Carbon-13 isotope effect for decarboxylation of phenylpropiolic acid (PPA) in concentrated phosphoric acids

• Autorzy: Zieliński M. , Zielińska A. , Papiernik-Zielińska H. , Ogrinc N. , Kobal I.
• Języki publikacji: EN

Abstrakty

EN

13C isotope effects on the decarboxylation of phenylpropiolic acid (PPA) in 93–97% H3PO4 and in 23% diphosphoric acid in orthophosphoric acid have been investigated from 293 to 353 K. The initial 13C fractionations in all three systems are in agreement with the 13C decarboxylation fractionations expected assuming the loss of the one carbon-carbon bond in the transition state. In 100% H3PO4 and in 23% diphosphoric acid in orthophosphoric acid later fractions of carbon dioxide are depleted in carbon-13 to a greater degree than expected, probably due to isotopic preequilibria between stable and decarboxylating forms of PPA. At 353 K and higher temperature strong deviations of the experimental rate constants and of the experimental 13C fractionations from the values extrapolated from lower temperature are observed. A tentative decarboxylation scheme operating in concentrated phosphoric acid media is proposed.

Słowa kluczowe

EN

carbon-13; concentrated phosphoric acids; decarboxylation isotope effects; decarboxylation mechanism; phenylpropiolic acid

• Wydawca: Institute of Nuclear Chemistry and Technology
• Czasopismo: Nukleonika
• Rocznik: 2000
• Tom: Vol. 45, nr 2
• Strony: 121--124
• Opis fizyczny: Bibliogr. 4 poz., rys.

Twórcy

autor

Zieliński M.

• Faculty of Chemistry, Jagiellonian University, 30-060 Kraków, Ingardena Str. 3, Poland Fax: [phone]

autor

Zielińska A.

• Faculty of Chemistry, Jagiellonian University, 30-060 Kraków, Ingardena Str. 3, Poland Fax: [phone]

autor

Papiernik-Zielińska H.

• Faculty of Chemistry, Jagiellonian University, 30-060 Kraków, Ingardena Str. 3, Poland Fax: [phone]

autor

Ogrinc N.

• J. Stefan Institute, SI-1000 Ljubljana Jamova Str. 39, Slovenia

autor

Kobal I.

• J. Stefan Institute, SI-1000 Ljubljana Jamova Str. 39, Slovenia

Bibliografia

• 1. Zielińska A, Zieliński M (2000) Deuterium isotope effect in the decarboxylation of phenylpropiolic acid in 85% D3PO4 in D2O. (to be submitted to Nukleonika)
• 2. Zielińska A, Zieliński M, Papiernik-Zielińska H (1999) Carbon-13 isotope effect for decarboxylation of phenylpropiolic acid (PPA) in orthophosphoric acid. Nukleonika 44:403–410
• 3. Zieliński M, Ogrinc N, Zielińska A, Kobal I, Papiernik-Zielińska H (2000) Carbon-13 isotope fractionation in the decarboxylation of phenylpriopiolic acid in orthophosphoric acid and in diphosphoric acid. Polish J Chem 74: 707-715
• 4. Zieliński M, Zielińska A, Paul H, Bernasconi S, Ogrinc N, Kobal I, Papiernik-Zielińska H (1999) Carbon-13 isotope effect in the decarboxylation of phenylpropiolic acid in sulphuric acid. Polish J Chem 73:1029–1036