Schlesinger process

Sodium borohydride contains 10.8 wt.% of hydrogen, but it shows unfavorable thermodynamics for use as reversible hydrogen storage material. Over 100 synthesis methods for the preparation of NaBH4 have been described, but only two have reached practical significance. In the Schlesinger process (Eq. (5.7)), trimethyl borate is boiled together with NaH in hydrocarbon oil at 250 °C [19] ... 

Sodium borohydride is primarily manufactured by the Schlesinger process, which involves reaction of trimethylborate with sodium hydride at 250-270°C, as given by Equation 16.8 [36]. Trimethylborate is made from boric acid and methanol (Equation 16.9) and sodium hydride is made from sodium metal and hydrogen (Equation 16.10). Thus, sodium borohydride is made from metallic sodium, boric acid, and hydrogen, as expressed by net Equation 16.12. 

The nucleation process produces small Pd catalytic sites dispersed on the surface of a substrate in an island network. Marton and Schlesinger (11) estimated that these islands are less than 10 A in diameter. The height of these islands is approximately 40 A (12). 

Schlesinger et al. 20) concluded, on the basis of in vitro rates of dimerization, that the dimerization of enzyme subunits in vivo would not be as rapid as observed unless the subunits were compartmentalized in the cell. The in vitro rate of dimerization seemed to be based upon reoxidation and dimerization of reduced monomers and showed a maximum at 65 /ig/ml with respect to protein concentration. The in vivo process may be rather different, however, and later studies by Schlesinger and Barrett 21) with unreduced monomers would seem to change this conclusion because their rates did not have a maximum with respect to protein concentration. 

Cyclic ethers, cyclic acetals, and some vinyl compounds can be polymerized by cationic processes. Photoinitiation of these polymerizations by ultraviolet light are known (12,106). Some extension of direct photolytic sensitization of cationic processes to visible wavelengths is obtained by the use of colored diazonium salts as initiators. For example, Schlesinger (11a) used diazonium salts substituted in the para position with electron withdrawing groups, but sensitivity was limited to the blue to green regions of the spectrum. 

Schlesinger and Marton (15) studied the nucleation and growth of electrolessly deposited thin nickel (Ni-P) films. These studies were later extended and complemented by the studies performed by Cortijo and Schlesinger (19, 20) on radial distribution functions (RDFs). RDF curves were derived from electron diffraction data obtained from similar types of films as well as electrolessly deposited copper ones. Those studies, taken together, have elucidated the process of crystallization in the electroless deposition of thin metal films. 

Bureau of Mines studies by M. D. Schlesinger, now in progress, indicate that nitrided fused iron catalysts operate successfully in the slurry process with about the same selectivity as observed in the fixed-bed tests. 

With the purpose of employing a more soluble form of complexed lithium hydride in such a process, Ziegler and Gellert heated ethylene in ether under pressure at 120-140 °C with LAH, which had been prepared for the first time by Schlesinger and coworkers. To Ziegler s gratification LAH was smoothly converted into lithium tetraethylaluminate (10), which could be isolated in high yield as a crystalline adduct. As proof of structure, the same adduct was also synthesized by the admixture of the lithium and aluminum ethyl derivatives in a 1 1 ratio (Scheme 2). This study represents the first authenticated instance of hydroalumination. 

BNF is a microbially mediated process that occurs in several types of bacteria and blue-green algae. This process uses the enzyme nitrogenase in an anaerobic environment to convert N2 to NH3. The microbes can be free-living or in a symbiotic association with the roots of higher plants. Legumes are the best-known example of this type of relationship (Schlesinger, 1997 Mackenzie, 1998) ... 

M. Gertner and M. Schlesinger, Electrochem. and Solid-State Lett. 6 (2003) J4. R. Hines, in Process for Making Electroformed Stents, Electroformed Stents, Inc.,... 

Potassium Borohydride. Potassium tetrahydrobo. rate. BH4K mol wt 53.95. B 20.06%, H 7.47%, K 72.47%. KBH4- Prepd from potassium tetramethoxyborohydride and dlborane at low temps Schlesinger et al. J. Am. Chem. Soc. 75, 199 (1953). Commercial process from sodium boro-hydride and NaOH in water Banus el al., ibid. 76, 3848 (1954). Review of potassium and other metal tetrahydrobo rates James, Wallbridge, Prog. Inorg. Chem. 11, 99-231 (1970). 

Why does N supply limit NPP and other ecosystem processes in many terrestrial eco.sy.stems In contrast to P, N is absent from most parent material (not all—see Dahlgren, 1994) it must be accumulated from the atmosphere. Nevertheless, even low inputs of N over thousands of years should more than account for the quantities of N w e observe in most ecosystems (Peterjohn and Schlesinger, 1990) still less time is required where N fixers are abundant. 

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