bluuebunny/crossref_metadata_2025 huggingface dataset:
Oil Shale
Authors: Piper Edwin M. , Heistand Robert N.
Published: July 2004

Oil shale, found in numerous geologic deposits throughout the world, has been used commercially on a very limited scale. The organic matter in oil shale exists as a complex, high molecular weight solid polymer in an inorganic rock matrix. Production costs for crude shale oil are generally much higher than those for conventional crude oil, in part because of the high concentrations of heteroatoms in the crude shale oil. Refining costs are also higher. Retorting processes for oil shale, as well as the upgrading processes needed to refine the crude shale oil into fuels and other products, are described. Shale oil asphalt is the most promising of these products. Several commercial oil shale operations exist, but these are all outside of the United States.
Oils, Essential
Authors: Mookherjee Braja D. , Wilson Richard A.
Published: July 2004

An essential oil is defined as the volatile ethereal fraction obtained from a plant or plant part by a physical separation process. The chemistry of essential oils, with particular reference to their use by the flavor and fragrance industry, is described for 63 different oils. Particular attention is paid to the chemical composition of typical commercially available samples of the oils (down to the 1% level) and, where available, comparison with the headspace constituents of the unprocessed or living botanicals. Reference is frequently made to the importance of trace constituents of the aroma and flavor of the oils. Current analytical methodology, economic aspects, as well as health, safety, and regulatory considerations, are discussed.
Olefins, Higher
Authors: Lappin G. R. , Nemec L. H. , Sauer J. D. , Wagner J. D.
Published: July 2004

This article discusses physical and chemical properties, production methods, uses, and safe handling of the even‐carbon‐number linear α‐olefins. Other higher olefins (branched and/or internal) are discussed briefly. The principal classes of chemical reactions for olefins are addition reactions (electrophilic and free‐radical) and substitution reactions. Common classes of transformations in industrial processes include oxo reaction (hydroformylation), oligomerization and polymerization, alkylation reaction, hydrobromination, sulfation and sulfonation, and oxidation. A low flash point is the main hazard associated with olefins. Flammability limits, autoignition temperatures, and flash points are listed. Olefins should be stored and shipped under an inert atmosphere as many applications are adversely impacted by low levels of moisture, peroxides, and oxygenates.

Most linear α‐olefins were produced from ethylene in 1993 with a total annual capacity of 2,136,000 metric tons. Ethylene oligomerization is discussed for the following commercial processes: (
1
) stoichiometric chain growth on aluminum alkyls followed by displacement (Albemarle); (
2
) catalytic chain growth on aluminum alkyls (Chevron‐Gulf); (
3
) catalytic chain growth using a nickel‐ligand catalyst (Shell); and (
4
) catalytic chain growth using a modified zirconium catalyst (Idemitsu).

Significant outlets for higher olefins are in the polymer, surfactant, and detergent industries. The C
4
, C
6
, and C
8
linear α‐olefins impart tear resistance and other desirable properties to linear low and high density polyethylene. The C
6
, C
8
, and C
10
linear α‐olefins give special properties to plasticizers used in flexible poly(vinyl chloride). The C
10
(and other carbon‐number) linear α‐olefins provide premium value synthetic lubricants.
Oligosaccharides
Authors: Girijavallabhan V. M. , Ganguly Ashit K.
Published: July 2004

Oligosaccharide antibiotics represented by the everninomicins, eg, everninomicin B (C66H99Cl2NO36) and everninomicin C (C63H93Cl2NO34); flambamycins, eg, flambamycin (), avilamycins, eg, avilamycin A (C61H88Cl2O32) and avilamycin B (C59H84Cl2O32); and curamycins, eg, curamycin A (C59H84Cl2O32), have complex and unique structural features. They are sometimes referred to as orthosomycins because characteristically these oligosaccharides possess two acid‐sensitive ortho ester linkages, cleavage of which results in the complete loss of antibiotic activity. Another structural feature common to all the oligosaccharide antibiotics is the presence of a substituted phenol ester derived from dichloroisoeverninic acid attached to the sugar ring B at C‐13, essential for the antibiotic activity. Oligosaccharide antibiotics are colorless solids, are often crystalline, and have defined melting points and optical rotations. They are sensitive to acid pH because of the ortho ester linkages. Yet all of them have an acidic phenolic group which makes the molecule relatively unstable to handling conditions. Everninomicin D is the principal component from cultures ofMicromonospora carbonacae.Chemical modification of the nitro group in everninomicin D has resulted in the formation of amino, mono‐ and dialkylamino,N‐acylamino, andN‐hydroxylamino (and its nitrone derivatives) everninomicin D, all of which possess great antibiotic activity against gram‐positive bacteria. Everninomicin B, a secondary component, has been extensively investigated because of its improved pharmacokinetic properties. Flambamycin, produced byStreptomyces hygroscopicusDS 23230, also has undergone substantial chemical degradative experiments during structure elucidation. The structure, chemical reactions, and biological properties have been thoroughly reviewed. Curamycin A is the primary component of the cultureStreptomyces curacoi.At least 16 avilamycins have been reported. Sporacuracin A, C63H94Cl2O35, mp 145–148°C, [α]D, and sporacuracin B, C63H94Cl2O35, mp 162–165°C, [α]D, are other probable members of the oligosaccharide antibiotic family. Oligosaccharides in general are highly potent, but are narrow‐spectrum antibiotics. Everninomicins are active against a wide variety of gram‐positive aerobes and anaerobes;Neisseria, Mycoplasma, and someMycobacteria.Potential for oligosaccharide antibiotics in both human and animal health care has been claimed.
Information Storage Materials, Optical
Authors: Kämpf Günther , Mergel Dieter
Published: July 2004

