Hydrogenation with Hydrogen Generated from Sodium

CATALYTIC HYDROGENATION WITH HYDROGEN GENERATED FROM SODIUM BOROHYDRIDE 4  

The special apparatus (Fig. 2) consists of two 500 ml Erlenmeyer flasks A and B having slightly rounded bottoms and fitted with Teflon -coated magnetic stirring bars and injection ports, a mercury-filled bubbler back-up prevention valve C, and a mercury-filled automatic dispenser D with airtight-connected insert delivery tube of a buret E. 

Hydrogenation of a compound may be carried out in the same vessel in which hydrogen is generated by decomposition of sodium borohydride. For this purpose the apparatus shown in Fig. 2 is simplified by leaving out the flask B. 

A medium-pressure apparatus is assembled from a stainless steel bomb, standard parts, valves, unions and copper or stainless steel tubing according to Fig. 4. 

After the hydrogenation has definitely finished the final reading of the hydrogen pressure is recorded and the excess of hydrogen is carefully bled off by opening the valve B. Only then is the bomb disconnected. The contents are filtered, the bomb is rinsed once or twice with the solvent. 

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Fig. 2 Apparatus for hydrogenation with hydrogen generated from sodium boro-hydride.

Structure of Dextrose.—Dextrose enters into a number of important reactions with other substances. Those which have a bearing on the structure of the carbohydrate will be first considered. Dextrose is reduced by hydrogen, generated from sodium-amalgam and water, to d-sorbitol, which is a hexahydroxy-alcohol,—... 

The price of sodium borohydride is currently too high by far for a practical application. Compared with hydrogen production from natural gas its price is 130 times higher. However, the idea of applying sodium borohydride as a fuel has the prerequisite of recycling the sodium borate product, and this could lower the price on the basis of mass production [98]. An alternative to hydrogen generation from sodium borohydride is the direct borohydride fuel cell, which is not within the scope of this book, so will not be discussed. 

Chinnappan, A., H. Kim, C. Baskar, and 1. T. Hwang. 2012. Hydrogen Generation from the Hydrolysis of Sodium Borohydride with New Pyridinium Dicationic Salts Containing Transition Metal Complexes. International Journal of Hydrogen Energy 37 (13) 10240-10248. 

Black Liquor Soap Acidulation. Only two-thirds of a typical black Hquor soap consists of the sodium salts of fatty acids and resin acids (rosin). These acids are layered in a Hquid crystal fashion. In between these layers is black Hquor at the concentration of the soap skimmer, with various impurities, such as sodium carbonate, sodium sulfide, sodium sulfate, sodium hydroxide, sodium Hgnate, and calcium salts. This makes up the remaining one-third of the soap. Cmde tall oil is generated by acidifying the black Hquor soap with 30% sulfuric acid to a pH of 3. This is usually done in a vessel at 95°C with 20—30 minutes of vigorous agitation. Caution should be taken to scmb the hydrogen sulfide from the exhaust gas. 

In chlor-alkali diaphragm cells, a diaphragm is employed to separate chlorine hberated at the anode from the sodium hydroxide and hydrogen generated at the cathode. Without a diaphragm, the sodium hydroxide formed will combine with chlorine to form sodium hypochlorite and chlorate. In many cells, asbestos diaphragms are used for such separation. Many types of diaphragm cells are available. 

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