bluuebunny/crossref_metadata_2025 huggingface dataset:
Amides, Fatty Acid
Authors: Johansson Ingegärd
Published: July 2004

Fatty acid amides, which contain a saturated or unsaturated alkyl chain derived from a fatty acid, can be divided into three categories. The first is primary monoamides in which R is a fatty alkyl or alkenyl chain of C5C23and R′ = R″ = H. The second is substituted monoamides, including secondary, tertiary, and alkanolamides in which R is a fatty alkyl or alkenyl chain of C5C23; R′ and R″ may be a hydrogen, fatty alkyl, aryl, or alkylene oxide condensation groups with at least one alkyl, aryl, or alkylene oxide group. The third category is bisamides where R groups are fatty alkyl or alkenyl chains. R′ and R″ may be hydrogen, fatty alkyl, aryl, or alkylene oxide condensation groups. Primary and secondary amides show strong hydrogen bonding that account for their high melting points and low solubilities in most solvents. With tertiary amides (disubstituted amides), hydrogen bonding is not possible, as exhibited by their increased solubility and lower melting points. Many fatty acid amides are essentially insoluble in water. Amides have a strong tendency to reduce friction on various surfaces by forming a layer on surfaces. This coating action may be attributed to their hydrophobic character and strong hydrogen bonding. Primary, secondary, and bisamides are widely used as lubricating or slip agents and alkanolamides. Their ethoxylated counterparts are commonly used as surfactants in personal care and detergent applications. Amides in general are stable to elevated processing temperatures, air oxidation, and dilute acids and bases. The dehydration of amides that produces nitriles is of great commercial value. The most widely used synthetic route for primary amides is the reaction of a fatty acid with anhydrous ammonia. Alkanol amides are made from triglycerides or fatty acid methyl esters reacted with monoethanolamine or diethanolamine that then can be ethoxylated with ethylene oxide under basic catalyses. Common products are stearamide, cocamide, ethylene bis(stearamide), cocamide, DEA or MEA, cocamidopropyl dimethyl amine, and cocamide monoethanolamine ethoxylate.
Amine Oxides
Authors: Maisonneuve B.
Published: July 2004

Amine oxides, known asN‐oxides of tertiary amines, are classified as aromatic or aliphatic, depending on whether the nitrogen is part of an aromatic ring system or not. This structural difference accounts for the difference in chemical and physical properties between the two types. The higher aliphatic amine oxides are commercially important because of their surfactant properties and are used extensively in detergents. Amine oxides that have surface‐acting properties can be further categorized as nonionic surfactants; however, because under acidic conditions they show cationic properties, they have also been called cationic surfactants. Most amine oxides undergo thermal decomposition between 90 and 200°C. Aromatic amine oxides, have some pharmaceutical importance, do not demonstrate surface‐acting properties and are more resistant than aliphatic amine oxides to reduction. Linear alpha‐olefins are the source of the largest volume of aliphatic amine oxides. Fatty alcohols and fatty acids are also used to produce amine oxides. Amine oxides used in industry are prepared by oxidation of tertiary amines with hydrogen peroxide solution. Amine oxides are used in the detergent, organic synthesis, textile, and pharmaceutical industries. Aliphatic amine oxides range from practically nontoxic to slightly toxic. Among the aromatics, 4‐nitroquinolineN‐oxide is a powerful carcinogen, producing malignant tumors on the skin of mice. 2‐Methyl, 2‐ethyl, and 6‐chloro derivatives of 4‐nitroquinoline oxide are also carcinogens.
Silica, Amorphous Silica
Authors: Waddell Walter H. , Evans Larry R.
Published: July 2004

Amorphous silica, a three‐dimensional, inorganic polymeric silicon dioxide, SiO2, does not have a crystalline structure as defined by the absence of definitive lines in x‐ray diffraction measurements. Amorphous silica can be naturally occurring or synthetic, and either anhydrous or surface‐hydrated with silanol groups. Synthetic amorphous silica can be divided into microamorphous silica and vitreous silica (glass) made by fusing quartz at temperatures greater than approximately 1700°C. A discussion of microamorphous silica is presented, including colloidal silica, ie, sol or stable dispersion of discrete particles; silicas gelled or precipitated from solution; and pyrogenic and fused silica. Amorphous silica is characterized by chemical composition, physical properties, and characteristics of its particles, with exact analytical procedures depending on the type and application. Various methods to prepare and characterize each type of amorphous silica, commercial applications including principal global manufacturers, and health and safety issues are discussed.
Biopolymers, Analytical Techniques
Authors: Ward Timothy
Published: July 2004

