Використання реакції азодеривації для визначення 2-хлорофенолу методом високоефективної рідинної хроматографії
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Date
2016
Authors
Мага, Іван
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Journal ISSN
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Abstract
Досліджено умови азодеривації 2-хлорофенолу з 4-нітрофенілдіазоній катіоном. Встановлено
оптимальні умови проведення реакції: рН 9–11,5; 20-кратний надлишок реагенту, 60-хвилинна
експозиція реагуючих речовин. Лінійна залежність площі хроматографічного піка від концентрації
2-хлорофенолу спостерігається в межах 25–5000 мкг/л. Розроблено методику визначення
2-хлорофенолу в ґрунтах методом високоефективної рідинної хроматографії (ВЕРХ). Методику
апробовано на модельних розчинах та на реальному об’єкті. Проведено метрологічну обробку
результатів.
Description
This paper presents a study of azoderivation reaction of azoderivation 2-сhlorophenole (CP) by
4-nitrophenildiazonium cation. The effect of hydrogen ions in the formation of azoderivative CP examined
within 3.6–13.7 pH is that it creates an environment with solution of HCl and NaOH. Maximum output of
azoderivates is observed within pH 9–11.5. Reduction of the output of azocompound CP at pH < 8 is due to
the dominance of its non-reactive molecular shape, and decrease at pH > 12 is caused by the decrease in
the concentration of diazonium cation. The effect of the reagent concentration was studied in a series of
experiments where the concentration of diazonium cation ranged from 1 to 30 times of the amount in relation
to the number of CP. Azoderivate is formed in the amount of about 50 % with the components ratio of 1:1.
With further increase of diazoreagent concentration to 10 times as its amount, the amount of azoderivates
production is rapidly growing. At concentrations of more than 10-fold quantities, almost complete formation
of azocompounds is achieved. In further studies, the 20-fold excess was used.
The kinetics of formation of azocompounds is studied. Almost half of azoderivates is formed during the
first few minutes of interaction of solutions, and significantly increases by the 40th minute of interaction of
components, then (40–100 min) it increases slightly. The optimum is a 60-minute exposure of solutions.
Significant exposure of solutions and a large (20-fold) excess of the reagent may be associated with a
high solvatation ability of CP, where the presence of phenolic groups causes a great ability to form hydrogen
bonds. The presence in the ortho-position of the benzenes ring of chlorine atoms, an electrophilic subsistent
level 1, polarises the bond in -O-H group more and enhances this ability. The presence of strong hydrogen
bonds can cause such kinetic inertness of hydroxocomplexes CP, formed in water solution, and the need of
the 10–20-fold excess of the reagent to achieve the complete reaction of derivatization.
Preferred extractants for extracting azoderivates 2-chlorophenoles proved to be dichloromethane and
chloroform. The linear dependence of the area of the chromatographic peak on the concentration of CP was
observed in the range of 25–5000 mg/l. The technique has been tested on samples of model and real objects.
A result of the study is the method for determination of CP in soils by high performance liquid chromatography.
Metrological processing results were achieved.
Keywords
2-хлорофенол, реакція азодеривації, методика визначення, ВЕРХ
Citation
Мага Іван Михайлович. Використання реакції азодеривації для визначення 2-хлорофенолу методом високоефективної рідинної хроматографії / Мага І. М. // Магістеріум. - 2016. - Вип. 63 : Хімічні науки. - С. 63-67.