The CHEM21 Solvent Selection Guide


Reproduced Content

The tables on this page are reproduced from from D. Prat, A. Wells, J. Hayler, Sneddon, C. R. McElroy, S. Abou-Shehada and P. J. Dunn, CHEM21 selection guide of classical- and less classical-solvents, Green Chem., 2016, 18, 288–296. The material is copyright to the Royal Society of Chemistry (RSC) and is reproduced here with their express permission. If you wish to reproduce it elsewhere you must obtain similar permission from the RSC.

In this video, Denis Prat explains the work of the CHEM21 consortium in developing its own solvent selection guide of classical and less-classical (including bio-derived) solvents, including its formulation and scope.

This work is also published as an open access article [1] alongside an associated Excel spreadsheet (in the supplementary data) that will enable the user to rank a solvent not included in the list according to the guidelines outlined in the publication.

Furthermore, the spreadsheet has now been adapted into an interactive tool for the platform.


Methodology

After the survey of existing solvent guides[1], the CHEM21 solvent team elaborated a methodology, based on easily available physical properties and GHS statements, permitting anyone to establish safety, health and environment criteria of any solvent, even if full data on the solvents are not yet available.[2] A simple way to obtain a preliminary ranking of the solvent (so-called “ranking by default”) was also proposed, based on a combination of these SHE criteria. The methodology was tested on the classical solvents having a clear ranking according to the survey, with a fair predictivity of 81%.

The SHE criteria are scored from 1 to 10, the highest figure representing the highest hazard level. A colour code is associated with these scores: 1 to 3: green, 4 to 6: yellow, 7 to 10: red.

The safety score derives mainly from the flash point, with contributions of the auto-ignition temperature (AIT), the resistivity and the ability to form explosive peroxides (statement EUH019 in GHS/CLP) (Table 1).

Table 1: Safety score
Basic Safety score 1 3 4 5 7
Flash Point (°C) > 60 23 to 60 22 to 0 -1 to -20 < -20
GHS H226  GHS symbol: symbol H225 or H224  GHS symbol: symbol
1 is added to the safety score for each of the following properties:
  • AIT < 200°C
  • Resistivity > 10 8 ohm.m
  • Ability to form peroxides (EUH019)
Any solvent with a high energy of decomposition (> 500 J/g), like nitromethane, would be scored 10.

As an example, the safety score of diethyl ether, with a FP of – 45°C, an AIT of 160°C, a resistivity of 3.10 11 ohm.m and an EUH019 statement is 7+1+1+1=10.

The health score derives mainly from the most stringent GHS H3xx statements, with a contribution of the boiling point, according to Table 2.

Table 2: Health score
Health score 2 4 6 7 9
CMR     H341 H351 H361 (CMR cat. 2) GHS symbol: symbol   H340 H350 H360 (CMR cat. 1) GHS symbol: symbol
STOT H304 H371 H373 GHS symbol: symbol H334 GHS symbol: symbol H370 H372 GHS symbol: symbol    
Acute toxicity H302 H312 H332 H336 EUH070 GHS symbol: symbol   H301 H311 H331 GHS symbol: symbol     H300 H310 H330 GHS symbol: symbol
Irritation H315 H317 H319 H335 EUH066 GHS symbol: symbol H318 GHS symbol: symbol   H314 GHS symbol: symbol  
CMR: carcinogen, mutagen or reprotoxic; STOT: single target organ toxicity 1 is added to this score if the boiling point is <85°C

If, after full REACH registration, there is no H3xx statement, the health score is 1. The score of newer solvents for which the REACH registration is not complete is 5 if the boiling point is 85°C or higher, otherwise, 6, unless a more stringent H3xx is attributed by the supplier.

The environment score takes into account both the volatility of the solvent (ability to form Volatile Organic Compounds) and the energy demand for recycling. Both are linked to the boiling point. The GHS H4xx statements are also important (Table 3). The environment score is based on the most stringent of these factors. For example, the score of 7 for heptane is due to its H410 statement, whereas the score of 7 for dichloromethane is as a result of its low boiling point.

