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 α-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[(4-methylphenyl)({[3-(tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]amino})methyl]phosphonate (BNP4). The prepared compounds were characterized by 1H and 13C 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 α-aminophosphonate derivatives have potential industrial applications as lubricant additives.