In addition to the established magnetic mass storage media (floppy disk, hard disk, tape) optical mass storage media (CD‐ROM (compact disk‐read only memory), WORM (write once, read many times), EOD (erasable optical disk)) are increasingly used. Generally, magnetic and optical media do not compete, but complement each other due to their specific advantages. Progress in optical data storage technology is closely connected with the development of suitable materials. This article illustrates in detail the current state of the art and the ongoing development of materials for optical data storage. For the information layer of WORM disks, dyes with high ir absorption, low heat conductivity, and good solubility are required. Besides polymethine dyes, biaxially substituted silicon–naphthalocyanines are used; also combinations of metal complexes are employed. The magneto‐optical materials for EOD‐disks in MOR (magneto‐optical recording) technique are primarily ferrimagnetic ternary amorphous alloys of rare‐earth (RE) and transition‐metals (TM) (GdTbFe, TbFeCo, DyFeCo). Ferrites with spinel‐ or garnet‐structure, eg, rare‐earth iron‐garnets (RIG), are commercially unimportant mainly due to their high deposition temperature. Co/Pt‐multilayers (MLs) exhibit interesting properties, but are still waiting for commercial introduction. Research concentrates on exchange‐coupled RE‐TM layers, which permit a direct overwrite procedure. Phase‐change materials for EOD‐disks in PCR (phase‐change recording) technique are primarily ternary alloys (eg, GeSbTe, InSbTe). Research focuses on materials with fast crystallization in parallel with high stability even at numerous write/read/erase cycles. As substrate materials for CD‐ROM disks, end group‐modified bisphenol A–polycarbonate (BPA‐PC) is employed exclusively. For WORM and EOD disks mainly BPA‐PC and sometimes glass is applied.
Titanium Compounds, Organic
Authors: Putzig Donald E. , Del Pesco Thomas W.
Published: July 2004

Organic titanium compounds are materials having a covalent bond between titanium and another atom that is also bonded to a carbon‐based group. Titanium tetrachloride, the basic raw material from which organic titanate compounds are made, is readily converted to tetraisopropyl titanate, TYZOR TPT, by the Nelles process. This ester can be converted by alkoxy exchange (transesterification) to a wide variety of tetraalkyl titanates, which in turn react with other ligands and chelating agents to give complexes having properties significantly different from the starting materials. This article covers all aspects of the organic titanium compound, from properties, reactions, and synthesis, to uses and health and safety factors.
Peroxides and Peroxide Compounds, Organic Peroxides
Authors: Sanchez Jose , Myers Terry N.
Published: July 2004

Organic peroxides are compounds possessing one or more oxygen–oxygen bonds that are thermally and photolytically sensitive to facile homolytic cleavage. Thermal decomposition rates are affected by the structure of the organic peroxide and the decomposition conditions. The initially formed free radicals from the oxygen–oxygen bond homolysis are reactive intermediates which quickly undergo a variety of subsequent reactions to form stable products. Thermolysis of organic peroxides is used commercially to initiate free‐radical reactions, eg, halogenation, vinyl monomer polymerization, unsaturated resin cure, polyolefin cross‐linking and rheology modification. Many organic peroxides also undergo reactions in which free radicals are not involved, eg, heterolyses, hydrolyses, reductions, and rearrangements.

This article reviews the physical and chemical properties, synthetic methods, and the principal commercial uses of organic peroxides of the following classes: hydroperoxides, dialkyl peroxides, α‐oxygen‐substituted hydroperoxides and dialkyl peroxides, ozonides, peroxyacids, diacyl peroxides, and alkyl peroxyesters. Class discussions cover the broad structural variation that is possible, including organomineral and polymeric derivatives when appropriate. Emphasis is placed on the relationship between peroxide structure and reactivity (thermal stability). Physical hazards associated with organic peroxide manufacture, handling, storage, transportation, and use are discussed. An overview of health hazards associated with handling of organic peroxides is presented.
Petroleum, Origin of
Authors: Barker Colin
Published: July 2004

Accumulation of oil and gas in natural reservoirs begins with sediments incorporating organic matter as these are deposited. Upon increasing depth of burial, rising temperature converts the complex insoluble organic material called kerogen into a lower molecular weight, solvent‐extractable material called bitumen. This reaction is essentially first‐order. Generation of bitumen occurs at lower temperatures in older rocks. Part of the bitumen may migrate and accumulate in reservoirs as a commercial accumulation of petroleum. This migration process is not fully understood. Bitumen is probably expelled from the source rock as a separate petroleum phase. The type of organic matter in the source rock exercises initial control on whether oil or gas is generated, but considerable modification of petroleum composition can occur after it accumulates in the reservoir. Rising temperature owing to increasing burial depth, water flowing past an oil reservoir, and bacteria can all play a role. Thus the origin of petroleum involves generation in source rocks, migration to a reservoir, and the possibility of further modification of composition after accumulation.
Glycols, Other Glycols
Authors: PARSONS T. E.
Published: July 2004

