Other Methods for Epoxide Determination

Dobinson, B.; Hofmann, Walter; Stark, B. P.

doi:10.1016/b978-0-08-012788-0.50006-9

Cited by 3 publications

(3 citation statements)

References 44 publications

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“…PO, an epoxide, contains a three-membered ring, whereas TMO, an oxetane, contains a four-membered ring. Both types of cyclic ethers undergo the same ring-opening reaction; however, the oxetanes undergo these reactions much less readily . Therefore, a slower rise in pH and subsequent longer gelation time are expected for TMO addition.…”

Section: Resultsmentioning

confidence: 99%

Role of Cyclic Ether and Solvent in a Non-Alkoxide Sol−Gel Synthesis of Yttria-Stabilized Zirconia Nanoparticles

et al. 2006

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The effects of cyclic ether (epoxide versus oxetane), solvent, and drying method were examined for a non-alkoxide sol−gel synthesis of yttria-stabilized zirconia (YSZ). YSZ sol−gel materials, from 3 to 25 mol % Y2O3, were successfully prepared with either propylene oxide (PO) or trimethylene oxide (TMO) in both aqueous and mixed ethanol−water solutions of Zr4+ and Y3+ chlorides. Supercritical drying (aerogels) produced fine, nanoparticulate networks, whereas drying under ambient conditions (xerogels) resulted in heterogeneous micrometer-sized hard agglomerates. The resulting materials were characterized using powder X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy, scanning electron microscopy, nitrogen adsorption/desorption analysis, and elemental analysis by inductively coupled plasma−atomic emission spectroscopy. The cyclic ether and solvent were found to be critical factors in the resulting as-prepared aerogel surface area and morphology. For a given solvent, aerogels prepared with PO had higher surface areas than did those prepared with TMO. For example, the surface areas of aerogels prepared in water were 453 and 295 m2/g for PO and TMO, respectively. Following calcination to 550 °C, however, the crystallized YSZ powders were similar, consisting of homogeneous nanoparticles (∼10 nm) with spherical morphologies and high surface areas (>100 m2/g). Elemental analysis, XRD, and electron microscopy indicated that Y2O3 and ZrO2 formed a homogeneous nanostructure over a wide range of Zr/Y ratios, corresponding to 3−25 mol % Y2O3.

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Section: Resultsmentioning

confidence: 99%

Role of Cyclic Ether and Solvent in a Non-Alkoxide Sol−Gel Synthesis of Yttria-Stabilized Zirconia Nanoparticles

et al. 2006

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“…We believe that the large difference in gel times for the above materials can be directly correlated to the relative reactivity of the respective epoxide. The 1,2-epoxides are more strained and, therefore, more reactive than the 1,3-epoxides to ring-opening reactions . For example, PO acts to raise the pH of the Fe 3+ solution more rapidly than DMO, hence, the more rapid gelation.…”

Section: Resultsmentioning

confidence: 99%

“…Both 1,2- and 1,3-epoxides undergo the same types of ring-opening reactions. However, the 1,3-epoxides undergo these reactions much less readily than the 1,2-epoxides 1 (a) 1,2-Epoxide and (b) 1,3-Epoxide Structures …”

Section: Introductionmentioning

confidence: 99%

Strong Akaganeite Aerogel Monoliths Using Epoxides: Synthesis and Characterization

2003

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The synthesis of iron(III) oxide aerogel monoliths was performed by adding any one of several different 1,2- and 1,3-epoxides to ethanolic Fe(III) salt solutions at room temperature. While all of the epoxides examined resulted in gel formation, robust low-density (∼30−40 kg/m3; 99% porous), high-surface-area (∼250−300 m2/g), aerogel monoliths were prepared by the addition of 1,3-epoxide derivatives to solutions of FeCl3·6H2O, followed by drying with supercritical CO2. Both types of iron(III) oxide aerogels (those made with 1,2- and 1,3-epoxides respectively) were characterized using elemental analysis, X-ray diffraction, thermal analysis, acoustic measurements, transmission electron microscopy, scanning electron microscopy, and N2 adsorption desorption analysis. Elemental analyses and powder X-ray diffraction indicated that the strong aerogel monoliths made with the 1,3-epoxides are made up predominately of polycrystalline β-FeOOH, akaganeite, and those made with the 1,2-epoxides are amorphous. To our knowledge, this is first known report of synthesis and characterization of akaganeite aerogel materials. Transmission electron microscopy analysis indicates that aerogels derived using 1,3-epoxides have a microstructure made up of a highly reticulated network of fibers with diameters from ∼5 to 35 nm and lengths several times that, whereas those resulting from the use of 1,2-epoxides consist of interconnected spherical particles, whose diameters are 5−15 nm. The difference in microstructure results in each type of aerogel displaying very distinct physical and mechanical properties. In particular, the stiffness of the β-FeOOH aerogels is remarkable for a transition metal oxide aerogel. Monolithic cylinders of β-FeOOH aerogel can be sintered at 515 °C, transforming to α-Fe2O3 without shattering.

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Aerogels and metal–organic frameworks for environmental remediation and energy production

et al. 2018

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Other Methods for Epoxide Determination

Cited by 3 publications

References 44 publications

Role of Cyclic Ether and Solvent in a Non-Alkoxide Sol−Gel Synthesis of Yttria-Stabilized Zirconia Nanoparticles

Role of Cyclic Ether and Solvent in a Non-Alkoxide Sol−Gel Synthesis of Yttria-Stabilized Zirconia Nanoparticles

Strong Akaganeite Aerogel Monoliths Using Epoxides: Synthesis and Characterization

Aerogels and metal–organic frameworks for environmental remediation and energy production

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