title: Esterification of 7-theophyllineacetic acid with diethylene glycol monomethyl ether.
abstract: The kinetics of esterification of 7-theophyllineacetic acid with diethylene glycol monomethyl ether in the presence of dicyclohexylcarbodiimide and 4-dimethylaminopyridine as catalyst was studied. According to the known mechanism, besides the main process, the side-reaction of intramolecular rearrangement with formation of pharmacologically active N-acylurea occurs. The course of the main and the side-process was monitored by RP-HPLC with UV-detection. For that purpose, quantification of both ester and N-acylurea in the reaction mixture was performed. Influence of the concentration of the reactants (acid, alcohol and catalyst) on the progress of esterification and preparation of the by-product was investigated. Based on the obtained results, the reaction conditions leading to maximal yield of the ester and N-acylurea are proposed. The possibility of turning esterification to the synthesis of the side-product was also found. Reactions of the preparation of both the ester and N-acylurea were found to follow first-order kinetics. The rate constants of both processes were estimated.
authors.affiliation: Department of Chemistry, Faculty of Pharmacy, Sofia, Bulgaria.
authors.forename: Boika
authors.initials: B
authors.lastname: Tsvetkova
authors.forename: Jasmina
authors.initials: J
authors.lastname: Tencheva
authors.forename: Plamen
authors.initials: P
authors.lastname: Peikov
mesh_terms: D015761:4-Aminopyridine / Q000031:analogs & derivatives / Q000737:chemistry; D004024:Dicyclohexylcarbodiimide / Q000737:chemistry; D004951:Esterification; D005026:Ethylene Glycols / Q000737:chemistry*; D007700:Kinetics; D013806:Theophylline / Q000031:analogs & derivatives* / Q000737:chemistry; D014508:Urea / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D005026:Ethylene Glycols; C048214:diethylene glycol monomethyl ether; D004024:Dicyclohexylcarbodiimide; D014508:Urea; D015761:4-Aminopyridine; D013806:Theophylline; C019140:acefylline; C003885:4-dimethylaminopyridine