Professor Vladimir Zaitsev

D.Sc., PhD, Corr. member of Acad. of Sci. of Ukraine

2006

  1.  V.N. Zaitsev, L.S. Kostenko, N.G. Kobylinskaya. Acid-base properties of silica-based ion-exchanger having covalently bonded aminodi(methylphosphonic) acid. Analytica Chimica Acta, 2006, V. 565, № 2, 157-162
    Acid–base properties of an organophosphorous silica-based ion-exchanger with covalently bonded complexone groups—N-propylaminodi(methylphosphonic) acid (AdPA-SiO2) were studied. By comparison of AdPA-SiO2 chemical analysis and data of pH and conductometric titration it was demonstrated that the composition of immobilised layer differ from sample to sample and might consist of 60–88% aminodi(methylphosphonic) acid and 12–40% of residual aminopropyl groups. Regardless of the multifunctional nature of AdPA-SiO2 interfacial layer, its acid–base properties can be predicted. All studied AdPA-SiO2 samples have the properties of strong multiprotic H4L acids with pK1 < 2.6. Incomplete transformation of amino groups to aminodiphosphonic acid plays the key role in determination of the conditions of AdPA-SiO2 ionisation in neutral and weak-basic media. Linear correlation was found for pK2 and amine-to-acid conversion degree (ω) with pK2 = 8.8 − 4.0ω. It allows us to determine the conditions of AdPA ionisation for all AdPA-SiO2 samples. The established correlation can be used to check the quality (the degree of interfacial layer heterogeneity) of AdPA-SiO2. The final measurable ionisation constant for AdPA-SiO2, pK3 = 7.9 ± 0.6 is 2-orders of magnitude higher then acidity constant for AdPA homogeneous analogue. It seems that such reduction is caused by increase of electro static interaction between movable counter-ions and negatively charged surface groups. Conductometric study of AdPA-SiO2 also suggests firm fixation of counter-ions in the interfacial layer.
  2. S.A. Alekseev, V.N.Zaitsev, J. Fraissard. Organosilicas with covalently bonded groups under thermochemical treatment. Materials Chemistry, 2006, V. 18, № 7, Р. 1981-1987.
    Silica-based hybrid materials having covalently immobilized vinyl (SiO2-C2H3), chloropropyl (SiO2-R-Cl), trimethylsilyl (SiO2-SiMe3), ethyl sulfonic acid (SiO2-R-SO3H), and aminopropyl (SiO2-R-NH2) groups, as well as the salt of the latter with HNO3 (SiO2-R-NH2·HNO3) were studied by different thermoanalytical methods: thermogravimetry (TGA), differential thermal analysis (DTA), and temperature-programmed desorption mass spectrometry (TDP-MS). It was demonstrated that TPD MS can be successfully used for the investigation of the interfacial layer in such materials. Particularly, it was shown that a side reaction between the grafted group and aromatic solvents is possible during the preparation of SiO2-C2H3 and SiO2-R-Cl. For SiO2-SO3H the formation of 2-Si-ethanesulfonic, 1-Si-ethanesulfonic, and 2,4-Si-butanesulfonic acid grafted groups with the predominance of the 2-Si isomer was found. The process of SiO2-NH2·HNO3 decomposition at 500 K may be applied for the preparation of silica modified by aldehyde groups. Mechanisms of thermal transformations of bonded layer were established and the key role of the reactions of grafted groups with silanols in such processes was demonstrated. As was found for SiO2-R-Cl and SiO2-R-NH2, the decomposition process with participation of silanols is realized in two stages. The first one occurs in the 400-700 K range and includes the interaction between organic groups and the neighboring silanol. The second decomposition stage occurs above 700 K and includes migration of the bonded groups on the silica surface.
  3.  I. V. Khristenko, Yu. V. Kholin, N. O. Mchedlov-Petrossyan, C. Reichardt, and V. N. Zaitsev Probing of Chemically Modified Silica Surfaces by Solvatochromic Pyridinium N-Phenolate Betaine Indicators. Kolloidnyi Zhurnal, 2006, Vol. 68, No. 4, pp. 558−565. The state of betaine indicators, 2,6-diphenyl-4-(2,4,6-triphenylpyridinium-1-yl)phenolate and 2,6-dichloro-4-(2,4,6-triphenylpyridinium-1-yl)phenolate, on the surfaces of aminosilicas, silica modified with aminodiphosphonic acid, and unmodified silica gel is studied with diffuse reflectance spectroscopy. The normalized polarity parameters are calculated for the surface layers of the sorbents. It is revealed that regions with substantially different polarity and acidity are present on the surface of chemically modified silicas.
