bluuebunny/crossref_metadata_2025 huggingface dataset:
Biosensors
Authors: Pietro William
Published: August 2004

The 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

Butyl 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

The 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

Kresge, 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

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

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

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

Calcium 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.
Calcium Chloride
Authors: Reid Kenneth I. G. , Kust Roger
Published: August 2004

Calcium chloride, CaCl
2
, is a white, crystalline salt that is very soluble in water. Solutions containing 30–45 wt % CaCl
2
are used commercially. Of the alkaline‐earth chlorides it is the most soluble in water. It is extremely hygroscopic and liberates large amounts of heat during water absorption and on dissolution. It forms a series of hydrates containing one, two, four, and six moles of water per mole of calcium chloride. Commercial applications of calcium chloride and its hydrates exploit one or more of its properties with regard to aqueous solubility, hygroscopic nature, the heat gained or lost when one hydrated phase changes to another. Because of high solubility in water, calcium chloride is used to obtain solutions having relatively high densities. Viscosity is an important property of calcium chloride solutions in terms of engineering design and in application of such solutions to flow‐through porous media. Significant quantities of calcium chloride are produced in the United States, Canada, Mexico, Germany, Belgium, Sweden, Finland, Norway, and Japan. In the United States the principal route for making calcium chloride is by the evaporation of underground brines. The primary CaCl
2
markets have not changed since the 1950s. Significant markets in the United States are for deicing during the winter and roadbed stabilization, and as a dust palliative during the summer. Use as an accelerator in the ready‐mix concrete industry is sizable but there is concern about the possible corrosion of steel in highways and buildings. Calcium chloride is also used in oil and gas well drilling. Food‐grade calcium chloride is used in cheese making to aid in rennet coagulation and to replace calcium lost in pasteurization. In the canning industry it is used to firm the skin of fruit such as tomatoes, cucumbers, and jalapenos. Food‐grade calcium chloride is used in the brewing industry as a basic component of certain beers. Above certain levels chloride is toxic to plants and animals. Calcium chloride solutions are used as antispasmodics, diuretics and in the treatment of tetany. Concentrated solutions of calcium chloride cause erythema, exfoliation, ulceration, and scarring of the skin. Injections into the tissue may cause necrosis. If given orally calcium chloride can cause irritation to the gastrointestinal tract unless accompanied by a demulcent. Calcium chloride has been give a toxicity or hazard level of 3.
Carbonic and Carbonochloridic Esters
Authors: Damle Suresh B.
Published: August 2004

The chemistry of carbonic and carbonochloridic esters, commonly referred to as chloroformates and carbonates, is reviewed. These materials are highly reactive with a variety of functional groups and lead to synthetic intermediates for use in pesticides, perfumes, drugs, polymers, dyes, and fuel additives. The article emphasizes the commercial aspects of the carbonate and chloroformate chemistry, including physical and chemical properties, manufacturing processes, analytical test methods, health and effects, environmental aspects, storage, transportation, and uses.
Carbon Dioxide
Authors: Pierantozzi Ronald
Published: August 2004

Carbon dioxide is valuable as a chemical intermediate, a liquid refrigerant, and a source of inert gas. It is produced from natural gas wells, lime‐kiln operations, and several other important processes. Most of the significant industrial processes for the production of CO2are reviewed in this article. Methods of purification include reaction and potassium permanganate, reaction with potassium dichromate, adsorption using activated carbon, liquefaction, and solidification. Numerous uses including food freezing, enhanced oil recovery, chemical manufacturing, refrigeration, and carbonation are reviewed.
Carbon Monoxide
Authors: Pierantozzi Ronald
Published: August 2004

Carbon monoxide is a valuable chemical intermediate. It is produced either from reforming of hydrocarbons or by coke and coal gasification. Numerous purification methods are available, depending on the method of production, to obtain chemical‐grade CO. This article reviews the physical properties, basic chemistry, industrially significant reactions, production and purifying methods, toxicity, and economics of producing carbon monoxide.

Methods of purification covered in this review are copper‐liquor scrubbing, cryogenic purification, the cosorb process, and adsorption processes. Industrially significant reactions covered are the water gas shift reaction, oxidation, disproportionation, the production of phosgene, methanol synthesis, acetic acid synthesis, hydroformylation, acrylic acid production, Fischer‐Tropsch chemistry, methanation, and nickel purification.
Cell Culture Technology
Authors: Karkare Subhash B.
Published: August 2004

Cell culture technology refers to thein vitroprocesses employed for the growth of mammalian, insect, or plant cells to manufacture biochemicals of commercial importance. Cell culture products, typically therapeutics or medical diagnostics, are regulated by the FDA. The market for cell culture‐derived products is growing and is expected to continue to grow into the 21st century.

