ラジカルアニオン

WordNet

of or relating to or constituting a linguistic root; "a radical verb form"
(mathematics) a quantity expressed as the root of another quantity
a character conveying the lexical meaning of a logogram
a person who has radical ideas or opinions
especially of leaves; located at the base of a plant or stem; especially arising directly from the root or rootstock or a root-like stem; "basal placentation"; "radical leaves" (同)basal
arising from or going to the root or source; "a radical flaw in the plan"
a negatively charged ion
black tropical American cuckoo

PrepTutorEJDIC

『根本的な』,『基本的な』 / 《しばしばR-》『急進的な』,過激な / (数学の記号で)根(こん)の / 《しばしばR-》急進堂員,主義者,過激論者 / (数学の記号で)根,根号 / (化学反応で)基(き),根
陰イオン

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/06/23 15:41:22」(JST)

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A radical ion is a free radical species that carries a charge.^[1] Radical ions are encountered in organic chemistry as reactive intermediates and in mass spectrometry as gas phase ions. Positive radical ions are called radical cations whereas negative radical ions are called radical anions.

Notation [edit]

In organic chemistry, a radical ion is typically indicated by a superscript dot followed by the sign of the charge: and . In mass spectrometry, the sign is written first, followed by the superscripted dot: and .^[2]

Radical anions [edit]

Many aromatic compounds can undergo one-electron reduction by alkali metals. For example the reaction of naphthalene with sodium in an aprotic solvent yields the naphthalene radical anion - sodium ion salt. In an ESR spectrum this compound shows up as a quintet of quintets (25 lines). In the presence of a proton source the radical anion is protonated and effectively hydrogenated like in the Birch reduction.

The electron is transferred from the alkali metal ion to an unoccupied antibonding p-p п* orbital of the aromatic molecule. This transfer is usually only energetically favorable if the aprotic solvent efficiently solvates the alkali metal ion. Effectiveness for this is in the order diethyl ether < THF < 1,2-dimethoxyethane < HMPA. In principle any unsaturated molecule can form a radical anion, but the antibonding orbitals are only energetically accessible in more extensive conjugated systems. Ease of formation is in the order benzene < naphthalene < anthracene < pyrene, etc. On addition of a proton source, the structure of the resulting hydrogenated molecule is defined by the charge distribution of the radical anion. For instance, the anthracene radical anion forms mainly (but not exclusively) 9,10-dihydroanthracene.

An example of a non-carbon radical anion is the superoxide anion, formed by transfer of one electron to an oxygen molecule.

A very effective way to remove any traces of water from THF is by reflux with sodium wire in the presence of a small amount of benzophenone. Benzophenone is reduced to the ketyl radical anion by sodium which gives the THF solution an intense blue color. However, any trace of water in THF will further reduce the ketyl to the colourless alcohol. In this way, the color of the THF signals the dryness and the distilled THF contains less than 10 ppm of water.^[3] This treatment also effectively removes any peroxides in the THF. Radical anions of this type are also involved in the Acyloin condensation.

Cyclooctatetraene is reduced by elemental potassium all the way to the dianion because the 10 electron system is aromatic. Quinone is reduced to a semiquinone radical anion. Semidiones are derived from the reduction of dicarbonyl compounds.

Radical cations [edit]

Cationic radical species are much less stable. They appear prominently in the mass spectrometry. When a gas-phase molecule is subjected to electron ionization one electron is abstracted by an electron in the electron beam to create a radical cation M⁺^.. This species represents the molecular ion or parent ion. A typical mass spectrum shows multiple signals because the molecular ion fragments into a complex mixture of ions and uncharged radical species. For example the methanol radical cation fragments into a methenium cation CH₃⁺ and a hydroxyl radical. In naphthalene the unfragmented radical cation is by far the most prominent peak in the mass spectrum. Secondary species are generated from proton gain (M+1) and proton loss (M-1).

Some compounds containing the dioxygenyl cation can be prepared in bulk.^[4]

Organic conductors [edit]

Radical cations figure prominently in the chemistry and properties of conducting polymers. Such polymers are formed by the oxidation of heterocycles to give radical cations, which condense with the parent heterocycle. For example, polypyrrole is prepared by oxidation of pyrrole using ferric chloride in methanol:

n C₄H₄NH + 2 FeCl₃ → (C₄H₂NH)_n + 2 FeCl₂ + 2 HCl

Once formed, these polymers become conductive upon oxidation.^[5] Polarons and bipolarons are radical cations encountered in doped conducting polymers.

