V. Andriyashin, Yuliya V. Bakhtiyarova, R. Cherkasov
Dec 1, 2012
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Russian Journal of Organic Chemistry
Abstract
Phosphorus-containing 2,6-di-tert-butyl-4-methylphenol derivatives exhibit a broad spectrum of antibacterial and antimycotic activity and are widely used as antioxidants [1, 2]. Depending on the substituents on the phosphorus atom, these compounds are active against pathogenic microorganisms in humans and animals, in particular against Staphylococcus aureus, Escherichia coli, Salmonella paratyphi B, Pseudomonas aeruginosa, and Candida albicans. We previously described a procedure for the synthesis of quaternary phosphonium derivatives of 2,6-di-tert-butyl-4methylphenol (I) by quaternization of tertiary phosphines with 3,5-di-tert-butyl-4-hydroxybenzyl bromide (II) which was prepared by bromination of phenol I with N-bromosuccinimide [3]. The reactions of benzyl bromide II with triphenylphosphine (III), methyldiphenylphosphine (IV), and tributylphosphine (V), as well as with 1,2-bis(diphenylphosphino)ethane (VI), 1,3-bis(diphenylphosphino)propane (VII), and 1,6-bis(diphenylphosphino)hexane (VIII), in diethyl ether at room temperature gave the corresponding crystalline phosphonium salts IX–XIV. The P NMR spectra of IX–XIV contained only one signal in the region δP 23.2–33.4 ppm, which corresponds to the phosphonium group. In the H NMR spectra of these compounds, a singlet at δ 2.5 ppm from protons in the tert-butyl groups, a doublet at δ ~6 ppm from the methylene protons, a singlet at δ 7 ppm from the OH proton, and a doublet at δ 8.0– 8.5 ppm from protons in the meta positions of the phenol ring were observed. The structure of phosphonium salt XII was confirmed by X-ray analysis; the results will be reported elsewhere. All newly synthesized phosphonium salts showed a high antimicrobial activity. 4-Bromomethyl-2,6-di-tert-butylphenol (II) was synthesized as described in [3]. mp 56°C. H NMR spectrum (CH3OD), δ, ppm: 2.80 s [18H, C(CH3)3], 5.97 s (1H, CH2Br), 7.00 s (1H, OH), 8.62 s (2H, C6H2). Found, %: C 60.54; H 8.01. C15H23BrO4. Calculated, %: C 60.21; H 7.75.