bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular Sieves
Authors: Kühl Günter H. , Kresge Charles T. 
Published: July 2004

Abstract
Molecular sieves are inorganic materials that possess uniform pores with diameters in either the micro‐ or meso‐size range. Heterogeneous catalysis and adsorption processes make extensive use of molecular sieves. The utility of these materials is manifested in their microstructures, which allow access to large internal surfaces and cavities that enhance catalytic and adsorptive capacity.
The most technologically important molecular sieves are zeolites, which are high capacity, selective adsorbents capable of separating molecules based on the size and shape of the molecule relative to the size and geometry of the main apertures of the structures. They adsorb molecules with a selectivity that is not found in other solid adsorbents. Structure, manufacture, uses, properties, health and safety factors, and economic aspects are discussed.
Molecular Recognition
Authors: Weber Edwin 
Published: July 2004

AbstractMolecular recognition is a central point. It may be said that without molecular recognition, there would be no life on this world. Vital biochemical processes such as enzyme action, molecular transport, genetic information, processing and protein assembly all involve molecular recognition as an essential action. Understanding of its principles is still a problem although a first elucidation of the rules that govern molecular recognition dates back to the late nineteenth century. The “lock‐and‐key” principle (1894) proposed that enzyme and substrate can be compared to lock and key getting selectivity between molecules involved. Earlier it was recognized that molecules do not act if they do not bind, thus introducing the concept of receptor. Finally binding or fixation requires interaction, affinity between the partners, that may be related to the idea of coordination of Werner.According to these basic concepts, molecular recognition implies complementary lock‐and‐key type fit between molecules. The lock is the molecular receptor and the key being the substrate that is recognized and selected to give a defined receptor–substrate complex, a coordination compound or a supermolecule. Hence molecular recognition is one of the three main pillars, fixation, coordination, and recognition, that lay foundation of what is now called supramolecular chemistry.
Molybdenum Compounds
Authors: Stiefel Edward I. 
Published: July 2004

AbstractMolybdenum, found naturally as molybdenite, is converted through MoO3to compounds in a wide range of oxidation states, coordination numbers, and states of aggregation. The diverse chemistry of molybdenum is manifest in a wide array of uses in biological and industrial systems. Molybdenum, an essential component of many enzymes, plays a primary role in nitrogen fixation and nitrate reduction in bacteria and plants, and sulfite and xanthine oxidation for microorganisms, plants, and animals. Industrially, molybdenum compounds are important in lubrication, where the disulfide and oil‐soluble molybdenum sulfur complexes serve as antifriction and antiwear agents; in hydrodesulfurization and hydrotreating of petroleum; ammoxidation and other catalytic processes; in anticorrosion formulations; as flame and smoke retardants; and in a variety of coatings and pigments. Biomedically, molybdenum is used in nuclear medicine and is under study in a number or therapeutic procedures. The trioxide, several molybdates, and the disulfide are available as bulk chemicals.
Monobactams
Authors: Lindner Klaus R. , Bonner Daniel P. , Koster William H. 
Published: July 2004

Abstractβ‐Lactam antibiotics are one of the best established classes of antimicrobial agents for the treatment of infectious diseases. By screening strains of bacteria that were specifically responsive to β‐lactam antibiotics, monocyclic β‐lactams, ie, monobactams, varying in substitution at the C‐3 position, were identified. The naturally occurring monobactams include SQ 26,180 (), SQ 26,445 (C12H20N4O9S), sulfazecin (C12H20N4O9S), and isosulfazecin (C12H20N4O9S). More recently, the 4β‐methyl analogue of SQ 26,445/sulfazecin was isolated using a differential antibacterial assay. Initial syntheses employed the sulfonation of an N‐1 unsubstituted azetidinone as the key step. The natural product SQ, 26,180 as well as other methoxylated monobactams were synthesized. Subsequently, many more C‐3 side‐chain analogues were prepared. A second, distinct chiral synthesis of monobactams was developed from β‐hydroxy amino acids. The methodology was also applied to the synthesis of 4α‐ and 4β‐methyl monobactams. The monobactams, like penicillins and cephalosporins, interfere with the synthesis of bacterial cell walls. B‐Lactam antibiotics bind to a series of penicillin‐binding proteins (PBPs) on the cytoplasmic membrane and their antibacterial effect is believed to result from inhibition of a subset of these PBPs known as peptidoglycan transpeptidases. Although naturally occurring monobactams have exhibited poor antibacterial activity, alteration of the C‐3 amide side chain has led to many potent new compounds. Aztreonam is a totally synthetic compound that exhibits potent and specific activity against a wide range of both β‐lactamase‐producing and nonproducing aerobic gram‐negative bacteria, includingPseudomonas aeruginosa, but displays minimal inhibition against anaerobic and gram‐positive aerobic bacteria, eg, staphylococci and streptococci. Two monobactams were in clinical use as of 1990. Aztreonam, manufactured by Bristol‐Myers Squibb, has the worldwide trademark of Azactam. Carumonam, manufactured by Takeda in Japan, has the trademark Amasulin.
Thin Films, Monomolecular Layers
Authors: Ulman Abraham 
Published: July 2004

