bluuebunny/crossref_metadata_2025_split huggingface dataset:
Graphite, Artificial
Authors: Lewis I. C. 
Published: August 2004

Abstract
The raw materials used in the production of manufactured carbon and graphite largely control the ultimate properties and practical applications of the final product. This dependence is related to the chemical and physical nature of the carbonization and graphitization processes. Essentially any organic material can be thermally transformed to carbon. The carbonization process through the elimination of heteroatoms and substituent hydrogen converts the organic precursor into a carbon polymer. This polymer consists of aromatic carbons arranged in large polynuclear aromatic ring systems. With continued heat treatment, this carbon is transformed to a more or less ordered three‐dimensional framework approaching the structure of graphite. Differences in the final material depend on the ease and extent of completion of these overall chemical and physical ordering processes. Filler materials include petroleum coke, coal‐tar pitch coke, natural graphite, carbon blacks and anthracite. Carbon articles are made by mixing a controlled size distribution of coke filler particles with a binder such as coal‐tar or petroleum pitch. In addition to the primary ingredients, the fillers and binders, minor amounts of other materials are added at various steps in the carbon and graphite manufacturing process. They can play an important role in determining the quality of the final product. Light extrusion oils and lubricants, are often added to the mix to improve the extrusion rates and structure of the extruded products. Chemical inhibitors are introduced to reduce the detrimental effects of sulfur in high sulfur cokes. Nearly all coke utilized in carbon manufacture is calcined. Calcination consists of heating raw coke to remove volatiles and to shrink the coke to produce a strong, dense particle.
Benzyl Chloride, Benzal Chloride, and Benzotrichloride
Authors: Lin Henry C. , Bieron Joseph F. 
Published: August 2004

AbstractWhen toluene reacts with chlorine under experimental conditions that promote free‐radical chlorination, a mixture of benzyl chloride, benzal chloride, and benzotrichloride is obtained. The product distribution is determined in large part by the chlorine:toluene ratio. Competing reactions result in chlorination of the aromatic ring, reducing the yield of side‐chain chlorination products.Benzyl chloride undergoes reactions typical of a reactive alkyl halide. Hydrolysis gives benzyl alcohol, reaction with ammonia yields benzylamines, and benzyl esters form by reaction with salts of carboxylic acids. Reaction with other nucleophiles yield substitution products; alkoxides give benzyl ethers and cyanide give phenylacetonitrile.Benzal chloride is hydrolyzed to benzaldehyde and benzotrichloride to benzoic acid. Benzotrifluoride is formed by the reaction of benzotrichloride with anhydrous hydrogen fluoride. Reaction conditions have been determined for aromatic ring chlorination and nitration of benzyl chloride, benzal chloride, and benzotrichloride.More than two‐thirds of benzyl chloride produced is used to make the plasticizer benzyl butyl phthalate. Nearly all of the benzal chloride produced is consumed in the manufacture of benzaldehyde. Benzotrichloride is used in the manufacture of benzoyl chloride and in the synthesis of the herbicide intermediatep‐chlorobenzotrifluoride.
Benzoic Acid
Authors: Opgrande Jarl L. , Dobratz C. J. , Brown Edward E. , Liang Jason C. , Conn Gregory S. , With Jan , Shelton Frederick J. 
Published: August 2004