The technology involved in cell growth is often dependent on cell line type. Hybridoma cells, used for the production of monoclonal antibodies, can be grown in suspension cultures in a manner similar to that used in microbial fermentation. Other cell systems require microcarriers or supports. All of these cells have higher shear sensitivity than microbial cells. Both batch and continuous processes, cell growth kinetics, cell aeration, growth media, product isolation, and purification are discussed, as are safety regulations and standards.
Cement
Authors: Helmuth Richard A. , Miller F. M. , Greening N. R. , Hognestad E. , Kosmatka Steven H. , Lang David
Published: August 2004

Inorganic hydraulic cements upon reaction with water form relatively insoluble, bonded aggregations having considerable strength and dimensional stability. The cement produced in the greatest volume is Portland cement which is most often used in concrete for construction. Portland cements contain calcium and silicon oxides together with additives such as alumina, ferrites, and gypsum.

Cement clinker chemistry and the Portland cement phases that form, including composition and reaction times, are discussed. Cement hydration and structure are described as are properties such as strength and porosity of the concretes and chemical admixtures formed. Either a dry or a wet process may be used in cement manufacture; both are described. The uses of Portland cements, special purpose and blended cements, and calcium aluminate cements are reviewed.
Chemiluminescence
Authors: Bronstein Irena , Kricka Larry J. , Givens Richard S.
Published: August 2004

Chemiluminescence is the emission of light from chemical reactions at ordinary temperatures. The reactions of chemiluminescence produce a reaction intermediate or product in an electronically excited state, and radiative decay of the excited state is the source of the light. Chemiluminescence relates to fundamental molecular interactions and transformations and its study provides access to basic elements of reaction mechanisms and molecular properties, efficient chemiluminescence can provide an emergency or portable light source, chemiluminescence provides means to detect and measure trace elements and pollutants for environmental control or clinically important substances, and classification of the bioluminescent relationship between different organisms defines their biological relationship and pattern of evolution.

Liquid‐phase, gas‐phase, and solid‐phase chemiluminescence are discussed as well as bioluminescence, which is characteristic of numerous marine and a few land organisms. The applications of chemical light include marking and illumination and several types of analyses such as flow injection, hplc, direct metal, titration indicators, immunoassay, bacteria and biomass determination, and air pollution.
Chemicals from Brine
Authors: Butts David
Published: August 2004

There are thousands of brine sources in the world that contain useful minerals. Some of these minerals are needed by living organisms to sustain life. Table salt, magnesium, lithium, potassium, and sulfates are but a few of these minerals.

Many brine minerals are used to process detergents, paper, plastics, preservatives, construction materials, foodstuffs, pharmaceuticals, and metals. Sodium chloride alone is used in 14,000 different products common to everyday living in the United States. Over one billion tons of brine each year is used in industries making it one of the largest processed ores in the world.

Use of brine is on the increase because much of it can be processed by solar evaporation. This saves the energy cost of fossil fuels and has the added benefit of not polluting the air. In addition there is an endless supply of some of the minerals in the oceans of the world.
Regulatory Agencies, Chemical Process Industry
Authors: Passow Nancy R.
Published: August 2004

Passow, Nancy R. (LONZA Inc.). The chemical process industry is highly regulated in the environmental, health, and safety area. Everything is affected, from the siting of a new facility to the transportation of raw materials and finished products, from the working conditions for employees to operating requirements for processes, packaging of finished goods, and dealings with the community.

The two main U.S. Federal agencies involved in the protection of human health and the environment are the Environmental Protection Agency (EPA) and the Occupational Safety and Health Administration (OSHA). EPA's principal concern is the protection of the environment; in most cases, the area outside of an industrial facility. Significant laws covered by EPA are the Clean Air Act Amendments; the Clean Water Act; Resource Conservation and Recovery Act; Comprehensive Environmental Response, Compensation, and Liability Act; Toxic Substances Control Act; and the Federal Insecticide, Fungicide, and Rodenticide Act. The principal function of OSHA is the protection of people, eg, employees, visitors, and temporary help, in the workplace. The principal law covered by OSHA is the Occupational Safety and Health Act.
Chlorinated Benzenes
Authors: Bryant James G.
Published: August 2004

