title: The influence of pH and temperature on the degradation kinetics of 4-methoxy-2-[3-(4-phenyl-1-piperazinyl)]propyl-2,3-dihydro-6-methyl-1,3-dioxo-1H-pyrrolo[3,4-c] pyridine in aqueous solutions.
abstract: The pH-rate profiles for hydrolysis of 4-methoxy-2-[3-(4-phenyl-1-piperazinyl)]propyl-2,3-dihydro-6-methyl-1,3-dioxo-1H-pyrrolo[3,4-c] pyridine (H) at 333, 343, 353 and 363 K over the pH range 0.4-5.0 was investigated. The decomposition was followed by the HPLC method (LiChrosorb 100 RP-18 column 250 x 4.0 mm I.D., dp = 5 microm; mobile phase: acetonitrile-phosphate buffer (pH = 2; 0.01 mole/L) (45: 55, v/v or 30: 70, v/v). The pH-rate profile indicated specific acid- and base-catalysed reactions as well as spontaneous water-catalysed degradation of two molecules of II (as a dication and monocation). The ionic strength effect, the pKa value (2.4; 6.2), the pHmin value (2.1) and thermodynamic parameters of the reaction (energy and enthalpy of activation and the frequency coefficient for the specific rate constants) were determined.
authors.affiliation: Department of Pharmaceutical Chemistry, Poznań University of Medical Sciences, 6 Grunwaldzka Str, 60-780 Poznań, Poland. imuszals@amp.edu.pl
authors.forename: Izabela
authors.initials: I
authors.lastname: Muszalska
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Wituła
mesh_terms: D000085:Acetates / Q000737:chemistry; D000465:Algorithms; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry* / Q000378:metabolism; D002021:Buffers; D055598:Chemical Phenomena; D002626:Chemistry, Pharmaceutical; D002627:Chemistry, Physical; D004355:Drug Stability; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D015394:Molecular Structure; D011809:Quinones / Q000737:chemistry* / Q000378:metabolism; D012996:Solutions / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: C478822:4-methoxy-2-(2-hydroxy-3-(4-phenyl-1-piperazinyl))propyl-2,3-dihydro-6-methyl-1,3-dioxo-1H-pyrrolo(3,4-c)pyridine; D000085:Acetates; D019086:Bridged Bicyclo Compounds, Heterocyclic; D002021:Buffers; D011809:Quinones; D012996:Solutions; D014867:Water