Topic
Silica gel
About: Silica gel is a research topic. Over the lifetime, 22313 publications have been published within this topic receiving 325516 citations. The topic is also known as: Amorphous silica & Precipitated amorphous silica.
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TL;DR: In this paper, an efficient synthesis of various substituted Hantzsch 1,4-dihydropyridines using silica gel-supported sodium bisulfate as heterogenous catalyst from an aldehyde, β-keto ester and ammonium acetate in acetonitrile is described.
97 citations
TL;DR: A new tris(2-aminoethyl) amine functionalized silica gel was prepared and investigated for selective solid-phase extraction of trace Cr(III), Cd(II) and Pb( II) prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES).
96 citations
TL;DR: Newly developed solid-phase extraction (SPE) tool with pipette-tip shape for purification of bio-samples of various characteristics, utilizing monolithic silica gel as medium, which is much effective and suitable for protein analysis.
96 citations
TL;DR: In this paper, the absorption spectra of silica gel were measured in order to assign the bands senstive to adsorption at 870 and around 950 cm−1.
Abstract: Infrared absorption spectra of the systems of silica gel - H216O,D216O,H218O, and some organic vapors were measured in order to assign the bands senstive to adsorption at 870 and around 950 cm−1. Deuteration of silica gel caused the absorption decrease at 870 cm−1 and the appearance of a band at 620 cm−1. The band around 950 cm−1 appearing by adsorption not only of water but also of organic vapors showed no shift on deuteration, but shifted toward low frequency side by 25 cm−1 on the substitution of 16O of surface silanol groups with 18O. From these facts the bands at 870, 620 and 950 cm−1 were assgned to Si–OH bending, Si–OD bending and Si–O stretching vibrations of surface silanol groups, respectively. The oxygen atom of silanol groups of silca gel was found to exchange with that of adsorbed water molecules even at room temperature for a sample treated at temperature below 300°C. On the other hand, higher reaction temperature of ca. 200°C was necessary for a sample calcined at 800°C. mechanism of the ox...
96 citations
TL;DR: In this article, Fourier transform infrared spectroscopy with photo-acoustic detection and chemical modification with trichlorosilane was used to study the porosity of three types of silica gel with different pore distributions.
Abstract: The distribution and reactivity of the different hydroxyl species on the surface of silica gel are studied using Fourier-transform infrared spectroscopy with photo-acoustic detection and chemical modification with trichlorosilane. The effect of the porosity is investigated using three types of silica gel with different pore distributions. The number of free and bridged hydroxyl groups on the surface of silica gel and their reactivity towards trichlorosilane is quantitatively assessed. It is concluded that smaller pore radii favour the condensation of bridged hydroxyl groups to free ones with increasing pretreatment temperature. Trichlorosilane reacts exclusively with free hydroxyl groups at high pretreatment temperatures, and partially with bridged hydroxyl groups at low pretreatment temperatures. The reactivity of the free hydroxyl groups is not affected by the pore radius, whereas the bridged hydroxyls become less reactive towards trichlorosilane as the pore radius decreases.
96 citations