WordNet

arrange into a group or groups; "Can you group these shapes together?"
(chemistry) two or more atoms bound together as a single unit and forming part of a molecule (同)radical, chemical group
any number of entities (members) considered as a unit (同)grouping
a set that is closed, associative, has an identity element and every element has an inverse (同)mathematical group
form a group or group together (同)aggroup
the activity of putting things together in groups
a system for classifying things into groups (同)pigeonholing
the univalent radical CH3- derived from methane (同)methyl_group, methyl radical
arranged into groups (同)sorted

PrepTutorEJDIC

(…の)『群れ』,集まり,小集団《+of+名》 / (主義・系統・種類などを同じくする人・物の)『派』,『団体』 / (ポミュラーソング歌手の)グループ / (動・植物分類上の)群;(化学の)基,原子団;(地質学上の)界;(数学の)群;(言語学上の)語派 / …‘を'一群に集める,一団にする《+『名』+『together』》 / (系統的に)…‘を'分類する,調和よく配合する《+『名』+『together』》 / 集まる,群(集団)をなす
グループに分けること;分類法 / (集まった物の)配置,配合

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/01/07 12:50:00」(JST)

wiki en

[Wiki en表示]

Methyl cation, anion, and radical

Methyl cation

The methylium cation (CH₃⁺) exists in the gas phase, but is otherwise not encountered. Some compounds are considered to be sources of "CH₃⁺", and this simplification is used pervasively in organic chemistry. For example, protonation of methanol gives a strongly electrophilic methylating reagent:

CH₃OH + H⁺ → CH₃⁺ + H₂O

Similarly, methyl iodide and methyl triflate are viewed as the equivalent of the methyl cation because they readily undergo S_N2 reactions by weak nucleophiles.

Methyl anion

The methanide anion (CH₃⁻) similarly exists only under exotic conditions. In discussing mechanisms of organic reactions, it is often a useful simplification to consider methyl lithium and related Grignard reagents as sal sources of "CH₃⁻", although this view is fiction. Such reagents are generally prepared from the methyl halides:

M + CH₃X → MCH₃

where M is an alkali metal.

Methyl radical

Main article: Methyl radical

The methyl radical has the formula CH₃. It exists in dilute gases, but in more concentrated form it readily dimerizes to ethane. It can be produced by thermal decomposition of only certain compounds, especially those with an -N=N- linkage.

Reactivity

The reactivity of a methyl group depends on the adjacent substituents. Methyl groups can be quite unreactive. For example, in organic compounds, the methyl group resists attack by even the strongest acids.

Oxidation

The oxidation of a methyl group occurs widely in nature and industry. The oxidation products derived from methyl are CH₂OH, CHO, and CO₂H. For example, permanganate often converts a methyl group to a carboxyl (-COOH) group, e.g. the conversion of toluene to benzoic acid. Ultimately oxidation of methyl groups gives protons and carbon dioxide, as seen in combustion.

Methylation

Main article: Methylation

Demethylation (the transfer of the methyl group to another compound) is a common process, and reagents that undergo this reaction are called methylating agents. Common methylating agents are dimethylsulfate, methyl iodide, and methyl triflate. Methanogenesis, the source of natural gas, arises via a demethylation reaction.^[2]

Deprotonation

Certain methyl groups can be deprotonated. For example, the acidity of the methyl groups in acetone ((CH₃)₂CO) is about 10²⁰ more acidic than methane. The resulting carbanions are key intermediates in many reactions in organic synthesis and biosynthesis. Fatty acids arise in this way.

Free radical reactions

When placed in benzylic or allylic positions, the C-H bond strength is decreased, and the reactivity of the methyl group increases. One manifestation of this enhanced reactivity is the photochemical chlorination of the methyl group in toluene to give benzyl chloride.^[3]

Etymology

French chemists Jean-Baptiste Dumas and Eugene Peligot, after determining methanol's chemical structure, introduced "methylene" from the Greek methy = "wine" + hȳlē = "wood" (patch of trees) with the intention of highlighting its origins, "alcohol made from wood (substance)",^[4] but with Greek language errors: the Greek for "wood (substance)" is xylo-. The term "methyl" was derived in about 1840 by back-formation from "methylene", and was then applied to describe "methyl alcohol".