Analytical techniques that utilize biopolymers, ie, natural macromolecules such as proteins, nucleic acids, and polysaccharides that compose living substances, represent a rapidly expanding field. The number of applications is large, eg, chiral chromatography, immunology, and biosensors, among others. Direct chiral resolution by liquid chromatography (lc) involves diastereomeric interactions between the chiral solute and the chiral stationary phase. Because biopolymers are chiral molecules and can form diastereomeric interactions with chiral solutes, they are ideal for use as chiral stationary phases. This property has led to a rapid growth of chromatographic stationary phases utilizing biopolymers to separate chiral molecules. Biopolymers are employed in many immunological techniques, including the analysis of food, clinical samples, pesticides, and in other areas of analytical chemistry. Immunoassays are specific, sensitive, relatively easy to perform, and usually inexpensive. One condition that must be met for the application of an immunochemical method is the stimulating of an immune response leading to the formation of antibodies in the immunized animal. These antibodies can then be isolated and used as highly specific analytical reagents (immunoassays). Analytes that can combine with the corresponding antibodies are called antigens. In general, large, rigid, chemically complex molecules make good antigens. Antibodies are proteins, found in many body fluids such as tears, saliva, and urine, that are present in highest concentrations in blood serum. The particular proteins which exhibit antibody activity are the immunoglobulins (Ig). Biologically derived polymers can be used as highly selective immobilized reagents in analytical applications. The immobilized enzyme electrode is the most common immobilized biopolymer sensor, consisting of a thin layer of enzyme immobilized on the surface of an electrochemical sensor. The advantages of immobilized enzyme electrodes include minimal pretreatment of the sample matrix, small sample volume, and the recovery of the enzyme for repeated use. Enzyme immunosensors are enzyme immunoassays coupled with electrochemical sensors. Enantiomeric separations are expected to continue to have a considerable economic impact on the development of new drugs and therapy in the biomedical field. The importance of immunoassays for food monitoring and in the detection of diseases is expected to continue to grow. The development of biosensors is expected to benefit monitoring therapeutic drug levels, office testing, and implantable devices because of the advantages of cost‐saving automation and improved data handling.
Growth Regulators, Animal
Authors: Beermann Donald H.
Published: July 2004

Growth regulation in animals involves complex interactions among several hormone and growth factor systems that are programmed genetically and modified by diet and the environment to determine rates of tissue and organ growth. Cell number, cell size and cell function are all influenced by these factors and result in significant variation in phenotypic characteristics of animals used for food production. Intervention strategies to enhance efficiency and composition of growth in meat animals were developed once control of metabolic processes was achieved. Four general classes of animal growth regulators have evolved. This article discusses chemical characteristics, mechanism of action and dose response relationships of representative products, and lists those approved by the Food and Drug Administration for growth intervention. Anabolic steroid implants are used in growing finishing cattle to enhance growth rate and efficiency. Ionophores are used in finishing cattle to enhance efficiency of gain. Subtherapeutic feeding of antibiotics to protect or improve animal health are declining in use. Two classes of metabolism modifiers, beta‐agonists and somatotropin, regulate growth primarily by enhancing skeletal muscle growth and concurrently reducing the rate of adipose tissue growth, with species and compound specificity that are significant. Both result in improved efficiency of growth when composition of gain is improved.
Genetic Engineering, Animals
Authors: Lucy Matthew C.
Published: July 2004

Embryo splitting and cloning by nuclear transfer are methods to mass‐produce identical copies of a single embryo or a single adult animal. A transgenic animal may have a stable modification, a stable deletion, or a stable insertion of a foreign gene into its genome. Transgenic animals can be classified as traditional transgenics where a gene is inserted at a random location in the genome or gene‐targeted transgenics (knock‐outs, knock‐ins, and conditional knock‐outs) where a specific gene within the genome is modified. Traditional transgenics are created by pronuclear microinjection, retroviral infection, sperm‐mediated gene transfer, or nuclear transfer. Gene targeting is done by using embryonic stem cells (mice) or somatic cells (farm animals). A DNA targeting vector is constructed that is designed to insert itself into the embryonic genome and inactivate a specific gene. Transgenic and gene targeted animals have become mainstays for scientific research. Transgenic farm animals are essential for the low‐cost production of recombinant proteins. The productivity of farmers may be improved through the use of transgenic farm animals. Pigs with deleted immune recognition genes may soon provide organs for transplantation into humans. Transgenic and gene targeted mice represent some of the most important tools for biomedical research in the twenty‐first century. To understand the function of a specific gene, a transgenic mouse is created that overexpresses the gene. Gene targeting is a step beyond simple overexpression of genes because the function of a gene is accessed by evaluating the phenotype of the gene‐deleted mouse. Conditional knock‐out mice may represent the final step in the evolution of genetic modification of animals.
Initiators, Anionic
Authors: Quirk Roderic P. , Monroy Victor M.
Published: July 2004

Anionic initiators for chain‐reaction polymerization are described. The general relationship between monomer structure, p

K
a
,

and appropriate initiating species is discussed. The scope and limitations of the use of alkali metals, aromatic radical anions, alkyllithium compounds, diphenylmethyl carbanions, fluorenyl carbanions, enolate anions, and alkoxides as initiators is presented. The uniqueness of alkyllithium initiators in hydrocarbon solvents for controlled living anionic polymerization is discussed.
Hormones, Pituitary‐Like Hormones
Authors: Matteri Robert L.
Published: July 2004

Hormones with structural and functional similarities to the hormones of the anterior pituitary gland fall into two main categories, ie, proteins of the prolactin/growth hormone (PRL/GH) family, and glycoproteins. Anterior pituitary‐like hormones are produced in the placenta by chorionic tissue, and so are normally found in the female during pregnancy. Placental lactogens, members of the PRL/GH family, support growth and development of mammary tissue in preparation for lactation. Chorionic gonadotropin is similar in structure to luteinizing hormone and supports the maintenance of early pregnancy. Chorionic gonadotropin is found in humans and lower primates, as well as in horses. Information on primary structure and commercial sources is provided when available.
Anthraquinone
Authors: Cofrancesco A. J.
Published: July 2004

