caa a22 4500 469110287 CHVBK 20180323133108.0 cr unu---uuuuu 170328e19920601xx s 000 0 eng 10.1007/BF02040725 doi (NATIONALLICENCE)springer-10.1007/BF02040725 Carbon-13 kinetic isotope effects in the decarbonylations of lactic acid containing13C at the natural abundance level [Elektronische Daten] [M. Zielinski, G. Czarnota, H. Papiernik-Zielinska] The13C kinetic isotope fractionation in the decarbonylation of lactic acid of natural isotopic composition by sulfuric acid has been studied in the temperature range of 20-80°C. The13C(1) isotope separation in the decarbonylation of lactic acid by concentrated sulfuric acid depends strongly on the temperature above 40°C. Below this temperature the13C isotope effect in the decarbonylation of lactic acid by concentrated sulfuric acid is normal similarly as has been found inthe decarbonylation of lactic [1-14C] acid. The experimental values of k(12C)/k(13C) ratios of isotopic rate constants for12C and13C are close to, but slightly higher than theoretical13C-kinetic isotope effects calculated (neglecting tunneling) under the asumption that the C(1)-OH bond is broken in the rate-controlling step of the dehydration reaction. Dilution of concentrated sulfuric acid with water up to 1.4 molar (H2O)/(H2SO4) ratio caused the increase of the13C isotope fractionation from 1.0273 found in concentrated sulfuric acid at 80.5°C to 1.0536±0.0008 (at 80.6°C). A discussion of the abnormally high temperature dependence of14C and13C isotope fractionation in this reaction and the discussion of the problem of relative14C/13C kinetic isotope effects is given. Akadùmiai Kiadó, 1992 Zielinski M. Isotope Laboratory (Laboratory of Nuclear Chemistry), Faculty of Chemistry, Jagiellonian University, Kraków, (Poland) aut Czarnota G. Isotope Laboratory (Laboratory of Nuclear Chemistry), Faculty of Chemistry, Jagiellonian University, Kraków, (Poland) aut Papiernik-Zielinska H. Isotope Laboratory (Laboratory of Nuclear Chemistry), Faculty of Chemistry, Jagiellonian University, Kraków, (Poland) aut Journal of Radioanalytical and Nuclear Chemistry Kluwer Academic Publishers 159/2(1992-06-01), 305-316 0236-5731 159:2<305 1992 159 10967 https://doi.org/10.1007/BF02040725 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02040725 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Zielinski M. Isotope Laboratory (Laboratory of Nuclear Chemistry), Faculty of Chemistry, Jagiellonian University, Kraków, (Poland) aut NATIONALLICENCE 700 1- Czarnota G. Isotope Laboratory (Laboratory of Nuclear Chemistry), Faculty of Chemistry, Jagiellonian University, Kraków, (Poland) aut NATIONALLICENCE 700 1- Papiernik-Zielinska H. Isotope Laboratory (Laboratory of Nuclear Chemistry), Faculty of Chemistry, Jagiellonian University, Kraków, (Poland) aut NATIONALLICENCE 773 0- Journal of Radioanalytical and Nuclear Chemistry Kluwer Academic Publishers 159/2(1992-06-01), 305-316 0236-5731 159:2<305 1992 159 10967 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer