Greener Solvents - American Chemical Society · PDF fileGreener Solvents Dr. Tamer Andrea ......

Greener Solvents

Dr. Tamer Andrea

Queen’s University

GreenCentre Canada

Typical stage of university technologies:

• Bench-test proof of utility

• Applications speculative and unproven

• Incomplete material characterization

• Grams of sample

• Manufacturing feasibility not studied

What Industry wants:

• Demonstrated scale-up

• Optimization

• Field-test proof of utility

• Kilograms of sample

The Commercialization Gap

Process for Technology Disclosures

Stage 1:

Quick Screening

Stage 2:

Technology

Assessment

Stage 3:

Technology

Development

Output: analysis of

commercialization potential

Output: technology

returned without

assessment

Output:

licensable

technology;

75/25 split $ $ Assessment indicates need

for PoP funding

GCC

Option

GCC

exclusive

license

Green Solvents

Dr. Philip Jessop

Queen’s University

GOALS OF GREEN CHEMISTRY: REDUCE SOLVENT USE

http://www.caraet.com/Waste_solvent.htm

Mass utilization in fine chemical production

Solvent 80-90%

Other

10-20%

“E” factor = Mass of waste

Mass of product

Industry segment Product tonnage E factor

Bulk chemicals 104 - 106 <1 - 5

Fine chemicals 103 - 104 5 - 50

Pharmaceuticals 10 - 103 25 - over 100

R. Sheldon, CHEMTECH 1994, 38.

PROBLEMS WITH CURRENTLY USED SOLVENTS

In the US in the early 1990’s:

• solvent production was 26 million tons p.a.

• of tracked chemicals, many of the top chemicals released or disposed of were solvents

(MeOH, toluene, xylene, CS2, MEK, CH2Cl2)

Organic solvent hazards

• flammable (almost all except chlorinated solvents)

• carcinogenic (chlorinated solvents and aromatics)

• high vapour pressure (i.e. inhalation route)

• narcotic (ether, chloroform)

• toxic (MeOH, CS2)

• mutagens/teratogens (toluene)

• peroxides (ethers)

• smog formation

OUTLINE

1. Reducing the Impact of Solvents

2. Solvent Properties

3. Greener Conventional Solvents

4. Unconventional Solvents

5. Conclusions

DECREASING THE IMPACT OF SOLVENTS

1. Reduce the volume of solvent

• use higher concentrations

• use solvent for more than one step

2. Make the solvents greener

• carefully chosen conventional solvents

• new green solvents

Murphy’s Law of Solvents

“The best solvent for any

process step is bad for the

subsequent step.”

AN IMAGINARY PROCESS

Solving Murphy’s Law of Solvents

1. A Compromise Solvent

2. A Switchable Solvent

CAREFUL SELECTION OF A TRADITIONAL SOLVENT

http://www.rx-pharmacy.cc/product_info.php?products_id=169

SWITCHABLE-POLARITY SOLVENT

Nature (2005) 436, 1102

Ind Eng Chem Res (2008) 47, 539

CO2

N2 or Ar

APPLICATION TO POLYSTYRENE SYNTHESIS

1.0 mL styrene

4.5 mL DBU/PrOH

45 mg initiator

75 ˚C

6 h

CO2

filter or centrifuge

+

Mn = 412,000

PDI = 1.57

N2

DECREASING THE IMPACT OF SOLVENTS

1. Reduce the volume of solvent

• use higher concentrations

• use solvent for more than one step

2. Make the solvents greener

• carefully chosen conventional solvents

• unconventional solvents

OUTLINE





5. Conclusions

PROPERTIES OF CONCERN

For green-ness

boiling point / energy to distill

flash point

energy to distill

cumulative energy demand

the 10 factors

For utility

polarity

basicity / hydrogen-bond accepting ability

acidity / hydrogen-bond donating ability

viscosity

THE TOOLBOX ANALOGY

KAMLET-TAFT SOLVATOCHROMIC PARAMETERS

cyclohexane


β (basicity)

α (acidity)