Obtaining anthraquinone by oxidizing anthracene with bichromate and sulfuric acid later became the first commercial method for the manufacture of anthraquinone from anthracene. For many years, anthraquinone provided the dyestuff industry with one of the greatest and most prolific building blocks for the manufacture of valuable dyestuffs noted for their outstanding fastness properties. However, in recent times production has fallen off considerably due to the high cost of manufacturing and the discovery of other classes of dyestuffs with good fastness properties. When sublimed, anthraquinone forms a pale yellow, crystalline material, needlelike in shape. It melts at 286°C and boils at 379–381°C. At much higher temperatures, decomposition occurs. Anthraquinone has only a slight solubility in alcohol or benzene and is best recrystallized from glacial acetic acid or high boiling solvents such as nitrobenzene or dichlorobenzene. It is very soluble in concentrated sulfuric acid. In general, anthraquinone is a relatively inert compound exhibiting stability toward oxidation. Only the reduction products involving the keto groups are of any academic or industrial importance. In the dyestuff industry, anthraquinone still ranks high as an intermediate for the production of dyes and pigments having properties unattainable by any other class of dyes or pigments. At this writing (1993) the only two processes for its production are by the Friedel‐Crafts reaction utilizing benzene, phthalic anhydride, and anhydrous aluminum chloride, and by the vapor‐phase catalytic oxidation of anthracene, the latter being preferred. Anthraquinone is a comparatively safe compound. It is a mild allergen and may cause skin irritation. It presents only a slight fire hazard on exposure to heat. The use of benzene in the Friedel‐Crafts process presents serious safety and health problems. Besides its major use in the manufacture of intermediates for anthraquinone dyes and pigments, anthraquinone is finding increasing interest as a catalyst in wood pulping in polymerization of various materials for plastics, and in the isomerization of vegetable oils.
Antioxidants, Polymers
Authors: Thomas Richard , Dexter Martin , King R. E.
Published: July 2004

Antioxidants are used to retard the reaction of organic materials with atmospheric oxygen. Such reaction can cause degradation of the properties of the polymer; loss of flavor and development of rancidity in foods; and a change in lubricants. The need for antioxidants depends on the chemical composition of the substrate and the conditions of exposure. High concentrations of antioxidants, ie, 0.5–2% based on the weight of he polymer, are used to stabilize polymers such as natural rubber and polyunsaturated oils. Saturated polymers have greater oxidative stability and require relatively low concentrations of stabilizers; ie, 0.01–0.05%, based on the weight of the polymer. The mechanism by which an organic material (RH) undergoes autoxidation involves a free‐redical chain reaction. High concentrations are also required in substrates that are highly sensitive to oxidation, such as unsaturated elastomers and acrylonitrile–butadiene–styrene (ABS). Thermally induced homolytic decomposition of peroxides and hydroperoxides to free radicals increases the rate of oxidation. Decomposition to nonradical species removes hydroperoxides as potential sources of oxidation initiators. The selection of an antioxidant or system of antioxidants is dependent on the polymer and the anticipated end use. Low concentrations of antioxidants ( < 0.01%) are added to polyethylene and polypropylene after synthesis and prior to isolation to retard oxidation of the polymers exposed to air. Polyunsaturated elastomers are sensitive to oxidation. Antioxidants are added to the elastomers prior to vulcanization to protect the rubber during drying and storage. Nonstaining antioxidants may be used. Staining antioxidants are preferred for the manufacture of tires. Gasoline and jet engine fuels contain unsaturated compounds that oxidize on storage, darken, and form gums and deposits. Radical scanvengers and alkylated paraphenylene diamines are used as stabilizers. Lubricants for gasoline engines are required to withstand harsh conditions. Relatively high concentrations of primary antioxidants and synergists are used to stabilize lubricating oils. The oxidation of food containing fats and oils results in a loss of sensory appeal and eventually rancidness. The U.S. Food and Drug Administration (FDA) regulations covering the use of direct food additives are stringent and few new materials have been regulated. The most commonly used materials are butylated hydroxytoluenen‐propyl gallatte, α‐tocopherol, and butylated hydroxyanisole. A number of antioxidants have been accepted by the FDA as indirect additives for polymers used in food applications.
Antibacterial Agents, Overview
Authors: Macielag Mark J. , Bush Karen , Weidner‐Wells Michele A.
Published: July 2004