  4. T. Kovalchuk, H. Sfihi, L. Kostenko, V. Zaitsev and J. Fraissard. Preparation, structure and thermal stability of onium- and amino-functionalized silicas for the use as catalysts supports. Journal of Colloid and Interface Science, Volume 302, Issue 1 , 1 October 2006, Pages 214-229
    We explored and compared several synthetic methods of grafting silica with strong (alkyltriphenylphosphonium, tetralkylammonium, propylpyridinium and dialkylimidazolium) and weak (γ-aminopropyl, γ-(N-imidazolyl)propyl) anion-exchanging groups starting with commercially available chloroalkyl- and γ-aminopropylsilanes. Structure of the intermediate and final materials was investigated by elemental analysis, titration, 13C, 29Si, 31P MAS NMR, DRIFT, and TPD MS. The derivatives of alkyltriphenylphosphonium, propylpyridinium and dialkylimidazolium cation can be prepared with satisfactory quaternisation yields (ca. 30–100%) via the nucleophilic substitution of γ-chloropropyl groups either in the silane or in chloropropylsilica, resulting in bonded phases with moderate densities: 0.2–1.0 group nm−2 (onium salts) and 0.2–1.5 group nm−2 (amines). Parallel one-pot end-capping/hydrophobization can be done if a mixture of target silane with end-capping reagent or γ-chloropropylsilane is used. The grafted layer is highly stable at the level of Si–C bonds and decomposes at ca. 400 °C, while the onium functions begin to decompose at ca. 250 °C, lowering the thermal stability of materials. Thus, anion-exchanging silicas can be envisaged for the use as catalyst supports at moderate temperatures.
  5. В.Н. Зайцев, В.А. Халаф, Г.Н. Зайцева Твердофазный Экстрагент Для Извлечения Фенола, На Основе Кремнезема Модифицированного Солью Арилдиазония // Украинский химический журнал, 2006, т. 72, №2, с.105-109.
  6. Трохименко О.М., Зайцев В.М., Пащенко Є.О. Спектрофотометричне визначення церію(ІV) за допомогою дифеніл-сульфокислоти // Укр. химич. журн. – 2006. – Т. 72, № 8. – С. 100-103.
  7. Зайцев В.Н., Георгиевский В.П., Наджафова О.Ю. Международная конференция «Аналитическая химия и химический анализ» AC&CA-05 посвященная 100-летию со дня рождения акад. НАН Украины А.К. Бабко// Фармаком. – 2006. – № 1;. – С. 7 - 11.
  8.  Зайцева Г.М., Халаф В.А., Конопліцька О.П., Зайцев В.М. Сорбційно-атомно-абсорбційне визначення Сu(II), Cd(II), Zn(II), та Pb(II) у питній воді за допомогою кремнезему, модифікованого пропілтіоетиламіном // Укр. хим. журнал.-2006.-72,№ 10. –C.108-113
  9.  Трохименко О.М., Зайцев В.М., Писарева Н.Є. Вплив аніонів мінеральних кислот на швидкість перебігу реакції Сендела-Кольтгофа // Укр. химич. журн.- 2006. - Т. 72, № 10. - С. 26-29.
  10.  Трохименко О.М., Зайцев В.М., Писарева Н.Є. (аспір.). Фотометричне визначення іодату в іодованій кухонній солі // Вісник Київського нац. ун-ту імені Тараса Шевченка. Хімія, 2006. - Т. 43. - С. 55-56.
  11.  Р.Н. Барабаш, С.А. Алексеев, В.Н. Зайцев, Д. Барбье. Устойчивость к окислению и модифицирование винилсиланами пористого кремния // Укр. хим. журн. — 2006. — 72, N 9-10. — С. 78-84.
    Исследована устойчивость пористого кремния к термическому и гидролитическому окислению. Показано, что одним из важнейших факторов, лимитирующих этот процесс, являются гидрофобно-гидрофильные свойства материала. Проведено закрепление трихлор- и триметокси-винилсиланов на поверхности пористого кремния по реакциям гидросилилирования и силанизирования. Показано, что закрепление на поверхности кремния этилен-2-трихлорсилильных групп приводит к значительному повышению гидрофильности материала, что в свою очередь вызывает его быструю коррозию за счет взаимодействия с находящимися в воздухе водными парами.
01-dez-15

Head of the laboratory of chemistry for organo-mineral materials

Department of analytical chemistry Taras Shevchenko National University of Kyiv
60 Vladimirskaya Str., Kiev Ukraine 01601

 ORCID Code
tel: +380-97-0980693, e-mail: vnzaitsev@gmail.com, http://anchem.knu.ua/ua/main_ukr.html
google scholar, researchgate, ResearcherID, LinkedIn ORCID