Table 3: Environment score

Environment score

3

5

7

10

BP (°C)

70-139

50-69

140-200

<50

>200

 

GHS/CLP

No H4xx after full REACH registration

H412, H413

GHS symbol: symbol

H400, H410, H411

GHS symbol: symbol

EUH420 (ozone layer hazard)

Other

 

No, or partial REACh registration

   

Water score= 1

 

If the REACH registration is not full and no H4xx has been attributed by the supplier, the environment score is 5 by default.

These S, H & E scores are combined according to Table 4 to give an overall scoring of the solvent. The ranking is imposed by the most stringent combination.

Table 4: Ranking by default

Score combination

Ranking by default

One score ≥ 8

Hazardous

Two “red” scores

Hazardous

One score =7

Problematic

Two “yellow” scores

Problematic

Other

Recommended

The ranking by default does not make the distinction between “hazardous” and “highly hazardous”. The decision to “ban” a solvent necessitates discussion at an organisational level. It is important to remember that the ranking methodology is only a model that gives a ranking by default and this should be critically assessed by occupational hygienists and other experts of any institution using it. For example, the scoring of chloroform as only “problematic” or of pyridine as “recommended” are not acceptable. This illustrates the limits of a health scoring system only based on GHS hazard statements. As the Occupational Threshold Limits of these solvents are available and very low (ppm range), CHEM21 finally ranked them as “highly hazardous” and “hazardous” respectively. Other decisions are more the result of the policy of the institution. CHEM21 finally decided to rank methanol and acetone as “recommended”, and on the contrary, cyclohexanone as “problematic”, for reasons which will not be debated here.


Solvent Tables

Reproduced Content

The tables on this page are reproduced from from D. Prat, A. Wells, J. Hayler, Sneddon, C. R. McElroy, S. Abou-Shehada and P. J. DunnCHEM21 selection guide of classical- and less classical-solventsGreen Chem.201618288–296..

It is copyright to the Royal Society of Chemistry (RSC) and is reproduced here with their express permission. If you wish to reproduce it elsewhere you must obtain similar permission from the RSC.

Table 1: CHEM21 solvent guide: ethers, hydrocarbons, halogenated

Family

Solvent

CAS

BP (°C)

FP  (°C)

Worst H3xx*

H4xxvel

Safety score

Health score

Env. score

Ranking by default

Ranking after discussion #

Water

Water

 