Glycols such as neopentyl glycol, 2,2,4‐trimethyl‐1,3‐pentanediol, 1,4‐cyclohexanedimethanol, and hydroxypivalyl hydroxypivalate are used in the synthesis of polyesters and urethane foams. Commercial preparation of neopentyl glycol can be via an alkali‐catalyzed condensation of isobutyraldehyde with 2 moles of formaldehyde (crossed Cannizzaro reaction). A number of derivatives of neopentyl glycol have been prepared; some show promise for commercial applications. 2,2,4‐Trimethyl‐1,3‐pentanediol can be produced by hydrogenation of the aldehyde trimer resulting from the aldol condensation of isobutyraldehyde.

The manufacture of 1,4‐cyclohexanedimethanol can be accomplished by the catalytic reduction under pressure of dimethyl terephthalate in a methanol solution. Hydroxypivalyl hydroxypivalate may be produced by the esterification of hydoxypivalic acid with neopentyl glycol or by the intermolecular oxidation–reduction (Tishchenko reaction) of hydroxypivaldehyde using an aluminum alkoxide catalyst.

Polyester resins are useful for preparation of coatings exhibiting a combination of hydrolytic stability, excellent weather resistance, and good flexibility.
Chloroethylenes
Authors: Snedecor Gayle , Hickman J. C. , Mertens James A.
Published: July 2004

The physical and chemical properties, manufacturing methods, uses, environmental concerns, and toxicity of 1,2‐dichloroethane are discussed.

1,2‐Dichloroethylene, also known as acetylene dichloride, dio‐form,α,β‐dichloroethylene, andsym‐dichloroethylene, exists in two isomers cis[156‐59‐2] and trans[156‐59‐2]. This solvent is used as an extraction solvent and as a chemical intermediate for other chlorinated solvents and compounds. The article describes the manufacturing, chemical and physical properties, storage and handling, toxicity, and its common uses.

Trichloroethylene, commonly referred to as “tri”, is a widely used vapor‐degreasing solvent. In recent years its popularity has fallen mostly because of environmental restrictions on its use. Trichloroethylene has excellent solvency properties for a large number of natural and synthetic substances. This article includes physical and chemical properties, production, and use information. In addition, safety, toxicological, and environmental regulations pertinent to trichloroethylene are reviewed.

Tetrachloroethylene [127‐18‐4], perchloroethylene, tetrachloroethene, commonly referred to as “perc,” is widely used in the dry‐cleaning industry as well as metal cleaning and vapor degreasing because of its excellent solvent properties. It has no flash point or flammable limits in air or oxygen. This article includes the physical and chemical properties of tetrachloroethylene, historical production within the United States, manufacturing locations and processes, as well as typical quality specifications. In addition, safety and toxicological considerations and environmental regulations pertinent to tetrachloroethylene are reviewed.

The Montreal Protocol has had an impact on all of the compounds discussed in this article.
Flame Retardants: An Overview
Authors: Gann Richard G. , Gilman Jeffrey W.
Published: July 2004

Flame retardant additives are ubiquitous in commercial products. They reduce fire losses by decreasing the likelihood of ignition and the rate of heat release of the products in which they are compounded. This article outlines the definition, applications, and functions of fire retardant additives. It also presents the classes of these chemicals and their market presence and risks.
Ceramics, Overview
Authors: Loehman Ronald
Published: July 2004

Ceramics are a class of inorganic, nonmetallic solids that are subjected to high temperature in manufacture or in use. The classification of ceramic, typically a polycrystalline material, extends to glasses, which are noncrystalline, and to such single‐crystal materials as a ruby laser. There are the low value‐added bulk or commodity materials such as pottery and abrasive grain, and the engineering or fine ceramics which are low volume, high value‐added, highly processed materials having carefully controlled properties. The most common ceramics are oxides, carbides, and nitrides, but silicides, borides, phosphides, sulfides, tellurides, and selenides are also ceramics, as well as elemental materials such as carbon and silicon.

Processing techniques play an important role in determining the properties of a ceramic. These techniques, the resultant structures, and the relationship to mechanical and electrical properties of engineered ceramics are discussed as are fracture and wear‐resistant materials, inorganic glasses, and optoelectronic and electronic ceramics.
Oxalic Acid
Authors: Sawada Hiroyuki , Murakami Toru
Published: July 2004

The properties of anhydrous oxalic acid and oxalic acid dihydrate are discussed, tabulating their physical and thermochemical constants. The reactions of oxalic acid are also included.

Five manufacturing processes which are employed for commercial production are illustrated: oxidation of carbohydrates, ethylene glycol process, propylene process, dialkyl oxalate process, and sodium formate process. The newest of the five, the dialkyl oxalate process (from UBE) is discussed in depth. Advances are covered, including a new synthetic route from CO2.

Economic aspects of oxalic acid are described, outlining the regional features in the world market. Shipment, storage, and handling are included, covering disposal methods. Health and safety factors and toxicology are also presented.

