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Full-Text Articles in Physical Sciences and Mathematics
Reactions Of Singlet Oxygen And Singlet Oxygen Mimics With Dicyclopropylethylenes: Comparison Of Reactivity And Mechanisms, Gina Elizabeth Alume
Reactions Of Singlet Oxygen And Singlet Oxygen Mimics With Dicyclopropylethylenes: Comparison Of Reactivity And Mechanisms, Gina Elizabeth Alume
FIU Electronic Theses and Dissertations
An extensive study of the reaction pathways of 1,1- dicyclopropyl ethylene, cis- and trans- 1,2-dicyclopropylethylenes has been undertaken with different electrophiles 4-methyl-1,2,4- triazoline-3,5-dione (MTAD), tetracyanoethylene (TCNE), and singlet oxygen (102). Comparison of reactivity and reaction mechanisms among the electrophiles is investigated. Singlet oxygen exhibits significantly lower reactivity compared to the other electrophiles. MTAD and TCNE react with dicyclopropylethylenes to produce predominantly "2+2" adducts and a small amount of the "ene" adducts. The "2+2" is the major product presumably because of the high activation energy leading to the highly strained "ene" products. Solvent trapping studies provide strong evidence of …
Hydrocarbon Speciation Studies In Ancient Sediments By High Temperature Supercritical Carbon Dioxide Extraction, Doraida Diaz
Hydrocarbon Speciation Studies In Ancient Sediments By High Temperature Supercritical Carbon Dioxide Extraction, Doraida Diaz
FIU Electronic Theses and Dissertations
Results on the application of high-temperature supercritical carbon dioxide extraction (HT-SFE) to the study of hydrocarbon (HC) speciation in geological samples are presented. Ancient sediments were treated by stepwise extractions, and by using a fresh sample each time. SFE temperatures ranged between 50 and 350°C. Individual analytes showed to be speciated in different ways throughout the solid matrix because different fractions are extracted under different energy conditions. Aromatic HCs appear to have a stronger association with the matrix than the aliphatics due to their higher polarity and molecular planarity. No evidence of geosynthesis of alkylaromatics during HT-SFE was obtained. Tri- …
Speciation Of Uranium And Organic Compounds On Solid Matrix Studied By Supercritical Fluid Extraction, Li Chen
FIU Electronic Theses and Dissertations
The liquid extraction and spectrophotometric quantitation of uranium from different solid matrices is compared to supercritical fluid extraction (SFE) using various combinations of 2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octadione (FOD), tri-n-butylphosphate (TBP), ethanol, and carbon dioxide measuring the UV absorption of the uranium-FOD complex. The matrix is shown to have a tremendous effect on the extractability of uranium from different solid matrices. Compared to liquid extraction, the SFE method yields higher recoveries, is significantly faster, is of equal or greater precision, and greatly reduces the amount of organic solvents used. In the second part of this work, the speciation of hydrophobic organic compounds (HOCs) in …