π* (polarity/polarizability)

protic

solvents

aprotic

solvents


protic

solvents

aprotic

solvents

β (basicity)

α (acidity)

π* (polarity/polarizability) cyclohexane

water

NEt3

CHCl3

tBuOH

HMPA

toluene

formamide

1.2

1.1

1.1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1

β

π* High polarity Low polarity

Hig

h b

asic

ity

Lo

w b

asic

ity

cyclohexane,

hexane,

heptane

Et2O

dioxane

THF

EtOAc

DMA

DMF

NMP

NEt3

DMSO OP(OEt)3

PhNO2

PhCN

pyridine

toluene p-xylene

anisole

propylene

carbonate sulfolane

HMPA

acetone

MeCN

MeNO2 CH2Cl2 CHCl3

NBu3

MEK

CCl4 &

Cl2C=CCl2 Cl2C=CClH

PhCl PhBr

EtO2CEt

BzNMe2

EtO2CCl3

butyrolactone

Me2py

4-Mepy

ClC2H4Cl

benzene

quinoline

tetramethyl-

urea

MeO2CH

MeOAc EtO2CPh

MeOC2H4OMe

Pr2O

SURVEY OF SOLVENTS (APROTIC)

Jessop, Green Chem (2012) 14, 1245

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1

β

π*

Hig

h b

asic

ity

Lo

w b

asic

ity

PhCH2OH

tBuOH

formamide

iPrOH

octanol

butanol hexanol

ethanol

ethylene

glycol acetic acid

water

glycerol hexanoic

acid

CF3CH2OH

phenol

methanol

(CF3)2CHOH

High polarity Low polarity

1-propanol

CF3CO2H

SURVEY OF SOLVENTS (PROTIC)


OUTLINE





5. Conclusions

PFIZER SOLVENT SELECTION GUIDE

WHICH SOLVENT IS GREENER?

General Comparison

• solvent impact

• solvent impact including manufacture

• energy to manufacture / cumulative energy demand

Application-Specific Comparision

• ISO LCA

solvent #1 solvent #2

ENVIRONMENTAL AND HEALTH RISKS

Capello et al., Green Chem (2007) 9, 927

Alcohols

Acetate esters

Acids

Acetonitrile

Dioxane

Formaldehyde

ENERGY REQUIREMENT FOR MANUFACTURE

0

50

100

150

200

250

300

Ethanol Hexane Acetone Toluene DMF EtOAc THF

MJ/k

g

Capello et al., Green Chem (2007) 9, 927

ENERGY REQUIREMENTS FOR A SOLVENT

How is DMF made? How is hexane made?

oil hexane distillation

WHICH SOLVENT IS GREENER?

General Comparison

• solvent impact

• solvent impact including manufacture

• energy to manufacture / cumulative energy demand

Application-Specific Comparision

• ISO LCA

solvent #1 solvent #2

Why would this give

a different result?

PROPOSED NEW GREEN ORGANIC SOLVENTS

Aparicio, Green Chem. (2009) 11, 65 Horvath, Green Chem., 2008, 10, 238

ethyl lactate g-valerolactone

2-methyltetrahydrofuran cyclopentylmethylether

Aycock, Org. Process Res. Dev. 2007, 11, 156 Watanabe, Org. Process Res. Dev. 2007, 11, 251

low toxicity, biodegradable, renewable low toxicity, biodegradable, renewable

doesn’t form peroxides, low solubility in water renewable

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1

β

π* High polarity Low polarity

Hig

h b

asic

ity

Lo

w b

asic

ity

heptane

EtOAc propylene

carbonate

acetone MEK

(EtO)2CO iPrOAc

PEG

PPG γ-valerolactone 2-MeTHF

GREEN SOLVENTS (APROTIC)


0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1

β

π*

Hig

h b

asic

ity

Lo

w b

asic

ity

tBuOH

iPrOH

butanol

ethanol

ethyl lactate

water

glycerol

methanol


1-propanol

GREEN SOLVENTS (PROTIC)


OUTLINE





5. Conclusions

UNCONVENTIONAL SOLVENTS

supercritical CO2 CO2-expanded liquid ionic liquid

liquid polymer switchable solvent water

IN WATER

Why not water?