Uses of oxalic acid are described, including separation/recovery of rare‐earth elements, metal treatment, bleaching agents, textile treatment, leather tanning, marble polishing, millet jelly production, etc. Derivatives, such as salts/complexes and organic derivatives, are also presented. Vol. 17, pp. 882–902, 91 refs to December 1993.
Oxo Process
Authors: Billig Ernst , Bryant David R.
Published: July 2004

The oxo process, also known as hydroformylation, is the reaction of carbon monoxide and hydrogen with an olefinic substrate to form isomeric aldehydes. Oxo aldehyde products range from C
3
to C
15
and are used as intermediates to alcohols, acids, polyols, and esters by the appropriate reduction, oxidation, or condensation chemistry.

Hydroformylation occurs most frequently in the liquid phase in the presence of a soluble metal catalyst, most frequently a member of the Co–Rh–Ir triad. The first commercial oxo catalyst was cobalt hydrocarbonyl, which has been largely replaced for both ethylene and propylene hydroformylation by more reactive, more selective ligand‐modified rhodium catalysts. Various metal catalysts and ligands, required reaction conditions, and mechanisms are discussed. The most widely employed commercial ligand is triphenylphosphine. Propylene is by far the dominant olefinic substrate subject to the oxo process. Butanals are the largest‐volume product. In the United States these aldehydes are converted principally to butanols; in Europe and Japan,
n
‐butanal is converted chiefly into the plasticizer alcohol, 2‐ethyl‐1‐hexanol. Other oxo process products include both linear and branched higher alcohols, propionaldehyde, and valeraldehyde. Vol. 17, pp. 902–919, 36 refs. to April 1995.
Paint and Finish Removers
Authors: White David L. , Bardole Jay A.
Published: July 2004

Finish removers play an important role in the recycling of durable goods. Finishes are removed from antiques in the process of restoration. Original equipment manufacturers remove coatings from rejected parts. Lead‐based paints are removed for the safety of those living in lead exposure environments. Finishes are removed from woods, metals, and plastics. No single type of remover can be effective in all of the 107 different applications in which removers are used. Finish removers include a major active component. The formulator can also choose from co‐solvents, diluents, evaporation retardants, emulsifiers, activators, thickeners, and corrosion inhibitors to make the remover best suited for any application. Considerations important when selecting a finish remover include how well it works, how quickly it works, and the cost per amount of work done. It is also important to consider the safety of the person using the remover and the impact the finish removal process will have on the environment. Manufacturing is best done in closed kettles for the protection of the worker and the environment.
Pantothenic Acid
Authors: Rawalpally Thimma R.
Published: July 2004

(R)‐Pantothenic acid is a water soluble B‐complex vitamin. Pantothenic acid is an essential vitamin needed to synthesize coenzyme A and the acyl carrier protein (ACP) portion of fatty acid synthetase. Both animals and microbes convert pantothenic acid into metabolically active coenzyme A by a number of enzymatic reactions. The pathway for this enzyme conversion has been elucidated and has been reviewed extensively. Only (R)‐pantothenic acid is biologically active. Although well‐defined pantothenic acid deficiency in humans has not been reported, deprivation of pantothenic acid results in metabolic impairments, including reduced lipid synthesis and energy production. (R)‐Pantothenic acid is extremely hygroscopic. Consequently, the major commercial form of pantothenic acid is calcium‐(R)‐pantothenate. The key step in the present commercial chemical synthesis of (R)‐pantothenic acid involves resolution of racemic pantolactone. Recent industrial synthetic efforts have been directed towards developing a method for enantioselective synthesis of (R)‐pantolactone either by chemical or microbial reduction of ketopantolactone. To date, the microbial reduction of ketopantolactone is a promising approach, but commercialization of this process has yet to be realized. Calcium‐(R)‐pantothenate is used in food and feed enrichment. Panthenol and pantyl ether are industrially important derivatives of pantothenic acid and are used in hair care products.
Recycling, Paper
Authors: Borchardt John K.
Published: July 2004

Recycling of used paper products is increasing rapidly, particularly in North America. Recovered paper that is recycled includes old newspapers and magazines, old corrugated containers, and printing and writing paper. Recycled paper products include newsprint, magazine paper, corrugated cartons, other boxes, and printing and writing paper.

Paper recycling mills are a series of unit operations designed to disintegrate paper to form pulp, detach ink and other contaminants such as adhesives from cellulose fibers, and separate the dispersed contaminants from the cellulose fibers. The fibers are optionally bleached and then made back into paper. The type of paper, types of contaminants present, and recycled paper product determine the choice of unit operations and their sequence. In particular, different ink types such as toner inks affect mill design and the choice of process chemicals. Both chemical and mechanical phenomena promote contaminant detachment from cellulose fibers and separation of the dispersed contaminant particles from pulp. Important chemicals used in paper recycling include agents to provide high pH, dispersants, surfactants, chelants, and bleaching agents. More paper recycling mills are clarifying and reusing process water. As a result, water clarification has become an important part of mill operations.
Papermaking Additives
Authors: Dulany Margaret A. , Batten George L. , Peck Michael C. , Farley Charles E.
Published: July 2004