AbstractMonomolecular layers, the thinnest of thin films, can be prepared by Langmuir‐Blodgett techniques or can result from self‐assembly of monolayers. The former generally takes place at a solvent–air interface. Self‐assembled monolayers generally form by adsorption of a surfactant‐like molecule on a solid substrate placed in a solution. Layers generally consist of large surfactant molecules, having both hydrophilic and hydrophobic sections. The design, preparation, and properties of these films are discussed. The various types of multilayer films are presented, as are the types of substrates employed. Whereas commercial production of these films has yet to be realized, the potential for monomolecular layers in sensors, electrooptics, and semiconductors is large.
Naphthenic Acids
Authors: Brient James A. , Wessner Peter J. , Doyle Mary Nn 
Published: July 2004

AbstractNaphthenic acids are mixtures of naturally occurring cycloaliphatic carboxylic acids recovered from petroleum distillates. The acids are present in varying amounts in crude oil and are typically recovered by caustic extraction of petroleum distillates boiling in the 200–370°C range. Commercial naphthenic acids are sold in various grades of purity. This article is a compilation of information on their composition, occurrence, manufacture, analysis, and expanding uses and was collected from a review of the literature through mid‐1993. Particular attention is paid to recent analytical methods that elucidate the structure of the various components of this complex mixture. In addition to the traditional wood‐treating and paint drier applications for the metal naphthenate soaps, new derivatives such as naphthenate esters and amides with uses as lubricants, surfactants, and corrosion inhibitors are also emphasized. An extensive supplementary bibliography is included for more detailed discussion of the referenced material.
Naphthalene Derivatives
Authors: Talukder Mannan , Kates Curtis R. 
Published: July 2004

AbstractNaphthalene derivatives are of diverse importance as intermediates for agricultural, construction, pharmaceutical, photographic, rubber, tanning, and textile chemicals. Production figures, economics, and processes are discussed on most commercially important compounds. Not many processes for manufacturing naphthalene derivatives have changed in recent years, though there are a few changes in the equipment design, the material of construction and in refining techniques to meet environmental regulations. Use of high purity petroleum‐derived naphthalene has, in some cases, resulted in better purity of the derivatives and elimination of expensive prepurification steps.Phenyl‐1,4‐dihydroxy‐2‐naphthoate has an important application in photographic materials in the United States, Europe, and Japan. Much attention has been focused on the manufacture of 2,6‐naphthalenedicarboxylic acid, a potential monomer in the production of polyester fibers and plastics with superior properties. Most naphthalene derivatives are intermediates and are manufactured for captive use, so that true production figures are difficult to obtain. Vol. 16, pp. 979–1017, 143 refs. to June 1994.
Neuroregulators
Authors: Briggs Clark A. , Holladay Mark W. , Kerwin James F. , Sullivan James P. , Williams Michael 
Published: July 2004

Abstract
Neuroregulators represent a diverse group of compounds that include both neurotransmitters and neuromodulators. Receptors for neuroregulators on both the cell surface and within the cell represent the molecular targets of the majority of drugs in clinical use. In order to classify an endogenous agent as a neurotransmitter, it must possess a number of general characteristics, which are described. Neurotransmitter receptors are grouped according to sequence homology and structures are given. In many cases human receptors have been cloned.
Nickel Compounds
Authors: Antonsen D. H. 
Published: July 2004

AbstractNickel compounds can be divided into the classic inorganic salts and a wide variety of organonickel compounds. The various compounds find use as plating salts, catalysts, in specialty ceramics and chemicals, as pigments, and in nickel metal refining. Commercially the most important are the inorganic nickel(II) compounds and nickel carbonyl, a highly toxic nickel(0) species.Nickel salts form a wide variety of complexes with nitrogen, phosphorus, and sulfur, as well as with oxygen and carbon π‐systems. Properties, manufacture, and uses of nickel compounds and complexes are discussed.
Niobium and Niobium Compounds
Authors: Schlewitz James H. 
Published: July 2004

