Structures of flavone and flavonol glycosides
SummaryLiterature information on the structures of O-glycosides of flavones and flavonols has been generalized. Using the methods of combinatorial mathematics, the possibility of a great diversity of the structure of the glycosides has been shown without taking into account their acylation, the dimensions of the oxide rings of the sugars, and the nature of the glycosidic bonds.
Isolation and structural determination of 13 flavonoid glycosides in Hibiscus esculentus (okra).
A B S T R A C T Eleven flavonol glycosides and two anthocyaninis, only one of which was previously identified, were isolated from the flower petals of okra, Hibiscus esculentus L. On the basis of chromatographic, spectral, anid degradative evidence, the following structural assignments were made: quercetin 4'-glucoside, quercetin 7-glucoside, quercetin 5-glucoside, quercetin 3-diglucoside, quercetini 4'-diglucoside, quercetin 3-triglucoside, quercetin 5-rhamnoglucoside, gossypetin 8glucoside, gossypetiin 8-rhamnoglucoside, gossypetin 3-glucosido-8-rhamnoglucoside, cyanidin 4'-glucoside, and cyaniidin 3-glucosido-4' glucoside. Some evidence was obtained of a pentahydroxy, monomethoxy-flavone glycoside. The total flavonoid content in the red portion of the petal was 0.48% of fresh weight; that in the white portion was 2.51%. The two anthocyanins comprised 28.5% of the flavonoid content of the red flower but only a trace of the content of the white. HIBISCUS ESCULENTUS L., commonly known as okra or gumbo, is a tropical annual of both
Full-scale measurements of SO2 gas phase concentrations and slurry compositions in a wet flue gas desulphurisation spray absorber
Abstract Two measurement campaigns were carried out at ENERGI E2's Asnaes Power plant, unit 5. The unit has a capacity of 620 MW e and is equipped with a wet flue gas desulphurisation (FGD) plant employing a counter-current spray absorber with five spray levels. In the first campaign, the power plant was firing Orimulsion ® with 2.85 wt% S resulting in a flue gas concentration of SO 2 exceeding 2000 ppmv. In the second campaign, the fuel applied was a low-S blended coal and the SO 2 concentration in the raw gas was around 400 ppmv. A novel probe for in situ sampling of gas phase concentrations in wet FGD spray absorbers was developed and applied for measuring axial profiles of the SO 2 gas phase concentrations in the absorber. The expected decrease in SO 2 concentrations along the height of the absorber was found in the spray section (from height 26.5 to 36.2 m) whereas the SO 2 concentration above the holding tank and below the gas inlet was quite low probably due to long local residence times in the region. Horizontal variations, due to somewhat different flow conditions near the column wall were investigated and the SO 2 concentrations were found to be higher near the wall. Measurements at different gross loads showed that the SO 2 gas phase concentration at a given position inside the absorber was roughly linearly related to the L/G ratio in the measuring interval. Turning off one of the lower spray levels, while burning coal with low S content, did not lower the overall removal efficiency of the absorber. However, the SO 2 gas phase concentration inside the lower part of the absorber was increased by a factor of 2–3. Measurements of slurry pH at different positions showed a decrease of approximately 0.5 units from the upper to the lower part of the absorber. The full-scale measurements provide a detailed set of experimental data for validation of mathematical models of a wet FGD spray absorber.