100

na

none

none

1

1

1

Recommended

Recommended

Alcohols

MeOH

67-56-1

65

11

H301

none

4

7

5

Problematic

Recommended

EtOH

64-17-5

78

13

H319

none

4

3

3

Recommended

Recommended

n -PrOH

71-23-8

97

15

H318

none

4

4

3

Problematic

Problematic

i -PrOH

67-63-0

82

12

H319

none

4

3

3

Recommended

Recommended

n -BuOH

71-36-3

118

29

H318

none

3

4

3

Recommended

Recommended

i -Butanol

78-83-1

107

28

H318

none

3

4

3

Recommended

Recommended

t -BuOH

75-65-0

82

11

H319

none

4

3

3

Recommended

Recommended

i -Amyl alcohol

123-51-3

131

43

H315

none

3

2

3

Recommended

Recommended

Benzyl alcohol

100-51-6

206

101

H302

none

1

2

7

Problematic

Problematic

Ethylene glycol

107-21-1

198

116

H302

none

1

2

5

Recommended

Recommended

1, 3-Propane diol

504-63-2

214

140

none

none

1

1

7

Problematic

Problematic

Glycerol

56-81-5

290

177

none

none

1

1

7

Problematic

Problematic

Ketones

Acetone

67-64-1

56

-18

H319

none

5

3

5

Problematic

Recommended

MEK

78-93-3

80

-6

H319

none

5

3

3

Recommended

Recommended

MIBK

108-10-1

117

13

H319

none

4

2

3

Recommended

Recommended

Cyclohexanone

108-94-1

156

43

H332

none

3

2

5

Recommended

Problematic

Esters

Methyl acetate

70-20-9

57

-10

H302

none

5

3

5

Problematic

Problematic

Ethyl acetate

141-78-6

77

-4

H319

none

5

3

3

Recommended

Recommended

n -PrOAc

109-60-4

102

14

H319

none

4

2

3

Recommended

Recommended

i -PrOAc

108-21-4

89

2

H319

none

4

2

3

Recommended

Recommended

n -BuOAc

123-86-4

126

22

H336

none

4

2

3

Recommended

Recommended

i -Butyl acetate

110-19-0

115

22

H336

none

4

2

3

Recommended

Recommended

i -Amyl acetate

123-92-2

142

25

none

none

3

1

5

Recommended

Recommended

γ-Valerolactone

108-29-2

207

100

n.a.

n.a.

1

5

7

Problematic

Problematic

Glycol diacetate

111-55-7

186

82

none

none

1

1

5

Recommended

Recommended

Diethyl succinate

123-25-1

218

91

n.a.

n.a.

1

5

7

Problematic

Problematic

* Only the highest scoring statements are shown. The lowest figure is given when there are more than one statement in the highest scoring category, for the sake of simplicity;

 

Table 1: CHEM21 solvent guide: ethers, hydrocarbons, halogenated

Family

Solvent

CAS

BP (°C)

FP (°C)

Worst H3xx*

H4xx

Safety score

Health score

Env. score

Ranking by default

Ranking after discussion #

Ethers

Diethyl ether

60-29-7

34

-45

H302

none

10

3

7

Hazardous

Highly hazardous

Diisopropyl ether

108-20-3

69

-28

H336

none

9

3

5

Hazardous

Hazardous

MTBE

1634-04-4

55

-28

H315

none

8

3

5

Hazardous

Hazardous

ETBE

637-92-3

72

-19

H336

none

7

3

3

Problematic

Problematic

TAME

994-05-8

86

-7

H302

none

6

2

3

Recommended

Recommended

CPME

5614-37-9

106

-1

H302

H412

7

2

5

Problematic

Problematic

THF

109-99-9

66

-14

H351

none

6

7

5

Problematic

Problematic

Me-THF

96-47-9

80

-11

H318

none

6

5

3

Problematic

Problematic

1,4-Dioxane

123-91-1

101

12

H351

none

7

6

3

Problematic

Hazardous

Anisole

100-66-3

154

52

none

none

4

1

5

Problematic

Recommended

DME

110-71-4

85

-6

H360

none

7

9

3

Hazardous

Hazardous

Hydrocarbons

Pentane

109-66-0

36

-40

H304

H411

8

3

7

Hazardous

Hazardous

Hexane

110-54-3

69

-22

H361

H411

8

7

7

Hazardous

Hazardous

Heptane

142-82-5

98

-4

H304

H410

6

2

7

Problematic

Problematic

Cyclohexane

110-82-7

81

-17

H304

H410

6

3

7

Problematic

Problematic

Me-Cyclohexane

108-87-2

101

-4

H304

H411

6

2

7

Problematic

Problematic

Benzene

71-43-2

80

-11

H350

none

6

10

3

Hazardous

Highly hazardous

Toluene

108-88-3

111

4

H351

none

5

6

3

Problematic

Problematic

Xylenes

1330-20-7

140

27

H312

none

4

2

5

Problematic

Problematic

D-Limonene

5989-27-5

175

49

H304

H400

4

2

7

Problematic

Problematic

Turpentine

8006-64-2

166

38

H302

H411

4

2

7

Problematic

Problematic

p-Cymene

99-87-6

177

27

n.a.

n.a.

4

5

5

Problematic

Problematic

Halogenated

DCM

75-09-2

40

na

H351

none

1

7

7

Hazardous

Hazardous

Chloroform

67-66-3

61

na

H351

none

2

7

5

Problematic

Highly hazardous

CCl 4

56-23-5

77

na

H351

H420

2

7

10

Hazardous

Highly hazardous

DCE

107-06-2

84

13

H350

none

4

10

3

Hazardous

Highly hazardous

Chlorobenzene

108-90-7

132

29

H332

H411

3

2

7

Problematic

Problematic

* Only the highest scoring statements are shown. The lowest figure is given when there are more than one statement in the highest scoring category, for the sake of simplicity;

Table 2: CHEM21 solvent guide: other solvents.

