Synthesis And Tribological Properties Of Phenylborate Esters Containing Schiff Base Group

Organoborate is a kind of lubricating oil additive with wide application prospects because of its good anti-friction and anti-wear properties,easy degradation and nontoxicity,but poor hydrolytic stability greatly limits its application.Therefore,it is of great significance to develop organoborate lubricant additives with high hydrolytic stability and excellent friction efficiency.Synthesis of intermediate(4-(2-(2,4-dinitrophenyl)hydrazine)methyl)phenylbo-ronic acid(referred to as intermediate a1)with 2,4-dinitrophenylhydrazine and4-formylphenylboronic acid.After the intermediate a1 was esterified with dod-e canol,cetyl alcohol and eicosyl alcohol,(4-(2-(2,4-dinitrophenyl)hydrazine)met-h yl)phenylboronic acid didodecyl ester(referred to as Borate-12),(4-(2-(2,4-din-it rophenyl)hydrazine-methyl)phenylboronic acid dihexadecyl ester(abbreviated as Borate-16),(4-(2-(2,4-dinitrophenyl)hydrazine)methyl)phenylborate dieicosate(abbreviated as Borate-20)and characterized its structure.Diethanolamine and bromododecane synthesis intermediate 3-dodecyl pentane-1,5-diol(referred to as intermediate b1),4-formylphenylboronic acid and n-butylamine synthesis intermediate(4-(butylimino)methyl)phenylboronic acid(referred to as intermediate M).After the reaction of intermediate b1 with intermediate M,4-vinylphenylboronic acid and 4-pyridineboronic acid,respectively to synthesize Nbutyl-1-(4-(6-dodecyl-1,3,6,2-dioxobane-2-yl)phenyl)methanamine(abbreviated as DBD),6-dodecyl-2-(4-vinylphenyl)-1,3,6,2-dioxaborane(DVD),6-dodecyl-2-(pyridin-4-yl)-1,3,6,2-dioxobane(DPD),Its structure was characterized.Six synthetic phenylborates were tested for thermal stability,hydrolytic stability and oil solubility.In various tests,the synthesized six phenylborates were found to have better performance than ZDDP.The friction coefficient and grinding diameter of six phenylborate lubricant additives in paraffin oil under different added mass fractions were tested by a four-ball friction and wear testing machine.Among them,the friction reduction efficiency of adding 0.01 % Borate-16 paraffin oil increased by 11.96 %,and the anti-wear efficiency of adding 0.07 % Borate-20 paraffin oil increased by 26.26 %.The anti-friction efficiency of 0.07 % DBD paraffin oil was increased by 15.21 %,and the anti-wear efficiency of 0.07 % DPD paraffin oil was increased by 42.42 %.The worn ball surfaces were analyzed by scanning electron microscopy and X-ray spectroscopy(SEM/EDS).The results showed that the wear surface of the steel balls with six phenylborates was flatter,and a chemical reaction film containing boron and nitrogen containing low shear strength was generated during the friction process.