Deuterated analogs

As described previously, nonradiative decay due to solvent interactions can severely reduce lanthanide luminescence through energy dissipation by vibronic modes, with the O—H oscillator being the most common and eflBcient quencher. However, if these O—H oscillators are replaced with lower-frequency O—D oscillators, the eflBciency of vibronic deactivation decreases substantially. Therefore, the rate constants for luminescence lifetimes (th o) of lanthanide excited states in water or alcoholic solvents are often much shorter than those in analogous deuterated solvents (td o)- This property can be utilized to determine the degree of solvation for luminescent lanthanides. 

As expected, the potentials decreased (phenolates more readily oxidized) when methoxy substituents were present (R = OMe, Table 1). Successive generation of species with one, two, and three phenoxyl radicals was supported by UV-vis spectroscopy on MeCN solutions generated by controlled potential coulometry at —30°C. Intense bands between 400-430 nm were observed that are particularly diagnostic of phenoxyl radicals (tt tt transition). Proof for coordination of the phenoxyl radical(s) to the metal ion in these compounds was obtained through EPR spectroscopy. For example, X-band EPR spectra of the 5 = 1/2 1-electron oxidized species [(L M]+ (1+) and (3" ), M = Sc and Ga respectively) and analogs deuterated at the benzylic positions showed hyperfme coupling to the metal ion nuclei 7=3/2, 0.23/0.29 mT " Sc, 7=7/2, 0.12mT). ... 

The reaction of PH3 with Fg can be carried out in a concentric burner [26] or by mixing the diluted reactants in a flow tube [18]. The reaction is accompanied by a bright emission with a continuum in the region of 320 to 600 nm [18, 26]. Cocondensation of Ar-diluted PH3 and a small excess of Fg in Ar at 16 K yielded PHgF as the dominant product, with PHF2 and PH3F2 as other major products, as well as HF, (HF)2, H3P HF, and a very small amount of PF3. The analogous deuterated products were found for the reaction of PD3. The low concentration of... 

During the course of base-catalyzed exchange in O-deuterated alcohols, the vinylic hydrogen in the a position to the ketone is replaced by deuterium, in addition to the hydrogens activated by enolization. Thus, under these conditions the exchange of androst-l-en-3-one (16, R = H) gives a trideuterio derivative (18) instead of the expected 4,4-d2 analog (16, R = D). " (For other examples see compounds 13, 19, 21, 23, 26 and 27.) Incorporation of this deuterium is due to rapidly reversible alcohol addition (16 -+17) and elimination (17 18) which competes with the enolization step. " ... 

There are ample precedents for reductions of double bonds in conjugated enones with lithium in deuterioammonia (see section V-C). Examples of the reduction of saturated ketones in deuterated media appear only as side reactions (over reductions) during the above mentioned conversions. For experimental details, therefore, one should consult the literature for the analogous reductions in protic medium (see also chapter 1). The use of deuterioammonia is essential for labeling purposes since by using liquid ammonia and methanol-OD the resulting alcohol contains no deuterium. For the preparation of deuterioammonia see section IX-D. 

Thus, the reduction of tosylhydrazones with sodium borodeuteride in dioxane provides only monodeuterated analogs. For the insertion of two deuteriums it is necessary to first exchange the hydrazone proton and to carry out the reduction in aprotic or deuterated solvents. Under these conditions the reduction of the tosylhydrazone derivatives of 7- and 20-keto... 

Homogeneous catalytic deuteration of various unsaturated 5a-spirostane derivatives is an excellent method for the preparation of side chain labeled analogs. Thus, saturation of the double bonds at positions 20(21), 23 and 24 provided the corresponding deuterated compounds (144), (145) and (146) in high isotopic purity. The preparation of (146) is a rare example of the saturation of an isolated trisubstituted double bond in the steroid field. 