Methyl is the IUPAC nomenclature of organic chemistry term for an alkane (or alkyl) molecule, using the prefix "meth-" to indicate the presence of a single carbon.

References

^ March, J. Advanced Organic Chemistry. 4th Ed. J. Wiley and Sons, 1992: New York. ISBN 0-471-60180-2.
^ Thauer, R. K., "Biochemistry of Methanogenesis: a Tribute to Marjory Stephenson", Microbiology, 1998, volume 144, pages 2377–2406.
^ M. Rossberg et al. “Chlorinated Hydrocarbons” in Ullmann’s Encyclopedia of Industrial Chemistry 2006, Wiley-VCH, Weinheim. doi:10.1002/14356007.a06_233.pub2
^ J. Dumas and E. Péligot (1835) "Mémoire sur l'espirit de bois et sur les divers composés ethérés qui en proviennent" (Memoir on spirit of wood and on the various ethereal compounds that derive therefrom), Annales de chimie et de physique, 58: 5-74; from page 9:
Nous donnerons le nom de méthylène (1) à un radical …
(1) μεθυ, vin, et υλη, bois; c'est-à-dire vin ou liqueur spiritueuse du bois.
(We will give the name "methylene" (1) to a radical …
(1) methy, wine, and hulē, wood; that is, wine or spirit of wood.)

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. 赤血球抗原および抗体のプライマー a primer of red blood cell antigens and antibodies
2. B群レンサ球菌感染症予防のための予防接種 vaccines for the prevention of group b streptococcal disease
3. 新生児および乳児におけるB群レンサ球菌感染症 group b streptococcal infection in neonates and young infants
4. PANDAS：A群レンサ球菌が関連した小児自己免疫性神経精神疾患 pandas pediatric autoimmune neuropsychiatric disorder associated with group a streptococci
5. 連鎖球菌扁桃咽頭炎の治療および予防 treatment and prevention of streptococcal tonsillopharyngitis

English Journal

Preparation, characterization and properties of nano-hydroxyapatite/polypropylene carbonate biocomposite.

Liao J1, Li Y2, Zou Q3, Duan X2, Yang Z2, Xie Y2, Liu H4.
Materials science & engineering. C, Materials for biological applications.Mater Sci Eng C Mater Biol Appl.2016 Jun 1;63:285-91. doi: 10.1016/j.msec.2016.02.054. Epub 2016 Feb 22.
The combination of nano-hydroxyapatite (n-HA) and polypropylene carbonate (PPC) was used to make a composite materials by a coprecipitation method. The physical and chemical properties of the composite were tested. Scanning electron microscope (SEM) observation indicated that the biomimetic n-HA cry
PMID 27040221

Introduction of double amidoxime group by double post surface modification on poly(vinylbenzyl chloride) beads for higher amounts of organic dyes, As (V) and Cr (VI) removal.

Ajmal M1, Demirci S2, Uzun Y3, Siddiq M1, Aktas N4, Sahiner N5.
Journal of colloid and interface science.J Colloid Interface Sci.2016 May 15;470:39-46. doi: 10.1016/j.jcis.2016.02.040. Epub 2016 Feb 18.
In this study, the synthesis of micron-sized poly(vinylbenzyl chloride) (p(VBC)) beads and subsequent conversion of the reactive chloromethyl groups to double amidoxime group containing moieties by post modification is reported. The prepared beads were characterized by SEM and FT-IR spectroscopy. Th
PMID 26930538

Identification and structural elucidation of three new tadalafil analogues found in a dietary supplement.

Lee JH1, Mandava S2, Baek SY3, Lee YM4.
Journal of pharmaceutical and biomedical analysis.J Pharm Biomed Anal.2016 May 10;123:1-9. doi: 10.1016/j.jpba.2015.10.039. Epub 2015 Oct 31.
Compounds elucidated as new tadalafil analogues were found to be adulterated in a dietary supplement and detected during routine analysis by HPLC with photodiode array detection. The UV spectra of these compounds were found to be almost identical to that of tadalafil. The unknown compounds were isol
PMID 26855379