P Cl

Cl

P(CH3)3

P(CH3)3

CO2 (g) + H2 (g)

H OH

O

(l)

Cat. NHR2, 100°C

130 atm 80 atm H NR2

O+

Aminemole of product/ mole of cat.

Acid Amide

0

820

1500

14

950

0

NH(C6H11)2

NH(C2H5)2

NH(CH3)2

Jessop, P.G., Hsiao, Y., Ikariya, T., Noyori, R., J. Am. Chem. Soc., 1996, 118, 344-355

49

Conclusions

• Carbon dioxide is kinetic and thermodynamically stable, however, it can be activated in the presence of strong nucleophiles and metal complexes with high electron density at the metal center

• Insertion into a metal- element bond (M-C, M-H and M-O) leads to the formation of new compounds that can react further to produce more interesting compounds

• The field of carbon dioxide utilization is still in its infancy, but it needs to grow up in order to alleviate our dependence on fossil fuels. This can only come with further research and more academic interests in this field.

50

Future directions

• Mechanistic studies to better understand the role of additives and the elimination of carboxylate and catalyst regeneration in order to build better catalysts

• It would be ideal to carry out these reactions efficiently under 1 atm of CO2

• Development of new reactions

• Coupling coordination chemistry with electrochemistry

51

Acknowledgements

Prof. Stahl and Prof Gellman

Stahl and Gellman Groups

Practice Talk Attendees

Brian Popp Avery WatkinsChris Scarborough Holly HaaseAmanda King Olivia JohnsonLauren Huffman Jessica Menke Richard McDonald Tulay AtesinNattawan DecharinXuan Ye

Special thanks to Lauren Huffman and Jason Leonard, for keeping me sane