Isotopic oxygen and

We said in Section 21.6 that mechanistic studies on ester hydrolysis have been carried out using ethyl propanoate labeled with lsO in the etherlike oxygen. Assume that Odabeled acetic acid is your only source of isotopic oxygen, and then propose a synthesis of the labeled ethyl propanoate. 

Research involving isotopes of oxygen is expanding into many branches of science and at present over a 150 papers a year are published on the subject. It is hoped that this chapter will stimulate investigations of biochemical problems involving isotopic oxygen and assist research workers in their task. 

Cheung A S C, Yoshino K, Freeman D E, Friedman R S, Dalgarno A and Parkinson W H 1989 The Schumann-Runge absorption-bands of 0 0 in the wavelength region 175-205 nm and spectroscopic constants of isotopic oxygen molecules J. Mol. Speotroso. 134 362-89... 

SMOW. standard mean ocean water (a standard for oxygen and hydrogen isotopes)... 

Since NRA focuses on inducing specific nuclear reactions, it permits selective observation of certain isotopes. This makes it ideal for tracer experiments using stable isotopes. Generally, there are no overlap or interference effects because reactions have very different Qvalues, and thus different resultant particle energies. This permits the observation of species present at relatively low concentrations. A good example is oxygen and O can be resolved unambiguously, as they are... 

Let us fix attention on a particular H20 molecule A in the interior of water (if we wish to identify this molecule we can suppose that it contains a nucleus of the oxygen isotope 01S) and let us consider the water molecules which happen to be nearest neighbors of this molecule at the moment. These molecules have been in contact with A for different lengths of time. Since all the molecules in the liquid wander about, there was a time when none of these molecules was in contact with A. Further, if we could now begin to watch these molecules, we should find that, after the lapse of different periods of time, they become separated from A and each is replaced by another molecule. Similar remarks can be made about the molecules which come into contact with any chosen molecule. We can now raise the question—-What is the rate of turnover of this process The rate depends on the degree of local order and disorder, which in turn depends on the strength and character of the forces between adjacent molecules. 

The interaction of small, well defined, rhodium clusters, Rh and Rhs, with O2 has been investigated (220) by matrix infrared, and UV-visible, spectroscopy, coupled with metal/02 concentration studies, warm-up experiments, and isotopic oxygen studies. A number of binuclear O2 complexes were identified, with stoichiometries Rh2(02)n, n = 1-4. In addition, a trinuclear species Rhs(02)m, m = 2 or 6, was identified. The infrared data for these complexes, as well as for the mononuclear complexes Rh(02)x, = 1-2 (229), are summarized in Table XI. Metal-concentration plots that led to the determination of... 

The interstitial air trapped during this process preserves a largely unaltered record of the composition of past atmospheres on time scales as short as decades and as long as several hundred thousand years. Such records have provided critical information about past variations in carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), carbon monoxide (CO), and the isotopic composition of some of these trace species. In addition, studies of the major elements of air nitrogen, oxygen, and argon, and their isotopic composition, have contributed... 

Horita, J. and Wesolowski, D. J. (1994). Liquid-vapor fractionation of oxygen and hydrogen isotopes of water from the freezing to the critical temperature. Geochim. Cosmochim. Acta. 58(16), 3425-3437. 

Shackleton, N. J. (1967). Oxygen isotope analyses and Pleistocene temperatures re-assessed. Nature 215, 15-17. 

Suggestions that phosphatic minerals in mammals could be used, however, revived the interest in climate reconstruction in continental interiors. Aquatic, cold-blooded animals like fish have body temperatures and body water oxygen isotopic compositions that are directly dependent on the water in which they live. For these animals, a commonly used equation describes the relationships among temperature, water oxygen isotopic composition and phosphate oxygen isotopic composition as (Longinelli and Nuti 1973 verified by Kolodny et al. 1983, among others) ... 

Epstein, S., Thompson, P. and Yapp, C. J. 1977 Oxygen and hydrogen isotopic ratios in plant cellulose. Science 198 1209-1215. 

Grossman, E. and Ku, T.-L. 1986 Oxygen and carbon isotope fractionation in biogenic aragonite temperature effects. Chemical Geology (Isotope Geoscience Section) 59 59-74. 

Although the radioactive isotope H has been extensively used for studies on the uptake of xenobiotics into whole cells, the intrusion of exchange reactions and the large isotope effect renders this isotope rather less straightforward for metabolic studies. Both deuterium H-labeled substrates, and oxygen and OH2 have, however, been extensively used in metabolic studies, since essentially pure labeled compounds are readily available and mass spectrometer facilities have become an essential part of structural determination. 

Aggarwal PK, ME Fuller, MM Gurgas, JF Manning, MA Dillon (1997) Use of stable oxygen and carbon isotope analyses for monitoring the pathways and rates of intrinsic and enhanced in situ biodegradation. 

Craig H (1957) Isotopic standards for carbon and oxygen and correction factors for mass-spectrometric analysis of carbon dioxide. Geochim Cosmochim Acta 12 133-149. 

After approximately 3 min on stream in the isotopic mixture of CH4/02/C 02/He, a steady-state value in the rate of formation is obtained (Fig. 3). This value is used to estimate the relative contribution of the CO2-reforming route to the overall production of CO (direct + indirect routes). Proper analysis of this result, taking into consideration scrambling of isotopic oxygen Figure 3. Transient isotopic labelling experiment atoms between the CO2 and O2 molecules... 

One-step hydroxylation of aromatic nucleus with nitrous oxide (N2O) is among recently discovered organic reactions. A high eflSciency of FeZSM-5 zeolites in this reaction relates to a pronounced biomimetic-type activity of iron complexes stabilized in ZSM-5 matrix. N2O decomposition on these complexes produces particular atomic oj gen form (a-oxygen), whose chemistry is similar to that performed by the active oxygen of enzyme monooxygenases. Room temperature oxidation reactions of a-oxygen as well as the data on the kinetic isotope effect and Moessbauer spectroscopy show FeZSM-5 zeolite to be a successfiil biomimetic model. 

Figure 1.31. Bivariable plot of oxygen versus carbon isotopic compositions of carbonates. Solid circle magnesite open circle dolomite open square calcite A oxygen and carbon isotopic compositions of igneous carbonates B oxygen and carbon isotopic compositions of marine carbonates (Shikazono et al., 1995).

Kawahata, H., Kusakabe, M. and Kikuchi, Y. (1987) Strontium, oxygen, and hydrogen isotope geochemistry of hydrothermally altered and weatherted rocks in DSDP Hole 504B, Costa Rica Rift. Earth Planet. 

Kusakabe, M. and Chiba, H. (1983) Oxygen and sulfur isotopic composition of barite and anhydrite Irom the Fukazawa deposit, Japan. Econ. Geol. Mon. 5, 292-301. 

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