Phase-transfer catalyst

Source: Wikipedia, the free encyclopedia.

In

salts
into the organic phase. Phase-transfer catalysis refers to the acceleration of the reaction upon the addition of the phase-transfer catalyst.

Liquid-liquid-liquid triphase transfer catalysis,Molecular Catalysis 466 (2019) 112–121

By using a PTC process, one can achieve faster reactions, obtain higher conversions or

organic solvents is reduced.[2][3]

Contrary to common perception, PTC is not limited to systems with

hydrophobic
reactants. PTC is sometimes employed in liquid/solid and liquid/gas reactions. As the name implies, one or more of the reactants are transported into a second phase which contains both reactants.

Types

Phase-transfer catalysts for anionic reactants are often

phosphonium salts are also used, e.g., hexadecyltributylphosphonium bromide. The phosphonium salts tolerate higher temperatures, but are unstable toward base, degrading to phosphine oxide.[4]

For example, the

aqueous sodium cyanide solution with an ethereal solution of 1-bromooctane does not readily occur. The 1-bromooctane is poorly soluble in the aqueous cyanide
solution, and the sodium cyanide does not dissolve well in the ether. Upon the addition of small amounts of hexadecyltributylphosphonium bromide, a rapid reaction ensues to give nonyl nitrile:

By the quaternary phosphonium cation, cyanide ions are "ferried" from the aqueous phase into the organic phase.[5]

Subsequent work demonstrated that many such reactions can be performed rapidly at around room temperature using catalysts such as

methyltrioctylammonium chloride in benzene/water systems.[6]

An alternative to the use of "quat salts" is to convert alkali metal cations into hydrophobic cations. In the research lab,

hydrophobic
exterior.

Chiral phase-transfer catalysts have also been demonstrated.[7]

Applications

PTC is widely exploited industrially.

cinchona alkaloids.[8]

See also

References

  1. ^ Katole DO, Yadav GD. Process intensification and waste minimization using liquid-liquid-liquid triphase transfer catalysis for the synthesis of 2-((benzyloxy)methyl)furan. Molecular Catalysis 2019;466:112–21. https://doi.org/10.1016/j.mcat.2019.01.004
  2. PMID 29711128
    .
  3. doi:10.1351/pac200072071399
    .
  4. ^
    doi:10.1002/14356007.a19_293
  5. doi:10.1021/ja00730a033
    .
  6. doi:10.1021/ja00842a006
    .
  7. PMID 22824891
    .
  8. doi:10.1021/cr068368n
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