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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elemental fluorine and reagents incorporating an oxygen-fluorine bond can be used for this purpose, they have largely been replaced by reagents containing a nitrogen-fluorine bond.Badoux, J.; Cahard, D. '' Org. React.'' 2007, ''69'', 347. 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-hybridi ... [...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 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 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. History The terms ''nucleophile'' and ''electrophile'' were introduced by Christopher Kelk Ingold in 1933, replacing the terms ''anionoid'' and ''cationoid' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbonyl Compounds
In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, 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, where 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, hydroxamates, and isocyanates. Examples of inorganic carbonyl compounds are carbon dioxide and carbonyl sulfide. A sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dearomatization
A dearomatization reaction is an organic reaction which involves arenes as reactants and in which the reaction products have permanently lost their aromaticity. This reaction type is of some importance in synthetic organic chemistry for the organic synthesis of new building blocks and in total synthesis. Several methods for the dearomatization of carbocyclic arenes exist: hydrogenation (Birch reduction), alkylative dearomatization, photochemical dearomatization, thermal dearomatization, oxidative dearomatization, dearomatization with transition metals and enzymatic dearomatization. Photochemical dearomatization Examples of photochemical reactions are those between certain arenes and alkenes forming +2and +4cycloaddition adducts. Enzymatic dearomatization Examples of enzymes capable of arene dearomatization are toluene dixoyhydrogenase, naphthalene dixoyhydrogenase and benzoyl CoA reductase. Transition-metal assisted dearomatization A classic example of transition-metal assis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anionic Surfactant
Surfactants are chemical compounds that decrease the surface tension between two liquids, between a gas and a liquid, or interfacial tension between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming agents, or dispersants. The word "surfactant" is a blend of ''surface-active agent'', coined . Agents that increase surface tension are "surface active" in the literal sense but are not called surfactants as their effect is opposite to the common meaning. A common example of surface tension increase is salting out: by adding an inorganic salt to an aqueous solution of a weakly polar substance, the substance will precipitate. The substance may itself be a surfactant – this is one of the reasons why many surfactants are ineffective in sea water. Composition and structure Surfactants are usually organic compounds that are amphiphilic, meaning each molecule contains both a hydrophilic "water-seeking" group (the ''head''), and a hydrop ... [...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 Selectfluor, a trademark of Air Products and Chemicals, is a reagent in chemistry that is used as a fluorine donor. This compound is a derivative of the nucleophillic base DABCO. It is a colourless salt that tolerates air and even water. It has ..., 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 Tri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
