Other sources of hydrogen

In addition to hydrogen gas, other sources of hydrogen are available. In principle, hydrogen may be obtained from any molecule containing hydrogen... 

Can hydrogen from biomass be made cost-competitive with gasoline and with other sources of hydrogen ... 

Efficiency of the overall process. In comparison with several other sources of hydrogen, the capability of attaining overall thermal-to-hydrogen energy efficiency in excess of 50 percent values by future technologies (e.g., the N-SMR, HTES, SI, and possibly other paths) is one of the advantages... 

Details of Preparation.—A tubulated retort is filled with alkali and the phosphorus is added in small pieces. The tubulure is then closed by a delivery tube, which is connected with a Kipp s apparatus or other source of hydrogen (the air may also be displaced by adding a little ether). The neck of the retort is connected with a tube which dips under water. The air is displaced by hydrogen and the retort then gently warmed so as to melt the phosphorus and give a steady evolution of gas. When sufficient has been collected the residual gas is expelled by a current of hydrogen and the phosphorus allowed to solidify before the retort is opened. 

Junge showed that H2, CH4, CO, and N2O belong to a group of atmospheric constituents, which are strongly influenced, by microbiological sources. Conversely, there is some evidence indicating other sources of hydrogen release, as mentioned above. The quantities of H2 released from some sources have not been quantitatively estimated. 

Although little water manages to pass through the cold trap, there are other sources of hydrogen in the upper air. As mentioned above, methane emissions from the surface mix upwards from the surface, as methane has no cold trap, and in the upper air photolysis leads eventually to release of H. In addition, there is a small emission of H2 from the surface, some of which will reach the upper part of the atmosphere however. Earth also sweeps up H and H2 from space. Over time, net hydrogen loss must have been limited we have kept the oceans. 

Process (5), Isotopic Exchange of Reactant Hexene. However, the moles of hydrogen atoms from the positions equilibrated in 2-hexene is 0.108(0.65) =0.070. This is much too small a quantity to mix with 0.20 moles of deuterium atoms to give (D ) = 0.35 even if we allow for the extra hydrogen added to the pool in the isomerization of cis- to trans-2-hexene. The only other source of hydrogen is in exchanged 1-hexene. This provides approximately the needed ratio D/H, for (D ) = 0.35. On this picture, 1-hexene in run 233 results from equilibration with a pool... 

SOLUTION Assuming that no other sources of hydrogen ions or acetate ions are present, [H "]/c ° = [A ]/c °, which we denote by x,... 

Other sources of hydrogen can be used instead of elemental hydrogen gas. In transfer hydrogenations a secondary alcohol has been employed as hydrogen donor. Noyori et al. have also made advances in this field. They use a catalyst system from [RuCbC -mesitylene)]2, iV-(p-toluenesulfo-nyl)-l,2-diphenylethylenediamine, and KOH in isopropanol. At room temperature acetophenone can be reduced in 15 h with this complex prepared in situ (substrate catalyst = 200 1) to 1-phenylethanol in 95% yield with an optical purity of 97 %. [15, 16] The... 

Other sources of hydrogen are provided by the conversion of oil or other feedstocks such as municipal solid waste and biomass, decomposition of hydrogen sulfide, or recovery from refinery offgases. 

In addition to NaBHj and LAH, there are other sources of hydrogen nucleophiles as well, but these two are the most common reagents. You should look through your textbook and lecture notes to see if you are responsible for being famihar with any other hydrogen nucleophiles. 

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