The chlorination of benzene can theoretically produce 12 different chlorobenzenes. However, technology and world events have substantially reduced chlorinated benzene to the current production of three significant products: monochlorobenzene ando‐ andp‐dichlorobenzenes. Monochlorobenzene represents over 50% of the total production of chlorobenzenes. The largest use for monochlorobenzene worldwide is the production of nitrochlorobenzenes, which are consumed to make dye and pigment intermediates, rubber processing chemicals, pesticides, pharmaceuticals, and other organic intermediates.o‐Dichlorobenzene is consumed primarily for 3,4‐dichloroaniline manufacture in the United States and Western Europe and in the emulsified form in Japan for treatment of garbage. The largest market worldwide forp‐dichlorobenzene is for deodorant blocks and moth control. A growing use is in the production of the high performance polymer, poly(phenylene sulfide) (PPS).

Manufacturing methods, specifications, handling precautions, and health and safety factors are covered. With the exception of their use in the production of high performance polymers, markets for chlorobenzenes are mature and overall demand is expected to show little, if any, growth over the next few years.
Chloroform
Authors: Holbrook Michael T.
Published: August 2004

Chloroform, CHCl3, at normal temperature and pressure is a heavy, clear, volatile liquid with a pleasant, ethereal, nonirritant odor. It is produced almost exclusively by the chlorination of methane or lower chlorinated methanes, though methane oxychlorination and carbon tetrachloride hydrogenation have been proposed. The U.S. chloroform capacity has been estimated at 258,000 t/yr but the actual capability is probably much higher because of the producer's ability to change their product mix between methylene chloride and chloroform. The main uses for chloroform are in the production of HCFC‐22 and fluoropolymers. Growth projections as high as 6% per year have been made for the early 1990s. Chloroform is regulated under a number of federal and state laws.
Chlorinated Paraffins
Authors: Houghton Kelvin L.
Published: August 2004

Chlorinated paraffins are well‐established products in a wide range of diverse applications in today's modern industry. Although as a class of products they have been available for over 50 years, their continuing use results from manufacturers taking advantage of new base feedstocks to develop advanced products to meet the increasing technical demands of the new and emerging technologies. The physical and chemical properties of chlorinated paraffins are determined by the carbon chain length of the paraffin and the chlorine content.

The range of products now available are used as plasticizers in PVC, rubber, surface coatings, adhesives, and sealants where they impart the added benefits of fire retardance and chemical and water resistance. As fire‐retardant additives they find specific usage in polyester resins, polyurethanes, and polyolefins. Chlorinated paraffins are also employed as extreme pressure additives in metal‐working lubricants, as components of fat liquors for leather treatment, and as solvents in carbonless copying paper.

Comprehensive studies on toxicity and environmental impact have been carried out over many years. The acute toxicity of chlorinated paraffins to mammals, birds, and fish is low. Although there is evidence of toxicity to some aquatic species, interpretation of the results is made complicated because of the very low solubility of chlorinated paraffins in water.
Chromatography
Authors: Kaiser Mary A. , Dybowski Cecil
Published: August 2004

Chromatography, a technique for separation and purification of chemical and biological substances, is used both in research laboratories and in industrial process‐control applications. The chromatographic process usually involves selective interactions between components of the sample with particles packed in a tube (column) as a fluid mixture of the components (the sample) percolates through the column. Because each component of the sample may interact with the particles to a different degree, each is retarded in its passage through the column to a different degree effecting the separation. If the fluid phase is a liquid, the technique is called liquid cromatography; if the fluid phase is a gas, the technique is called gas chromatography; if the fluid is supercritical, the technique is called supercritical‐fluid chromatography. The success of a separation of a particular mixture (the efficiency of the separation) depends on the chemical nature of the packing material, the physical structure of the system, and a host of practical considerations. Chromatography involves the interaction of materials with surface‐bound phases, and it may also be used to characterize the physical and chemical interactions that underlie the process.
Chromium Compounds
Authors: Page Billie J. , Loar Gary W.
Published: August 2004

Chromium compounds and their important uses are described. Chemical properties of the low valence compounds, Cr(‐II) through Cr(I), and those of Cr(IV) and Cr(V) are discussed as are those of the commercially important oxidation states of Cr(II), Cr(III), and Cr(VI).