AbstractBenzoic acid, C6H5COOH, is the simplest member of the aromatic carboxylic acid family. In the United States, virtually all benzoic acid is manufactured by the continuous liquid‐phase air oxidation of toluene. Benzoic acid and its salts and esters find application in medicinals, food and industrial preservatives, cosmetics, resins, plasticizers, dyestuffs, and fibers. Benzoic acid in the free state, or in the form of simple derivatives such as salts, esters, and amides, is widely distributed in nature. In its chemical behavior benzoic acid shows few exceptional properties; the reactions of the carboxyl group are normal, and ring substitutions take place as would be predicted. The growth of demand for benzoic acid is expected to increase at a rate of between 1 and 2% per year. Glycol dibenzoate plasticizers have been growing at close to 10% annually for several years, in part due to environmental concerns with regard to phthalate plasticizers. The growth of the diet soft drink market has increased the demand for sodium and potassium benzoates. All of the benzoic acid producers in the United States employ the liquid‐phase toluene air oxidation process. The bulk of benzoic acid production capacity is consumed internally by the producers. Kalama converts over half of its production to phenol. A large portion of Velsicol's benzoic acid production is utilized in the manufacture of glycol dibenzoate plasticizer esters. Benzoic acid is available in industrial and technical grades, and in grades meeting the specifications of theUnited States Pharmacopeia, theFood Chemicals Codex, or theBritish Pharmacopeia. Benzoic acid's toxicity is rated as moderate (3 on a scale of 1–6). Healthy individuals may tolerate small doses (under 0.5 g of benzoates per day) mixed with food without ill effects. The principal safety concern in handling molten benzoic acid is its elevated temperature. Thermal burns may result from improper handling of the molten product. Benzoic acid derivatives include benzoyl chloride (C6H5COCl), benzoic anhydride ((C6H5CO)2O), benzoic acid salts, and benzoic acid esters.
Biosensors
Authors: Pietro William 
Published: August 2004

AbstractThe detection of trace and low levels of biologically active substances is among the most significant and challenging analytic technologies. Any discrete sensing device that relies on a biologically derived component as an integral part of its detection mechanism is known as a biosensor. All biosensors are composed of two basic parts, the molecular recognition component and the transducer component. The molecular recognition component is typically a complex chemical system usually extracted or derived directly from a biological organism. The function of the molecular recognition component is to interact specifically with a target compound, ie, the chemical to be detected. The molecular recognition component must be capable of discerning the presence of a target in a solution containing possibly hundreds of other compounds, some of which may have molecular structures closely resembling that of the target. The term selectivity is used to quantify the degree to which a molecular recognition system responds specifically to a target while rejecting compounds having related molecular structures. There are three principal classes of molecular recognition components used in biosensors: enzymes or catalytic proteins; immunoglobins, which are biological macromolecules that selectively bind to foreign substances invading an organism; and chemoreceptors, biomolecular units responsible for sensory reception in living organisms. Each class comprises a vast number of highly selective possible molecular recognition components. Once the molecular recognition component interacts with its target, a user‐readable signal must be generated. This is the purpose of the transducer component. Ideally, the generated signal should not only report the presence of target but should also relay information concerning the amount or concentration of target compound in the test solution. Four main types of analytical transducer components employed in biosensors are optical, electrochemical, field effect transistor, and piezoelectric. The term sensitivity is used to quantify the ability of a biosensor to reliably report target level. There are two separate uses of the term. Increasing the sensitivity of a biosensor frequently refers to decreasing the lowest concentration of target for which the biosensor provides a reliable, reproducible, and unambiguous response. Second, sensitivity can also refer to the smallest change in concentration from some nominal level of target compound that the biosensor can unambiguously report. Factors influencing the selection of an appropriate transducer component include compatibility with the molecular recognition component and the environment in which the biosensor is to be used. Development and optimization of biosensor techniques is a rapidly growing research area. Biosensor designers are striving for lower detection limits, higher sensitivity, greater selectivity, and lower occurrences of false‐positive signals.
Butyl Alcohols
Authors: Billig Ernst 
Published: August 2004