In papermaking, chemical additives can be characterized either as process additives or as functional additives. Process additives are materials that improve the operation of the paper machine and include retention, formation, and drainage aids; defoamers; wet‐web strength additives; pitch control agents; effluent treatment aids; slimicides and biocides; and creping aids. Functional additives are materials that enhance or alter specific properties of the paper product, and include sizing agents; dry‐strength and wet‐strength additives; fillers; pigments; and synthetic fibers. Process additives are primarily added internally, ie, at the wet end of the paper machine, while the sheet is being formed. Functional additives may be added either internally or onto the surface of the sheet, ie, at the dry end of the paper machine. The chemistry, mechanisms, and interactions of these various additives with other additives and with the papermaking fibers are discussed. Methods that test the effectiveness of the chemical additives are mentioned. Attention is also given to the effect that recycled fibers have on the use of papermaking additives, and to other environmental concerns.
Patents, Literature
Authors: Simmons Edlyn S. , Kaback Stuart M.
Published: July 2004

Patents form a significant component of the literature of technology. The intensification of effort on research and development in the aftermath of World War II produced a sharp increase in the number of patents being produced and led to the increased publication of unexamined patent applications, which compounded the growth of this literature. Among the outgrowths of this situation have been a modification of patent documents, especially their front pages, to make them more informative, the introduction of a wide range of new services that provide alerting and retrospective search capabilities for patents, the rapid development of computer storage and searching techniques for patent information, and the rapid development of archival and delivery systems for patent documents themselves. The contributions of many governmental, scientific, and commercial organizations to these developments are surveyed in this article.
Antimicrobial Peptides
Authors: Mor Amram
Published: July 2004

The twentieth century antibiotic armamentarium included a number of peptide‐based compounds, mostly produced by spore‐forming microorganisms. Characteristically, these peptide antibiotics are synthesized by multienzymatic complexes and display complicated molecular structures. Peptide antibiotics, however, were seldom the drugs of choice for systemic therapy because of toxicities. At the dawn of the twenty‐first century, the use of peptide‐based antibiotics is envisioned anew with more optimism, due to the discovery of a novel class of ribosome derived antimicrobial peptides that display promising properties. Animal‐derived antimicrobial peptides are believed to kill target cells by disrupting their membrane(s). Compared with conventional antibiotics this peptide‐based antimicrobial system represents several advantages: (1) antimicrobial peptides seem to escape most known drug resistance mechanisms; (2) they have a large spectrum of potential targets with rapid cidal activity toward bacteria, protozoa, yeast, fungi, enveloped viruses, and cancer cells; (3) they portray a highly modulable antimicrobial system since peptide chemistry allows a multitude of simple, rapid and cost‐effective chemical modifications. In addition to their membrane disrupting activity, antimicrobial peptides are reportedly able to—directly as well as indirectly ‐ modulate responses of the innate immune system. Such antimicrobial system is attracting increasing interest for a variety of potential biomedical applications, including its use in therapeutics and as a food preservative. A few antimicrobial peptides are presently being evaluated in various stages of clinical trials, mostly for topical applications. In the future, however, the deplorable situation of ever increasing multidrug resistance and the lack of available alternatives may reveal strong enough arguments to stimulate the development of strategies that will allow the safe systemic administration of such peptides and put to advantage their incontestable advantageous properties.
Perchloric Acid and Perchlorates
Authors: Mendiratta Sudhir K. , Dotson Ronald L. , Brooker Robert T.
Published: July 2004

Perchlorates are chlorine oxyanions in which the chlorine is present in its highest oxidation state (\documentclass{article}\pagestyle{empty}\begin{document}${{\rm{+}}7}$\end{document}). The most outstanding property of the perchlorates, which are more stable than other chlorine oxyanions, is their oxidizing ability. Most cations form perchlorate compounds. Commercially, one of the most important compounds of this class is ammonium perchlorate, used as an oxidizer in propellant formulations for solid rocket fuel. Perchlorates are also used in explosives and pyrotechnics, in dry batteries, and in oxygen‐generation systems. Commercial perchlorates are prepared by electrochemical oxidation. Perchloric acid, commercially available as a 72% aqueous solution, is one of the strongest of the mineral acids. Properties, manufacturing, and uses of these compounds are described.
Fluorine‐Containing Polymers, Perfluoroalkanesulfonic Acids
Authors: Savu Patricia
Published: July 2004

Perfluoroalkanesulfonic acids and their derivatives are of commercial significance because of their unusual acid strength, chemical stability, and the surface activity of the higher members of the series (eight carbons and larger). The best method of preparation is via the perfluorinated sulfonyl fluorides derived from electrochemical fluorination, although other methods including direct fluorination with fluorine gas are known. The first member of the series, trifluoromethanesulfonic acid, is one of the strongest acids known. Alkyl esters of trifluoromethanesulfonic acid are among the best leaving groups known and are commonly used in that capacity in displacement reactions. Lithium trifluoromethanesulfonate solutions are very conductive and can find application as electrolytes in primary lithium batteries and as antistats for films.