Sodium chromate and dichromate production from imported chromite ore, and the production of other chromates, dichromates, and chromic acid are summarized. The manufacture of water‐soluble trivalent compounds is also given. Regulations concerning shipments, specifications, and analytical test methods are discussed as are the health and safety factors of chromium compounds.

The environmental impact and waste management practices of chromium compounds is also of importance. Chromium compounds of various oxidation states are used commercially as pigments, in metal finishing, leather tanning, drilling muds, and in wood preservation. Chromium compounds are also used in alloys, batteries catalists, photosensitive gels, and as reagent grade chemicals.
Coatings
Authors: Wicks Zeno W.
Published: August 2004

Coatings.The field of coatings is reviewed with emphasis on the changes resulting from increasingly restrictive regulations especially with regard to solvent emission. Principles of film formation, and principal classes of resins and polymers, solvents, and pigments used are covered. Topics important to the design of coatings such as color matching, flow, film defects, adhesion, exterior durability, corrosion control, and mechanical and rheological properties are discussed. The principal classes of uses of coatings are architectural coatings, which includes flat wall paint, exterior house paint, and gloss enamels; product coatings, which includes primers, high solids and water‐borne top coats, coil coatings, radiation cure coatings, powder coatings, and wood coatings; and special purpose coatings, ie, heavy‐duty maintenance and marine coatings, and automotive refinish paints.
Coffee
Authors: Wasserman Gerald , Stahl Howard D. , Rehman Warren , Whitman Peter
Published: August 2004

This article presents a description of the coffee processing technology, coffee chemistry, and coffee consumption trends. Special attention is given to green coffee processing, the chemistry of green coffee, the chemical effects of roasting and brewing coffee, as well as the chemistry of instant coffee. Processing and packaging of roasted, ground, instant, and decaffeinated coffees are discussed. The economics of green coffee, as well as the import and world production figures for 1989‐1990, are included. New coffee biotechnology and products are presented.
Color Photography, Instant
Authors: Walworth Vivian K. , Mervis Stanley H.
Published: August 2004

Instant color photography began in 1963 with a one‐step print process providing a finished photograph within a minute after exposure. Outwardly dry processing under ambient conditions is initiated within the camera upon release of reagent from a sealed pod that is provided as part of the film unit. Integral print films, introduced in 1972, retain the developed photosensitive layers concealed within the print. Instant film configurations also include print and transparency processing independent of the camera. Subtractive instant color processes use dye‐developers and dye‐release compounds to generate images comprising preformed dyes. Dye‐release compounds are also utilized in wet‐processed reprographic films and in photothermographic films for hard copy from images generated by instruments or computers. Additive instant color transparencies comprise microscopic black‐and‐white silver images formed by exposure of a panchromatic emulsion layer through an integral color screen. The chemistry of the various systems is discussed. Instant color films are utilized in many professional fields, especially those involved in documentation or imaging.
Computer‐Aided Engineering (CAE)
Authors: Tayyabkhan M. T. , Britt H.
Published: August 2004

This article explains the use of computer programs for process simulations and for process and equipment design. Many of the newer techniques such as design optimization, process synthesis, data reconciliation, expert systems, and risk assessments using fault tree analyses have been included here. Process dynamics and process control are treated briefly because they are covered elsewhere in articles on instrumentation and control. CAD, CADD, and CAM (computer‐aided drafting, design, and manufacturing) and management of the construction of process plants also are treated in other articles. Microprocessors have become accessible and popular. An explanation of the use of microprocessor spreadsheets for engineering calculations also has been included here.
Copyrights and Trademarks, Copyrights
Authors: Koenigsberg I. Fred
Published: August 2004

Copyright developed after the invention of the printing press as a means of protecting works of authorship. The United States Copyright Law derives from a constitutional grant to Congress to promote progress in science and learning. Copyright protects original works of authorship of all types. Copyright does not protect ideas, concepts, methods, systems, processes, research, or facts themselves, but only their expression. Copyright may protect utilitarian works, but only to the extent that they contain physically or conceptually separable original works of authorship.

Copyright is a property right and may be transferred or licensed and owned jointly. Copyright is owned initially by the author. In the case of works made for hire, the employer or other person for whom the work is created is deemed to be the author. Copyright formalities, that is, notice, deposit, and registration, are of less importance now than they were previously, but are still encouraged. No copyright notice is necessary on copies of works first published after March 1, 1989. Copyright registration is entirely permissive, but enables important legal procedural rights.

