Study On Synthesis Of Complexes With Ligands Containing Sulphur Atoms And Their Applications In Rubber As Vulcanization Accelerators

In this thesis, the development, synthesis and analysis means of rare earth complexes with ligands containing sulphur atoms are described indetail. At the same time, the properties and applications in industry of all kinds of vulcanization accelerators have been reviewed. A series of novel rare earth and II B metal complexes with ligands contained sulphur atoms have been prepared here and their accelerating vulcanization properties have also been studied.1. Eight complexes of rare earths with 2-mercaptobenzothiazole, RELC12.RE(OH)3 XH2O ( L=2-mercaptobenzothiazole, RE= La - Gd, Y, except for Pm, X = 0, 2-4), were synthesized in anhydrous ethanol and characterized by elemental analyses, IR spectrometry and thermal analyses. The results show that the ligand is coordinated to the RE ion through both the exocyclic sulfur and the thiazole nitrogen.2. Seven complexes of light rare earths with dibenzyldithiocarbamate, RE(BDTC)3-2H2O ( RE = La-Gd, Y, except for Ce and Pm, BDTC = dibenzyldithiocarbamate). They are characterized by elemental analysis, IR spectra and TG-DTA technique, which shows that ligand is coordinated to the rare earth ion through two sulphur atom donors.3. Based on the complexes Nd(BDTC)3 2H2O, the crystal of [Nd(BDTC)3(HMPA)2] (HMPA = hexamethylphosphoric triamide) has been prepared and its structure has been unequivocally established by an X-ray crystallographic study. The neodymium ion is coordinated to six sulphur atoms from three ligands and two oxygen atoms of HMPA, the average Nd-S distances being 2.950 A and Nd-O distances being 2.374 A. Crystal data: triclinic, space group P-1, a = 11.8219(7), b = 15.4349(10), c = 19.6577(12) A, a= 91.630(1),b= 104.425(1), r= 107.937(1) Dc=1.323 Mg/m3, for Z=2, R=0.0522, for 34771 observed reflections.4. A stable complex [Hg(BDTC)2] was synthesized through the reaction of NaBDTC with HgCl2. Its structure and properties were characterized by X-ray crystallography, IR and thermal analysis. The mercury ion is coordinated to four sulphur atoms of two ligands with two short Hg-S distances of 2.4064 A and two long Hg-S distances of 2.7736 A. A monomeric motif, featuring distorted tetrahedral geometries, is found. The crystal is orthorhombic system, space group Pbcn, with a = 16.4738(10), b= 18.6418(11), c =9.4000(6) A, V = 2886.8(3) A3 , and Z = 4.Changing the synthesis conditions, two Zinc complexes [Zn(BDTC)2] and [Zn(BDTC)2Py] (Py= pyridine) are prepared and studied by X-ray crystallography, IR and thermal analyses. The structure of [Zn(BDTC)2] is similar to that of complex [Hg(BDTC)2]. The zinc ion is coordinated to four sulphur atoms from two ligands. But four Zn-S distances within the relatively narrow deviation of 0.03 A are almost same. The crystal of [Zn(BDTC)2] is Orthorhombic system, space group Pbcn and Z = 4.[Zn(BDTC)2] was assembled to a novel complex [Zn(BDTC)2Py] by using pyridine. In [Zn(BDTC)2Py] the zinc ion is coordinated to four sulphur atoms and one nitrogen atom of pyridine. The coordination of pyridine ligand results in the Zn-S distances falling within wide deviation of 0.3 A. Crystal belongs to Triclinic, space group P-1 and Z = 2.5. In NR/BR/SBR blend, the vulcanizing properties of lanthanide 2-mercaptobenthiazole complexes as vulcanizing accelerators have been studied, which indicates the cross-licked rubber accelerated by the rare earth complexes has good physical mechanical properties.6. The vulcanization behavior of novel cure accelerator [Nd(BDTC)3(HMPA)2] in nature rubber and the mechanical properties of its vulcanizate were studied. The results indicates that the vulcanization of NR accelerated by [Nd(BDTC)3(HMPA)2] has the typical steep cure curve. The NR vulcanizate accelerated by the Nd complex has better physical mechanical properties than that by NOBS and CZ/TMTD.