AbstractButyl alcohols encompass the four structurally isomeric 4‐carbon alcohols of empirical formula C4H10O. One of these, 2‐butanol, can exist in either the optically active\documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}${R{(}-{)}}$\end{document}or\documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}${S{(}+{)}}$\end{document}configuration or as a racemic (\documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}${\pm }$\end{document}) mixture. The butanols are all colorless, clear liquids at room temperature and atmospheric pressure with the exception oft‐butyl alcohol which is a low melting solid; it also has a substantially higher water miscibility than the other three alcohols. The butanols undergo the typical reactions of the simple lower chain aliphatic alcohols. The principal commercial source of 1‐butanol isn‐butyraldehyde, obtained from the Oxo reaction of propylene. The largest‐volume commercial derivatives of 1‐butanol aren‐butyl acrylate and methacrylate. These are used principally in emulsion polymers for latex paints, in textile applications and in impact modifiers for rigid poly(vinyl chloride). All four butanols are thought to have a generally low order of human toxicity. The C‐4 alcohols are preferably stored in baked phenolic‐lined steel tanks. However, plain steel tanks can also be employed. Storage under dry nitrogen is also recommended since it limits flammability hazards.
Butyraldehydes
Authors: Billig Ernst 
Published: August 2004

AbstractThe two isomeric butanals,n‐ and isobutyraldehyde, C4H8O, are produced commercially almost exclusively by the Oxo reaction of propylene. They also occur naturally in trace amounts in tea leaves, certain oils, coffee aroma, and tobacco smoke. The butanals are highly flammable, colorless liquids of pungent odor. These aldehydes are miscible with most organic solvents, eg, acetone, ether, ethanol, and toluene, but are only slightly soluble in water. The reactions ofn‐ and isobutyraldehyde are characteristic aldehyde reactions of oxidation, reduction, and condensation. The majority (92% in 1988) of the butyraldehyde produced in the United States is converted into 1‐butanol and 2‐ethylhexanol (2‐EH). The remaining (8%)n‐butyraldehyde production of the United States goes into (in decreasing order): poly(vinyl butyral), 2‐ethylhexanal, trimethylolpropane, methyl amyl ketone, and butyric acid. A large portion of the total U.S. consumption of isobutyraldehyde goes into the production of isobutyl alcohol and isobutyraldehyde condensation and esterification products. The other principal isobutyraldehyde derivative markets are neopentyl glycol, isobutyl acetate, isobutyric acid, isobutylidene diurea, and methyl isoamyl ketone. The merchant market for the two aldehydes is relatively insignificant, most of the production being employed captively.n‐Butanol is the highest volume derivative ofn‐butyraldehyde in the United States. In Western Europe, Japan, and other countries, 2‐EH is dominant. The most activen‐butyraldehyde derivatives were expected to be PVB, as more regions require automotive safety glass, and trimethylolpropane. Although tests have shown thatn‐butyraldehyde causes some adverse physiological effects, there is no danger to health in normal plant practice. Both aldehydes have a pungent, penetrating odor. Their vapors as well as the neat liquids can cause skin, eye, and respiratory organ irritation. Stainless steel, baked phenolic‐lined steel, or aluminum are often used for storage and handling ofn‐ and isobutyraldehyde. Storage of the aldehydes under nitrogen preserves the integrity of the material.
Butyl Rubber
Authors: Kresge Edward , Wang H‐C. 
Published: August 2004

AbstractKresge, Edward and Wang, H‐C. (Exxon Chemical Co.). Butyl rubber and other isobutylene polymers in wide use include various homopolymers and copolymers. Low levels of unsaturation for subsequent cross‐linking are incorporated by copolymerization with isoprene. Halogenation at the unsaturation site provides additional cross‐linking mechanisms and covulcanization with highly unsaturated elastomers. Polymers containing star branches, conjugated‐diene sites, divinylbenzene, and brominatedp‐methylstyrene have also been synthesized. Isobutylene polymers are polymerized by a cationic mechanism using a Bronsted acid as an initiator and a Lewis acid as a coinitiator, eg, H2O and AlCl3. Molecular weights range from several hundred for terminally unsaturated polybutenes to over 106for elastomer grades.Mw/Mnis typically 3–5.TheTgof polyisobutylene is about −70°C, and the polymer is amorphous in the unstrained state. The polymers exhibit a broad damping peak and a low plateau modulus. They display an exceptionally low permeability to gases, and are widely used as air retention barriers in tires. Optimum physical properties are obtained by compounding with carbon black and other fillers. Various mechanisms are used to cross‐link the compounds into elastomeric vulcanizates. Sulfur is used to provide polysulfidic cross‐links, while resin and zinc oxide cure systems give carbon–carbon cross‐links. Besides inner tubes and innerliners, butyl rubbers are used in blends to improve cut growth resistance and wet skid resistance. Blends with thermoplastic resins improve toughness. Polybutenes enjoy extensive use as adhesives and caulks, and are chemically modified for use in lubricants as dispersants.
Cadmium and Cadmium Alloys
Authors: Carr D. S. 
Published: August 2004

