Cryptate ether, also known as cryptoalkane, is a kind of artificial synthesis, which can be used withcationDouble ring and multi ring and multi tooth ligands that coordinate.The most common and important cave ether is N [CH2CH2OCH2CH2OCH2CH2CH2] 3N.The preparation of caveoline is difficult and expensive;However, compared withcrown etherSomething like thatCoordination agentCompared with the alkali metal ions, the cave ethers are more tightly bound and more selective.Through coordination, the hole ether can reduce the solubility in organic compoundssolventIs dissolved in another phase, used asphase transfer catalyst, accelerating the rate of chemical reaction;It can also stabilize alkali metal positive ionsalkalide andElectronic saltTo synthesize.In addition, it can also help Sn9Zintl ion (Zintl ion)crystal。
Cryptate ether, also known as cryptoalkane, is a kind of artificial synthesis, which can be used withcationDouble ring and multi ring and multi tooth ligands that coordinate."Cave ether（cryptand）”The term "cavity" refers to that the shape of the coordination body is like a hole, which willsubstrateThe molecules are contained inside.The whole molecule is a three-dimensional structure.So it is similar to thecrown etherCompared with, the cave ether complex is more stable, and has a good effect on theselectivityAlso stronger.The composite formed hasLiposolubility。Donald J. Cram 、Jean-Marie Lehn andCharles J. Pedersen Through the combination of para hole ether andcrown etherConducted research and createdSupramolecular chemistryAnd thus obtained the 1987Nobel Prize in Chemistry。
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Fig. 1 Cavitation ether diagram
The most common and important cave ether is N [CH2CH2OCH2CH2OCH2CH2CH2] 3N (Figure 1),IUPAC nameIt is 1,10-diaza-4,7,13,16,21,24-hexaoxabicyclo [8.8.8] hexadecane, commonly known as[2.2.2] - Cavalier。The numbers in square brackets indicate the number of oxygen atoms on each bridge between the two nitrogen bridgeheads.
Holoaminealkali metalcationIt has very high affinity withalkaliThe salts containing alkali metal anions such as K can be successfully obtained by metal interaction.
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The three-dimensional internal cavity of caveoline can be tightly combined with foreign ions to form a complex calledCryptic compound。The strongest combination ability isHardCations of, including NH4（Ammonium ion）AndLanthanide、alkali metal、alkaline-earth metalCations of.Caveoether utilizationnitrogenandoxygenAs different ions coordinate with these ions, different alkali metal cations can be distinguished or separated by selecting appropriate hole ethers due to their different binding abilities with different three-dimensional structures.
Similar to crown ethers, macrocyclic ethers are generally prepared by condensation reaction of amine and halohydrocarbon.However, due to the more complex ring system, the yield of cryptate ethers is usually not high.
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The preparation of caveoline is difficult and expensive;However, compared withcrown etherSomething like thatCoordination agentCompared with the alkali metal ions, the cave ethers are more tightly bound and more selective.Through coordination, the cave ether can dissolve salts that are generally insoluble in organic solvents in another phase, and can be used asphase transfer catalyst, accelerating the rate of chemical reaction;It can also stabilize alkali metal negative ionsalkalide andElectronic saltTo synthesize.In addition, it can also help Sn9Zintl ion (Zintl ion)crystal。
In productionRadiomedicineDrugs needed for imagingFluorodeoxyglucose(FDG for short), will use [2-2-2] hole ether to complexe the potassium ion in the reactant KF, improve the nucleophilicity of radioactive F ion, so as to connect F toDeoxyglucoseMedium.