Antibacterial agents are synthetic compounds that kill or prevent the growth of bacteria. They exhibit selective toxicity to bacterial cells either because they inhibit a biochemical target present solely in bacteria or because they exhibit greater affinity for the bacterial target than the mammalian counterpart. Antibacterial agents are used in the treatment and/or prevention of infections due to pathogenic bacteria in humans and animals. The search for synthetic antiinfective agents began in the early 1900s with Paul Ehrlich's pioneering research on organoarsenicals. Currently, five classes of synthetic antibacterial agents are marketed for therapeutic use: the antitubercular agents, nitrofurans, oxazolidinones, quinolones, and the sulfonamides and combinations. Taken as a whole, drugs from these classes are used to treat a broad range of bacterial diseases, including tuberculosis, urinary tract infections, respiratory tract infections, and infections due to multidrug‐resistant bacteria. Emergence of resistance has limited the usefulness of the antitubercular agents and sulfonamides as sole therapy. The nitrofurans and the oxazolidinones have found their own niches, principally in the treatment of urinary tract infections and serious gram‐positive infections, respectively. The quinolones, by virtue of their broad spectrum of antimicrobial activity, oral bioavailability, good tissue distribution, and well‐understood safety profile, retain a prominent position in the armamentarium of antibacterial drugs.
Furnaces, Electric, Arc Furnaces
Authors: Cotchen J. Kevin
Published: July 2004

Furnaces, Electric, Arc Furnaces. J. Kevin Cotchen (MAN GHH Corp.). Arc furnaces used in electric melting, smelting, and electrochemical operations are of two basic designs; indirect and direct arc. The arc of the indirect‐arc furnace is maintained between two electrodes and radiates heat to the charge. The arcs of the direct‐arc furnace are maintained between the charge and the electrodes, making the charge a part of the electrical power circuit. Not only is heat radiated to the charge, but the charge is heated directly by the arc and the current passing through the charge.

Indirect‐arc furnaces have been used primarily in foundries for melting copper, copper alloys, and other nonferrous metals that have a low melting point. Direct‐arc furnaces include open‐arc furnaces, d‐c arc furnaces; submerged arc‐furnaces; and arc‐resistance furnaces. All new furnace installations require pollution control equipment. This normally consists of off‐gas afterburning (sometimes with energy recovery), and dust collection equipment, typically a baghouse.
Paint, Architectural
Authors: Leman Arthur A.
Published: July 2004

Paint is one of the most common and widely used materials in home and building construction and decoration. This broad use comes from paint's ability to provide improved appearance, decoration, as well as protection of the substrate to which it is applied. Paint is defined as “any liquid, liquefiable, or mastic composition designed for application to a substrate in a thin layer which is converted to an opaque solid film after application.” This article focuses on the types of paints commonly referred to as architectural coatings, house paints, or trade sales paints.

Familiar coatings cover a wide range of products such as paints, primers, stains, varnishes, and sealers. Most paints are available in a wide variety of colors and appearances, and are made up of four basic groups of chemical raw materials: binders or resins, pigments, solvents, and additives. Proper choice and amount of both binder and pigments, as well as the volume relationships between the two, govern the overall performance properties of paints. The manufacture of house paints involves mixing together these raw material ingredients in such a way that the finished paint is a homogeneous mixture of evenly distributed ingredients. Along with the formulation and manufacture of high quality paint, proper surface preparation and correct application of house paints are important for good durability and performance.
Polyethers, Aromatic
Authors: White Dwain M.
Published: July 2004

The aromatic polyethers described in this article are engineering thermoplastics which have excellent physical properties and desirable high temperature properties. Two general classes of materials are described. One class of polyethers comprises polymers with only arylene ether linkages in the backbone, ie, the 1,4‐polyphenylene oxides. The principal commercial material, poly(2,6‐dimethyl‐1,4‐phenylene oxide) is prepared by oxidative coupling polymerization of 2,6‐dimethylphenol. Its synthesis, reaction mechanism, and properties are described. In addition, compatible blends of poly(phenylene oxides) with polymers such as polystyrene, as well as other types of blends, are mentioned. A second general class of aromatic polyethers that is covered consists of materials containing alternating sequences of polyarylene ethers and other arylene units which are linked by functional groups other than ethers. The latter group includes the commercial materials: polyethersulfones, polyetherketones, and polyetherimides. Syntheses and properties of these are presented.
Ascorbic Acid
Authors: Kuellmer Volker
Published: July 2004

Vitamin C was the first vitamin to be manufactured by chemical synthesis on an industrial scale, and today more vitamin C is produced than any other vitamin. Major suppliers of vitamin C are Hoffmann‐La Roche, BASF, Takeda, and Merck‐Darmstadt. Additional production occurs in Eastern Europe, India, and China. Most of the current industrial production is based on the efficient second synthesis developed by Reichstein and Grüssner in 1934. Various attempts to develop a superior, more economicalL‐ascorbic acid process have been reported since 1934. Much time and effort has been developed to find other methods of vitamin C synthesis by fermentation. The use of the fermentation process for the cost‐effective production ofL‐ascorbic acid, however, requires further improvement.

Both epidemiological and biochemical studies indicate that vitamin C may play an important role in the prevention of cancer, cataracts, and other disorders. However, there are many gaps in the knowledge of vitamin C, eg, in its role in nutritional interrelationships and in metabolic interactions, as well as its role in prevention of various diseases in humans.

