Proton Abstraction from 4-Nitrophenyl[bis(ethylsulphonyl)]methane with TMG, TBD and MTBD Bases in Acetonitrile

• Autorzy: Jarczewski, A. , Binkowska, I.
• Języki publikacji: EN

Abstrakty

EN

4-Nitrophenyl[bis(ethylsulphonyl)]methane has been synthesized and used in kinetic studies of proton abstraction induced by 1,1,3,3-tetramethylguanidine (TMG), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and 7-methyI-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) bases in acetonitrile. The pK, values of this carbon acid in water and in acetonitrile solvents are 10.08 and 22.8 respectively. The electronic spectra of 4-nitrophenyl[bis(ethylsulphonyl)]methane and its anion ar well defined and temperaturę dependent. The rates of proton abstraction are large as the reaction occurs in the range of microseconds. The relaxation times were studied by spectrophotometric temperature-jump technique. The rate constants for proton transfer reaction promoted by TMG, TBD and MTBD bases in acetonitrile are: 1.39x10 5-2.1 Ix10 5; 8.8x10 6-19.2x10 6; 0.84x105-2.43x 10S [dm3 mol-1 s-1] respectively between 20-40°C. The enthalpies of activation are: deltaH# = 18.1, 28.7 and 40.0 [kJ mol-1] for TMG, TBD and MTBD respectively. The entropies of activation are all negative: deltaS# = -84.9, -13.6, -14.3 [J mol-1 deg-1] for the same sequence of bases reacting with 4-nitrophenyl[bis(ethylsulphonyl)]methane in acetonitrile solvent. The general discussion of the results obtained and their comparison with those for proton transfer reaction carried out with "normal" C-acids is given.

Słowa kluczowe

EN

kinetics; proton transfer; T-jump; 4-nitrophenyl[bis(ethylsulphonyl)]methane; TMG; TBD; MTBD bases; activation parameters

• Czasopismo: Polish Journal of Chemistry
• Rocznik: 2001
• Tom: Vol. 75, nr 12
• Strony: 1895-1903
• Opis fizyczny: Bibliogr. 39 poz., rys.

Twórcy

autor

Jarczewski, A.

autor

Binkowska, I.

• Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland tei: 00-4861-8291-479,