関: R

WordNet

the 18th letter of the Roman alphabet (同)r
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
any of a series of univalent groups of the general formula CnH2n+1 derived from aliphatic hydrocarbons (同)alkyl_group, alkyl radical
arranged into groups (同)sorted

PrepTutorEJDIC

resistance / 17歳以下父兄同伴映画の表示 / rook
(…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）』「2016/10/11 03:17:30」(JST)

wiki en

[Wiki en表示]

Isopropyl group

Methyl group

In organic chemistry, an alkyl substituent is an alkane missing one hydrogen.^[1] The term alkyl is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula C_nH_2n+1. A cycloalkyl is derived from a cycloalkane by removal of a hydrogen atom from a ring and has the general formula C_nH_2n-1.^[2] Typically an alkyl is a part of a larger molecule. In structural formula, the symbol R is used to designate a generic (unspecified) alkyl group. The smallest alkyl group is methyl, with the formula CH₃−. ^[3]

Alkyls in everyday life

The word root alkyl is encountered in several contexts. Alkylation is an important operation in refineries, for example in the production of high-octane gasoline. Alkylating antineoplastic agents refer to a class of compounds that are used to treat cancer. In such case, the term alkyl is used loosely. For example, nitrogen mustards are well-known alkylating agents, but they are more complex than a mere hydrocarbon. In chemistry, alkyl refers to a group, a substituent, that is attached to other molecular fragments. For example, alkyl lithium reagents have the empirical formula Li(alkyl), where alkyl = methyl, ethyl, etc. A dialkyl ether is an ether with two alkyl groups, e.g., diethyl ether (O(C₂H₅)₂).

Alkyls in medicinal chemistry

In medicinal chemistry, the incorporation of alkyl chains into some chemical compounds increases their lipophilicity. This strategy has been used to increase the antimicrobial activity of flavanones and chalcones.^[4]

Alkyl cations, anions, and radicals

Usually alkyl groups are attached to other atoms or groups of atoms. Free alkyls occur as neutral compounds, as anions, or as cations. The cations are called carbocations. The anions are called carbanions. The neutral alkyl free radicals have no special name. Such species are usually encountered only as transient intermediates, but some are quite stable and can be "put into a bottle". Typically alkyl cations are generated using super acids, alkyl anions are observed in the presence of strong bases, and alkyl radicals are generated by a photochemical reaction. Alkyls are commonly observed in mass spectrometry of organic compounds.

Nomenclature

Alkyls form homologous series. The simplest series have the general formula C_nH_2n+1. Alkyls include methyl, CH₃· (named after methane), ethyl (C₂H₅·), propyl (C₃H₇·), butyl (C₄H₉·), pentyl (C₅H₁₁·), and so on. Alkyl groups that contain one ring have the formula C_nH_2n−1, e.g. cyclopropyl and cyclohexyl. The naming convention is taken from IUPAC nomenclature:

Number of carbon atoms	1	2	3	4	5	6	7	8	9	10	11	12
Prefix	meth-	eth-	prop-	but-	pent-	hex-	hept-	oct-	non-	dec-	undec-	dodec-
Group name	Methyl	Ethyl	Propyl	Butyl	Pentyl	Hexyl	Heptyl	Octyl	Nonyl	Decyl	Undecyl	Dodecyl

These names are used to name branched chained structures, for example 3-methylpentane:

The structure of 3-methylpentane is viewed as consisting of two parts. First, five atoms comprise the longest straight chain of carbon centers. The parent five-carbon compound is named pentane (highlighted blue). The methyl "substituent" or "group" is highlighted red. According to the usual rules of nomenclature, alkyl groups are included in the name of the molecule before the root, as in methylpentane. This name is, however, ambiguous, as the methyl branch could be on various carbon atoms. Thus, the name is 3-methylpentane to avoid ambiguity: The 3- is because the methyl is attached to the third of the five carbon atoms.

If there is more than one of the same alkyl group attached to a chain, then the prefixes are used on the alkyl groups to indicate multiples (i.e., di, tri, tetra, etc.)

This compound is known as 2,3,3-trimethylpentane. Here three identical alkyl groups attached to carbon atoms 2, 3, and 3. These numbers are included in the name to avoid ambiguity on the position of the groups, and "tri" indicates that there are three identical methyl groups. If one of the methyl groups attached to the third carbon atom were an ethyl group, then the name would become 3-ethyl-2,3-dimethylpentane. Note that when there are different alkyl groups, they are listed in alphabetical order.

In addition, each position on an alkyl chain can be described according to how many other carbon atoms are attached to it. The terms primary, secondary, tertiary, and quaternary refer to a carbon attached to one, two, three, or four other carbons respectively.