Although much additional knowledge concerning the various factors affecting the ascorbic acid status of humans has been acquired in the past decade, the optimum ascorbic acid intake necessary to maintain peak physical and mental health still needs to be established.
Antiparasitic Agents, Avermectins
Authors: Fisher Michael H. , Mrozik Helmut
Published: July 2004

In 1976 scientists at the Merck Corporation discovered a complex of eight closely related natural products, subsequently named avermectins A1athrough B2b, in a culture ofStreptomyces avermitilisMA‐4680 (NRRL8165) originating from a soil sample collected at Kawana, Ito City, Japan and isolated by the Kitasato Institute. Designated A1a(C49H74O14), A1b(C48H72O14), A2a(C49H76O15), A2b(C48H74O15), B1a(C48H72O14), B1b(C47H70O14), B2a(C48H74O15), and B2b(C47H72O15), they are among the most potent anthelmintic, insecticidal, and acaricidal compounds known. Two avermectins, abamectin (the avermectin B1) and ivermectin, which is saturated at C‐22–C‐23, have been commercialized to date. Avermectin B1is the most effective of the avermectin family of natural products against agriculturally important insects and mites. Ivermectin is active against two significant phyla of animal parasite: the Nemathelminthes or nematodes (roundworms) and the Arthropoda (insects, ticks, and mites). Avermectins are highly lipophilic substances and dissolve in most organic solvents. Avermectin B1and ivermectin both contain two secondary and one tertiary hydroxy group. The two secondary alcohols are readily acetylated with acetic anhydride in pyridine. Avermectin B1and ivermectin have two secondary hydroxy groups susceptible to oxidation to the corresponding ketones. Ivermectin (,23—dihydroavermectin B1) is obtained by catalytic reduction of avermectin B1. Methylation of avermectins B1and B2leads to the corresponding derivatives of the A series. The worldwide acceptance of ivermectin in livestock production and health care of companion animals has made it the largest selling animal health drug. Abamectin is in commercial use as an agricultural pesticide and its applications are continuing to expand.
Azine Dyes
Authors: Smith Roy E.
Published: July 2004

Azine, oxazine, and thiazine dyes were among the earliest of synthetic dyes. The names are derived from the 6‐member heterocyclic ring system present in all dyes of these classes: 1,4‐diazine, 1,4‐oxazine, and 1,4‐thiazine. Azine, oxazine, and thiazine dyes were historically more important than they are at present. However, at least one example of each, introduced more than 100 years ago, is still offered commercially today. Azo and anthraquinone dyes have largely displaced them in commercial application. Azo dyes offer better fastness and broader shade ranges at more economical prices. Azine dyes are used extensively as biological stains. Colors are mostly yellow to red. Oxazine dyes have seen use as laser dyes and titration indicators. Oxazine dyes containing sulfonic acid groups are claimed to be suitable for dyeing leather in brown shades. Methylene Blue CI Basic Blue 9(CI 52015), is the classic thiazine dye still in use today. Thiazine is not important in dyes as such, but it is a part of some reactive dyes.
Sugar, Beet Sugar
Authors: Cleary Michael
Published: July 2004

Sugar beets, grown in temperate climates predominately in the northern hemisphere, provide about one‐third of the world sugar supply and about half of the U.S. requirements. The crop is usually harvested at the end of the growing season and held in large storage piles until processing. The beet root, weighing 1–2 kg, contains 12–20% sucrose, 70–75% water, 2% other solubles, and ca 5% insoluble material, which is eventually dried and sold as an animal feed by‐product. The beets are sliced, the solids extracted countercurrently, the juice purified with lime and carbon dioxide then filtered and concentrated, and the sucrose recovered by crystallization in vacuum pans. The final mother liquor, molasses which is about 50% sucrose, may be sold as a by‐product or subjected to chromatographic separation to further recover sucrose and occasionally betaine. Markets for the present and near terms are steady or increasing at a rate of 3–4% per year whereas prices are flat. Although some market segments seem to prefer cane sugar over beet sugar, competitive advantages in the United States depend mainly on the ability to produce and deliver the product at the lowest cost.
Benzene
Authors: Fruscella William
Published: July 2004

Benzene, C6H6, is a volatile, colorless, and flammable liquid aromatic hydrocarbon possessing a distinct, characteristic odor. Benzene is used as a chemical intermediate for the production of many important industrial compounds, such as styrene (polystyrene and synthetic rubber), phenol (phenolic resins), cyclohexane (nylon), aniline (dyes), alkylbenzenes (detergents), and chlorobenzenes. These intermediates, in turn, supply numerous sectors of the chemical industry producing pharmaceuticals, specialty chemicals, plastics, resins, dyes, and pesticides. Benzene has also found limited application in medicine for the treatment of certain blood disorders, such as polycythemia and malignant lymphoma, and in veterinary medicine as a disinfectant. Benzene, along with other light high octane aromatic hydrocarbons such as toluene and xylene, is used as a component of motor gasoline. Benzene is no longer used in appreciable quantity as a solvent because of the health hazards associated with it. Since the 1950s, benzene production from petroleum feedstocks has been very successful and accounts for ∼ 95% of all benzene obtained. Benzene is the simplest and most important member of the aromatic hydrocarbons. Petroleum‐derived benzene is commercially produced by reforming and separation, thermal or catalytic dealkylation of toluene, and disproportionation. Benzene is also obtained from pyrolysis gasoline formed in the steam cracking of olefins. World capacity was 40 × 106t as of Jan. 2000. Several different grades of benzene are commercially available. Benzene is classified as a flammable liquid and should be stored away from any potential source of ignition. Benzene is shipped by rail tank cars, trucks, barges, and tankers. Because of the flammability, toxicity, and volatility of benzene, transfers from one vessel to another are conducted in closed systems. Benzene should be handled only where adequate ventilation is provided; protective clothing and self‐contained respirators are recommended. Benzene is classified as a hazardous waste. Benzene emissions and effluent streams from petroleum refineries or benzene processing plants are also subject to strict federal regulations.
Biocatalysis
Authors: Pannuri Sachin , DiSanto Rocco , Kamat Sanjay
Published: July 2004