Isotope labeling by derivative formation with deuterated reagents is useful for the preparation of analogs such as dg-acetonides, da-acetates, da-methyl ethers, dg-methyl esters, etc. The required reagents are either commercially available or can be easily prepared. (The preparation of da-methyl iodide is described in section IX-F. Various procedures are reported in the literature for the preparation of dg-acetone, da-diazometh-ane57.i63.i73 and da-acetyl chloride. ) These reactions can be carried out under the usual conditions and they need no further discussion. A convenient procedure has been reported for the da-methylation of sterically hindered or hydrogen bonded phenolic hydroxyl functions by using da-methyl iodide and sodium hydroxide in dimethyl sulfoxide solution. This procedure should be equally applicable to the preparation of estradiol da-methyl ether derivatives. 

The mechanism suggested earlier for the similar isomerization 34 35 involving the reaction of a 1,2-dihydroquinoline molecule with the starting quinolinium salt 33 (Scheme 11) is analogous to that of 4//-thiopyran isomerization discussed above (cf. Scheme 3) and is supported by deuterated substrate studies (85CJC412). Further support for this mechanism is the absence of such isomerization for 4-substituted derivatives such as 1,4-dimethyl-1,2-dihydroquinoline [94JCS(CC)287]. 

The compounds were also run with D20 leaking into the ion source from a stainless steel reservoir. The resulting mass spectra show partial exchange of the hydroxyl protons with deuterium. From the shifts of the peaks in the mass spectra of the deuterated analogs, the number of exchangeable hydrogens retained in each fragment can be determined. 

The structures shown for ions, such as in Equations 7 and 8, are entirely speculative since the mass spectrum gives only relative abundance of the various m/e-groups formed. Chemical reasoning, meta-stable-ion peaks, peak shifts in the deuterated analogs, and published mass spectra of similar compounds are the bases for the proposed modes of fragmentation and for the postulated structures.)... 

The method using GC/MS with selected ion monitoring (SIM) in the electron ionization (El) mode can determine concentrations of alachlor, acetochlor, and metolachlor and other major corn herbicides in raw and finished surface water and groundwater samples. This GC/MS method eliminates interferences and provides similar sensitivity and superior specificity compared with conventional methods such as GC/ECD or GC/NPD, eliminating the need for a confirmatory method by collection of data on numerous ions simultaneously. If there are interferences with the quantitation ion, a confirmation ion is substituted for quantitation purposes. Deuterated analogs of each analyte may be used as internal standards, which compensate for matrix effects and allow for the correction of losses that occur during the analytical procedure. A known amount of the deuterium-labeled compound, which is an ideal internal standard because its chemical and physical properties are essentially identical with those of the unlabeled compound, is carried through the analytical procedure. SPE is required to concentrate the water samples before analysis to determine concentrations reliably at or below 0.05 qg (ppb) and to recover/extract the various analytes from the water samples into a suitable solvent for GC analysis. 

GC/MS. GC/MS is used for separation and quantification of the herbicides. Data acquisition is effected with a data system that provides complete instrument control of the mass spectrometer. The instrument is tuned and mass calibrated in the El mode. Typically, four ions are monitored for each analyte (two ions for each herbicide and two ions for the deuterated analog). If there are interferences with the quantification ion, the confirmation ion may be used for quantification purposes. The typical quantification and confirmation ions for the analytes are shown in Table 4. Alternative ions may be used if they provide better data. 

The analogous decomposition process was observed for related germylide-nephosphanes.32 Although the thermolysis of 12a was carried out in deuterated solvents, no deuterium incorporation was observed. Further work is needed in order to explore the reaction mechanism. In contrast to 12a, the thermolysis behavior of phosphasilenes 15 is quite different. 

A large number of calculations have been done to determine the vibrational frequencies of some simple silenes. The parent silene and its deuterated analogs have been investigated (4,9,188) as well as 1,1-dimethylsilene, its deuterated derivatives (38,181), and 1,1-dichlorosilene (4). For the undeuterated compounds a Si=C stretching vibration of approximately 1000 cm-1 was calculated. Deuteration usually results in a decrease of this value. 

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