References [edit]

^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "radical ion".
^ Sparkman, O. David (2000). Mass spectrometry desk reference. Pittsburgh: Global View Pub. p. 53. ISBN 0-9660813-2-3.
^ The Benzophenone Ketyl Still Pot - [www.rhodium.ws]
^ Solomon, I. J.; Brabets, R. I.; Uenishi, R. K.; Keith, J. N.; McDonough, J. M. (1964). "New Dioxygenyl Compounds". Inorganic Chemistry 3 (3): 457. doi:10.1021/ic50013a036. edit
^ "Polypyrrole: a conducting polymer; its synthesis, properties and applications" Russ. Chem. Rev. 1997, vol. 66, p.443ff.(http://iopscience.iop.org/0036-021X/66/5/R04)

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English Journal

Antioxidative and functional properties of protein hydrolysate from defatted skipjack (Katsuwonous pelamis) roe.

Intarasirisawat R, Benjakul S, Visessanguan W, Wu J.SourceDepartment of Food Technology, Faculty of Agro-Industry, Prince of Songkla, University, Hat Yai, Songkhla 90112, Thailand.
Food chemistry.Food Chem.2012 Dec 15;135(4):3039-48. doi: 10.1016/j.foodchem.2012.06.076. Epub 2012 Jun 29.
Antioxidative and functional properties of protein hydrolysate from defatted skipjack (Katsuwonous pelamis) roe, hydrolysed by Alcalase 2.4L (RPH) with different degrees of hydrolysis (DH) at various concentrations were examined. As DH increased, the reduction of DPPH, ABTS radicals scavenging activ
PMID 22980906

Antiradical activity of different parts of Walnut (Juglans regia L.) fruit as a function of genotype.

Akbari V, Jamei R, Heidari R, Esfahlan AJ.SourceDepartment of Biology, Faculty of Science, Urmia University, Serow Road, Urmia, Iran. Electronic address: akbarivali.bio85@yahoo.com.
Food chemistry.Food Chem.2012 Dec 15;135(4):2404-10. doi: 10.1016/j.foodchem.2012.07.030. Epub 2012 Jul 20.
The objective of this work was to analyse phenolic compounds and antiradical capacity of different parts of walnut fruit among six genotypes of Juglans regia L. Therefore, total phenolic and flavonoid content were determined and methanolic extracts of walnut genotypes were considered by the reducing
PMID 22980820

Japanese Journal

Pulse radiolysis study of polystyrene-based polymers with added photoacid generators: Reaction mechanism of extreme-ultraviolet and electron-beam chemically amplified resist

Okamoto Kazumasa,Yamamoto Hiroki,Kozawa Takahiro,Fujiyoshi Ryoko,Umegaki Kikuo
Jpn. J. Appl. Phys. 54(2), 026501, 2015-01-06
… In this study, the intermediate of the proton source of acid (a radical cation of the base polymer) in the presence of a photoacid generator (PAG) was investigated by the pulse radiolysis method. … The deprotonation kinetics of the radical cation of poly(4-hydroxystyrene) (PHS) in solutions with and without PAG shows only a small difference. … However, the yield of radical cations of poly(4-methoxystyrene) (PMOS) as a model of the resist with a protecting (releasing) group increases upon adding PAG. …
NAID 150000110155

Diagnosis of superoxide anion radical induced in liquids by atmospheric-pressure plasma using superoxide dismutase

Tani Atsushi,Fukui Satoshi,Ikawa Satoshi,Kitano Katsuhisa
Jpn. J. Appl. Phys. 54(1S), 01AF01, 2014-11-17
… confirm the formation of the superoxide anion radical (O<inf>2</inf><sup>−</sup>∙) in liquids by atmospheric-pressure plasma, we investigated plasma-induced radical species in water using the electron spin resonance (ESR) spin-trapping technique combined with two proteins: superoxide dismutase (SOD), which has enzymatic activity to quench the superoxide anion radical, and bovine serum albumin (BSA), which does …
NAID 150000110047

Acid generation mechanism in anion-bound chemically amplified resists used for extreme ultraviolet lithography

Komuro Yoshitaka,Yamamoto Hiroki,Kobayashi Kazuo,Utsumi Yoshiyuki,Ohomori Katsumi,Kozawa Takahiro
Jpn. J. Appl. Phys. 53(11), 116503, 2014-10-07
… An anion-bound polymer (ABP), in which the anion part of onium salts is polymerized, has attracted much attention from the viewpoint of the control of acid diffusion. … On the basis of experimental results, the acid generation mechanism in anion-bound chemically amplified resists was proposed. …
NAID 150000109878