Bioorganic catalysis is emerging as a powerful tool to complement traditional catalytic reactions in organic synthesis. A wide range of reactions can be catalyzed using biocatalysts, and this article attempts to introduce the reader to the variety of reactions that have been demonstrated. Although these reactions are possible in the laboratory, the challenge is to make them economically feasible on an industrial scale. Each biotransformation process has some unique obstacles to overcome before it is translated from the laboratory to commercial scale, and some of these problems are discussed. Biocatalytic properties are amenable to dramatic modification using genetic and solvent engineering, setting them apart from traditional catalysts. Many biocatalytic processes are being run on a commercial scale and one such reaction utilizing a transaminase is presented as a case study.
Biosensors
Authors: Turner A. P. F. , Laschi Serena , Mascini Marco
Published: July 2004

Biosensors
are chemical sensors in which the recognition system utilizes a biochemical mechanism. The term biosensor has been variously used to a number of devices either used to monitor living system or incorporating biotic elements. The current consensus is that this term should be reserved for sensors incorporating a biological element such as an enzyme, antibody, nucleic acid, microorganism, or eukariotic cell where the biological element is in intimate contact with the transducer. The main purpose of the recognition system is to provide specificity to the biosensor, thus creating a device able to detect either a specific molecular target or a related family of compounds. The ability of biosensors to detect trace and low levels of biologically active substances is the main characteristic of these systems, and for this reason they have applications in the fields of medicine, biotechnology, food, and environmental science.
Bismuth and Bismuth Alloys
Authors: Chagnon Mark J.
Published: July 2004

The element bismuth, Bi, found in Group 15 (VA) of the Periodic Table, has at no. 83, at wt 208.98. Its valences are +5 and +3. Bismuth is a silvery metal having a high metallic luster and exhibiting a slightly pink tinge on a cleanly broken surface. The metal itself is brittle in nature and easily broken. Bismuth is referred to as a minor metal. Bismuth occurs in the earth's crust in a concentration of approximately 0.1 ppm on the average. The physical properties of bismuth are characterized by a low melting point, a high density, and expansion on solidification. The thermal conductivity of bismuth is lower than that of any other metal except mercury. Bismuth is mined primarily as a by‐product of the processing of ores of other metals, mostly copper and lead. The principal portion of the bismuth in copper ores follows the copper into the matte. During the conversion of the matte to blister copper most of the bismuth fumes off. The fumes are caught in the baghouse or Cottrell system. The portion of the bismuth remaining with the blister copper is separated during the electrolytic refining in the slimes. The bismuth found in the lead ore accompanies the lead through the smelting operation right up to the last refining steps. Bismuth is leached from roasted tin concentrates and other bismuth‐bearing materials by means of hydrochloric acid. There are four basic forms of bismuth that are readily available commercially: ingot, needle, pellet, and powder. The three primary categories of uses of bismuth in industry are chemical, metallurgical additive, and fusible alloy. The Chemical category can be broken down into pharmaceuticals, cosmetics, catalysts, industrial pigments, and electronics, and the metallurgical additive category into steel, aluminum, and cast‐iron additives. The fusible alloy category is divisible into more than a dozen subcategories dependent on a specific application. Because bismuth alloys with certain other metals to give low melting point alloys, bismuth is particularly well‐suited for a number of uses. No industrial poisoning from bismuth has been reported. Ingestion and inhalation of dusts and fumes should be avoided.
Bismuth Compounds
Authors: Breunig Hans Joachim
Published: July 2004