Derivatives of the longer‐chain perfluoroalkanesulfonic acids have a number of unique surface‐active properties and have formed a basis for a number of commercial products. The longer‐chain acids and their salts, particularly C8F17SO3H and higher, are surface‐active agents in aqueous media. They reduce the surface tension of water to levels not possible with hydrocarbon surfactants. Preparation of difunctional perfluoroalkanesulfonates and their derivatives is discussed, including fluorosulfonylacetyl fluoride. Fluorosulfonyldifluoracetyl fluoride is an important industrial intermediate used in the production of Du Pont's Nafion ion‐exchange membranes and in many other applications.
Perfumes
Authors: Schreiber William L.
Published: July 2004

This article surveys the essential aspects of perfume creation and the fragrance industry, providing brief notes on the history of fragrance use and a list of odor descriptors. It discusses the creation of and illustrates with examples both fine and functional fragrances, summarizing in particular the performance requirements of the latter group in a number of applications. It describes different perfume ingredients, natural as well as synthetic, and offers information about their origin, fragrance characteristics, and uses. In addition, it examines the chemical structures and odors of some typical aroma chemicals by functional groups.

The article also covers such topics on fragrance research as the analysis of natural products, synthesis of aroma chemicals, structure–odor considerations, process research and development, and psychological effects of fragrance. Finally, it reviews the manufacture and quality control of perfumes and ingredients, and supplies an overview of the economic, safety, environmental, and regulatory aspects of the industry.
Feeds and Feed Additives, Pet Foods
Authors: Corbin James
Published: July 2004

Studies have provided extensive information about the nutritional requirements of dogs and cats. Commercial pet food is available in canned, semimoist, and dry forms; dry food may be either pelleted or extruded. Pet food formulations contain as many as 50 nutrient (amino acids, fats, fibers, etc) and nonnutrient (antioxidants, flavor enhancers, etc) additives. The Association of American Feed Control Officials has developed nutrient profiles for dog and cat foods.
Feedstocks, Petrochemicals
Authors: Aubrey Darryl C.
Published: July 2004

Petrochemicals are derived from natural gas or petroleum and can be broadly classified as olefins or aromatics. The choice of feedstock for a given operator is primarily an economic issue, but may be constrained by technical considerations or local availability of indigenous hydrocarbons. Feedstock economics are influenced by fuels products markets and the seasonal effects in fuels prices. Olefins are produced primarily by the thermal cracking of hydrocarbon feedstocks such as ethane, propane, naphtha, or gas oil. In the United States the most important olefin feedstocks are ethane and propane, which are recovered from natural gas, whereas in most of the rest of the world naphthas are the dominant feedstocks. Lesser quantities of olefins, primarily propylene, are produced from refinery off‐gases. Aromatics are recovered from refinery catalytic reformer operations and pyrolysis gasoline from olefin plants based on naphtha or gas oil feedstock. In the United States, reformer operations are the most important source; in the rest of the world, pyrolysis gasoline is the dominant feedstock. Although alternative feedstocks have been the subject of much research, only minimal usage can be expected over the coming decades.
Controlled Release Technology, Pharmaceutical
Authors: Edgren David , Leeper Harold , Nichols Kirstin , Wright Jeremy
Published: July 2004

Controlled release dosage forms enhance the safety, efficacy, reliability, and convenience of drug therapy by controlling the rate and duration of drug release to control drug actions and to reduce the frequency of drug administration, thus encouraging patient compliance. Controlled release pharmaceuticals are designed to release drugsin vivoaccording to a predictable, therapeutically rational programmed rate to achieve the optimal serum‐drug concentration in the minimal time. The most familiar of these systems are taken orally, but a growing number are designed for less conventional body sites such as the rectum, skin, oral cavity, nose, lungs, eyes, uterus, and vagina. The energy sources for controlled drug delivery are typically processes or properties such as biodegradation, diffusion (from matrix and membrane systems), elasticity, electricity, osmosis, pH sensitivity, and vapor pressure. Increasingly important applications of controlled release technology include patterned, targeted, triggered, and closed‐loop delivery.
Phosphazenes
Authors: Books Jeffrey T.
Published: July 2004

Polyphosphazene elastomers are phenolic or fluoroalkoxy substituted polymers with a backbone of alternating phosphorus and nitrogen atoms. They have a number of advantages due to the flexibility of the backbone and its inertness. Fluoroalkoxyphosphazenes have found utility in applications requiring low temperature flexibility, oil resistance, and stability to 150–175C. Damping properties have also proven useful. Aryloxyphosphazenes are nonflammable without containing halogens. This has led to applications requiring extreme fire safety. This article discusses these properties and the resulting uses of these materials. Background information is provided on the synthesis routes to these elastomers and related compounds. Toxicology is briefly mentioned, and limited references are also provided to other application areas of phosphazene derivatives.
Phosgene
Authors: Dunlap Kenneth L.
Published: July 2004

Phosgene is a colorless, low boiling liquid which is manufactured by reaction of carbon monoxide and chlorine over activated carbon. It is a very toxic substance, and extensive safety procedures and equipment have been developed to help ensure the safe handling of phosgene. Phosgene is an important and widely used intermediate for chemical synthesis. Its primary use is for the manufacture of polyisocyanates for the polyurethane industry. Other uses are the production of polycarbonate, chloroformates, agrochemicals, and intermediates for pharmaceuticals and dyestuffs.
Phosphorus Compounds
Authors: Fee Darrell C. , Gard David R. , Yang Chen‐Hsyong
Published: July 2004

