A mild, convenient protocol for the synthesis of cis-aziridines employs a catalytic amount of Brnsted acid. Diazo compound decomposition via alkylation or homocoupling upon exposure to a proton source is slow relative to [2 + 1] annulation in the presence of a Schiff base. A. L. Williams, J. N. Johnston, J. Am. Chem.
The tropical savanna is a biome characterized by tall grasses and occasional trees. Large regions of tropical savanna extend through the nations of Botswana, Namibia, and Kenya in Africa, southern Brazil, India, and Australia. Surprisingly, the Everglades of southern Florida in North America is also a tropical savanna. Photo  2000-www.arttoday.com.
Botswana's mineral resources include silver, diamonds, gemstones, iron ore, copper, nickel, salt, soda ash, potash and coal. Botswana has natural hazards which include the periodic drought. In addition, seasonal August winds blow from the west, carrying sand and dust across the country, obscuring visibility. The environmental issues for Botswana, in southern Africa, include limited fresh water resources, overgrazing, and desertification. Copyright information: The images on this page were composed by Angela King and Brad Cole and are copyright by Geology.com 2008.