Isotope labelling techniques

Benzoates. The selective debenzoylation of sucrose octabenzoate [2425-84-5] using isopropylamine in the absence of solvents caused deacylation in the furanose ring to give 2,3,4,6,1/3/6 -hepta- and 2,3,4,6,1/6 -hexa-O-benzoyl-sucroses in 24.1 and 25.4% after 21 and 80 hours, respectively (54). The unambiguous assignment of partially benzoylated sucrose derivatives was accompHshed by specific isotopic labeling techniques (54). Identification of any benzoylated sucrose derivative can thus be achieved by comparison of its C-nmr carbonyl carbon resonances with those of the assigned octabenzoate derivative after benzoylation with 10 atom % benzoyl—carbonyl chloride in pyridine. 

The double isotope label technique and inorganic reaction mechanisms. J. O. Edwards and P. D. Fleischauer, Inorg. Chim. Acta, Rev., 1968, 2, 53-63 (35). 

A dual isotope labeling technique [85] has been used to measure membrane permeability in plant cells, based on the selective permeabiHty of the membranes of living cells to tritiated water and carbon-14 labeled mannitol. Kieran [29] showed that the results of the dual isotope labeling and Evan s Blue staining methods correlated well as indicators of cell viability however, the latter was preferable in terms of reagent cost and ease of analysis. 

Both pathways have been shown to be relevant for PCDD/F formation in municipal-waste incinerations. Chlorophenols can be converted to PCDD by copper species known in synthetic chemistry as the Ullmann type II coupling reaction. By use of isotope labeling techniques in competitive concurrent reactions with both reactions performed in laboratory experiments it was shown that precursor theory pathways from chlorophenols may be more important compared to the de novo pathway, but either competing pathway strongly depends on such conditions as temperature, air flow rate, and residence time. It may be difficult to model the complex reahty of large incinerators using relevant laboratory experiments. 

B. Slow exchange studied by isotopic labeling technique... 

B. Slow Exchange Studied by Isotopic Labeling Technique... 

To study water exchange on aqua metal ions with very slow exchange of water molecules, an isotopic labeling technique using oxygen-17 can be used. A necessary condition for the applicability of this technique is that the life time, tm, of a water molecule in the first coordination shell of the ion is much longer that the time needed to acquire the 0-NMR spectrum. With modern NMR spectrometers and using enrichments up to 40% in the acquisition time can be as short as 1 s. 

Metal isotope labelling techniques have been used to clarify the M—N bond assignments in the octahedral [Zn(HIm)6lCl2 and pseudotetrahedral [Zn(HIm)2X2] complexes (X = Br, I, N03, NCS Him = imidazole).417 Much lower frequencies (208 cm 1) are observed for the octahedral complexes as compared to the tetrahedral (255,239 cm-1). A comparison with other N-bonded species shows that the frequency is governed by both the mass of the ligand L and the strength of the M—L bond. 

Further spectroscopic characterization of this compound was made using an isotope-labeling technique [71]. In the reaction of H02 with DCDO, the two O—H stretching bands were shifted only slightly to 3558.8 and 3649.2 cm 1, while the C—H stretching band was replaced by a C—D stretching band at about 2200 cm 1. These results further support the... 

The mechanism of hydrazine decomposition has been studied much less than that of hydrogen peroxide, and the mechanism actually is not known. We may take some clues however from studies of its oxidation in aqueous solution by metal salts, in which kinetic and isotope labelling techniques were used. As the main mechanism for the oxidation of hydrazine by ferric ion the following was proposed 57) ... 

An even more detailed mechanistic scrutiny of photochemical and thermal 6e electrocyclizations of the parent system (1,2) has recently emerged using resonance Raman spectroscopic and isotopic labeling techniques, respectively. 

Tanaka, Y., Miyajima, T., Koike, I., Hayashibara, T., and Ogawa, H. (2006). Translocation and conservation of organic nitrogen within the coral-zooxantheUa symbiotic system of Acropora pukhra, as demonstrated by dual isotope-labeling techniques. /. Exp. Mar. Biol. Ecol. 336(1), 110—119. 

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