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Electrophilic Fluorination
Electrophilic fluorination is the combination of a carbon-centered nucleophile with an electrophilic source of fluorine to afford organofluorine compounds. Although elemental fluorine and reagents incorporating an oxygen-fluorine bond can be used for this purpose, they have largely been replaced by reagents containing a nitrogen-fluorine bond. Electrophilic fluorination offers an alternative to nucleophilic fluorination methods employing alkali or ammonium fluorides and methods employing sulfur fluorides for the preparation of organofluorine compounds. Development of electrophilic fluorination reagents has always focused on removing electron density from the atom attached to fluorine; however, compounds containing nitrogen-fluorine bonds have proven to be the most economical, stable, and safe electrophilic fluorinating agents. Electrophilic N-F reagents are either neutral or cationic and may possess either sp2- or sp3-hybridized nitrogen. Although the precise mechanism of electrophil ... [...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] |
Carbonyl Compounds
In organic chemistry, a carbonyl group is a functional group with the formula , composed of a carbon atom double-bonded to an oxygen atom, and it is divalent at the C atom. It is common to several classes of organic compounds (such as aldehydes, ketones and carboxylic acid), as part of many larger functional groups. A compound containing a carbonyl group is often referred to as a carbonyl compound. The term carbonyl can also refer to carbon monoxide as a ligand in an inorganic or organometallic complex (a metal carbonyl, e.g. nickel carbonyl). The remainder of this article concerns itself with the organic chemistry definition of carbonyl, such that carbon and oxygen share a double bond. Carbonyl compounds In organic chemistry, a carbonyl group characterizes the following types of compounds: Other organic carbonyls are urea and the carbamates, the derivatives of acyl chlorides, chloroformates and phosgene, carbonate esters, thioesters, lactones, lactams, hydroxamat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dearomatization
A dearomatization reaction is an organic reaction in which the reactants are arenes and the products permanently lose their aromaticity. It is of some importance in synthetic organic chemistry for the organic synthesis of new building blocks and in total synthesis. Types of carbocyclic arene dearomization include hydrogenative (Birch reduction), alkylative, photochemical, thermal, oxidative, transition metal-assisted and enzymatic. Photochemical Examples of photochemical reactions are those between certain arenes and alkenes forming +2and +4 cycloaddition adducts. Enzymatic Examples of enzymes capable of arene dearomatization are toluene dixoyhydrogenase, naphthalene dixoyhydrogenase and benzoyl CoA reductase. Transition metal-assisted A classic example of transition metal-assisted dearomatization is the Buchner ring expansion. Catalytic asymmetric dearomatization reactions (CADA) are used in enantioselective synthesis Enantioselective synthesis, also called asymmetric ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anionic Surfactant
Surfactants are chemical compounds that decrease the surface tension or interfacial tension between two liquids, a liquid and a gas, or a liquid and a solid. The word ''surfactant'' is a Blend word, blend of "surface-active agent", coined in 1950. As they consist of a water-repellent and a water-attracting part, they enable water and oil to mix; they can form foam and facilitate the detachment of dirt. Surfactants are among the most widespread and commercially important chemicals. Private households as well as many industries use them in large quantities as detergent, detergents and cleaning agents, but also for example as emulsion#Emulsifiers, emulsifiers, wetting agents, foaming agents, Antistatic agent, antistatic additives, or dispersants. Surfactants occur naturally in traditional plant-based detergents, e.g. Aesculus, horse chestnuts or Sapindus, soap nuts; they can also be found in the secretions of some caterpillars. Today one of the most commonly used anionic surfa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N-Fluoropyridinium Triflate
''N''-Fluoropyridinium triflate is an organofluorine compound with the formula 5H5NF3SCF3. It is a white solid with low solubility in polar organic solvents. The compound is used as an electrophilic fluorinating agent. It is a salt, consisting of the ''N''-fluoropyridinium cation ( 5H5NFsup>+) and the triflate anion. Related reagents include Selectfluor, which is also an N-fluorinated salt. ''N''-Fluoropyridinium cations are not only electrophilic fluorinating agents (i.e., sources of "F+"), they are also one-electron oxidants.Kiselyov, A. S., "Chemistry of N-fluoropyridinium salts", Chemical Society Reviews 2005, vol. 34, page 1031. References {{DEFAULTSORT:Fluoropyridinium triflate, N- Reagents for organic chemistry Triflates Fluorinating agents Pyridinium compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