Etymology

The first named alkyl radical was ethyl, named so by Liebig in 1833 from the German word "aether" (i.e., the substance now known as diethyl ether) and the Greek word ύλη (hyle), meaning "matter".^[5] This was followed by methyl (Dumas and Peligot in 1834, meaning "spirit of wood"^[6]) and amyl (Auguste Cahours in 1840^[7]). The word alkyl was introduced by Johannes Wislicenus in or before 1882, based on the German word "Alkoholradicale" and then-common suffix -yl.^[8]^[9]

References

^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "alkyl groups".
^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "cycloalkyl groups".
^ Virtual Textbook of Organic Chemistry Naming Organic Compounds
^ Mallavadhani UV, Sahoo L, Kumar KP, Murty US (2013). "Synthesis and antimicrobial screening of some novel chalcones and flavanones substituted with higher alkyl chains". Medicinal Chemistry Research. doi:10.1007/s00044-013-0876-x.
^ Rocke, Alan (2012). From the Molecular World: A Nineteenth-Century Science Fantasy. Springer. p. 62. ISBN 978-3-642-27415-2. Ethyl radicals (named by Liebig in 1833 from the Greek and German word "aether" plus Greek "hyle"
^ Rocke, Alan (2012). From the Molecular World: A Nineteenth-Century Science Fantasy. Springer. p. 62. ISBN 978-3-642-27415-2. The methyl radical ... named from Greek roots, by Dumas and Peligot in 1834: methyl = methy + hyle ("spirit" + "wood")
^ Rocke, Alan (2012). From the Molecular World: A Nineteenth-Century Science Fantasy. Springer. p. 62. ISBN 978-3-642-27415-2. Amyl radicals ("amilène" was coined by Auguste Cahours in 1840, to designate a substance from potato starch after fermentation and distillation
^ Rocke, Alan (2012). From the Molecular World: A Nineteenth-Century Science Fantasy. Springer. p. 62. ISBN 978-3-642-27415-2. "Alkyl" was coined without fanfare by Johannes Wislicenus, professor at Würzburg; an early use (perhaps not the first) is in his 1882 article [22, 244]. The word was derived from the first three letters of "Alkoholradicale" combined with the suffix -yl; it was (and is) a generic term for any of those radicals who bear the "first names" methyl, ethyl, propyl, butyl, amyl, etc.
^ Wisclicenus, Johannes (1882). "Ueber die Schätzung von Haftenenergien der Halogene und des Natriums an organischen Resten". Ann. Chem. 212: 239–250.

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. 肝疾患を有する患者における化学療法による肝毒性および用量調整 chemotherapy hepatotoxicity and dose modification in patients with liver disease
2. 小児における特発性ネフローゼ症候群の治療 treatment of idiopathic nephrotic syndrome in children
3. 小児、思春期および成人期の横紋筋肉腫：治療 rhabdomyosarcoma in childhood adolescence and adulthood treatment
4. 真性多血症の予後および治療 prognosis and treatment of polycythemia vera
5. 小児におけるステロイド抵抗性特発性ネフローゼ症候群 steroid resistant idiopathic nephrotic syndrome in children

English Journal

Molecular design of the phenol type extractants.

Semenov SA, Reznik AM.SourceLomonosov Moscow State University of Fine Chemical Technology, prospect Vernadskogo, 86, Moscow, 119571 Russia.
SpringerPlus.Springerplus.2013 Dec;2(1):120. Epub 2013 Mar 20.
A method of optimisation of new extractants structure using the desirable function has been developed. Earlier the desirable function has been proposed by Harrington (Ind Qual Control 21: 494-498, 1965) for the optimisation of processes with several response functions. The developed method of optimi
PMID 23543841

Mass spectrometry identification of alkyl-substituted pyrazines produced by Pseudomonas spp. isolates obtained from wine corks.

Bañeras L, Trias R, Godayol A, Cerdán L, Nawrath T, Schulz S, Anticó E.SourceMolecular Microbial Ecology Group, Institute of Aquatic Ecology, University of Girona, Facultat de Ciències, C/Maria Aurèlia Capmany 69, E-17071 Girona, Spain.
Food chemistry.Food Chem.2013 Jun 15;138(4):2382-9. doi: 10.1016/j.foodchem.2012.12.030. Epub 2012 Dec 28.
We investigated the pyrazine production of 23 Pseudomonas isolates obtained from cork in order to assess their implications in off-flavour development. Off-flavour development in cork stoppers is a crucial process in maintaining the high quality of some wines. Pyrazine production was analyzed by hea
PMID 23497899

Effects of anionic structure on the dissolution of cellulose in ionic liquids revealed by molecular simulation.

Zhao Y, Liu X, Wang J, Zhang S.SourceBeijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex System, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China; School of Chemistry and Environmental Science, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang, Henan 453007, PR China.
Carbohydrate polymers.Carbohydr Polym.2013 May 15;94(2):723-30. doi: 10.1016/j.carbpol.2013.02.011. Epub 2013 Feb 18.
Although ionic liquids (ILs) have shown promise in the pretreatment of cellulose and lignocellulosic biomass, there is no established rule to guide the rational design of such ILs up to date. In this work, the mixtures of cellulose with a series of ILs having the same cation [C2mim](+) but different
PMID 23544626