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Description:
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The use of synthetic ionophores in both academic and industrial settings continues to increase . Growth in this field of chemistry has created a need for ionophores with pendant groups which allow for further chemical elaboration . This dissertation treats the synthesis of such ionophores .
Crown ethers (macrocyclic polyethers ) and cryptands (macrobicyclic polyethers ) which bear hydroxymethyl functions are prepared from benzyl -protected and allyl -protected precursors , respectively . Crown ethers containing ionizable chromogenic subunits are synthesized from benzocrown ether and hydroxymethylcrown ether starting materials in high yields . Neutral fluorogenic crown ethers are obtained in two steps from commercially -available starting materials . A series of novel bis -crown ethers results from condensation of diacid chlorides with hydroxy -16 -crown -5 compounds .
Several bis -crown ethers are tested for their ability to complex the alkali metal cations by the picrate extraction method . Results indicate that the formation of 2 :1 (crown :cation ) complexes with potassium ion may be promoted by linking two oxymethyl -15 -crown -5 units ortho on an aryl ring . A broad spectrum of small -ring four -oxygen crown ethers are tested by the same method for their ability to extract lithium ion . Results indicate that the 14 -crown -4 ring size is the best suited in extraction capacity and selectivity for the complexation of lithium . Chloroform solutions of the ionizable chromogenic crown ethers are tested for their response upon contact with aqueous solutions of the alkali metal hydroxides . It is determined that the l -amino -2 ,4 -dinitro -6 -trifluoromethylbenzene chromophore is the best suited for incorporation into chromogenic crown ethers because of its acidity , high extinction coefficient and well -resolved spectral shift upon ionization . |