Metric chemical

The chemical constitution of a molecule or an ensemble of molecules (EM) of n atoms is representable by a symmetric n X n BE-matrix and corresponds accordingly to a point P in TR ( +D/a an n(n +1)/2 dimensional Euclidean space, the Dugundji space of the FIEM(A). The "city block distance of two points P i and P 2 is twice the number of electrons that are involved in the interconversion EMi EM2 of those EM that belong to the points Pi and P2. This chemical metric on the EM of an FIEM provides not only a formalism for constitutional chemistry, but also allows us to use the properties of Euclidean spaces in expressing the logical structure of the FIEM, and thus of constitutional chemistry 3e>32c>. 

The chemical metric has also a geometric interpretation. ) Observe first that any X matrix B corresponds to a point of R< (or to a vector, if is regarded as a vector... 

Thus, the chemical metric on the EM of an FIEM provides not only a formalism for constitutional chemistry, but also allows us to fully use the properties of Eudidean spaces in expressing the logiccd structure of the FIEM. 

Then, using the chemical metric, F B) is isometric with F E) and B is isometric with E. 

For any type of substrate, being it either an ordered or a disordered one, it is convenient to numerically measure distances, say, end-to-end SAWs distances, in a metric which takes into account the topology of the structural connecting paths. This so-called topological or chemical metric (where the space in which it is defined is referred to as f-space) is the natural metric of the structure, in which the distance between two substrate points equals the length of the shortest path on the structure connecting them. An example illustrating the difference between the f-distance and the standard Euclidean distance (in r-space) for a disordered structure is shown in Fig. 1. 

Dimeihylamine, C2H7N, (CH3)2NH. Colourless, inflammable liquid with an ammoniacal odour, mp -96" C, b.p. 7°C. Occurs naturally in herring brine. Prepared in the laboratory by treating nitrosodimetbyl-aniline with a hot solution of sodium hydroxide. Dimethylamine is largely used in the manufacture of other chemicals. These include the solvents dimethylacetamide and dimethyl-formamide, the rocket propellant unsym-metrical dimethylhydrazine, surface-active agents, herbicides, fungicides and rubber accelerators. 

Production and Shipment. Estimated adiponitrile production capacities in the U.S. in 1992 were about 625 thousand metric tons and worldwide capacity was in excess of lO metric tons. The DOT/IMO classification for adiponitrile is class 6.1 hazard, UN No. 2205. It requires a POISON label on all containers and is in packing group III. Approved materials of constmction for shipping, storage, and associated transportation equipment are carbon steel and type 316 stainless steel. Either centrifugal or positive displacement pumps may be used. Carbon dioxide or chemical-foam fire extinguishers should be used. There are no specifications for commercial adiponitrile. The typical composition is 99.5 wt % adiponitrile. Impurities that may be present depend on the method of manufacture, and thus, vary depending on the source. 

The 0X0 or hydroformylation reaction was discovered in Germany in 1938 (10) and was first used on a commercial scale by the Enjay Chemical Company (now Exxon) in 1948. By 1990 the total world alcohol capacity based on this general technology was over four million metric tons per year (see Oxo... 

The workforce consists of 92 shift and 8 daily workers. Approximately 20 to 30 different fine chemicals are produced per year which range ia volume from 20 to 200 metric tons per train and ia campaign length from 20 to 180 days. 

Not many fine chemicals have a production value exceeding 10 million per year. Less than a do2en achieve production volumes above 10,000 metric tons per year and sales of > 100 million per year. Apart from the pharmaceutical and pesticide fine chemicals these comprise the amino acids (qv), L-lysine and n,T-methionine used as feed additives (see Feeds AND FEED ADDITIVES), and vitamins ascorbic acid and nicotinic acid. 

Fine chemicals are generally considered chemicals that are manufactured to high and weU-defined standards of purity, as opposed to heavy chemicals made in large amounts to technical levels of purity. Fine chemicals usually are thought of as being produced on a small scale and the production of some fine chemicals is in tens or hundreds of kilograms per year. The production of others, especially fine chemicals used as dmgs or food additives (qv), is, however, in thousands of metric tons (see Pharmaceuticals). For example, the 1990 U.S. production of aspirin [50-78-2] and acetaminophen [103-90-2] was on the order of 20,500 t and 15,000 t, respectively. 

U.S. production of bromine trifluoride is several metric tons per year mostiy used in oil-weU cutting tools. Air Products and Chemicals, Inc. is the only U.S. producer. The 1992 price was ca 80/kg. 

