Kinetic study of the isotope exchange reactions of malonic acid and its derivatives in various acidic D2O media using 1H NMR spectroscopy. Implication in the Belousov-Zhabotinsky reaction
✍ Scribed by M.-C. Hsu; J.-J. Jwo
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 144 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0538-8066
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✦ Synopsis
The kinetics of the isotope exchange reactions of RCH(COOH) 2 (R"H, D, Me, Et, Bu, and Ph) in D 2 O solution were studied by using 1 H NMR spectroscopy. It was observed that the rate of isotope exchange reaction was inhibited by the presence of 1 M of DNO 3 , DCl, DBr or D 2 SO 4 and catalyzed by the presence of 4 M of D 2 SO 4 . No inhibition effect was observed in the case of D 3 PO 4 . The effect of inorganic acids follows the order of D 3 PO 4 Ͼ D 2 SO 4 Ͼ Ͼ (DNO 3 , DCl, DBr). The conjugated base (RCH(COOD)(COO Ϫ )) of RCH(COOD) 2 plays an important role in the isotope exchange reaction. The presence of deuterium ion suppresses the generation of RCH(COOD)(COO Ϫ ) ion from RCH(COOD) 2 and inhibits the rate of isotope exchange. In general, the order of reactivity of RCH(COOH) 2 toward isotope exchange with deuterium atom is R" Ph Ͼ (H, Br) Ͼ Me Ͼ (Et, Bu).