Sources of Deuterium

Unlike other elements, the variability of isotopic composition of hydrogen from different sources is great enough to be a factor in the location, design, and economic performance of heavy-water plants. 

The deuterium content of natural waters varies from place to place and from time to time because of isotopic fractionation which occurs when water evaporates from land or sea or is condensed from the air. The deuterium content of natural waters relative to standard water samples has been determined by a number of investigators representative results of two workers are abstracted in Table 13.1. The percent differences from standards have been converted to atom percent deuterium by using the indicated deuterium content of the standards, which, however, are less accurately known than the differences. 

Ocean water in the tropics contains around 0.0156 a/o (atom percent) deuterium. Water vapor in the air in equilibrium with the ocean has a deuterium content about 7 percent lower than seawater because H O has a higher vapor pressure than HDO. Consequently, water vapor over the ocean should contain about 0.0156/1.07 = 0X)146 a/o deuterium. The fust rain to fall out from this water vapor is richer in deuterium than 0.0146 percent, again because of the 

West coast of Greenland North American Rivers +2.42 151.6 

Craig [C13], standard (mean ocean water) contains 0.01566 a/o D according to Horibe and Kobayakawa [H6]  

---

Suggest methods for the preparation of each of these using D2O as the source of deuterium, butanols of your choice, and any necessary organic or inorganic reagents. 

Lithium aluminum deuteride (LiAlD ) is used as a source of deuterium atoms (heavy hydrogen, D-2) to produce tritium (jT-3) (super heavy hydrogen) for coohng nuclear reactors. 

This transformation was further studied and the catalyst load could be decreased to 0.2 equiv.35 33 A mechanism was proposed through deuterium incorporation experiments, and the conclusion was that there was no 1,2 shift of the deuterium present in the starting material (A, Scheme 5.3) since exclusive formation of furans D deuterated on position 3 could be explained by the presence of an external source of deuterium (such as D20). Therefore, it is believed that after silver(I) coordination to the allenyl system (A, Scheme 5.3), the attack by the carbonyl oxygen may lead to an oxo cation intermediate B. Finally, proton lost would generate silver furan C that would lead to furan D after silver release (Scheme 5.3).39... 

Is there any source of deuterium other than that produced by the big bang 15 billion years ago A number of possible sources have been considered, but Schramm himself developed compelling arguments that deny other possible sources." So we have a prediction there should be about 3.5 deuterium atoms for every... 

Denterinm is invariably prepared from heavy water, which itself is mannfactnred by the electrolytic emichment of water, and is available for use as a moderator in nuclear reactors. D2O is useful as a source of deuterium in deuterium-labeled compounds. Deuterium compounds such as heavy water have been extensively studied. In Table 3, a number of physical properties of normal water and heavy water are compared. 

The production of acetylene as the major gaseous product in the reaction of butadiyne (equation 9) occurs in part via C2H radicals when short wavelength radiation is used , but with 254 nm radiation it is suggested that a molecular process occurs in a non-linear excited state. The evidence for this additional process is that no C2HD is formed when perdeuteriopropyne is present as a source of deuterium to trap the radicals. 

Protonation of metal arsenides provides high yields of AsHj and alkyl- or arylarsines ". These reactions, by substitution of DjO for H O, are especially useful sources of deuterium-labeled products ... 

Compounds labeled at various positions by isotopic atoms are useful in determining reaction mechanisms and in following the fate of compounds in biological systems. Outline a possible synthesis of each of the following labeled compounds using H30H as the source of and D7O as the source of deuterium. 

Strongest evidence for a rapid equilibration of the a-halo sulfone with its a- and a -anions comes from reactions performed in D2O. If such reactions are interrupted before they are complete, the recovered a-halo sulfones are almost fully deuterated at both the a- and a -positions. Furthermore, the alkene products are also essentially fully deuterated, this time at the vinylic positions. When allowed to run to completion, this forms the basis of a very useful preparative method for deuterium-labeled alkenes (Scheme 8 and equation 24). Not only is a high percentage incorporation possible, but the source of deuterium is very cheap. 

Both seawater and freshwater can be a source of deuterium. But freshwater is preferred because corrosion and other problems are less severe with it. Natural gas is available in large quantities, but there is no... 

The chemical exchange reactor replenishes the depleted stream by chemical exchange reaction with an abundant source of deuterium. ... 

Since reaction (19.12) is the only source of deuterium in the course of electroless Ni-P deposition, the rate of reactions (19.11) and (19.12) can be studied by online mass spectrometry under open-circuit conditions as well as a function of the electrode potential similar to analogous measurements in Ni(II)-ffee hypophosphite solutions (see Sections 19.6.1 and 19.6.2). To avoid changes in the membrane permeability due to nickel deposition, each measurement has been carried out on a new specimen of the Ni-sputtered Teflon membrane. 

Protium is a stable isotope and makes up more than 99.9% of naturally occurring hydrogen. Deuterium (D) can be isolated from hydrogen it can form compounds such as "heavy water," D2O. Heavy water is a potential source of deuterium for fusion processes. Tritium (T) is unstable, hence radioactive, and is a waste product of nuclear reactors. 

Methane cannot be used as working substance in a distillation process because its relative volatility is so close to unity. This is regrettable in view of the large amount of natural gas that might be used as a source of deuterium. 

Since 1913 scientists had accepted the existence of isotopes, but conventional wisdom claimed that isotopes of a given element could not be differentiated or separated by a chemical process. Urey challenged and overturned this thinking in 1932 by showing that deuterium (D2) could be concentrated in the form of deuterium oxide, or heavy water (D2O), and then converted back into pure deuterium by electrolysis of the D2O. Deuterium and deuterium oxide are convenient sources of deuterium-labeled compounds that today are used routinely in medicine and science. 

Deuterium distributions are similar for products from reactions using overlayers of either D or N2 gas (see Table 3), deuterated Raney nickel, and substrate in dioxane (N produced less deuterium in products because of atmospheric contamination from light water). Therefore, the mechanism for incorporation of deuterium is independent of the source of deuterium. 

In a convenient modification of the above procedure (64), it is possible to use D20-dioxane as a source of deuterium. Thus if anthracene is dissolved in D2O-dioxane and treated with high pressure (3000 psi) CO at 175°, 36-d4 can be formed. The D2O probably reacts with CO in the water-gas shift reaction ... 

Among the tools used to study reaction mechanisms, the replacement of an atom by one of its isotopes has proven unique in its efficiency. In organic chemistry, which is mostly concerned with carbon and hydrogen containing compounds, replacing protium with deuterium has frequently been used, especially in tracer studies, to follow reaction paths and in kinetic studies and to determine isotope effects on reaction rates. In nature, hydrogen is essentially composed of atoms in which the nucleus is a single proton. However, it contains 0.0156% of deuterium, in which the nucleus also contains a neutron. A major source of deuterium is heavy water, D2O, which is prepared on industrial scale by the electrolytic enrichment of normal water. 

---