Historically, the annual consumption of nickel fluoride was on the order of a few metric tons. Usage is droppiag because nickel fluoride is Hsted ia the EPA and TSCA s toxic substance iaventory. Nickel fluoride tetrahydrate is packaged ia 200—500-lb (90.7—227-kg) dmms and the 1993 price was 22/kg. Small quantities for research and pilot-plant work are available from Advance Research Chemicals, Aldrich Chemicals, Johnson/Matthey, Pfalt2 and Bauer, PCR, and Strem Chemicals of the United States, Fluorochem of the United Kingdom, and Morita of Japan. 

Because of its excekent combination of properties, processibkity, and relatively low price compared to other fluoropolymers, PVDF has become the largest volume fluoropolymer after PTFE consumption in the United States has grown from zero in 1960 to about 6200 metric tons in 1991 (186). About 49% of the consumed volume is PVDF modified by copolymerization with 5—12-wt % HFP to enhance flexibkity. In 1992, Hst price for homopolymer powders was 15.32/kg, and for pekets 15.42/kg the reported market price was 14.09—14.22/kg (187). In the United States, almost ak PVDF is suppHed by Ausimont USA, Inc., Elf Atochem North America, Inc., and Solvay Polymers, Inc. Ausimont and Elf Atochem are producers Solvay is an importer of the resin. Smak amounts of resin are imported from Germany by Huls America, Inc, and from Japan by Kureha Chemical Industry Co., Ltd. PVDE producers and their trademarks are Hsted in Table 4. 

Total hafnium available worldwide from nuclear zirconium production is estimated to be 130 metric tons annually. The annual usage, in all forms, is about 85 t. The balance is held in inventory in stable intermediate form such as oxide by the producers Teledyne Wah. Chang (Albany, Oregon) and Western Zirconium in the United States Ce2us in France Prinieprovsky Chemical Plant in Ukraine and Chepetsky Mechanical Plant in Russia (crystal bar). 

Heat stabilizers protect polymers from the chemical degrading effects of heat or uv irradiation. These additives include a wide variety of chemical substances, ranging from purely organic chemicals to metallic soaps to complex organometaUic compounds. By far the most common polymer requiring the use of heat stabilizers is poly(vinyl chloride) (PVC). However, copolymers of PVC, chlorinated poly(vinyl chloride) (CPVC), poly(vinyhdene chloride) (PVDC), and chlorinated polyethylene (CPE), also benefit from this technology. Without the use of heat stabilizers, PVC could not be the widely used polymer that it is, with worldwide production of nearly 16 million metric tons in 1991 alone (see Vinyl polymers). 

Much more important is the hydrogenation product of butynediol, 1,4-butanediol [110-63-4]. The intermediate 2-butene-l,4-diol is also commercially available but has found few uses. 1,4-Butanediol, however, is used widely in polyurethanes and is of increasing interest for the preparation of thermoplastic polyesters, especially the terephthalate. Butanediol is also used as the starting material for a further series of chemicals including tetrahydrofuran, y-butyrolactone, 2-pyrrohdinone, A/-methylpyrrohdinone, and A/-vinylpyrrohdinone (see Acetylene-DERIVED chemicals). The 1,4-butanediol market essentially represents the only growing demand for acetylene as a feedstock. This demand is reported (34) as growing from 54,000 metric tons of acetylene in 1989 to a projected level of 88,000 metric tons in 1994. 

In 1990 world consumption of lanthanides was approximately 35,000 metric tons (45). The most important markets were the United States /Canada (32.8%), China (18.6%), Europe (15.8%), Japan (14.5%), Eastern Europe (9.5%), the rest of Asia (7.3%), and the rest of the world (1.4%). The principal rare-earth manufacturers in 1993 were Molycorp Inc. and RhcJ)ne-Poulenc in the United States RhcJ)ne-Poulenc and Treibacher Chemische WAG in Europe Shinetsu Chemical, Nippon Yttrium, Mitsubishi Chemical Inc., and Santoku Metal Inc. in Japan Indian Rare Earths in India and several additional companies located in the CIS and in the Baotou, Gansu, Yue Long, and Jiangxi provinces in China. 

Use of lead ia modem iadusttial society results from its unique physical and chemical properties. By the middle of the nineteenth century, world production of lead had risen to 1 x 10 metric tons per year, passed 1 x 10 t /yr early in the twentieth century, and reached 1.5 x 10 t /yr by midcentury. Lead production is expected to reach 5.6 x 10 t/yr by the year 2000. 

The processing wastes come from the hides and processing chemicals. The hide wastes are the largest problem. For each metric ton of hides received at the tannery the following wastes are generated ... 

In 1991, the average value per metric ton of lime in bulk was reported to be 78.44 for agricultural lime, 68.12 for constmcfion lime, 54.90 for chemical lime, and 82.62 for refractory lime. The average value for total lime was 57.02/t. 

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