In this project, 5-methyl-4, 6- dinitroisophthalic acid was synthesized from oxidation of 2, 4-dinitro-1, 3, 5-trimethyl benzene. The compounds, acetic acid-3, 5-diacetoxy-2, 4-dimethyl-phenyl ester, 2, 4, 6-triacetoxy-benzoic acid methyl ester, 2, 4-diacetoxy-6-hydroxy-benzoic acid methyl ester, 6-acetoxy-3-acetyl-2, 4-dihydroxy benzoic acid metyl ester, 4-acetoxy-3-acetyl-2, 6-dihydroxy benzoic acid metyl ester, 3, 5-diacetyl-2, 4, 6-trihydroxy benzoic acid metyl ester were synthesized from the Friedel-Crafts acylation reaction of electron rich arene, acetic acid-3, 5-diacetoxy-phenyl ester using chloroformate acylating reagent. The syntesized compounds were characterized by GC/Mass, 1 H-NMR, 13 C-NMR and FT-IR. Fries rearrangment reaction of acetic acid-3, 5-diacetoxy-phenyl ester was used for the synthesis of derivatives, salicylates. In second part of this project, theoretical studies on four pasibble tautomer of 2, 4, 6-trihydroxy-benzene-1, 3, 5-tricarboxylic acids using quantum chemistry calculations are performed. Tautemric structure and hy; all relevant conformer were optimized by MP2 calculation at the 6-311++G(d,p) basis set. The total energy, relative energy and optimized geometries were calculated. Energy data showed that enolic form of 2, 4, 6-trihydroxy-benzene-1, 3, 5-tricarboxylic acid to be most stable structure among all conformers. In the following, Stable conformer of each class determined and factors affecting on stability this conformers examined, and formation cooperative hydrogen bonds in these structures was recognized as a stability factor. Finally, natural band orbital (NBO) theory and atoms in molecule (AIM) analysis are applied to assess the nature of the hydrogen bonds in stable conformer each category and to account their effects on the stability of the molecular arrangement. The data obtained by the analysis of the AIM and NBO demonstrate to formation of strong hydrogen bonding as a factor in the stability of conformer each category.