Hydrogenation gas-solid

Keywords N-vinylisatin, hydrogenation, gas-solid reaction, /V-ethyldioxindole, /V-cthylisatin... 

In gas-solid extractions the sample is passed through a container packed with a solid adsorbent. One example of the application of gas-solid extraction is in the analysis of organic compounds for carbon and hydrogen. The sample is combusted in a flowing stream of O2, and the gaseous combustion products are passed through a series of solid-phase adsorbents that remove the CO2 and 1T20. 

Hydrogen gas is vigorously evolved and the solids ultimately undergo a color change from gray to white. 

Chemical Reactivity - Reactivity with Water Reacts vigorously with water with the release of flammable hydrogen gas Reactivity with Common Materials No reactions Stability During Transport Stable at temperatures below 225 C Neutralizing Agents for Acids and Caustics Neutralize only when accidental reaction with water is complete. Do not neutralize the flammable solid with aqueous solutions. Spent reaction solution may be neutralized with dilute solutions of acetic acid. Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

The compounds formed by the reaction of hydrogen with the alkali and alkaline earth metals contain H- ions for example, sodium hydride consists of Na+ and H- ions. These white crystalline solids are often referred to as saline hydrides because of their physical resemblance to NaCL Chemically, they behave quite differently from sodium chloride for example, they react with water to produce hydrogen gas. Typical reactions are... 

Hydrogen for weather balloons is often supplied by the reaction between solid calcium hydride, CaH2, and water to form solid calcium hydroxide, Ca(OH)2, and hydrogen gas, H ... 

Some catalysts used in gasoline manufacture consist of finely divided platinum supported on an inert solid. Suppose that the platinum is formed by the high temperature reaction between platinum dioxide, PtOj, and hydrogen gas to form platinum metal and water. 

Hydrogen-absorbing alloy can reversible absorb and desorb a large amount of hydrogen. Hydrogen gas is rapidly absorbed in the gas phase, then desorbed on the alloy (gas-solid reaction). In the electrode reaction, the alloy electro-chemically absorbs and desorbs hydrogen in an alkaline solution (electrochemical reaction) ... 

A solution of 13.5 g (21 mmol) of diisopinocamphenylborane in 250 mL of hexane is treated at 0 C with 7.1 g (47 mmol) of trifluoromethanesulfonic acid in a dropwise fashion which results in the evolution of hydrogen gas. The mixture is stirred for 3 h at 0 "C and then at r.t. overnight. At OX the reaction proceeds with slow, but steady, hydrogen evolution without problem (an induction period which results in a rapid exotherm in the Mukaiyama procedure has been reported30). After stirring overnight, a small amount of solid material appears. The solvent is evaporated and the residue is used without further purification 99.8% ee. 

Chemistry is concerned with the properties of matter, its distinguishing characteristics. A physical property of a substance is a characteristic that we can observe or measure without changing the identity of the substance. For example, a physical property of a sample of water is its mass another is its temperature. Physical properties include characteristics such as melting point (the temperature at which a solid turns into a liquid), hardness, color, state of matter (solid, liquid, or gas), and density. A chemical property refers to the ability of a substance to change into another substance. For example, a chemical property of the gas hydrogen is that it reacts with (burns in) oxygen to produce water a chemical property of the metal zinc is that it reacts with acids to produce hydrogen gas. The rest of the book is concerned primarily with chemical properties here we shall review some important physical properties. 

Self-Test L.2A Calculate the mass of potassium metal needed to react with 0.450 g of hydrogen gas to produce solid potassium hydride, KH. 

A sample of gaseous arsine, AsH3, in a 500.0-mL flask at 300. Torr and 223 K, is heated to 473 K, at which temperature arsine decomposes to solid arsenic and hydrogen gas. The flask is then cooled to 273 K, at which temperature the pressure in the flask is 508 Torr. Has all the arsine decomposed Calculate the percentage of arsine molecules that have decomposed. 

In a simple version of a fuel cell, a fuel such as hydrogen gas is passed over a platinum electrode, oxygen is passed over the other, similar electrode, and the electrolyte is aqueous potassium hydroxide. A porous membrane separates the two electrode compartments. Many varieties of fuel cells are possible, and in some the electrolyte is a solid polymer membrane or a ceramic (see Section 14.22). Three of the most promising fuel cells are the alkali fuel cell, the phosphoric acid fuel cell, and the methanol fuel cell. 

C16-0102. Coal (solid carbon plus a collection of impurities) can be converted to a mixture of carbon dioxide and hydrogen gas by the following process ... 

Interstitial Solid Solutions Interstitial solid solutions involve occupation of a site by introduced ions or atoms, which is normally empty in the crystal structure, and no ions or atoms are left out. Many metals form interstitial solid solutions in which small atoms (e.g., hydrogen, carbon, boron, nitrogen) enter empty interstitial sites within the host structure of the metal. Palladium metal is well known for its ability to absorb an enormous volume of hydrogen gas, and the product hydride is an interstitial sohd solution of formula PdH, 0 0.7, in which hydrogen atoms occupy... 

In the vast majority of gas-solid reactions, gaseous or evaporated compounds react at the surface of a solid catalyst. These catalytic processes are very frequently used in the manufacture of bulk chemicals. They are much less popular in processing of the large molecules typical of fine chemistry. These molecules are usually thermally sensitive and as such they will at least partially decompose upon evaporation. Only thermally stable compounds can be dealt with in gas-solid catalytic processes. Examples in fine chemicals manufacture are gas-phase catalytic aminations of volatile aldehydes, alcohols, and ketones with ammonia, with hydrogen as... 

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