Theoritical And Experimental Study Of DB14C4 And Its Complex

The applications of lithium and their compounds are more and more extensive, but in China the extraction of lithium from brine lake is always a problem as the ratio of magnesium and lithium is very high, and the properties of lithium and magnesium are very similar, crown ethers that are man-made cyclic multidentate ligand have been the most investigated. The selectivity of crown ethers toward metal ions might be useful for extraction of metal ions from natural sources, which are very important in application of crown ether. The properties of crown ethers depend on their constitutions. There are very important relationships between structure of the crown ether and cation selectivity as well as their complex chemistry. An attempt to find an most excellent method to prepare dibenzo-14-crown-4 using catechol, lithium hydroxide, 1,3-dibromopropne by optimizing conditions of the reaction and using supersonic synthesis method in this paper. Furthermore, using a type U-type cell fluxes and selectivities for competitive Li⁺,Mg²⁺ transport across bulk membranes by the lipophilic dibenzo-14-crown-4 carrier have been determined in a variety of solvents. In addition, a quantum mechanical research which use the density functional theory to optimize configuration and analyse frequency at B3LYP/6-31G level in the Gaussian 98 was carried out. The results show, when using the mix of isoamyl alcohol and dimethyl sulfoxide as solvent, and the first adding ratio of 1, 3-dibromopropane is 1/4,1/3, the quantity of 1, 3-dibromopropane is far more than pyrocatechol, it's favorable for the formation of intermediate product. Only using dimethyl sulfoxide as solvent, during the period of ultrasonic synthesis in the temperature 80℃, reaction speed are quicker(2h), productivity is also fairly good(40.3%). Using a type U-type cell fluxes and selectivities for competitive Li⁺,Mg²⁺ transport experiments in chloroform, acetone, methanol, The selectivity is different and the mobility also existence difference in different solvents, in the chloroform, the lithium mobility is maximal(14.8%), the selectivity to the lithium is also higher. Dibenzo-14-crown-4 can form crystal with LiSCN, LiOH, and some structure parameters of complex are obtained with crystal diffraction. Three stable configurations are obtained with optimized structure calculating, and all the frequency value is positive, the strongest relatively infrared intensity appears respectively in frequency for 1241 cm^-1, 1219cm^-1, 1233 cm^-1. The comparison with the experimental value which the strongest infrared intensity appears respectively 1249 cm^-1,1230 cm^-1 in conventional synthesis and supersonic synthesis is carried out. The agreement is faily good between theoretical value and experimental value, it suggests the reasonable prediction can be carried out with Guassian program.