Li, 1995

http://students.washington.edu/~haoli/photo_gallery/archives/olympic/

SWITCHABLE WATER

water &

B

water &

[BHn][HCO3]n

CO2

-CO2

• low ionic strength

• low osmotic pressure

• good solvent for polar organics

• high ionic strength

• high osmotic pressure

• poor solvent for polar organics

Mercer, Jessop, et al. ChemSusChem (2010) 3, 467

Mercer, Jessop, et al. Green Chem (2012) 14, 832

water, B, &

product CO2 water, B, &

product filter water &

[BHn][HCO3]n

product product

-CO2

IONIC LIQUIDS

NaCl, mp 801 ˚C

NaBF4, mp 384 ˚C

[PiBu3Me]O3SC6H4Me, mp < RT

Nonvolatile

Nonflammable

Doesn’t create smog

No inhalation hazards

BY GENERAL COMPARISON, ARE IONIC LIQUIDS GREEN?

Zhang, Env. Sci. Tech. (2008) 42, 1724


CHEMICAL STEPS IN SOLVENT SYNTHESIS


LIQUID POLYMERS

LIQUID POLYMERS

ionic liquids liquid polymers

Nile Red scale

Heldebrant, Jessop et al. Green Chem (2006)

SOME ORGANIC SOLVENTS ARE VOLATILE

Volatile Solvents

• flammability

• high insurance costs

• vapour losses

• smog formation

• inhalation hazards

- toxic,

- narcotic,

- mutagenic,

- carcinogenic

Nonvolatile Solvents

• no flammability

• low insurance costs

• no vapour losses

• no smog formation

• no inhalation hazards

SWITCHABLE-HYDROPHILICITY SOLVENTS

Green Chem (2010) 12, 809

Green Chem (2011) 13, 619

A REAL WORLD PROBLEM

extract

with

solvent distill

Green Chem (2010) 12, 809

hexane emissions to air in Canada (NPRI, 2007)

SOY EXTRACTION WITHOUT DISTILLATION

extract

with

solvent

H2O

CO2

-CO2

Green Chem (2010) 12, 809

Green Chem (2011) 13, 619

52

USING A SWITCHABLE-HYDROPHILICITY SOLVENT

extract

Add water

& CO2

- CO2

oil sands

OIL SANDS

53

OUTLINE





• Ionic Liquids

• Liquid Polymers

• Switchable Solvents

• Gas-Expanded Liquids

• Supercritical Fluids

5. Conclusions

EXPANSION OF LIQUIDS BY CO2

CO2-expanded NEt3 (Jessop, 1996)

Volumetric expansion of aprotic solvents by CO2

at 40˚C (Kordikowski, 1995)

Characteristics:

• tunable polarity

• tunable solvent properties

• lowered melting point

• improved mass transfer rates

• improved solubility of reagent gases

EFFECT OF SOLVENT CHOICE

Expansion with CO2 increases in the order:

water < ionic liquid liquid polymer < protic polar < aprotic polar < nonpolar

Class Examples Volumetric

change

Properties that

change

Properties that

don’t change

I Water

Glycerol

Very small Acidity Most

II Hexane

Methanol

DMF

Very large All None

III Ionic liquids

Liquid polymers

Crude oil

Moderate Viscosity

Phase behaviour

Polarity

review paper: Jessop & Subramaniam, Chem. Rev. (2007) 107, 2666

VISCOSITY

0

200

400

600

800

1000

1200

1400

0 20 40 60 80 100 120 140 160

P, bar

Vis

cosity,

cp

Crude oil

Viscosity of CO2-expanded crude oil at 49 ˚C

Simon & Graue, J. Petrol. Technol. (1965) 102.

