title: Raman spectroscopic analysis of the interaction between squaric acid and dimethylsulfoxide.
abstract: The investigation of solutions of squaric acid in dimethylsulfoxide (DMSO) by Raman spectroscopy has facilitated the observation of the presence of different species derived from squaric acid such as the squarate dianion in solutions of 0.3M and 0.5M concentration and the hydrogen-squarate ion in solution concentrations greater than 2.0M. The method described by Alía and coworkers was used to calculate the two pK values corresponding to the ions produced by squaric acid interacting with DMSO: the hydrogen squarate (pK1=0.80) ion and the squarate dianion (pK2=0.84). From the spectroscopic data it has been also possible to determine the complex formation between associated squaric acid/DMSO in the proportion squaric acid 1:1 DMSO in which the associated squaric acid is hydrogen-bonded to the S atom in the DMSO structure.
authors.affiliation: Núcleo de Espectroscopia e Estrutura Molecular, Departamento de Química, Universidade Federal de Juiz de Fora, Juiz de Fora, MG 36036-900, Brazil.
authors.forename: Stéfanos L
authors.initials: SL
authors.lastname: Georgopoulos
authors.forename: Howell G M
authors.initials: HG
authors.lastname: Edwards
authors.forename: Luiz Fernando C
authors.initials: LF
authors.lastname: de Oliveira
mesh_terms: D003503:Cyclobutanes / Q000737:chemistry*; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D012996:Solutions; D013059:Spectrum Analysis, Raman; D014732:Vibration
chemical_list: D003503:Cyclobutanes; D012996:Solutions; C030042:squaric acid; D004121:Dimethyl Sulfoxide