[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

3.2.3. Hydroformylation 2467 3.2.4. Dimerization 2468 3.2.5. Oxidative Cleavage and Ozonolysis 2469 3.2.6. Metathesis 2470 4. Terpenes 2472 4.1. Pinene 2472 4.1.1. Isomerization: R-Pinene 2472 4.1.2. Epoxidation of R-Pinene 2475 4.1.3. Isomerization of R-Pinene Oxide 2477 4.1.4. Hydration of R-Pinene: R-Terpineol 2478 4.1.5. Dehydroisomerization 2479 4.2. Limonene 2480 4.2.1. Isomerization 2480 4.2.2. Epoxidation: Limonene Oxide 2480 4.2.3. Isomerization of Limonene Oxide 2481 4.2.4. Dehydroisomerization of Limonene and Terpenes To Produce Cymene 2481

Chemical Routes for the Transformation of Biomass into Chemicals

Technology development for the production of biobased products from biorefinery carbohydrates—the US Department of Energy’s “Top 10” revisited

비만아 부모의 돌봄 경험: q 방법론

인공고관절의 세라믹 볼 헤드의 기계적 안정성 평가를 위한 3 차원 유한요소 해석

Synthetic analogues of the microporous minerals umbite (AM-2) and penkvilksite, polytype 2O (AM-3), have been prepared. The facile syntheses of two other titanosilicates, AM-1 and AM-4, have also been reported. AM-1 and the previously reported, layered titanosilicate known as JDF-L1 have been shown to have the same structure. AM-4 is a new microporous titanosilicate with a unique and unknown structure, containing eight different Na sites. All AM-n materials have been characterized by several techniques, viz. SEM, powder XRD, single- and triple-quantum 23Na and 29Si MAS NMR, water adsorption measurements, and TGA/DSC. AM-n materials are thermally stable up to ca. 600 °C. The dehydration−hydration processes seem to be reversible (or quasi reversible) for AM-1, -2, and -3 but not so for AM-4.

Synthesis and Structural Characterization of Microporous Umbite, Penkvilksite, and Other Titanosilicates

The isomerization of glucose was studied in water at 100 °C in the presence of various metallosilicates as solid base catalysts, namely the titanosilicates ETS-10, ETS-4 and AM-4, a sodium yttrium silicate analogue of the mineral montregianite (AV-1), an alkali calcium silicate analogue of the mineral rhodesite (AV-2), and a calcium silicate analogue of the mineral tobermorite (TOB). Fructose yields in the range of 20–40% were obtained within 2-h reaction. These results are either similar to or better than those achievable with the commercial zeolite Na–X or aqueous NaOH. Depending on the nature of the catalyst, different factors account for deactivation, such as loss of crystallinity, sodium/potassium leaching and surface passivation. Two of the more promising materials, AV-1 and TOB, were quite stable under the reaction conditions, as evidenced by powder X-ray diffraction analyses for the fresh and used catalysts. The used TOB catalyst exhibited a steady performance when recycled and for AV-1 fructose yields increased in recycling runs. The activity of the solid bases, with the exception of AV-1, could be correlated with the basicity characterized by Knoevenagel condensation tests.

Isomerization of d-glucose to d-fructose over metallosilicate solid bases

Microporous AM-11 crystalline niobium silicates were studied as solid acid catalysts for the dehydration of xylose in a water-toluene solvent mixture at 140–180 °C. After 6 h at 160 °C, xylose conversions of up to 90% and furfural yields of up to 50% were achieved, and the catalysts could be reused without loss of activity or selectivity. The calcined AM-11 catalysts gave higher furfural yields than HY zeolite and mordenite, under identical reaction conditions. Ordered mesoporous MCM-41-type niobium silicates with Si/Nb molar ratios of either 25 or 50 were also found to be recyclable catalysts for xylose dehydration, and gave furfural yields consistently in the range of 34–39% (after 6 h reaction at 160 °C).

https://link.springer.com/content/pdf/10.1007/s10562-006-0046-6.pdf

Liquid-phase dehydration of D-xylose over microporous and mesoporous niobium silicates

A hexaamine cage with pyridyl spacers was synthesized in good yield by a [2+3] Schiff-base condensation followed by sodium borohydride reduction. The protonation constants of the receptor as well as its association constants with Cl−, NO3−, AcO−, ClO4−, SO42−, H2PO4−, and H2AsO4− were determined by potentiometry at 298.2 ± 0.1 K in H2O/MeOH (50:50 v/v) and at ionic strength 0.10 ± 0.01 M in KTsO. These studies revealed that although dihydrogen phosphate is less charged than sulfate, it is still appreciably bound by the receptor at low pH, suggesting that the pyridyl nitrogen is accepting hydrogen bonds from dihydrogen phosphate. It is also shown that dihydrogen phosphate is capable of effectively competing with sulfate for the receptor at higher pH, being selective for hydrogen phosphate at pH about 7.0. 31P NMR experiments supported these findings. The fact that the receptor shows such a marked preference for hydrogen phosphate based mainly in its hydrogen bond accepting/donating ability in a highly comp...

Paula Brandão

Papers

Synthesis and Structural Characterization of Microporous Umbite, Penkvilksite, and Other Titanosilicates

Isomerization of d-glucose to d-fructose over metallosilicate solid bases

Liquid-phase dehydration of D-xylose over microporous and mesoporous niobium silicates

Polyaza cryptand receptor selective for dihydrogen phosphate.

The first large-pore vanadosilicate framework containing hexacoordinated vanadium