AbstractNiobium, also known as columbium, is used primarily as an alloy addition to steels. Ferroniobium and nickel‐niobium are the most frequently used alloys. Niobium is also vital to the formation of superalloys, and its compounds find use in nuclear fuel rods, optical glass, as ferroelectrics, semiconductors, and in superconducting material. Of primary interest is the stability of niobium metal and its alloys to corrosion. The occurrence, extraction, refining, and metallurgy of niobium is described. The analytical procedures for determination of niobium and its impurities are discussed. The primary niobium compounds, which range from the refractory borides and carbides through the ferroelectric salts of niobic acid, are presented.
Nitrobenzene and Nitrotoluenes
Authors: Adkins Rick L. 
Published: July 2004

AbstractNitrobenzene is a pale yellow to yellowish brown liquid with a boiling point of 207–212°C, depending on its purity. It is a very toxic substance with a maximum allowable concentration (PEL) of 1 ppm. In 1992, 612,350 metric tons of nitrobenzene were produced with a bulk price of $0.73/kg. The commercial production of nitrobenzene involves the direct nitration of benzene using a mixture of nitric and sulfuric acids, with typical yields of 96–99%. The main derivatives of nitrobenzene areortho‐,meta‐, andpara‐nitrochlorobenzene. These are toxic, with a PEL of 0.1 ppm forp‐nitrochlorobenzene.Nitrotoluene exists as three isomers:o‐,m‐, andp‐nitrotoluene. Theo‐ andm‐nitrotoluenes are clear yellow liquids at 25°C, whereasp‐nitrotoluene is a crystalline solid (mp 53.5°C). The nitrotoluenes are fairly toxic, with a PEL of 2 ppm. In 1992, 26,000 metric tons of mononitrotoluene were produced, with the bulk prices foro‐,m‐, andp‐nitrotoluene being $1.15/kg, $2.54/kg, and $3.64/kg, respectively. The commercial processes for mononitrotoluene and nitrobenzene are similar.
Nitration
Authors: Albright Lyle F. 
Published: July 2004

Abstract

Organic compounds are nitrated by both ionic and free‐radical reactions. Ionic nitrations are employed extensively with aromatics, compounds containing hydroxy groups (such as alcohols, glycerol, and cellulose), and amines. Nitronium ions (

) and sometimes nitrosonium ions (NO
+
) attack the above compounds to start the nitration reactions. Nitronium ions are present in most nitrating agents employed, including mixtures of HNO
3
and H
2
SO
4
; mixtures of N
2
O
4
and H
2
SO
4
; HNO
3
; and N
2
O
5
. The chemistry and physical steps during nitrations that involve two liquid phases are discussed. Key features of several important commercial nitrations are described, which in some cases exhibit extremely rapid rates of nitration. Considerable effort has been made to develop commercial processes with improved safety of operation, reduced environmental problems, lesser energy demands, lower operating costs, and increased yields of nitrated products. Certain nitrated products can only be produced using N
2
O
5
as a nitrating agent. Some N
2
O
5
processes likely will be commercialized in the near future for the production of high explosives and nitramines. Paraffins and cycloparaffins react with HNO
3
or NO
2
via free‐radical steps to form nitroparaffins. The chemistry and processes are discussed. Vol. 17, pp. 68–80, 39 refs. to June 1993.
Nitro Alcohols
Authors: Bollmeier Allen F. 
Published: July 2004

AbstractNitro alcohols are obtained from nitroparaffins by reaction with aldehydes in the presence of an alkaline catalyst. Only 2‐nitro‐1‐butanol, 2‐ethyl‐2‐nitro‐1,3‐propanediol, 2‐methyl‐2‐nitro‐1‐propanol, 2‐methyl‐2‐nitro‐1,3‐propanediol, and 2‐hydroxymethyl‐2‐nitro‐1,3‐propanediol, the five nitro alcohols produced with formaldehyde, are manufactured in commercial quantities. All these nitro alcohols except nitrobutanol are crystalline solids when pure, are highly soluble in water, and are only moderately toxic by ingestion.The principal use of the nitro alcohols is as intermediates for the synthesis of amino alcohols by hydrogenation. The nitro alcohols also are a convenient starting material for the synthesis of diamines by a two‐step process involving the formation of a nitro amine by reaction of the hydroxyl group with a primary amine followed by hydrogenation.2‐Methyl‐2‐nitro‐1‐propanol finds commercial use to promote adhesion of rubber to tire cord in radial tires. It also can serve as a source of formaldehyde in polymer cross‐linking. 2‐Hydroxymethyl‐2‐nitro‐1,3‐propanediol is a registered biocide useful for control of bacteria in such end uses as metalworking fluids and cooling tower water. This compound also finds acceptance in chemical toilets as an odor control agent.
Nitroparaffins
Authors: Bollmeier Allen F. 
Published: July 2004

