Introduction Arynes are reactive intermediates derived from substituted arenes which participate in some aromatic nucleophilic substitutions and some cycloaddition reactions. It is non isolable very reactive species with the hexagonal planar ring structure with six pi delocalizing and 2 additional pi electrons. The additional 2 pi electrons do not affect the aromatic character of ring as it does not interfere with the Huckel number. Arynes are so highly reactive that they exist as stable species only at very low temperatures, e.g., 8 K for benzyne. Arynes may be derived from substituted benzenes, fused arenes and pyridines. Structure of Benzyne The sp 2 orbitals involved in the ‘triple bond’ are at 90 o to the p-orbitals of the aromatic pi-system Instead of an overlap between two 2p orbitals (as in an alkyne) the “triple bond” is formedthrough overlap of two adjacent sp2 orbitals in the plane of the ring (i.e., at right angles to, and completely independently of, the aromatic