Carbon compounds artificial

Methane from Carbides.—Another method of preparation is of interest and importance because of its connection with theories as to the formation of methane and other hydrocarbons in petroleum. With some metals carbon forms compounds which are very stable at high temperatures, and which have been artificially produced in the electric furnace (about 35O0°C.) by Moissan. These metallic carbon compounds, known as carbides, are, most of them, easily decomposed by water at ordinary temperatures, and when so decomposed they yield various members of the hydrocarbon group of compounds. A familiar example of this class of reactions is the one by which acetylene gas is made by the action of water on calcium carbide. The carbide of aluminium decomposes with water and yields methane according to the foUowing reaction ... 

Even so, as has been pointed out, silicon may have had a part to play in the origin of life on Earth. A curious fact is that terrestrial life forms utilize exclusively right-handed carbohydrates and left-handed amino acids. One theory to account for this is that the first prebiotic carbon compounds formed in a pool of "primordial soup" on a silica surface having a certain handedness. This handedness of the silicon compound determined the preferred handedness of the carbon compounds now found in terrestrial life. An entirely different possibility is that of artificial life or intelligence with significant silicon content. 

The carbon compounds individuated and identified in carbon chemistry—the remaining stoichiometric plant and animal substances and the pure carbon compounds isolated from coal tar, as well as the artificial carbon compounds created in the laboratory—were nested in extended networks of experiments and work on paper. In the late 1840s, when the culture of carbon chemistry was firmly established, the individuation and identification of carbon compounds required quantitative elemental analysis, control of stoichiometric purity by studies of the chemical properties and reactions of a substance, experimental examination of their proximate components or constitution (later structure ), and work on paper with chemical formulae to demarcate the substances and to model their constitution and chemical reactions. Analysis of composition (qualitative and quantitative), control of purity, studies of reactions, and modeling on paper allowed chemists to draw ever more sophisticated... 

Perfluorinated compounds are also potentially useful as inert reaction media, particularly when one of the reactants is gaseous. The high solubiHty of oxygen and carbon dioxide in perfluorinated Hquids has allowed their use as blood substitutes (41) and as oxygenation media for biotechnology (42). One product, Fluosol DA (43) (Green Cross Corp.), has been commercialized, and there is an abundant patent art in this area (see Blood, artificial). 

Sodium is not found ia the free state ia nature because of its high chemical reactivity. It occurs naturally as a component of many complex minerals and of such simple ones as sodium chloride, sodium carbonate, sodium sulfate, sodium borate, and sodium nitrate. Soluble sodium salts are found ia seawater, mineral spriags, and salt lakes. Principal U.S. commercial deposits of sodium salts are the Great Salt Lake Seades Lake and the rock salt beds of the Gulf Coast, Virginia, New York, and Michigan (see Chemicals frombrine). Sodium-23 is the only naturally occurring isotope. The six artificial radioisotopes (qv) are Hsted ia Table 1 (see Sodium compounds). 

The carbon dioxide generated by the personnel in the artificial atmosphere of submarines and spacecraft must be removed from the air and the oxygen recovered. Submarine design teams have investigated the use of potassium superoxide, K02, as an air purifier because this compound reacts with carbon dioxide and releases oxygen (Fig. 4.16) ... 

FIGURE 40 Patina. Patina is a colored (usually green) layer of corrosion products that frequently develops naturally on the surface of copper and copper alloys exposed to the environment. Since it is sometimes appreciated aesthetically and as a proof of age, patina is also developed artificially, by chemical means, as a simulated product of aging. Copper patina generally includes such compounds as copper oxides, carbonates, and chlorides. In bronze and brass patinas, these compounds are mixed with the oxides of tin and lead resulting from the corrosion of the other components of the alloys. In any particular patina there may be many layers, not necessarily in the order shown in the illustration. 

Photolytic. Major products reported from the photooxidation of 2,3-dimethylbutane with nitrogen oxides are carbon monoxide and acetone. Minor products included formaldehyde, acetaldehyde and peroxyacyl nitrates (Altshuller, 1983). Synthetic air containing gaseous nitrous acid and exposed to artificial sunlight (A. = 300-450 nm) photooxidized 2,3-dimethylbutane into acetone, hexyl nitrate, peroxyacetal nitrate, and a nitro aromatic compound tentatively identified as a propyl nitrate (Cox et al., 1980). 

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