AbstractFour nitroparaffins are commercially available. These four, nitromethane, nitroethane, 1‐nitropropane, and 2‐nitropropane, are medium‐boiling liquids which are excellent solvents for a wide variety organic compounds and polymers. Some physical properties of these nitroparaffins and a few higher mononitroparaffins and polynitro compounds are presented. The nitroparaffins can undergo a number of reactions which give them utility for synthesis of other compounds of commercial importance. These reactions are discussed. Of particular importance is their ability to form nitronate salts with alkalis. This reaction is the first step for the halogenation reaction, eg, for the synthesis of the fumigant chloropicrin, or the condensation with carbonyl compounds for the synthesis of nitro alcohols.Production of the four commercial nitroparaffins is by vapor‐phase nitration of propane with nitric acid. Some 41,000 t of mixed nitroparaffins can be produced annually. All the nitroparaffins are flammable liquids. Their principal hazard is by inhalation. Special attention is required for handling nitromethane because it can be detonated under certain circumstances. The bulk of nitroparaffin production is used for synthesis of other chemical products. Nitromethane is useful as a fuel in drag racing and model airplanes, however, and nitroethane and 1‐nitropropane see use as solvent in coatings.
Nitric Acid
Authors: Clarke Stephen I. , Mazzafro William J. 
Published: July 2004

AbstractNitric acid is a strong acid, a powerful oxidizing compound, and a nitrating agent. These properties make it an important basic chemical compound that is used in the production of many important chemicals such as fertilizers, polyurethanes, organic chemical intermediates, pharmaceuticals, synthetic fibers, dyes, insecticides, fungicides, and explosives. Nitric acid is produced through the oxidation of ammonia to nitrogen oxides, which are then absorbed by water to produce nitric acid. Weak nitric acid processes produce nitric acid in the concentration range of 50–65 wt %. The two main types of weak acid process are the monopressure process and the dual‐pressure process. The monopressure process operates at either moderate (0.3–0.6 MPa) or high pressure (0.7–1.2 MPa). The dual‐pressure process performs the conversion of ammonia at atmospheric or moderate pressures (0.3–0.6 MPa) and the absorption of nitrogen oxides at high pressure (1.1–1.5 MPa). Nitrogen oxides in the tail gas leaving the process are reduced to below environmental regulatory limits by either extended absorption or catalytic abatement. Strong nitric acid of 98–99 wt % is produced by either extractive distillation or direct strong nitric acid process. The extractive distillation process uses either magnesium nitrate or sulfuric acid as a dehydrating agent to surpass the maximum boiling azeotrope of nitric acid. The direct strong nitric acid process is similar to the weak nitric acid process, but has additional processing steps that bypass the azeotrope to produce strong nitric acid. Information on the chemical and physical properties, manufacturing processes, materials of construction, uses, safety and health, analytical methods, and process licensors of nitric acid is included.
Nitrile Rubber
Authors: Mackey Donald , Jorgensen August H. 
Published: July 2004

AbstractNitrile rubbers are copolymers of 1,3‐butadiene and acrylonitrile that have been produced by emulsion polymerization for about 50 years. They carry the ASTM designation NBR. A wide variety of products are available from a number of worldwide suppliers. The primary uses of NBR are in seals, O‐rings, hose, and gaskets, where resistance to hydrocarbon fluids like gasoline and oil is required. A second important use is in the modification of plastic materials to provide impact resistance and flexibility. This article covers the properties and uses of NBR and its hydrogenated derivative HNBR. Manufacturing processes, world usage and capacity, and toxicological considerations are also described.
Nitrides
Authors: Markel Eric J. , Leaphart M. E. 
Published: July 2004

