Diethyl α-aminophosphonate containing lubricating additives synthesized from (3-aminophenyl)boronic acid pinacol ester

In this paper, (3-aminophenyl)boronic acid pinacol ester was employed as a raw material to react with different aromatic aldehydes. Then diethyl phosphite was introduced to produce the addition reaction of carbon nitrogen double bond to prepare four diethyl alpha-aminophosphonate derivatives, which were diethyl[phenyl({[3-(tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]amino})methyl]phosphonate (BNP1), diethyl[(4-methoxyphenyl)({[3(tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]amino})methyl]phosphonate (BNP2), diethyl [(4-nitrophenyl) ({[3-(tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]amino})methyl]phosphonate (BNP3), and diethyl[(4methylphenyl)({[3-(tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]amino})methyl]phosphonate (BNP4). The prepared compounds were characterized by H-1 and C-13 NMR, MS, FT-IR and PL (Photoluminescence Spectroscopy). Four derivatives perform high thermal stability. In addition, it exhibits good friction properties for rapeseed oil (RSO) at low concentrations. Compared with BNP1, BNP2 and BNP4, BNP3 exhibits best on friction-reducing and anti-wear performances attributed to the strong electron withdrawing ability of the nitro group in BNP3, which is also reflected in the solid-state fluorescence. Therefore, the four diethyl alpha-aminophosphonate derivatives have potential industrial applications as lubricant additives.

Automated summary

In this study, four diethyl alpha-aminophosphonate derivatives were synthesized by reacting (3-aminophenyl)boronic acid pinacol ester with different aromatic aldehydes and diethyl phosphite. The compounds showed high thermal stability and good friction properties for rapeseed oil at low concentrations. Among them, BNP3 exhibited the best friction-reducing and anti-wear performances due to the strong electron withdrawing ability of the nitro group. This suggests potential industrial applications of these derivatives as lubricant additives.