Methyl linolenate was separated from its analogues by a new extraction system constructed by solvent

imidazolium based ionic liquids and cuprous salt. Firstly

the effect of ionic liquid on the dissolution of CuCl in acetonitrile

N

N

-dimethylformamide (DMF)

methanol and water was evaluated by visual observation.[C

4

Mim

]

[Cl

]

can improve the dissolution of CuCl in acetonitrile. Then

for the new system as acetonitrile-ILs-CuCl

extraction equilibrium

distribution ratio and selectivity of methyl linolenate and its analogues were determined by gas chromatography analysis and the mass balance. The extraction time

IL structures and CuCl concentrations were investigated. Distribution ratio decreased slightly

but selectivity increased significantly with the addition of CuCl

[C

4

Mim

]

[Cl

]

or[C

4

Vim

]

[NTF

2

]

into acetonitrile.[C

4

Vim

]

[NTF

2

]

had higher selectivity than[C

4

Mim

]

[Cl

]

. But the selectivity of the system combining CuCl with[C

4

Vim

]

[NTF

2

]

was much lower than with[C

4

Mim

]

[Cl

]

. For the CuCl-[C

4

Mim

]

[Cl

]

-acetonitrile

the e

xtraction efficiency was better than CuCl-acetonitrile

increasing Cu

+

concentration effectively improved the separation selectivity when ratio of CuCl/[C

4

Mim

]

[Cl

]

was less than 1. Compared with previous aqueous AgNO

3

extractions

the method of using CuCl is a much cheaper and practical way to enrich unsaturated fatty acid.