Copyright generally endures for the life of the author plus 50 years, for works first created or copyrighted on or after January 1, 1978; or for an initial term of 28 years and a renewal term of 47 years, for works first copyrighted before January 1, 1978. Copyright protects the rights to reproduce the work in copies, to prepare derivative works, of public distribution, of public performance, and of public display. These rights are not absolute, because certain exceptions, such as the fair use and first sale doctrines, apply.
Crystallization
Authors: Rousseau Ronald W.
Published: August 2004

This article provides an overview of crystallization that can be used by scientists and engineers, regardless of their familiarity with the operation. Key aspects of the use of crystallization for separation, purification, or other purposes are covered; especially noteworthy is the coverage relating product purity, morphology, and size distribution to the kinetic phenomena of crystal nucleation and growth. Current studies have shown that crystallizer variables such as mixing and the rate at which supersaturation is generated influence the purity of recovered crystals. Crystal morphology can be affected by variables modifying inherent growth kinetics of crystal faces or by changing interfacial or solution properties. Theory is mixed with empiricism in showing the role of operating variables such as supersaturation, magma density, and agitation in determining crystallization kinetics. Methods are illustrated for coupling crystallization kinetics with population balances on continuous and batch crystallizers to determine crystal size distributions. In addition, the bases of using selective removal functions (clear‐liquor advance, classified‐fines removal, and classified‐product removal) to influence the characteristics of size distributions is presented. Qualitative characteristics of batch crystallizers are presented and the role nucleation plays in determining the general behavior of product size distributions from such systems is described. Finally, a summary of industrial practice and equipment is presented; both crystallization from solution and from the melt are included in the summary; attention is given to the emerging importance of crystallization from the melt.
Cyanine Dyes
Authors: Sturmer David M.
Published: August 2004

Cyanine dyes and the related merocyanines and oxonols are commercially important dyes for high technology uses, including spectral sensitization of photographic films, optical filtering/light modulation, dye lasers, and biological staining agents. The primary chromophores and heterocycles in these dyes are outlined with specific reference to chemical reactions that allow the synthesis of almost every type of cyanine and related dye. Known structure‐property relationships for the cyanines are extensive, and examples are included for properties such as color, substituent effects, solubility, self‐association (aggregation), electrochemical behavior, photochemical reactions, and biological uses.
Cyclopentadiene and Dicyclopentadiene
Authors: Keenan Michael J.
Published: August 2004

Cyclopentadiene is the most widely studied, conjugated cyclodiene in the history of organic chemistry. The more stable form, dicyclopentadiene, has a multitude of applications. This article discusses the physical properties of these compounds, chemical reactions, derivatives, manufacturing processes, and applications.

Cyclopentadiene undergoes the Diels‐Alder reaction with itself and with a wide variety of olefins and diolefins. In addition, it can be functionalized to many derivatives and can be polymerized with itself and other olefins. The derivatives are used in polyesters, perfumes, elastomers, and pesticides. Metallocene complexes of cyclopentadiene have been extensively studied and are useful as catalysts.

Dicyclopentadiene is used in polymers with itself and with other hydrocarbons, in polyester resins, bodied oils, elastomers, polycarbonates, and pharmaceuticals. Total worldwide recoverable dicyclopentadiene capacity exceeds 175,000 metric tons per year.
Design of Experiments
Authors: Hahn Gerald J.
Published: August 2004

The main reason for designing an experiment statistically is to obtain unambiguous results at a minimum cost. The need to learn about interactions among variables and to measure experimental error are added reasons.

Statistically planned experiments are characterized by (1) the proper consideration of extraneous variables; (2) the fact that primary variables are changed together, rather than one at a time, in order to obtain information about the magnitude and nature of interactions and to gain improved precision in the final estimates; and (3) built‐in procedures for measuring the various sources of random variation and for obtaining a valid measure of experimental error.