Phosphorus compounds exhibit an enormous variety of chemical and physical properties as a result of the wide range in the oxidative states and coordination numbers for the phosphorus atom. The intermediate electronegativity of phosphorus also plays a role. Phosphorus oxides, halides, sulfides, hydrides (phosphines), nitrogen compounds, and metal phosphides, as well as organophosphorus compounds, are reviewed. Emphasis is placed on the commercially important phosphorus trichloride, phosphorus pentachloride, phosphorus pentasulfide, phosphorus(V) oxide, and phosphine. Structure and nomenclature of phosphorus compounds and their organic derivatives are presented. Properties of the P–O, P–S, P–H, P–C, and P–X (\documentclass{article}\pagestyle{empty}\begin{document}${{\rm{X}}={\rm{halogen}}}$\end{document}) bonds are given. The manufacture of the commercial phosphorus compounds are outlined. Phosphorus compounds are found in or used as intermediates for the manufacture of oil additives, heat‐transfer and hydraulic fluids, water‐treatment chemicals, catalysts, herbicides, flame retardants, pesticides, pharmaceuticals, semiconductors, and surfactants. Intermediates in the preparation of organophosphorus derivatives are reviewed.
Phosphine and Its Derivatives
Authors: Rickelton William A.
Published: July 2004

Phosphine, PH3, was discovered over 200 years ago but the first, large‐scale production of this compound and its derivatives did not begin until the mid‐ to late 1970s. The delay was due largely to the pyrophoric and highly toxic nature of phosphine which requires specialized technology for safe handling. Nevertheless, two viable manufacturing processes were eventually invented, patented (in 1961 and 1962), and later commercialized.

This article describes these processes and compares their advantages and disadvantages. However, more emphasis is given to the growing number of applications for this relatively new and versatile class of specialty chemicals. Phosphine itself is used both as a dopant in semiconductors and as a fumigant for grain silos. The former requires high purity or electronic‐grade phosphine, whereas in the latter case, less pure phosphine is employed as a 2% mixture with carbon dioxide. The derivatives of phosphine, such as alkylphosphinic acids, phosphine oxides, and phosphonium salts find utility as textile flame retardants, mining chemicals, solvent extraction reagents, biocides, phase‐transfer catalysts, and uv photoinitiators. The chemistry involved in the synthesis of these compounds is discussed in addition to the applications.
Flame Retardants, Phosphorus
Authors: Weil Edward D.
Published: July 2004

One of the principal classes of flame retardants for plastics and textiles is that of phosphorus, phosphorus‐nitrogen, and phosphorus‐halogen compounds. These flame retardants are also used for wood and paper. The mechanisms of action, which may be in the condensed or vapor phase or in both, are presented. The interactions with other flame retardants are discussed.

Commercial phosphorus‐based flame retardants include some inorganic compounds as well as both additive and reactive organic phosphorus systems. These materials range from simple salts to oligomeric compounds and encompass both liquids and solids. Some commercial products are pure compounds. Others are mixtures. The various compounds, corresponding structures, and specific uses are given. The toxicity of these products is discussed.
Photodetectors
Authors: Wadsworth Mark
Published: July 2004

Photodetectors, based on photon absorption or thermal emission, are made from semiconductor materials that are very sensitive in the spectral range from ultraviolet to far infrared. Detector figures of merit such as responsivity, noise, noise equivalent power and detectivity, and ideal performance and cooling requirements are given. Modes of operation include charge‐coupled device, photovoltaic diode, photoconductor, and bolometer. Most semiconductor detectors operate as photon detectors where the minimum photon energy detected is defined by a discrete activation energy of the semiconductor. However micromachined bolometers are in development for thermal imaging and chemical spectroscopy. Materials and detector types are discussed.

Detector material preparation technologies are presented for intrinsic detectors where the photon absorption coefficient is high, and for the low absorption coefficient detectors such as impurity‐doped Ge or Si. Fabrication technology making possible large photodetector focal planes that detect photons and perform signal processing are integrated structures either in monolithic form or in hybrid form. The monolithic arrays range up to 106detectors. The hybrid focal planes, mostly for infrared detection, contain up to 105. Photodetector arrays have been developed for imaging across the spectrum and are used in CCD cameras, chemical spectroscopy, missile seekers, and night vision equipment.
Photography
Authors: Locker David J.
Published: July 2004

Conventional silver halide‐based photography is discussed. The key subprocesses in the photographic industry are examined. The manufacture of photographic films and papers begins with the production of silver halide microcrystals which are grown via the controlled mixing of silver nitrate and alkali halides in an aqueous environment, a process generally referred to as emulsion precipitation. To increase the light sensitivity of the resulting microcrystals, two sensitization processes are employed: chemical sensitization and spectral sensitization. Chemical sensitization usually involves the addition of trace levels of gold‐ and sulfur‐containing compounds to the surface of the microcrystalline silver halide grains. These sensitizing chemicals increase the sensitivity of the crystals to photons absorbed during exposure. Because silver halides do not significantly absorb photons with wavelengths greater than 500 nanometers, spectral sensitizing dyes are adsorbed to the surfaces of the microcrystals. Dyes are selected to provided sensitivity to different wavelengths depending on the photographic application. After the sensitization process is complete, the silver halide crystals can be coated on film or paper bases. Gelatin is used as the supporting vehicle for the sensitized microcrystals. Exposure generates mobile conduction band electrons and valence band holes and ultimately yields small nuclei which contain only a few atoms of metallic silver. These silver nuclei are referred to as latent‐image centers and provide a site for subsequent catalytic amplification during development. High amplification gains during development, image sharpness, low granularity, and archival permanence of developed photographic images are some of the reasons why conventional photography holds a preeminent position in the image‐formation industry.
Photocatalysis
Authors: Serpone Nick
Published: July 2004

