Synthesis And Lubricating Property Study Of 1,3,4-thiadiazole Derivatives

Lubricating oil has been used in various types of mechanical and hydraulic devices, which usually contains certain amounts of additives. The performance of the lubricating oil has a very close relationship with the additives. The development of mechanical equipment requires the additives with good performances, such as anti-wear, anti-friction, anti-oxidation, anti-corrosion, extreme pressure resistance, etc. Study found that sulfur plays a very important role for the extreme pressure resistance property of lubricating oil, and nitrogen can slow the corrosion of sulfur to metal surfaces in the friction process. Nitrogen can help to form a protective film with anti-wear and anti-friction effects. Among various kinds of compounds with nitrogen and sulfur elements, active elements can be combined with different functional groups in the same molecule by 1.3,4-thiadiazole derivatives. This kind of compound has good friction effect, with little damage to the environment. So it's a kind of multifunctional additive with application prospect.In this paper, five kinds of compounds which couidn't be studied and used in the field of lubricating oil additive were synthesized taking 5-amino-2-mercaptol,3,4-thiadiazole as raw material. The naming of the five kinds of compounds are 5-amino-2-thioalkyl-1,3,4-thiadiazo-le,5-acetamide-2-thioalkyl-1,3,4-thiadiazole,5-amino-1.3,4-thiadiazole-2-sulfenylaceticacid-ester,5-acetamide-1,3,4-thiadiazole-2-sulfenylaceticacidester,5-acetamide-2-alkyldithio-l-3,4-thiadiazole.They include forty-two compounds and twenty-one of them are novel. Among the known twenty-one compounds, part of them were synthesized using the new methods. The molecular structures of them were confirmed by HRMS, IR and'H NMR. The thermal stability, anti-friction and extreme pressure resistance performances of five novel compounds were determined. The corrosion resistance performance of thirty-one compounds were determined.The thermogravimetric analysis result showed that the thermal decomposition temperature of the determined compounds are between 250 centigrade to 300 centigrade, which indicated that they have good thermal stability. The corrosion resistance performance of these additives in liquid paraffin were studied by the copper corrosion method. The experiment showed that the copper corrosion level had reduced to la or 1b level from 1b or 3a level after adding additives. The anti-friction and extreme pressure resistance performances of all selected additives were determined by SRV tests. The result indicated that the friction coefficient of lubricating oil samples decreased by 40?60% after adding additives. The extreme pressure value increased by 50?200% after adding additives. The measured additives have good anti-friction and extreme pressure resistance performances.