Family

Solvent

CAS

BP (°C)

FP (°C)

Worst H3xx*

H4xx

Safety score

Health score

Env. score

Ranking by default

Ranking after discussion #

Aprotic polar

Acetonitrile

75-05-8

82

2

H319

none

4

3

3

Recommended

Problematic

DMF

68-12-2

153

58

H360

none

3

9

5

Hazardous

Hazardous

DMAc

127-19-5

166

70

H360

none

1

9

5

Hazardous

Hazardous

NMP

872-50-4

202

96

H360

none

1

9

7

Hazardous

Hazardous

DMPU

7226-23-5

246

121

H361

none

1

6

7

Problematic

Problematic

DMSO

67-68-5

189

95

none

none

1

1

5

Recommended

Problematic

Sulfolane

126-33-0

287

177

H360

none

1

9

7

Hazardous

Hazardous

Dimethyl carbonate

616-38-6

90

16

none

none

4

1

3

Recommended

Recommended

Ethylene carbonate

96-49-1

248

143

H302

none

1

2

7

Problematic

Problematic

Propylene carbonate

108-32-7

242

132

H319

none

1

2

7

Problematic

Problematic

Cyrene

53716-82-8

203

61

H319

none

1

2

7

Problematic

Problematic

HMPA

680-31-9

>200

144

H350

none

1

9

7

Hazardous

Highly hazardous

Nitromethane

75-52-5

101

35

H302

none

10

2

3

Hazardous

Highly hazardous

Acids

Formic acid

64-18-6

101

49

H314

none

3

7

3

Problematic

Problematic

Acetic acid

67-19-7

118

39

H314

none

3

7

3

Problematic

Problematic

Ac 2 O

108-24-7

139

49

H314

none

3

7

3

Problematic

Problematic

Amines

Pyridine

110-86-1

115

23

H302

none

3

2

3

Recommended

Hazardous

TEA

121-44-8

89

-6

H314

none

6

7

3

Problematic

Hazardous

* Only the highest scoring statements are shown. The lowest figure is given when there are more than one statement in the highest scoring category, for the sake of simplicity.

Miscellaneous

Methoxy-ethanol

109-86-4

125

42

H360

none

3

9

3

Hazardous

Hazardous

Ethyl L-lactate

687-47-8

155

47

H318

none

3

4

5

Problematic

Problematic

Lactic acid

50-21-5

230

113

H318

none

1

4

7

Problematic

Problematic

TH-furfuryl alcohol

97-99-4

178

75

H360

none

1

9

5

Hazardous

Hazardous

Carbon disulfide

75-15-0

46

-30

H361

H412

9

7

7

Hazardous

Highly hazardous


Interactive Tool: Solvent Ranking

For the solvent you are assessing, complete the information one question at a time below.  When you get to the end, the tool will calculate the scores and overall ranking by default for the solvent. 

As a reminder, to rank the solvent you will need access to the following information:

  • Boiling point, flash point, auto-ignition temperature, resistivity;
  • Whether or not it is an ether that forms explosive peroxides;
  • GHS statements and symbols;
  • Whether or not it is hazardous to the ozone layer; and
  • Whether or not it is fully registered for REACH.

Boiling point (℃)

 
  1. D. Prat, A. Wells, J. Hayler, Sneddon, C. R. McElroy, S. Abou-Shehada and P. J. Dunn, CHEM21 selection guide of classical- and less classical-solvents, Green Chem., 2016, 18, 288–296.
  2. D. Prat, J. Hayler and A. Wells, A survey of solvent selection guides, Green Chem., 2014, 16, 4546-4551.
  3. D. Prat, A. Wells, J. Hayler, Sneddon, C. R. McElroy, S. Abou-Shehada and P. J. Dunn, CHEM21 selection guide of classical- and less classical-solvents, Green Chem., 2016, 18, 288–296.