Bismuth is the fifth member of the nitrogen family of elements and like its congeners possesses five electrons in its outermost shell, (6s2)(6p3). In many compounds, the bismuth atom utilizes only the three 6pelectrons in bond formation and retains the two 6selectrons as an inert pair. Compounds are also known where bismuth is bonded to four, five, or six other atoms. Many bismuth compounds do not have simple molecular structures and exist in the solid state as polymeric chains or sheets. Inorganic compounds of bismuth include bismuthine, bismuthides, bismuth halides, bismuth oxide halides, bismuth oxides and bismuthates, higher oxides of bismuth and related compounds, sulfides and related compounds, and bismuth salts. In a manner similar to phosphorus, arsenic, and antimony, the bismuth atom can be either tri‐ or pentacovalent. Methylbismuthine, CH3BiH2, and dimethylbismuthine, (CH3)2BiH, are prepared by the lithium aluminum hydride reduction of methyldichlorobismuthine, CH3BiCl2, and dimethylchlorobismuthine, respectively. Tertiary bismuthines appear to have a number of uses in synthetic organic chemistry and for a number of other industrial purposes. Chloro‐, dichloro‐, bromo‐, and dibromobismuthines are best prepared by the reaction of a tertiary bismuthine and bismuth trichloride or tribromide. Tetraalkyl‐ and tetraaryldibismuthines can be obtained by the reaction of a sodium dialkyl‐ or diarylbismuthide and a 1,2‐dihaloethane. Dibismuthines tend to be thermally unstable. They also are very sensitive to oxidation. Organobismuth(V) compounds have found considerable use as oxidizing agents. After the tertiary bismuthines, the triarylbismuth dihalides constitute the most important class of organobismuth compounds and are by far the largest class of compounds containing pentacovalent bismuth. Very few trialkylbismuth dihalides have been prepared. In addition to use in organic synthesis and limited industrial use, triarylbismuth dihalides have been used as catalysts for the carbonation of epoxides to form cyclic carbonates. A number of bismuthonium ylides, have been prepared and their reactions studied. A number of pentaarylbismuth compounds are known. Pentaphenylbismuth, C30H25Bi, is a violet‐colored, crystalline compound that decomposes spontaneously after standing for several days in a dry nitrogen atmosphere. It has been studied as a reagent in organic synthesis where it can act either as an oxidizing or an arylating agent. Commercially available preparations of Bismuth subsalicylate (Pepto‐Bismol), a basic salt of varying composition, corresponding approximately too‐HOC6H4CO2(BiO), and De‐Nol, tripotassium dicitratobismuthate (bismuth subcitrate) are applied in the treatment of duodenal ulcers, gastritis and diarrhea.
Blood Substitutes
Authors: Winslow Robert M.
Published: July 2004

Artificial blood is herein defined as consisting of red cell substitutes. Red cell substitutes are solutions intended for use in patients whose red cells are either not available or their use is to be avoided for other reasons. More than 100 years of research have been invested in the quest to produce a solution that can be used safely in humans.

Hemoglobin can exist in either of two structural conformations, corresponding to the oxy (Rrelaxed) or deoxy (Ttense) states. The key differences between these two structures are that the constrained T state has a much lower oxygen affinity than theRstate and theTstate has a reduced tendency to dissociate into subunits that can be filtered in the kidneys. Traditional efforts to modify hemoglobin to serve as a cell‐free O2carrier have been directed at stabilization of the T conformation, which would be expected to lower O2affinity of native hemoglobin and to reduce its renal excretion. Currently, the optimal O2affinity of a cell‐free hemoglobin has recently been called into question, but there is no doubt that subunit dissociation needs to be controlled or eliminated.

Differences in the reactions considered to be useful in the production of hemoglobin‐based blood substitutes are determined by the dimensions and reactivity of the cross‐linking reagents. Even small differences among structures of the reagents can yield products having very different properties. In addition, the conditions of the reaction are very important, not only in regard to the state of ligation, ie, oxygen saturation, but also in regard to the presence of agents or molecules that block or compete for certain reactive sites.

Hemoglobin exists in red blood cells in a highly purified form. However, red cell membranes and plasma contain components that could potentially cause toxicity in recipients of large volumes of hemoglobin preparations. Rabiner's method for the filtration purification of hemoglobin was a significant advance over older centrifugation methods, but some hemoglobins prepared in this way have still caused unwanted reactions.

In addition to human blood, bovine and recombinant hemoglobins have also been used as starting materials for products. These are not without their own problems, such as the fear of bovine spongiform encephalitis (BSE) virus in bovine blood and the extensive purification needed to isolate hemoglobin from bacterial or yeast cultures. As of this writing, one product is before the Federal Department of Agriculture (FDA) for final marketing approval, one is in prolonged clinical trials, two have failed dramatically, and at least two new and novel products are in preclinical or early clinical stages.
Boric Acid Esters
Authors: Docks Edward L.
Published: July 2004

The general formula for boric acid esters is B(OR)3. The lower molecular weight esters such as methyl, ethyl, and phenyl are most commonly referred to as methyl borate, ethyl borate, and phenyl borate, respectively. Some of the more common boric acid esters used in industrial applications are trimethyl borate, trimethyl borate azeotrope, triethyl borate, triethyl borate azeotrope, tri‐n‐propyl borate, triisopropyl borate, tri‐n‐butyl borate, triphenyl borate, tricresyl borate, trimethoxyboroxine, and triisopropoxyboroxine. Most reported boric acid esters are trialkoxy or triaryloxy boranes. The esters range from colorless low boiling liquids to solids that possess high melting points. Boric acid esters usually have an odor similar to the hydroxy compound from which they are derived. Alkyl boric acid esters derived from straight‐chain alcohols and aryl boric acid esters are stable to relatively high temperatures. Trialkoxyboranes from branched‐chain alcohols are much less stable, and boranes from tertiary alcohols can even decompose at 100°C. Decomposition of branched‐chain esters leads to mixtures of olefins, alcohols, and other derivatives. Methods used for the preparation of borate esters, include the esterification of boric acid or boric oxide, B2O3, and transesterification. Most methyl borate is produced by Morton International and used captively to manufacture sodium borohydride. Aryl borates produce phenols when in contact with water and are therefore subject to shipping regulations governing such materials and must carry a Corrosive Chemical label. Lower alkyl borates are flammable; methyl, ethyl, and butyl borates must be stored in approved areas. Other compounds are not hazardous. Boric acid esters are used in the production of sodium borohydride, gas fluxing, as polymer additives, in hydraulic fluids and lubricants, as biocides, and in hydrocarbon oxidation.
Boron, Elemental
Authors: Jansen Linda H.
Published: July 2004

