کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1206903 965249 2009 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Statistical optimization of the silylation reaction of a mercaptosilane with silanol groups on the surface of silica gel
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آنالیزی یا شیمی تجزیه
پیش نمایش صفحه اول مقاله
Statistical optimization of the silylation reaction of a mercaptosilane with silanol groups on the surface of silica gel
چکیده انگلیسی

Thiol-modified silica is often used as an intermediate product for further synthesis of modified stationary phases for chromatography or purification processes. Different conditions were used to synthesize such thiol-modified particles, but systematic optimizations remained scarce. In this study the reaction conditions for the synthesis of mercaptopropyl-modified silica were optimized. The general synthetic method consists in slurrying the silica gel in toluene before adding 3-mercaptopropyldimethoxymethylsilane together with a tertiary amine as catalyst (here dimethylaminopyridine). Reaction time and temperature were optimized using a full factorial design of experiment (DoE) from 3 to 25 h with temperature varying between 45 and 105 °C. The surface coverage of the silica with mercaptopropyl-groups was analyzed by two different ways (elemental analysis and chemical surface reaction with 2,2′-dipyridyl disulfide followed by HPLC-UV analysis of stoichiometrically liberated pyridyl-2-thione). We obtained a three-dimensional (3D) plot of the surface coverage as a function of reaction time and temperature. The arch-shaped hyperplane allowed us to determine an optimum with regard to time and temperature, which yields to the highest surface coverage possible. We also verified that the increase of the surface coverage does not lead to a decrease of the stability of the surface modification by subjecting the gels to treatment with high temperature and acidic conditions. The stability was monitored by different chromatographic methods. Moreover, 29Si cross-polarization-magic angle spinning (CP-MAS) NMR spectra of materials prepared by different conditions allowed to confirm that the Si species on the surface were essentially the same, while there was only a minute difference in signal intensities for the individual Si species for materials obtained by distinct temperatures.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Chromatography A - Volume 1216, Issue 16, 17 April 2009, Pages 3473–3479
نویسندگان
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