Heavy water acidity

Heavy water, see Hydrogen[ H] oxide Heazlewoodite, see rn-Nickel disulfide Hematite, see Iron(III) oxide Hermannite, see Manganese silicate Hessite, see Silver telluride Hieratite, see Potassium hexafluorosilicate Hydroazoic acid, see Hydrogen azide Hydrophilite, see Calcium chloride Hydrosulfite, see Sodium dithionate(III)... 

For this type of reaction the value of the solvent deuterium isotope effect is often a conclusive argument for the proposed mechanism 16). Rate measurements of 1 in acetic acid-acetate buffers in light and heavy water resulted in an isotope effect ktiiO lkozo of 2.5, and A oac/ doac of 9. A ratedetermining proton transfer to the /3-carbon atom of the enamine has been proposed and accounts for the experimental results I6-18 Eq. (5). 

The concentrations of the different intermediates are determined by the equilibrium constants. The observation of immonium ions [Eq. (5)] in strongly acidic solutions by ultraviolet and NMR spectroscopy also Indicates that these equilibria really exist (23,26). The equilibria in aqueous solutions are of synthetic interest and explain the convenient method for the preparation of 2-deuterated ketones and aldehydes by hydrolysis of enamines in heavy water (27). 

To slow down and control the rate of reaction, a moderator is also required. Typically, the moderator is boric acid, graphite, or heavy water (D20) and is present in the high-purity water, which also serves as a primary coolant for the fuel and the reactor vessel. The tremendous heat generated by nuclear fission is transferred to this closed-loop coolant, which is contained within a reactor primary-coolant circulation system. The high-purity water coolant also contains a suitable pH buffer such as lithium hydroxide, which has the additional effect of limiting the corrosion of fuel-cladding and other components. 

The sulfoxidation of normal Cl4-CI7 paraffins with sulfur dioxide, oxygen, and water is performed under UV radiation in parallel reactors (1 in Fig. 3). The reaction enthalpy is dissipated by cooling of the paraffin in heat exchangers. The 30- to 60-kW UV lamps are cooled by a temperature-controlled water cycle. The reaction mixture leaving the reactors separates spontaneously into two phases in 2. The lighter paraffin phase is recirculated to the reactors. The composition of the heavy raw acid phase is shown in Table 5. 

The reaction between permangante ion and neutral formic acid follows similar bimolecular kinetics with k2 = 1.1 x 10 exp(—16.4x 10 /lt7 )l.mole . sec . No primary kinetic isotope effect was found for this path either in light or heavy water. However, Mocek and Stewart have reported that in very strong sulphuric acid the oxidations of neutral substrate by both HMnO and MnOj display substantial isotope effects. 

An operational approach to the determination of the acidity of solutions in deuterium oxide (heavy water) was suggested by Glasoe and Long. This quantity, pD, is determined in a cell consisting of an aqueous (H20) glass electrode and a saturated aqueous calomel reference electrode on the basis of the equation... 

Hydrogen sulfide has a variety of industrial uses. Its major use is in the production of elemental sulfur and sulfuric acid. Hydrogen sulfide is also used in the manufacture of sodium sulfide and thiophenes. It is used in metallurgy and in the production of heavy water for the nuclear industry (Beauchamp et al. 1984 HSDB 1998). In the past, hydrogen sulfide was used as an agricultural disinfectant. 

This means that the ionization and rearrangement need not be concerted and that symmetrical protonated ethylene can not be a major intermediate in the reaction. A similar experiment with isobutylamine and nitrous acid in heavy water gave products that contained no carbon-deuterium bonds. Since it is known that the -complex formed from isobutylene and acid is in rapid equilibrium with protons from the solvent, none of this can be formed in the nitrous acid induced deamination. This in turn makes it probable that the transition state for the hydrogen migration is of the sigma rather than the -bonded type.261... 

Colorless gas with a strong odor of rotten eggs detectable at 0.005 ppm. However, it can cause olfactory fatigue and the sense of smell is not reliable. Used industrially to produce elemental sulfur, sulfuric acid, and heavy water for nuclear reactors. 

In 1933, Schoenheimer, who was medically qualified and had been working with Aschoff in the Pathology Institute in Freiburg, moved to Columbia University, New York, and was joined the next year by David Rittenberg. Rittenberg had just spent some time in Urey s laboratory in the Rockefeller Institute learning techniques for handling deuterium. Their first experiments concerned the metabolism of deuterated fatty acids in rats and the demonstration (see below) that 2H from heavy water was incorporated by the animals into fatty acids and cholesterol. 

The most important applications of hydrogen sulfide involve the production of sodium sulfide and other inorganic sulfides. Hydrogen sulfide obtained as a by-product often is converted into sulfuric acid. It also is used in organic synthesis to make thiols or mercaptans. Other applications are in metallurgy for extracting nickel, copper, and cobalt as sulfides from their minerals and in classical qualitative analytical methods for precipitation of many metals (see Reactions). It also is used in producing heavy water for nuclear reactors. 

Water participates in carbocation formation59,60 by generating the strong acid H[Al(OH)Hlg3],6,59 which forms a carbocation through an alkyl halide intermediate60 or via direct hydride ion abstraction.6 Experiments with heavy water by Pines further proved its cocatalytic effect indicating that HC1 (HBr) formed is not the real activator.60,61... 

Anhydrous deuterophosphoric acid can be prepared by condensing the stoichiometric amount of heavy water onto phosphorus(Y) oxide in a vacuum line. The mixture is warmed to complete the reaction and fractionally crystallized to constant melting point. The method can also be used to prepare crystalline orthophosphoric acid, H3P04, and when only small quantities are required, is preferable to methods involving the dehydration of aqueous solutions of the acid.1... 

Deuterosulfuric acid can be prepared by condensing the stoichiometric amount of heavy water onto sulfur (VI) oxide in an apparatus similar to that described on page 83. 

About 10 g. of pure sulfur(VI) oxide is prepared in the apparatus shown in Fig. 13. Concentrated oleum is placed in flask A which is cooled, evacuated, and sealed at point 1. Tube B is cooled in liquid air until the required amount of sulfur(VI) oxide has distilled over it is then sealed at point 2. Further purification of the trioxide by vacuum distillation is usually unnecessary. The procedure for reaction of the oxide with the required amount of heavy water (2.5018 g./lO g. SOs) is similar to that described in the preparation of deuterophosphoric acid except that sulfur(VI) oxide, being more volatile than phosphorus (V) oxide, should be cooled to —78° before being placed in the side arm of Fig. 14. An inert Fluorlube tap grease is recommended. Limb E is cooled and the apparatus evacuated slowly to prevent volatilization and entrainment of sulfur (VI) oxide in the vacuum line. When the oxide has been completely... 

Reverse osmosis also serves some of the waste management and resource recovery needs in the metals and metal finishing industry. Effluent streams from mining and plating operations containing heavy metals, acids, and other chemicals can be treated with reverse osmosis to recover both the metal as its salt, and purified water for reuse. For metal ion recovery from dilute solutions, however, reverse osmosis faces competition from conventional solvent extraction, membrane-based solvent extraction, and its variant, coupled transport (see Section V.F.3). 

Ionization of Acetylene. Acetylene is known to possess acidic properties and when it is shaken with heavy water the density of the latter becomes less in alkaline solution indicating an exchange between the hydrogen of the acetylene and the deuterium ions of the water. The exchange does not take place with measurable velocity in acid solutions where the dissociation of the weak acetylene acid is repressed. 

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