Deuterium containing

The slightly different physical properties of deuterium allow its concentration in ordinary hydrogen (or the concentration of a deuterium-containing compound in a hydrogen compound) to be determined. Exchange of deuterium and hydrogen occurs and can be used to elucidate the mechanism of reactions (i.e. the deuterium is a non-radioactive tracer). Methanol exchanges with deuterium oxide thus ... 

Raman Spectroscopy. Raman spectroscopy is an excellent method for the analysis of deuterium containing mixtures, particularly for any of the diatomic H—D—T molecules. For these, it is possible to predict absolute light scattering intensities for the rotational Raman lines. Hence, absolute analyses are possible, at least in principle. The scattering intensities for the diatomic hydrogen isotope species is comparable to that of dinitrogen, N2, and thus easily observed. 

The most plausible fusion reaction for producing energy commercially involves two isotopes of hydrogen, deuterium (D) and tritium (T), or H and H. Deuterium contains one proton and one neutron for an atomic number of two. Tritium contains one proton and two neutrons for an atomic number of three. The reaction is... 

Hartshorn and Ridd48 showed that there is a negligible solvent isotope effect on nitrating anilinium ions in sulphuric acid and deuterated sulphuric acid (cf. an earlier less accurate determination by Brickman and Ridd48). The absence of a solvent isotope effect also argues against reaction on the free base because the free base concentration would be lower by a factor of about four in the deuterium-containing medium. Consequently, the differences in the rate coefficients in Table 6... 

The log rate versus acid strength curve for the latter compound is of the exact form expected for reactions of the free base, whilst that of the former compound is intermediate between this form and that obtained for the nitration of aniline and phenyltrimethylammonium ion, i.e. compounds which react as positive species. That these compounds react mainly or entirely via the free base is also indicated by the comparison of the rate coefficients in Table 8 with those in Table 5, from which it can be seen that the nitro substituent here only deactivates weakly, whilst the chloro substitutent appears to activate. In addition, both compounds show a solvent isotope effect (Table 9), the rate coefficients being lower for the deuterium-containing media, as expected since the free base concentration will be lower in these. 

Further substrate and solvent isotope effects were measured by Batts and Gold472 for the dedeuteration and detritiation of labelled 1,3,5-trimethoxy-benzene in aqueous protium- and deuterium-containing perchloric acid. Contrary to the observations above, they found the rate coefficients for dedeuteration to detritiation to be independent of the concentration of the catalysing acid (Table 125). Detritiation in the deuterium-containing aqueous perchloric acid media occurred 1.68 times faster than in the protium-containing media. 

However, using acetate buffers, the observations of Eaborn et al.471 were confirmed in that rates were faster in the protium- than in the deuterium-containing media. Furthermore, an earlier observation of Kresge and Chiang473 (see below)... 

For Rh(I)/BINAP-catalyzed isomerizations of allylic amines, the mechanistic scheme outlined in Eq. (2) has been proposed. The available data are consistent with the notion that Rh(I)/PF-P(o-Tol)2-catalyzed isomerizations of allylic alcohols follow a related pathway [11]. For example, the only deuterium-containing product of the reaction depicted in Eq. (9) is the l,3-dideuterated aldehyde, which estabhshes that the isomerization involves a clean intramolecular 1,3-migration. The data illustrated in Eqs. (10) and (11) reveal that the catalyst selectively abstracts one of the enantiotopic hydrogens/ deuteriums alpha to the hydroxyl group. 

In the study of multiple exchange reactions, it is desirable to work with a high ratio of deuterium to hydrocarbon. This minimizes the influence of isotopic dilution of the deuterium on the rate of production of the more highly deuterated species during the early part of the reaction. The use of deuterium containing as small a percentage of hydrogen as possible is also important if true initial distributions of products are to be obtained. 

The selected primary ions can also be characterized by ion molecule reactions with the FTMS-2000 dual cell and/or surface induced reactions (48). Reactions specific for particular functionalities can be used to count the number of these in a primary ion such as the number of hydrogen atoms that can be exchanged with a deuterium-containing species (59). Further, their position may well be distinguished by the reaction s effect on fragment ions in MS-II spectra. 

Evidence in support of this mechanism is provided by using the deuteride DCo(CO)4 as catalyst, when CH2DCH2CHO is the only deuterium-containing organic product of the reaction. In the isomerisation of isopropylmagnesium bromide the mechanism appears to be... 

Figure 1. Formulas of C -TFIC and Ae -THC and deuterium containing internal...

When the amine-assisted photodechlorination of 4-chlorobiphenyl was performed in deuterium-containing solvents such as CH3CN/D20 or CD3OD, incorporation of deuterium into biphenyl was observed390. This is considered to indicate the occurrence of another pathway for the transformation of ArCT into ArH (equations 100-102). 

Correction must be made for the pATa of the deuterated solvent. Bases are stronger in deuterium-containing acidic media than in the analogous protium-containing one. For primary amine protonation in the pH range, A pKa is —0.55 units, and for weaker bases, —0.35 units (60JA15). A standard value of 0.4 was therefore used in all cases. 

The mass spectral fragmentation reactions of a number of derivatives used in GC-MS have been reported including a series of esters of the JV-trifluoroacetates [152] and the pertrimethylsilyl derivatives [153-155] and their carbon-13- [156] and deuterium-containing analogues [157]. General reviews of the mass spectra of the common amino acids and their derivatives are also available [151,158]. 

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