The book "Synthesis of 2-methyl-4-selenoquinazolone, 2-phenylbenzoselenazole and its derivatives. Dissertation submitted for the degree of Doctor of Philosophy at the Faculty of Pure Science of Columbia University" is the result of the scientific research of the author Chen Yu㯙-Guang. The book describes in detail the process of synthesis of these compounds, their properties and possible applications. The dissertation is a significant contribution to the development of chemical science, where the author highlights the methods, results, and conclusions of research conducted in the process of preparing for obtaining an academic degree.