given the phthalide (2a and 2e) in excellent yield, whereas at higher temperature, the benzyl bromo gives excellent yield of bromo substituted 7-Aminophthalides (3a and 3e). The structures (3a and 3e) was proved by single crystals data. In case of Benzyliodo (1b), gives iodo substituted 7-Aminophthalide (3b) but yield is poor (5%). It can be explained as, even though Iodide ion is oxidized to iodine/iodonium ion in sulfuric acicd, due to higher temperature it sublimes before it reacts with 7-amino phthalide (2a). In case of chloro substrate (1f), the liberated chloride ion form HCl, due to inability of sulfuric acid to oxidize the chloride ion to chloronium ion (or chlorine gas). The CBZ protected aniline with methoxy group (1i) does not given any corresponding anisole derivatives, even prolong the reaction time at higher temperature. Substituted on benzene sulfonate group (1c,1d, and 1f,1g) are also giving the same results (2a and 2e). When dibromo substrate (1j) under these conditions gives 2j (not isolated) and 3j, respectively. During the formation of 3j, it is understood that 3-bromo phthalide is first formed, followed by hydrolysis to give the 3hydroxy-7-Aminophthalide. This study clearly shows that other halogens, chlorine (sulfuric acid unable to oxidize) and iodine (sublime properties) are not effective as bromine. Finally, the temperature factor is significant since at 100 o C, irrespective of halogenated substrates, the intermediate phthalides 2a, 2e and 2j (not isolated) is formed, and whereas at 170 o C, formation of halide substituted 7-amino phthalide is depends on halogenated substrate. Bromine as external source: Independently, the 7-Amino phthalide (2a and 2e), and its sulfonated substrate (16) on treatment (table-3) with 1.0 eq of bromine in conc sulfuric acid at 100 o C obtains the mono brominated 7-Aminophthalides (3a and 3e), this is due to availability of bromonium ion by cleavage of bromine molecules, whereas at 170 o C as expected we isolated the dibromo derivatives 4a and 4e respectively. These products (4a and 4e) The reaction is exceptionally clean and easy workup is required to obtained spectrally pure substances. No side products were isolated from any reaction. However, despite its utility and simplicity, limitations are sometimes encountered, particularly with acid sensitive benzyl bromide substrates, which are cleaved in acidic medium.