Novel water soluble γ-phosphonates and phosphonic acid quaternary ammonium compounds (QAC) with different
alkyl chain lengths, a dansyl (DNS) fluorescent tag ([RN+Me2(CH2)3P(O)(OR1)2]Br-; R = CH3, C18H37, -DNS-NH-
(CH2)3; R1 = Et, iPr, or H) or pyridinium ([C5H5N+(CH2)3P(O)(OR1)]Br-; R1 = iPr, or H) were synthesized in two or three
steps (Arbuzov, Menshutkin and bis-dealkylation reactions) under MW conditions within minutes in good yields. These
protocols were then compared to thermal heating (TH). Both H2O and MeCN were found to be effective solvents for the
Menshutkin and the bis-dealkylation of phosphonate QAC. These reactions were carried out for the first time under MW
heating sequentially or in a one-vessel procedure with mineral acids. New compounds were characterized by NMR spectroscopy,
HRMS spectrometry and in two instances (17, 20) by X-ray crystallography. We provide X-ray crystallographic
evidence for the isolation of the QAC phosphonic acids as the free acids containing the Br- counter ion instead of the previously
suggested phosphobetaine internal salts. Self-assembled monolayers of the phosphonic acid QAC prepared in this
study are expected to be suitable antimicrobial coatings for metal surfaces used for biomedical applications.
Keywords: Arbuzov, didealkylation, environmentally friendly methods, Menshutkin, microwave, monolayers, phosphonate,
phosphonic acid, quaternary ammonium antimicrobials, stainless steel coatings.
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