Boron, B, is unique in that it is the only nonmetal in Group 13 (IIIA) of the Periodic Table. Boron, at wt 10.81, at no. 5, has more similarity to carbon and silicon than to the other elements in Group 13. There are two stable boron isotopes,10B and11B, which are naturally present at 19.10–20.31% and 79.69–80.90%, respectively. There is a very low cosmic abundance of boron. Boron is the 51st most common element present in the earth's crust at a concentration of three grams per metric ton. Elemental boron has a diverse and complex chemistry, influenced by its having a high ionization energy; by its small size; and by virtue of the electronegativities of boron (2.0), carbon (2.5), and hydrogen (2.1) all being very similar, resulting in extensive and unusual covalent chemistry. Boron has an expected valence of three. There is no formation of univalent compounds. Boron has a high affinity for oxygen‐forming borates, polyborates, borosilicates, peroxoborates, etc. Boron reacts with water at temperatures >100°C to form boric acid and other boron compounds. In addition to being an amorphous powder, boron has four crystalline forms: α‐rhombohedral, β‐rhombohedral, α‐tetragonal, and β‐tetragonal. Boron is an extremely hard refractory solid having a hardness of 9.3 on Mohs' scale and a very low (1.5 × 10−6 Ω−1 cm−1room temperature electrical conductivity so that boron is classified as a metalloid or semiconductor. These values are for the α‐rhombohedral form. The high ionization energies and small size prevent boron from adopting metallic bonding to compensate for its electron deficiency and that of other hypoelectronic elements. A high purity (>99%) boron comes from the direct thermal decomposition of boron hydrides such as diborane, B2H6. The Moissan process, the reduction of boric oxide with magnesium, is the most widely used commercial process for producing boron. Elemental boron is used in very diverse industries ranging from metallurgy to electronics. Other areas of application include ceramics, propulsion, pyrotechnics, and nuclear chemistry. Boron is nontoxic. It is a nutrient essential to plant growth. Workplace hygienic practices include avoiding the breathing of boron dust.
Carboxylic Acids, Branched‐Chain Acids
Authors: Johnson Robert W. , Cantrell Robert R.
Published: July 2004

Branched‐chain acids contain at least one branching alkyl group, which causes different physical, and in some cases different chemical, properties than their corresponding straight‐chain isomers. For example, stearic acid has a melting point of about 69°C, whereas isostearic acid has a melting point of about 5°C.

Manufacturing procedures for most branched‐chain acids are well known. Oxo process acids are manufactured from branched‐chain olefins using hydroformylation followed by oxidation. Neo acids are prepared from selected olefins using carbon monoxide. 2‐Ethylhexanoic acid is manufactured by an aldol condensation of butyraldehyde followed by an oxidation. Isostearic acid is produced from the monomeric acids obtained in the dimerization of unsaturated C
18
fatty acids.

Cobalt and manganese salts of 2‐ethylhexanoic acid are used in the formulation of greases and lubricants. Derivatives of isostearic acid have been used as pour point depressants in two‐cycle engine oils, as textile lubricants, and in cosmetics. The hazards of handling branched‐chain acids are similar to those encountered with other aliphatic acids of the same molecular weight.
Bromine, Organic Compounds
Authors: Ioffe David , Kampf Arieh
Published: July 2004

The scope of the article is limited to those organic bromine compounds having industrial application. The organic bromine compounds are prepared and produced either by substitutive or additive bromination. Organic bromine compounds, in which the bromine atom is retained in the final molecular structure, and where its presence contributes to the properties of the desired products, are the largest segment in terms of consumed volumes. This segment includes mainly flame retardants, biocides, gasoline additives, halons, bromobutyl rubber, pharmaceuticals, and dyes. Brominated flame retardants are the more significant and voluminous part of all bromine derivatives. Bromine consumption in flame retardants forms half of organic bromine compounds consumption. Brominated flame retardants are divided into two general classes according to their relation to polymers ‐ additive flame retardants and reactive flame retardants. The more significant and expanding group of brominated biocides is for water treatment.

Organic bromine compounds have traditionally played an important role as intermediates in the production of agrochemicals, pharmaceuticals and dyes, while new process developments that results in new applications in UV sunscreens, high performance polymers and others.
Powders, Handling, Bulk Powders
Authors: Marinelli Joseph , Carson John W.
Published: July 2004

When work on the development of the theory of bulk solids flow began in the early 1950s, bulk solids were thought to behave much like liquids, and thus were expected to flow easily from bins. Powder flow is not always reliable, however. The field of bulk solids flow has since been developed to allow design of equipment and testing methods.

Typical flow problems include no‐flow (arching, ratholing), erratic flow, flooding, limited discharge rate, and segregation. Flow patterns experienced by bulk solids include funnel flow, which occurs when some of the material in a bin moves toward the outlet while the rest remains stationary; mass flow, where all of a material is in motion whenever any is withdrawn; and expanded flow, which uses the best aspects of funnel flow and mass flow.

Equipment design, maintenance, and special considerations including sifting, particle velocity, and entrainment are discussed.