CO2 CAN TRIGGER INSOLUBILITY AND IMMISCIBILITY

Polar solids are precipitated from solution when the solvent is expanded with CO2

CO2

CO2

pressure

Some miscible liquids become immiscible when expanded with CO2

Solvent A Solvent B P, bar

water methanol 80

water 1-propanol 68

water acetic acid 75

water acetone 26

water THF <10

water 1,4-dioxane <28

water MeCN <19

OUTLINE





• Ionic Liquids

• Liquid Polymers

• Switchable Solvents

• Gas-Expanded Liquids

• Supercritical Fluids

5. Conclusions

SUPERCRITICAL CO2

SOLUBILIZING POWER DEPENDS ON DENSITY

Fe3(CO)12

CO2

CO2 AS A SOLVENT

DuPont fluoropolymer plant, N.C

Natex CO2 decaffeination plant

CO2 dry cleaning

http://www.natex.at/album/index.htm

http://www.metropolitanmachinery.com/sail_star.htm

http://www.pharmaceutical-technology.com/contractors/purification/novasep/novasep3.html

Prep SFC (Novasep)

http://www.metropolitanmachinery.com/sail_star.htm

scCO2 AS A SOLVENT

Safety Nonflammable Pressure

Nontoxic

In-situ fire/explosion suppression

Economics Free Pressure

Environment Recycled material

No smog, ozone contribution

Naturally occurring

Process benefits Rapid mass transfer Pressure

High solubility of reagent gases Low solubility of some reagents

Controllable solubilizing power

Easy to separate

ADVANTAGES DISADVANTAGES

OVERVIEW OF UNCONVENTIONAL GREEN SOLVENTS

ionic liquids

switchable

polarity

solvent

switchable

hydrophilicity

solvent

water

cxl acetone

cxl MeOH

ethanol

scCO2

SURVEY

If the adoption of greener solvents over the next 20-30 years will reduce

environmental damage from human activities, then the adoption of what class of

solvents will be responsible for the greatest reduction in environmental damage?

• Bioderived solvents (glycerol, 2-methylTHF, valerolactone, etc.)

• CO2 (liquid, supercritical, expanded liquid)

• Conventional organic solvents (carefully selected)

• Ionic liquids

• Switchable solvents

• Solvent-free conditions

• Water (including liquid, superheated, supercritical, on-water)

SURVEY

survey results solvents described in related papers in

Green Chemistry in 2010

WHAT DO WE CHOOSE TO STUDY?

CONCLUSIONS

No solvent is perfectly green.

The nonconventional solvents are more exciting, but it’s

the conventional ones that are greening the industry.

We’re making progress populating the map with green

solvents.

Is it really green? Consider the solvent’s synthesis and

its effect on the entire process.

CATIONS AND ANIONS

emim

bmim

hmim

hyd

rop

hil

ic

hyd

rop

ho

bic

co

ord

ina

tin

g

no

nc

oo

rdin

ati

ng

GREEN SOLVENTS

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1

β

π*

aprotic

protic


Hig

h b

asic

ity

Lo

w b

asic

ity

heptane

EtOAc acetone

MEK

tBuOH

iPrOH

BuOH

EtOH

water

MeOH

[bmim]BF4

[bmim]NTf2

[bmim]O3SOMe4

MeTHF (est.)

PrOH

γ-VL (est.)

iPrOAc

Water (150 ˚C) Water (275 ˚C)

MTBE, CypOMe (est.)

DISSOLVING CELLULOSE

Solvents known to dissolve cellulose:

Strong alkali & CS2

Cellosolve (EtOCH2CH2OH)

ZnCl2 solution

DMA / LiCl

Review: Green Chem., 2006, 8, (4), 325-327

Graenacher, US Pat.

1943176, 1934 Rogers, JACS (2002)

124, 4974

Uses of IL cellulose solutions

• separation from lignin

• prep of cellulose for conversion to EtOH

• derivatization of cellulose

ELECTROCHEMISTRY AND ELECTRODEPOSITION

Trulove & Mantz, in Ionic Liquids in Synthesis

MCl3 + 3e-

M + 3Cl-

Greener Solvents - American Chemical Society · PDF fileGreener Solvents Dr. Tamer Andrea ......

Documents

Transcript of Greener Solvents - American Chemical Society · PDF fileGreener Solvents Dr. Tamer Andrea ......