Abstract

Cadmium, Cd, a Group 12 (IIB) element occurring between zinc and mercury, is a soft, ductile, silver‐white metal having a distorted hexagonal close‐packed structure. The crustal abundance of cadmium is somewhere between 0.1 and 0.5 ppm, and several cadmium minerals have been identified, the most common being greenockite, CdS. Cadmium is generally encountered in zinc ores, zinc‐bearing lead ores, or complex copper–lead–zinc ores, where, however, it forms an isomorphic impurity in the zinc mineral sphalerite, ZnS. For this reason, cadmium is almost invariably recovered as a by‐product from the processing of zinc, lead, and copper ores. Its oxidation state in almost all of its compounds is

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, although a few compounds have been reported in which cadmium exists in the

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oxidation state. There are eight natural isotopes. Cadmium forms a fume of brown‐colored cadmium oxide, CdO, when heated in air. Other elements which react readily with cadmium metal upon heating include the halogens, phosphorus, selenium, sulfur, and tellurium. Cadmium is rapidly oxidized by hot dilute nitric acid. Cadmium occurs primarily as sulfide minerals in zinc, lead–zinc, and copper–lead–zinc ores. Beneficiation of these minerals, usually by flotation or heavy‐media separation, yields concentrates which are then processed for the recovery of the contained metal values. Cadmium follows the zinc with which it is so closely associated. Air pollution problems and labor costs have led to the closing of older pyrometallurgical plants, and to increased electrolytic production. Cadmium production is dependent on the processing of zinc ores, which often contain 0.2 to 0.4% cadmium. Cadmium is classified as a toxic metal. Acute industrial poisoning by cadmium dust or fume can occur during the melting or pouring of cadmium metal; the welding, burning, or heating of cadmium‐plated steel; or spraying, brazing, and overheating of cadmium metal. Protection should be provided by a properly designed exhaust ventilation system or by a suitable individual filter or air‐supplied respirator. Industrial exposure to cadmium fumes and dust has been reported to result in emphysema, hypertension, kidney failure, osteomalacia, and perhaps an increased incidence of cancer. To help maintain the balance between supply and demand for cadmium, efforts can be made to recycle such cadmium‐containing materials as spent nickel–cadmium batteries as well as dusts and other residues from the pigment industry. Consumption of cadmium is in batteries, coating and plating, pigments, plastics and synthetic products, and alloys and other uses. Cadmium is an important component in brazing and low melting alloys, used in bearings, solders, and nuclear reactor control rods.
Calcium Carbide
Authors: Cameron William L. 
Published: August 2004

