1. Good Extraction Performance
WP2: Design, Selection & Synthesis of (task-specific) ionic liquids
Contact: Katharina Schröder
Hydrophobic ionic liquids for metal extraction
Literature data for IL-assisted metal extraction is primarily based on
“Bistriflimide” NTf2- (state of the art)
Some examples with PF6-
Few examples with long-chain alkyl sulfonates/alkylsulfates or
Long-chain quarternary phosphonium cations
What we are looking for:
Cheap
Hydrophobic
Non-toxic
Good Extraction Performance

2. Selection of (task-specific) ionic liquids: Cost
Docusate (Doc), Diisoctylphosphinate (DOP)

3. Selection of (task-specific) ionic liquids
As a compromise between cost, physical and biological properties, we selected three different anions:
Anion
Structure
Prize (Aldrich, )
Advantage
Disadvantage
Bistriflimide
NTf2-
€ 218/100 g
Low viscosity
Chemical inert
Literature approved
Prize!
Diisooctyl-phosphinate
DOP-
€ 39/100 g
Cheap
Task-specific extractant
Non-toxic
Viscosity?
Purity?
Docusate
Doc-
€ 21/100 g
Biologically approved (GRAS-compound)
Thermal stability?
Note: Dialkylphosphinic acids are used as extractants for Co & Ni (e.g. Cyanex 451) and provide not only a cheap and hydrophobic anion source, but also a task-specific extractant!

4. Selection of (task-specific) ionic liquids
These anions were paired with the following cations:
Cation
Choline
Betaine
Butylmethyl-imidazolium
Tributyl-methyl-ammonium
Tributyl-methyl-phosphonium
Trihexyl-tetradecyl-phosphonium
Structure
Advantage
Cheap, non-toxic
GRAS
Cheap,
non-toxic,
State of the Art
Cheaper than imidazolium compounds
Chemically inert,
high thermal stability
Chemically inert;
high thermal stability;
cheap
Very hydrophobic
Dis-
advantage
Limited stabiity
High mps
Prize, Toxicity
Toxicity
(Aqua-)toxicity

5. Step 1 Step 2 Step 3 Step 4 Step 5
Work-Flow I
April 2014
February 2014
December 2013
Step 1
Conference Call
Selection of 18 hydrophobic ionic liquids
Step 2
Small-Scale Synthesis
Lab Scale g
Step 3
Assessment of Properties I
Structure 1H, 13C NMR, IR, MS
Characterization of physical properties
Step 4
Selection of suitable candidates
Repeat Lab-Scale Synthesis 100 g
Complete Characterization: DSC, TGA, Viscosity, Water Content
Step 5
Application for Extraction Experiments

6. Work-Flow II Cation/Anion Choline [C4mim] N4441 P4441 P66614 N(Tf)2-
[C4mim]
N4441
P4441
P66614
N(Tf)2-
TECN – Lab scale
SOLV Lab scale
VUT – Lab scale
Docusate
Dialkyl-phosphinate