Hydroxy acid, oxidation, bromine The oxidation of glycollic, lactic, a-hydroxybutyric, and 2-phenyllactic acids by aque­ ous bromine has been studied. The reaction is of first order with respect to the oxidant and the anion of the hydroxy acid respectively. The active oxidising species is molecular bromine. The oxidation of ci,a-dideuterioglycollic acid indicated a kinetic isotope effect, ^h /^...

Introduction Conclusions References

The sharp resistive transitions in superconducting single crystals of natural abundance and 99% 13C-enriched Rb3C60 reveal the carbon isotope effect with unprecedented accuracy. The measured isotope exponent aC 0.21 6 0.012 is outside the error bars of all previous reported values. Our precise value for aC, combined with Tc, aRb , and an ab initio calculation of the frequency distribution of th...

Stable isotope labeling (SIL) still has not been used very much in pediatric and perinatal clinical pharmacology. However, this method has numerous advantages. It allows one to determine the concentration of drugs with great sensitivity, thereby allowing quantification in small amounts of biologic samples. It also allows quantification with great specificity, eliminating interference by drug me...

Compound specific isotope analysis (CSIA) has been applied to monitor bioremediation of groundwater contaminants and provide insight into mechanisms of transformation of chlorinated ethanes. To date there is little information on its applicability for chlorinated methanes. Moreover, published enrichment factors (ε) observed during the biotic and abiotic degradation of chlorinated alkanes, such ...

Adenosine 5'-phosphate was synthesized with 3H or 14C label specifically located as [1'-3H]AMP, [1'-14C] AMP, [5'-3H]AMP, and [5'-14C]AMP. The synthesis was accomplished from adenine and glucose or adenine and ribose using enzymes from the pentose pathway and/or from the purine salvage pathways. Structural analysis of the compounds confirmed the locations of the radiolabels. The methods provide...

Intrinsic deuterium-induced isotope effects have been measured and analyzed for compounds having one or two phenyl groups specifically labelled at different positions in a molecule. Some typical examples of directional and orientational dependence of the effects have been given. Different magnitudes of isotope effects that are transmitted in opposite directions have been observed. Thus, in p-2H...

Isotopic effects associated with molecular absorption are discussed with reference to natural phenomena including early solar system processes, Titan and terrestrial atmospheric chemistry, and Martian atmospheric evolution. Quantification of the physicochemical aspects of the excitation and dissociation processes may lead to enhanced understanding of these environments. Here we examine a physic...

H/D isotope effect on the circular dichroism spectrum of methyl α-D-glucopyranoside in aqueous solution has been analyzed by multicomponent density functional theory calculations using the polarizable continuum model. By comparing the computational spectra with the corresponding experimental spectrum obtained with a vacuum-ultraviolet circular dichroism spectrophotometer, it was demonstrated th...