KiloMentor is always on the lookout for methods to separate components of a mixture by partitioning between immiscible liquids. Better known ones are methanol or acetonitrile with hydrocarbons. Many different solvent pairs may show immiscibility between ambient temperature and -20 C and this temperature range is easily accessible inside a jacketed reactor where liquid-liquid partitioning is done at scale. It is in the laboratory that this temperature range is inconvenient to achieve.
Below are listed some less-common immiscible pairs that may prove useful.
Dimethylsulfoxide - Xylene
Dimethylsulfoxide - Diethyl Ether
Dimethylformamide - Xylene
Dimethylformamide -Diisopropylether
Trichloroethylene - Xylene
Acetic acid - Hexane
Methyl t-Butyl Ether (TBME) -Sulfolane
The DMF /Diisopropyl ether immiscibility suggests that one look for an Upper Critical SolutionTemperature (UCST) between DMF and TBME at below room temperature. A small amount of water could be added to the DMF to raise the UCST.
Since DMSO and diethyl ether have immiscibility it suggests that one explore for a UCST between DMSO and TBME below ambient temperature.
What would the miscibility be between a mixture of xylene and diethyl ether with DMSO? Both xylene and diethyl ether are separately immiscible with DMSO.
To get rid of the diethyl ether suppose we try a mixture of xylene and TBME with DMSO?
How about a mixture of DMSO and trichloroethylene with xylene? Both DMSO and trichloroethylene are separately immiscible with xylene.
Dimethylsulfoxide or DMF reactions could be worked up by extraction into m-Xylene followed by azeotropically removing the xylene as an azeotrope with water after cold extracting the xylene to remove residual dipolar aprotic solvent.
Both m-xylene and isopropylbenzene form azeotropes with water that can be used to quickly remove the organic as a clean phase. Can either of these be useful for isolating organics formed in the solvents DMF or DMSO? You tell me- I’m retired; you have a lab.
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