Abstract

Chemically pure calcium carbide, Ca
2
C, is a colorless solid; however, the pure material can be prepared only by very special techniques. Commercial calcium carbide is composed of calcium carbide, calcium oxide, CaO, and other impurities present in the raw materials. Industrial‐grade calcium carbide contains about 80% as CaC
2
, 15% CaO, and 5% other impurities. In the United States calcium carbide‐based acetylene is mainly used in the oxyacetylene welding market, although some continues to be used for production of such chemicals as vinyl ethers and acetylenic alcohols. Calcium carbide is used extensively as a desulfurizing reagent in steel and ductile iron production, allowing steel mills to use high sulfur coke. The exothermic reaction of calcium carbide and water‐yielding acetylene forms the basis of the most important industrial use of calcium carbide. An important use of calcium carbide has developed in the iron and steel industries, where the carbide has been found to be an effective desulfurizing agent for blast‐furnace iron. Calcium carbide is produced commercially by reaction of high purity quicklime and a reducing agent such as coke in an electric furnace at 2000–2200°C. Commercial calcium carbide, containing about 80% CaC
2
, is formed in the liquid state. The liquid calcium carbide is tapped from the furnace into cooling molds. Calcium carbide is classed as a hazardous chemical under U.S. Department of Transportation regulations. Domestic shipments are mainly in steel tote bins. Containers must be marked “Flammable solid, dangerous when wet” and have the United Nations designation UN 1402. Although acetylene is considered to be a material having a very low toxicity, a threshold limit value (TLV) of 2500 ppm has been established by NIOSH. In the presence of a small amount of water carbide may become incandescent and ignition of the evolved air–acetylene mixture may occur. Nonsparking tools should be used when working in the area of acetylene‐generating equipment.
Calcium and Calcium Alloys
Authors: Hibbins Stephen G. 
Published: August 2004

Abstract

Calcium, Ca, a member of Group 2 (IIA) of the Periodic Table between magnesium and strontium, is classified, together with barium and strontium, as an alkaline‐earth metal and is the lightest of the three. Calcium metal does not occur free in nature; however, in the form of numerous compounds, it is the fifth most abundant element, constituting 3.63% of the earth's crust. Calcium is mainly used as a reducing agent for many reactive, less common metals; to remove bismuth from lead; as a desulfurizer and deoxidizer for ferrous metals and alloys; and as an alloying agent for aluminum, silicon, and lead. Pure calcium is a bright, silvery‐white metal, although under normal atmospheric conditions freshly exposed surfaces of calcium quickly become covered with an oxide layer. The metal is extremely soft and ductile. Calcium's usefulness as a structural material is limited by low tensile strength and high chemical reactivity. Calcium has a valence electron configuration of 4
s
2
and characteristically forms divalent compounds. It is very reactive and reacts vigorously with water, liberating hydrogen and forming calcium hydroxide, Ca(OH)
2
. Calcium does not readily oxidize in dry air at room temperature but is quickly oxidized in moist air or in dry oxygen at about 300°C. Calcium reacts with fluorine at room temperature and with the other halogens at 400°C. Calcium is an excellent reducing agent and is widely used for this purpose. Although in Western countries the aluminothermic process has completely replaced the electrolytic method, electrolysis is believed to be the method used for calcium production in the People's Republic of China and the Commonwealth of Independent States (CIS). Because of its extreme chemical reactivity, calcium metal must be carefully packaged for shipment and storage. The metal is packaged in sealed argon‐filled containers. Calcium is classed as a flammable solid and is nonmailable. Calcium metal and most calcium compounds are nontoxic. Care must be taken, however, to avoid contact with water owing to the exothermic liberation of hydrogen and the resulting explosion hazard. Direct alloying of the pure metals is normally used in the production of 80% calcium–magnesium, 70% magnesium–calcium, and 75% calcium–aluminum alloys.
Fluorine Compounds, Inorganic, Calcium
Authors: Mahmood Tariq , Lindahl Charles B. 
Published: August 2004

AbstractCalcium fluoride, commonly called fluorspar or fluorite, is the principal fluoride‐containing mineral. Whereas there are some domestic U.S. sources, much of the fluorspar used in the United States is imported. Fluorspar is marketed in several grades: metallurgical fluorspar sold as gravel, lump, or briquettes; ceramic‐grade fluorspar; and acid‐grade fluorspar. The latter is used in the open‐hearth process for the production of steel as well as to produce hydrogen fluoride.