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Aniline
Aniline (From , meaning ' indigo shrub', and ''-ine'' indicating a derived substance) is an organic compound with the formula . Consisting of a phenyl group () attached to an amino group (), aniline is the simplest aromatic amine. It is an industrially significant commodity chemical, as well as a versatile starting material for fine chemical synthesis. Its main use is in the manufacture of precursors to polyurethane, dyes, and other industrial chemicals. Like most volatile amines, it has the odor of rotten fish. It ignites readily, burning with a smoky flame characteristic of aromatic compounds. It is toxic to humans. Relative to benzene, aniline is "electron-rich". It thus participates more rapidly in electrophilic aromatic substitution reactions. Likewise, it is also prone to oxidation: while freshly purified aniline is an almost colorless oil, exposure to air results in gradual darkening to yellow or red, due to the formation of strongly colored, oxidized impurities. Ani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Group
In chemistry, amines (, ) are organic compounds that contain carbon-nitrogen bonds. Amines are formed when one or more hydrogen atoms in ammonia are replaced by alkyl or aryl groups. The nitrogen atom in an amine possesses a lone pair of electrons. Amines can also exist as hetero cyclic compounds. Aniline is the simplest aromatic amine, consisting of a benzene ring bonded to an amino group. Amines are classified into three types: primary (1°), secondary (2°), and tertiary (3°) amines. Primary amines (1°) contain one alkyl or aryl substituent and have the general formula RNH2. Secondary amines (2°) have two alkyl or aryl groups attached to the nitrogen atom, with the general formula R2NH. Tertiary amines (3°) contain three substituent groups bonded to the nitrogen atom, and are represented by the formula R3N. The functional group present in primary amines is called the amino group. Classification of amines Amines can be classified according to the nature and number o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diazonium Compound
Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide. The parent, compound where R is hydrogen, is diazenylium. Structure and general properties Arene derivatives According to X-ray crystallography the linkage is linear in typical diazonium salts. The bond distance in benzenediazonium tetrafluoroborate is 1.083(3) Angstrom, Å, which is almost identical to that for dinitrogen molecule (N≡N). The linear free energy constants σm and σp indicate that the diazonium group is strongly electron-withdrawing. Thus, the diazonio-substituted phenols and benzoic acids have greatly reduced p''K''a values compared to their unsubstituted counterparts. The p''K''a of phenolic proton of 4-hydroxybenzenediazonium is 3.4, versus 9.9 for phenol itself. In other words, the diazonium group raises the ionization constant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrophilic Aromatic Substitution
Electrophilic aromatic substitution (SEAr) is an organic reaction in which an atom that is attached to an aromatic ring, aromatic system (usually hydrogen) is replaced by an electrophile. Some of the most important electrophilic aromatic substitutions are aromatic nitration, aromatic halogenation, aromatic sulfonation, alkylation Friedel–Crafts reaction and acylation Friedel–Crafts reaction. Illustrative reactions The most widely practised example of this reaction is the ethylation of benzene. :: Approximately 24,700,000 tons were produced in 1999. (After dehydrogenation and polymerization, the commodity plastic polystyrene is produced.) In this process, acids are used as catalyst to generate the incipient carbocation. Many other electrophilic reactions of benzene are conducted, although on a much smaller scale; they are valuable routes to key intermediates. The nitration of benzene is achieved via the action of the nitronium ion as the electrophile. The Aromatic sulfonation, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrobenzene
Nitrobenzene is an aromatic nitro compound and the simplest of the nitrobenzenes, with the chemical formula C6H5 NO2. It is a water-insoluble pale yellow oil with an almond-like odor. It freezes to give greenish-yellow crystals. It is produced on a large scale from benzene as a precursor to aniline. In the laboratory, it is occasionally used as a solvent, especially for electrophilic reagents. As confirmed by X-ray crystallography, nitrobenzene is a planar molecule. Production Nitrobenzene is prepared by nitration of benzene with a mixture of concentrated sulfuric acid, water, and nitric acid. This mixture is sometimes called "mixed acid." The production of nitrobenzene is one of the most dangerous processes conducted in the chemical industry because of the exothermicity of the reaction (Δ''H'' = −117 kJ/mol). World capacity for nitrobenzene in 1985 was about 1,700,000 tonnes. The nitration process involves formation of the nitronium ion (NO2+), followed by an e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aromatic Amine
In organic chemistry, an aromatic amine is an organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ... consisting of an aromatic ring attached to an amine. It is a broad class of compounds that encompasses anilines, but also many more complex aromatic rings and many amine substituents beyond . Such compounds occur widely. Aromatic amines are widely used as precursor to pesticides, pharmaceuticals, and dyes. Aromatic amines in textiles Since August 2012, the new standard EN 14362-1:2012 ''Textiles - Methods for determination of certain aromatic amines derived from azo colorants - Part 1: Detection of the use of certain azo colorants accessible with and without extracting the fibres'' is effective. It had been officially approved by the European Committee for Sta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrosobenzene
Nitrosobenzene is the organic compound with the chemical formula, formula C6H5NO. It is one of the prototypical organic nitroso compounds. Characteristic of its functional group, it is a dark green species that exists in equilibrium with its pale yellow Dimer (chemistry), dimer. Both monomer and dimer are diamagnetism, diamagnetic. Monomer-dimer equilibrium Nitrosobenzene and other nitrosoarenes typically participate in a monomer-dimer equilibrium. The dimers are often favored in the solid state, whereas the deeply colored monomers are favored in dilute solution or at higher temperatures. The dimers can be formulated as Ar(O−)N+=N+(O−)Ar. They exist as ''cis''- and ''trans''-isomers due to the presence of the N–N double bond. The dimers are sometimes called azobenzenedioxides. The cis-trans isomerization occurs via the intermediacy of the monomer. In the case of nitrosobenzene itself, the Metastability, metastable monomeric form could be prepared by sublimation onto a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annulene
Annulenes are monocyclic hydrocarbons that contain the maximum number of non-cumulated or conjugated double bonds (' mancude'). They have the general formula C''n''H''n'' (when ''n'' is an even number) or C''n''H''n''+1 (when ''n'' is an odd number). The IUPAC accepts the use of 'annulene nomenclature' in naming carbocyclic ring systems with 7 or more carbon atoms, using the name ' 'n''nnulene' for the mancude hydrocarbon with ''n'' carbon atoms in its ring, though in certain contexts (e.g., discussions of aromaticity for different ring sizes), smaller rings (''n'' = 3 to 6) can also be informally referred to as annulenes. Using this form of nomenclature 1,3,5,7-cyclooctatetraene is nnulene and benzene is nnulene (and occasionally referred to as just 'annulene'). The discovery that 8nnulene possesses a number of key properties associated with other aromatic molecules was an important development in the understanding of aromaticity as a chemical concept. In the related annul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleophile
In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are Lewis bases. ''Nucleophilic'' describes the affinity of a nucleophile to bond with positively charged Atomic nucleus, atomic nuclei. Nucleophilicity, sometimes referred to as nucleophile strength, refers to a substance's nucleophilic character and is often used to compare the affinity of atoms. Neutral nucleophilic reactions with solvents such as Alcohol (chemistry), alcohols and water are named solvolysis. Nucleophiles may take part in nucleophilic substitution, whereby a nucleophile becomes attracted to a full or partial positive charge, and nucleophilic addition. Nucleophilicity is closely related to basicity. The difference between the two is, that basicity is a thermodynamic property (i.e. relates to an equilibrium state), but nucleop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenylhydrazine
Phenylhydrazine is the chemical compound with the formula . It is often abbreviated as . It is also found in edible mushrooms. Properties Phenylhydrazine forms monoclinic prisms that melt to an oil around room temperature which may turn yellow to dark red upon exposure to air. Phenylhydrazine is miscible with ethanol, diethyl ether, chloroform and benzene. It is sparingly soluble in water. Preparation Phenylhydrazine is prepared by reacting aniline with sodium nitrite in the presence of hydrogen chloride to form the diazonium salt, which is subsequently reduced using sodium sulfite in the presence of sodium hydroxide to form the final product.''Merck Index of Chemicals and Drugs, 9th ed.'' monograph 7098 History Phenylhydrazine was the first hydrazine derivative characterized, reported by Hermann Emil Fischer in 1875. He prepared it by reduction of a phenyl diazonium salt using sulfite salts. Fischer used phenylhydrazine to characterize sugars via formation of hydrazones ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyurethane
Polyurethane (; often abbreviated PUR and PU) is a class of polymers composed of organic chemistry, organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane term does not refer to the single type of polymer but a group of polymers. Unlike polyethylene and polystyrene, polyurethanes can be produced from a wide range of starting materials resulting in various polymers within the same group. This chemical variety produces polyurethanes with different chemical structures leading to many List of polyurethane applications, different applications. These include rigid and flexible foams, and coatings, adhesives, Potting (electronics), electrical potting compounds, and fibers such as spandex and polyurethane laminate (PUL). Foams are the largest application accounting for 67% of all polyurethane produced in 2016. A polyurethane is typically produced by reacting a polymeric isocyanate with a polyol. Since a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish
A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can be grouped into the more basal (phylogenetics), basal jawless fish and the more common jawed fish, the latter including all extant taxon, living cartilaginous fish, cartilaginous and bony fish, as well as the extinct placoderms and acanthodians. In a break to the long tradition of grouping all fish into a single Class (biology), class (Pisces), modern phylogenetics views fish as a paraphyletic group. Most fish are ectotherm, cold-blooded, their body temperature varying with the surrounding water, though some large nekton, active swimmers like white shark and tuna can hold a higher core temperature. Many fish can communication in aquatic animals#Acoustic, communicate acoustically with each other, such as during courtship displays. The stud ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Combustion
Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combustion does not always result in fire, because a flame is only visible when substances undergoing combustion vaporize, but when it does, a flame is a characteristic indicator of the reaction. While activation energy must be supplied to initiate combustion (e.g., using a lit match to light a fire), the heat from a flame may provide enough energy to make the reaction self-sustaining. The study of combustion is known as combustion science. Combustion is often a complicated sequence of elementary reaction, elementary Radical (chemistry), radical reactions. Solid fuels, such as wood and coal, first undergo endothermic pyrolysis to produce gaseous fuels whose combustion then supplies the heat required to produce more of them. Combustion is often hot e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
