Olah, George A. Formerly, Loker Hydrocarbon Research Institute, University of Southern California, Los Angeles, California. Nobelist.
Prakash, G.K. Surya Loker Hydrocarbon Research Institute, University of Southern California, Los Angeles, California.
- Alkylated metals
- Transition-metal carbides
- Unsaturated transition-metal compounds
- Protonated alkanes
- Hypercarbon intermediates
- Links to Primary Literature
- Additional Readings
One of the foundations of organic chemistry is A. Kekulé's concept of the tetravalency of carbon (also suggested by A. S. Couper). This led to the octet rule, proposed by G. N. Lewis in 1916, that only a maximum of four ligands can be bound to carbon by two-electron two-center sigma bonds, for a total of eight electrons around carbon. Violations of the octet rule in the compounds of the second and higher rows of the periodic table are recognized, but carbon, being a first-row element, cannot extend its valence shell. Through quantum theory, it is understood that the idea of bonding pairs of electrons always being between two atomic centers is, at best, only an approximation. Many organic molecules require a description that involves the electrons in the bond being distributed over two or more atoms. The majority of these molecules are conjugated unsaturated π systems that are described in terms of delocalized bonds, as in benzene [structure (1),
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 9000 highly qualified scientists and 43 Nobel Prize winners.
MORE THAN 8500 articles and Research Reviews covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information