Deuterated compounds Methanol

COC, w-HOBE, norcocaine, cocaethylene, benzoylecgonine, AEME, and deuterated componnds nsed as internal standards (BE-dj, COC-dj, and CE-d ) as 1.0 mg/mL (unlabeled compounds) or 100 pg/mL (deuterated compounds) methanolic stocks (Cerilliant, Round Rock, TX). 

The H-NMR and the C-NMR spectra of isoxsuprine HCl were obtained using a Bruker Instruments system operating at 300, 400, or 500 MHz (proton NMR), or at 75, 100, or 125 MHz (carbon NMR). Standard Bruker software was used to obtain DEPT, COSY, and BETCOR spectra. All measurements were obtained with the compound being dissolved in deuterated methanol, using tetramethylsilane as the internal standard. 

The H NMR spectra of organic compounds are usually obtained in an aprotic solvent at concentration levels of a few percent. The most widely used solvent is deuterated chloroform (CDC13), sufficiently polar to dissolve most organic compounds. Acetone-r/6 (C3D60), methanol-e 4 (CD3OD), pyridinc-r/5 (C5D5N) and heavy water (D20) are also used. 

The amount of futile acetylation observed for this compound in the rat, at ca. 7-10% for parent compound and metabolites, was less than that seen for phenacetin and similar to that found for paracetamol itself. The bulk of the radio-label was rapidly excreted in urine as practolol itself (albeit with 7-10% reacetylation) and the remainder as either the ring-hydroxylated metabolite or its glucuronide conjugate. As in previous examples, deuterated methanol was used in the mobile phase rather than methanol in order to be able to more easily observe the acetyl resonances of practolol and related compounds. 

As a typical example, the cHPLC-NMR separation of an extract of black beetles is shown in Figure 7.3.2.3. The methanolic extract was prepared from the vessels of one hundred black beetles (Palembus ozularis) by Marit Wahren-dorf at the Institute of Pharmaceutical Biology (Prof. Dr. Michael Wink) in Heidelberg, Germany [16]. These insects are found in South America and their vessels contain anti-inflammatory compounds which can act against asthma. As the extract was received with a non-deuterated solvent, before the injection into the chromatographic system, the solvent was evaporated and then methanol-d4 was used to dissolve the dry extract. 

The presence of this non-exchangeable pool for PAHs is implied by the results of experiments which compared the extraction rates of native PAHs and spiked perdeuterated compounds from SRM 1649 urban dust (Burford et al., 1993). Extraction with supercritical C02 quantitatively recovered the deuterated PAHs within 30 min. C02 alone removed native PAHs more slowly and incompletely, C02/ methanol gave improved yields. Differences in volatilization of PAHs from urban particles into a clean airstream occurred, depending on whether the PAHs were native to the particles or added by surface coating (Poster et al., 1995). 

Refluxing ajaconine in methanol afforded a mixture from which a new compound identified (87) as 7a-hydroxyisoatisine (82) was isolated. The structure of the latter was established by 1H- and UC-NMR spectroscopy. When ajaconine was refluxed in CH3OD under nitrogen, a mixture of C-19, C-20-deuterated ajaconine (206) and C-19,C-20-deuterated 7 -hydroxy-isoatisine (207) was formed. Incorporation of deuterium in 206 and 207 indicated that ajaconine ionized and rearranged to 207 and that these species are in equilibrium in refluxing methanol. 

When the following compound is treated with sodium methoxide in methanol, two elimination products are possible. Explain why the deuterated product predominates by about a 7 1 ratio (refer to Problem 6-75). 

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