This research focuses on a computational analysis of the barrierless reactions of transient carbenes and biradicals. Computational approaches to tunneling and entropy controlled reactions will be examined with a specific emphasis on developing the theoretical underpinning needed to predict product ratios. Undergraduate students involved in the research will be introduced to modern computational approaches to chemical dynamics and semi-empirical electronic structure theory. With this Standard Grant, the Organic and Macromolecular Chemistry Program supports the research and educational activities of Dr. Charles Doubleday of the Department of Chemistry at Columbia University. Dr. Doubleday will focus his research efforts on the theoretical analysis of the reaction dynamics of carbenes and biradicals. Although implicated as intermediates in a number of organic transformations, in most cases these species can not be observed experimentally because of their short lifetimes. Computational methods capable of treating these barrierless organic reactions will be developed and tested through the prediction of reaction product ratios. Dr. Doubleday's educational activities will include introducing undergraduates to the development and testing of modern computational approaches to chemical dynamics.