A Density Functional Theory Study On Design, Synthesis And Mechanism Of Thiocarbamate

This project applies molecule design technology to design and synthesize the novel thionocarbamate collectors for copper-sulphur separation. After theoretical analysis of the relationship between structure and flotation properties of flotation collectors, the research aims to determine the correlation between the flotation collector’s performance and its the frontier molecular orbital theory such as the form and energy, to screen out the appropriate molecular structure of collector, and to conduct the organic synthesis experiment and flotation verified test for the verification of structure-performance quality. This technology adopted will improve the sustainable development of mineral resources as it shortens the research cycle of new pharmaceutical molecules and reduces the investment.Density functional theory (DFT) was applied to investigate the geometric and electronic properties of a series of xanthate collectors. The reactivity of xanthate collectors was analyzed by using the energy of highest occupied molecular orbital (EHOMO), natural population analysis (NPA) charge, electronegativity (x), hardness index (η). The results show that xanthate anions is the active ingredient in flotation solution, and the bonding atom of xanthate anion is S atom of C—bond. The energy of HOMO can be used to interpret that the flotation activity of straight chain xanthates (C1-C6) increases with the alkyl chain growth. The more the branched chains of carbon atom attached to the polar group in the xanthate isomers is, the stronger the flotation activity is. The order of the flotation activity of C3-C5 xanthates isomers is as follows:tert-alkyl xanthate>sec-alkyl xanthate >iso-alkyl xanthate.DFT was applied to investigate the geometric and electronic structures of a series of xanthogen formates. According to the Klopman’s generalized perturbation theory, the relationship between flotation performance of collectors and quantum chemical parameters was analyzed by using the energies and shape of frontier orbitals, natural bond orbital (NPA) charge, electronegativity (x), hardness index (η). The results show that the bonding atom of xanthogen formates is S atom of C=S bond. These parameters such as the energy of highest occupied molecular orbital (EHOMO), NPA charge and electronegativity can only infer the flotation activity of collectors. The selectivity of xanthogen formates is mainly related to the copper atoms on the surface of chalcopyrite donate d-orbital electron to the lowest unoccupied molecular orbital (LUMO) and second lowest unoccupied molecular orbital (LUMO+1) of collectors resulting in the formation of a back donation covalent π-bond, thus improving flotation power for chalcopyrite and selectivity against pyrite. The energies of LUMO and LUMO+1 can be used to interpret the selectivity of xanthogen formates.Through the previous theoretical findings two novel collectors of Thionocarbamate are constructed:IP-BIAN and IPEE. Based on density functional theory and reaction energy criteria, the sequence of the two collectors and the common Thionocarbamate is shown in the following structure: IPECTC＞＞IP-BIAN>PAC＞Z-200>IPEE; and then the thionocarbamate molecular is synthesized. It turns out that the test result identifies the prediction after the flotation verified test of pure mineral, artificial mineral and actual mineral.