AbstractNitrides may be classified as being ionic or salt‐like, metallic, nonmetallic or diamond‐like, or volatile. Additionally, sulfur and phosphorus form polymeric nitride species. Whereas many nitrides exist, only a few are produced commercially. Transition‐metal binary nitrides, made on a small scale, are used for high strength and hardness primarily as refractory coatings. Boron, aluminum, and silicon nitrides are produced on much larger scales and find use as refractories, ablative materials, abrasives, and coatings. Lithium nitride finds application in batteries and catalysts. Gallium and indium nitrides are used in such optoelectronic devices as light‐emitting diodes. The properties of transition‐metal metallic nitrides and the diamond‐like nonmetallic nitrides are described. The manufacture and processing of nitride coatings by case hardening is presented as well as the processing of the structurally important silicon nitride.
Antibacterial Agents, Nitrofurans
Authors: Schwan Thomas J. , Ebetino Frank H. 
Published: July 2004

AbstractThe nitrofurans encompass a class of synthetic antibacterials characterized by the 5‐nitro‐2‐furanyl group. Nitrofurans include furium, C9H7N3O4S; furazolidone,\documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}${{\rm{C}}{_{14}}{\rm{H}} _{12}{\rm{N}}{_{6}}{\rm{O}}{_{6}}{\rm{{\cdot{}}}}{\rm{HCl}}}$\end{document};Z‐furan, C7H6N2O4; furylfuramide, C11H8N2O5; nitrovin,\documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}${{\rm{C}}{_{14}}{\rm{H}} _{12}{\rm{N}}{_{6}}{\rm{O}}{_{6}}{\rm{{\cdot{}}}}{\rm{HCl}}}$\end{document}; furalazine C9H7N5O3; acetylfuratrizine, C11H9N5O4; panfuran‐S, C11H11N5O5; nifuroxime, C5H4N2O4; nitrofurazone, C6H6N4O4; nifuraldezone, C7H6N4O5; nihydrazone, C7H7N3O4; nitrofurantoin, C8H6N4O5; nifuratel, C10H11N3O5S; nitrofurathiazide, C13H12N4O6S; nifurtoinol, C9H8N4O6; and nifurprinol, C12H10N2O4. Several nitrofurans have been marketed in the human and veterinary areas because of their broad spectrum of activity and relatively mild toxicity. Nitrofurans are generally stable, water‐insoluble crystalline solids, which decompose (darken) upon prolonged exposure to light or alkali. Nitrofurantoin is bactericidal at the concentrations achieved in the urinary tract and highly effective against the corresponding pathogens. Since its introduction for use in uncomplicated urinary tract infections, essentially no resistance development has occurred, unlike nearly all other antimicrobials. Nitrogurazone, furazolidone, and nitrofurantoin have been used therapeutically for over 30 yr with no reports of human neoplasia. Most commercial nitrofurans are derived from 5‐nitro‐2‐furancarboxaldehyde or the corresponding diacetate.
N‐Nitrosamines
Authors: Wishnok John S. 
Published: July 2004

AbstractN‐Nitrosodialkylamines (nitrosamines) are a large group of substances containing the NNO group and various substituents on the amine nitrogen. They can be synthesized by reaction of the corresponding amines with nitrosating agents such as acidic nitrite, N2O3, N2O4, or inorganic nitrosyl compounds. They can be analyzed by gas or liquid chromatography with detection generally based on measurement of nitric oxide that is released from the nitrosamines by pyrolysis, photolysis, or acid hydrolysis. Many of the nitrosamines are agents which damage the liver in animals and humans. Most nitrosamines are known animal carcinogens, and some are suspected human carcinogens. Nitrosamines are metabolized by several enzyme systems, the most important being the cytochrome P450 family. Metabolic conversion to active electrophiles that react with DNA appears to be the initiating event in nitrosamine carcinogenesis. Humans may be exposed to nitrosamines by several routes including diet, commercial or industrial preparations such as cutting fluids, cosmetics, or sunscreens, tobacco products, and synthesis inside the body. Nitrosamines have not been unequivocally shown to be human carcinogens, but evidence relating oral cancer to the use of smokeless tobacco is increasingly persuasive.
Nomenclature In the Petroleum Industry
Authors: Barker Colin 
Published: July 2004

Abstract
Activities in the petroleum industry range from exploration, to oil and gas recovery or production, refining, distribution, and marketing. The nomenclature used has been derived from the disciplines of geology, petroleum engineering, and chemistry. This, combined with the complex nature of oil and many refined products, makes for a terminology that is often not systematic and has many poorly defined terms. An outline of the more widely used terms from exploration, production, and refining is included.