When photons are implicated in a catalytic reaction, the system becomes a photocatalytic one. The catalyst may accelerate the photoreaction by interaction either with a substrate in its ground or an excited state, and/or with the primary photoproduct. Although not yet commercially viable, photocatalytic processes may provide an alternative to the traditional routes to water purification, destroying bacterial substances, and dissolved organics in waste streams. The process can be homogeneous, employing an oxidant and ultraviolet light, or heterogeneous, utilizing air, semiconductor particles (the photocatalyst), and ultraviolet radiation. These various pathways are discussed.

The mechanistic details of using semiconductor particles as light harvesters is reviewed, as are the mechanisms by which the photooxidation occurs. Examples of aqueous dissolved organic compounds photooxidized to carbon dioxide and water in the presence of titanium dioxide, air, and near‐ultraviolet radiation are given.
Photoconductive Polymers
Authors: Wang Ying
Published: July 2004

Photoconductive polymers are insulators in the dark but become conductive when irradiated by light. They are widely used in the imaging industry as either photosensitive receptors or carrier transporting material in copy machines and laser printers (electrophotography). This is one of the few areas in electronics in which polymers are used on a large‐scale industrial basis and are clearly superior or equivalent to inorganic semiconductors.

This article reviews material properties of a wide variety of photoconductive polymers. Important parameters such as carrier mobility and charge‐generation efficiency are tabulated. Mechanisms for charge generation and charge transport of polymers are discussed. Potential applications in areas other than electrophotography are also considered.
Phthalocyanine Compounds
Authors: Loebbert Gerd
Published: July 2004

Phthalocyanines, a class of organic dyes, were discovered in 1907 and today are the main organic blue and green pigments in the industry. Phthalocyanines form complexes with a variety of chemical elements. The most important phthalocyanine, copper phthalocyanine, is produced worldwide. Synthesis usually starts with phthalodinitrile and metal or phthalic anhydride, urea, and metal salts as the starting materials. The reactions can be carried out in a solvent or at higher temperatures in a dry state. The chemical stability and physical properties have stimulated applications of phthalocyanines in fields like semiconductors, catalysts, lasers, and lubricants. However, 90% of the phthalocyanines are used as pigments for printing inks, paints, coatings, plastics, textile, and spin dyeing industries. Phthalocyanine dyes are predominantly used for dyeing of textiles, paper, and leather. The predominant phthalocyanine derivatives are formed with halogens (green pigments), sulfonic acids, and sulfonyl chlorides (dyes).
Phthalic Acids and Other Benzenepolycarboxylic Acids
Authors: Park Chang‐Man , Sheehan Richard J.
Published: July 2004

There are 11 benzenepolycarboxylic acids, some of which are sold as the anhydride or the methyl ester. Two of these substances, terephthalic acid and phthalic anhydride, are principal chemical products. Two others, isophthalic acid and trimellitic anhydride, have substantial commercial sales. The rest have low volume specialized applications or are not available commercially. This is a review of the basic physical properties, manufacturing methods, production volumes and prices, toxicological aspects, and uses of these compounds.

Terephthalic acid and its dimethyl ester rank about tenth in tonnage for all organic chemicals, and production is expanding substantially. They are used to make poly(ethylene terephthalate) for fibers, film, and containers. The principle mode of commercial manufacture is direct liquid‐phase oxidation ofp‐xylene using a homogeneous heavy metal–bromine catalyst system. Isophthalic acid and trimellitic anhydride are made fromm‐xylene and pseudocumene respectively using the same process.

Phthalic anhydride is made primarily by gas‐phase oxidation ofo‐xylene over a fixed catalyst containing vanadium and titanium oxides. It is used as a raw material for plasticizers, unsaturated polyesters, and other resins.
Chromogenic Materials, Piezochromic
Authors: Samat A. , Guglielmetti R.
Published: July 2004

In its most general sense the term, piezochromism, is defined as the change in color of a solid under compression.

There are three aspects of the phenomenon: The color of a solid results from the absorption of light in selected regions of the visible spectrum by promotion of an electron from the ground electronic state to a higher level. If the two electronic energy levels are perturbed differently by pressure, compression results in a color change. This is the basic definition of pressure tuning spectroscopy.

A discontinuous change of color occurs when a crystalline solid undergoes a first‐order phase transition from one crystal structure to another.

The phenomenon of most interest is change in color of a solid as a result of a change in the molecular geometry of the molecules that make up the solid.

The main piezochromism systems are organic molecules in crystals and polymer films (anils, conjugated polymers, polysilenes, heterocyclic compounds, betaine derivatives), coordination compounds and metal cluster compounds, and organometallic complexes of copper (II). Their behavior and physico–chemical properties are discussed.