METHYLATION, METAL catalysts, and FLUORINATION

Owing to the excellent performance of fluorinated compounds in the areas of pharmaceuticals, agrochemicals, and materials chemistry, organic chemists have made great efforts towards the selective incorporation of fluorine or fluorinated moieties into organic molecules through nucleophilic, electrophilic, radical, and metal-catalyzed pathways. Impressive progress in fluorination and perfluoroalkylation (especially trifluoromethylation) reactions has been made over the past few decades. However, methods for incorporating lightly fluorinated groups (such as −CF2H) are still underdeveloped, in spite of their important applications in pharmaceuticals and agrochemicals. This Focus Review summarizes recent developments in metal-catalyzed direct difluoromethylation reactions. [ABSTRACT FROM AUTHOR]

CARBON compounds, DENITRIFICATION, STABLE isotopes, RIPARIAN plants, and STREAM restoration

Organic carbon is important in regulating ecosystem function, and its source and abundance may be altered by urbanization. We investigated shifts in organic carbon quantity and quality associated with urbanization and ecosystem restoration, and its potential effects on denitrification at the riparian-stream interface. Field measurements of streamwater chemistry, organic carbon characterization, and laboratory-based denitrification experiments were completed at two forested, two restored, and two unrestored urban streams at the Baltimore Long-Term Ecological Research site, Maryland, USA. Dissolved organic carbon (DOC) and nitrate loads increased with runoff according to a power-law function that varied across sites. Stable isotopes and molar C:N ratios suggested that stream particulate organic matter (POM) was a mixture of periphyton, leaves, and grass that varied across Site types. Stable-isotope signatures and lipid biomarker analyses of sediments showed that terrestrial organic carbon sources in streams varied as a result of riparian vegetation. Laboratory experiments indicated that organic carbon amendments significantly increased rates of denitrification (35.1 ± 9.4 ng N·[g dry sediment]-1h-1; mean ± SE) more than nitrate amendments (10.4 ± 4.0 ng N·[g dry sediment]-1h-1) across streamflow conditions and sites. Denitrification experiments with naturally occurring carbon sources showed that denitrification was significantly higher with grass clippings from home lawns (1244 ± 331 ng N·g dry sediment-1·h-1, and overall unrestored urban Sites showed significantly higher denitrification rates than restored and forest sites. We found that urbanization influences organic carbon sources and quality in streams, which can have substantial downstream impacts on ecosystem services such as denitrification. [ABSTRACT FROM AUTHOR]

SCIENCE teachers, TEACHER training, CHEMISTRY education, HIGH schools, OCCUPATIONAL training, SECONDARY education, EFFECTIVE teaching, HIGH school students, and EDUCATION research

The article discusses studies about developments in professional training of science teachers in high schools in the U.S. A chemistry teacher should have as a minimum, college courses in general inorganic chemistry, organic chemistry, qualitative analysis, quantitative analysis and physical chemistry. Organic chemistry is studied because of the basic principles and general information involved and the important role organic substances play in modern life. One of the conclusions reached by the Committee on Preparation of High School Chemistry teachers is that more extensive training and other sciences is urgently needed in many cases and these needs should be met either by decreasing the requirements in educational course, by increasing the number of credits required for graduation.