A well‐planned experiment is often tailor‐made to meet specific objectives and to satisfy practical constraints. The final plan may or may not involve a standard textbook design. If possible, a statistician knowledgeable in the design of experiments should be called in early, made a full‐fledged team member, and be fully apprised of the objectives of the test program and of the practical considerations and constraints. Designing an experiment is often an iterative process requiring rework as new information and preliminary data become available. With a full understanding of the problem, the statistician is in an improved position to respond rapidly if last‐minute changes are required and to provide meaningful analyses of the subsequent experimental results.
Diamines and Higher Amines, Aliphatic
Authors: Carter Richard G. , Doumaux Arthur R. , Kaiser Steven W. , Umberger Pamla R.
Published: August 2004

The aliphatic diamine and higher amine family encompasses a wide range of multifunctional and multireactive compounds. The so‐called ethyleneamines family, which includes ethylenediamine and its homologues, the polyethylene polyamines, have found the broadest commercial application. Representative physical and chemical properties are given. Three main processes are used currently to produce the ethyleneamines: the reaction of ethylene dichloride with ammonia to produce the whole spectrum of ethyleneamine products; the reductive amination of monoethanolamine to produce the lighter ethyleneamines, mainly ethylenediamine; and the catalytic reaction of monoethanolamine with ethylenediamine to produce higher ethyleneamines. Worldwide capacity for ethyleneamines is about 295 t/yr. Typical specifications and test methods, storage and handling guidelines, and health and safety factors are discussed. This family of compounds finds use in a wide variety of applications by virtue of their unique combination of reactivity, basicity, and surface activity. With a few significant exceptions, they are used predominantly as intermediates in the production of functional products. Significant applications include fungicides, lubricant and fuel additives, epoxy curing agents, polyamide resins, paper resins, and chelates.
Chlorine Oxygen Acids and Salts, Dichlorine Monoxide, Hypochlorous Acid, and Hypochlorites
Authors: Wojtowicz John A.
Published: August 2004

The hydrolysis of chlorine gives rise to a pH‐dependent complex system involving no less than six equilibria in which the oxidizing power of the parent element is preserved in hypochlorous acid, chlorine monoxide, and hypochlorite. The physical and chemical aspects of this unique family of compounds, including organic and other nonmetal hypochlorites, are outlined, their preparation and manufacturing processes are surveyed, and important uses are cited. Corrosion problems and potential hazards in handling and use of these compounds are also discussed.

Hypochlorous acid is the active biocidal agent when hypochlorites are employed in disinfection and sanitation. It is an intermediate in the manufacture of hypochlorites, chloramines, and chlorohydrins. A process for production of HOCl in concentrations as high as 60% has recently been developed.

The commercially important hypochlorites are Ca(OCl)2, NaOCl solution, LiOCl, chlorinated trisodium phosphate, and to a lesser extent hemibasic Ca(OCl)2and bleaching powder. They are used primarily in sanitation and bleaching applications. Although the use of chloroisocyanurates in swimming pool sanitation is increasing, hypochlorites remain the dominant products in this area. The most important solid hypochlorite is Ca(OCl)2, which is marketed in partially hydrated form and to a lesser extent as an almost anhydrous product. Several new processes for its manufacture are described.

Continued research interest involve use of hypochlorites for selective epoxidation, oxidation, and chlorination, and use of chlorine monoxide as a highly selective agent for aromatic ring and side chain chlorination.
Disinfectants and Antiseptics
Authors: Block Seymour S.
Published: August 2004

Disinfectants and antiseptics are employed in the prevention of diseases of bacterial, parasitic, fungal, and viral origin. Hospital acquired infections, AIDS, Legionnaires disease, tuberculosis, and cholera are a few of the diseases controlled in part through the use of disinfectants and antiseptics.

Disinfectants and antiseptics are antimicrobial agents used as preservatives, sporicides, sanitizers, etc. Chemical groups employed as disinfectants and antiseptics include halogens, acids, aldehydes, nitrogen heterocycles, peroxygen, phenolic, and sulfur metal compounds. Disinfectants also may be classified as either surface‐active agents or gaseous sterilants. Numerous analytical tests exist for establishing the activity and application of disinfectants. Antiseptics, considered drugs, come under the jurisdiction of FDA testing guidelines.
Distillation
Authors: Fair James R.
Published: August 2004

Distillation is the most widely used industrial method for separating liquid mixtures into their constituents. In chemical plants and petroleum refineries, distillations are normally carried out in vertical columns containing devices for bringing the flowing liquid mixture into intimate contact with a flowing vapor mixture that is generated by partial vaporization of the liquid. This article covers the fundamental physical and mathematical relationships that are needed for the design of new distillation columns as well as the analysis of existing columns.

The article is divided into four main topics: vapor‐liquid equilibria; distillation processes; distillation columns, both plate and packed; and distillation as a separation method. Minor divisions include such special topics as steam distillation, molecular distillation, distillation literature sources, and economics. Sufficient information is given to enable the user to carry out preliminary designs of a variety of systems, and guidance is provided for cases where additional resources might be needed.