Hydrocarbon radical (from the Latin. Radix "root"), also hydrocarbon residue in chemistry - a group of atoms connected to the functional group of the molecule . Usually during chemical reactions, the radical passes from one compound to another without change. But the radical itself may contain functional groups, so with its “immutability” you need to be careful: for example, the amino acid aspartic acid contains in that part of the molecule, which is generally regarded as an amino acid residue , another carboxyl group . Often the hydrocarbon radical is simply called a radical , which can cause confusion with the concept of a free radical . Some hydrocarbon radicals may also be functional groups , for example, phenyl (–C 6 H 5 ), vinyl (–C 2 H 3 ), etc. Hydrocarbon radicals are usually hydrocarbon residues that are part of many organic compounds .
Content
Nomenclature
Monovalent hydrocarbon radicals
The name of the hydrocarbon radical is formed from the root of the name of the hydrocarbon by adding to it the suffix -yl . The suffixes "-en" and "-in" are preserved in order not to lose the idea of the saturation of the hydrocarbon radical. In more complex hydrocarbon radicals, for example, polycyclic , the suffix "-an" is preserved [1] , probably due to greater harmoniousness. Before the suffix "-il" indicates the sequence number of the carbon atom from the beginning of the chain of carbon atoms of the radical, which has a free valence - except the case if the first atom in the chain has a free valence. The numbering of the chain comes from the end nearest to the free valence. If in the carbon chain on one side of an atom with free (s) valence (s) all hydrogen atoms are replaced , then the atom with free valences is considered the first in the chain. Earlier, the nature of an atom with a free valence — primary, secondary ( sec- or sec- ), tertiary ( terc- or tert- ) —is used in trivial names (see below ). In the trivial names are also used the roots of the historical names of substances or related concepts. For example:
- −CH 3 - methyl ( meth en + -yl )
- −C 2 H 5 - ethyl ( eth an + + yl )
- -CH 2 -CH = CH-CH 3 - but-2-enyl
- At the top is depicted spiro [4.5] decan-8-il.
- - prop-2-yl or isopropyl
- -CH 2 -CH (CH 3 ) 2 - 2-methylpropyl or isobutyl
- -CH (CH 3 ) -CH 2 -CH 3 - but-2-yl or sec -butyl, or sec -butyl
- −C 6 H 5 - Phenyl ( hair dryer [2] + -yl )
- -CH = CH 2 - vinyl [3]
Polyvalent hydrocarbon radicals
If a radical is able to adhere to a carbon atom to form a double or triple bond or to attach to several carbon atoms at once (that is, it has several free valencies), it is called polyvalent (in the specific case bi-, trivalent, etc.) ). The names of such radicals are built by attaching the suffix “-iliden” or “-ylidin” to the root of the hydrocarbon name, respectively. Previously, the exceptions to this rule were methylene and methin (but not now); however, these names apply.
l-agreement
Polyvalent hydrocarbon radicals may also be named according to the l-agreement. In this case, the name is built according to the following scheme: [substituent at an atom with free valence] - [atomic number with free valence] l n - [name of the hydrocarbon that would have been obtained if free valencies of bonds with hydrogen atoms were formed at the site]. n here is the number of free valences possessed by an atom.
Examples
- > CH-CH 3 - ethylidene
- > C 6 H 4 - phenylidene (there are 3 isomers: "1,2-", "1,3-" and "1,4-", or ortho-, meta- and para-)
- The bottom right shows 6-aminyl-bicyclo [2.2.2] oct-4-en-2-ylidene or 6-aminyl-2l 2- bicyclo [2.2.2] oct-4-ene
Formulas in the formulas
If it does not matter what hydrocarbon radical is in a molecule, then it is often denoted simply by the letter R (for example, the general formula of the homologous series of alcohols is R − OH). Sometimes the symbol Org is used instead of R. If the compound contains several different radicals, they are designated R, R ', R ", R 4 , etc.
Sometimes it is necessary to separate aromatic , heterocyclic and alkyl radicals. To do this, instead of the symbol R use:
- for aliphatic ( alkyl ) - Alk [4] or Ak [5]
- for aromatic ( aryl ) - Ar [4] [5] [6]
- for heterocyclic ( heteroaryl ) - Het [4] or Har [5]
In organic chemistry, abbreviations are often used:
- Saturated hydrocarbon radicals:
- Methyl - Me [5] [6] [7] , for example, methanol MeOH
- Ethyl - Et [5] [6] [7] , for example, diethyl ether Et 2 O
- Propyl - Pr [5] [6] [7] , for example, (N, N-dipropyl) -aminopropane ( tripropylamine )
- Isopropyl - i-Pr [5] , for example, isopropyl benzene
- Butyl - Bu [5] [6] [7]
- tert-butyl - t-Bu [5]
- Pentyl - Pe [5] [7]
- Hexyl - Hx [5] [7]
- Heptyl - Hp [7]
- Octyl - Oc [5] [7]
- Nonyl - Nn [7]
- Unsaturated hydrocarbon radicals:
- Allyl - All [4]
- Vinyl - Vin [4] , Vi [5]
- Cyclic hydrocarbon radicals (cycloalkyls):
- Adamantyl - Ad [8] or Adm [5]
- Cyclohexyl - Cy [6]
- Cyclopentadienyl - Cp [6] [8]
- Aromatic hydrocarbon radicals (aryls):
- Phenyl - Ph [5] [6] , for example, phenol PhOH
- Phenylene - Pn [5]
- Benzyl - Bn [6] [8]
- Mesityl (2,4,6-trimethylphenyl) - Mes [6]
- Tolyl - Tol [8]
- Trityl (triphenylmethyl) - Tr [6] [8]
- Polycyclic aromatic hydrocarbon radicals (polycyclic aryls):
- Anthracenil - An [5]
- Pyrenil - Pyr [5]
- Perilenil - Per [5]
- Tetracenil - Tet [5]
- Naphthyl - Nh [5]
- Heterocyclic hydrocarbon radicals (heteroaryls):
- Pyridyl - Py [4] [5]
- Thienyl - Tp [5]
- Furil - Fr [5]
- Sulfonyls :
- Methylsulfonyl (mesyl) - Ms [6]
- Tolylsulfonyl (tosyl) - Ts [4] [6] [8] or Tos
- Triflil (i.e., trifluoromethylsulfonyl ) - Tf [4] [6] [8]
- Carbonyls :
- Acetyl - Ac [4] [6]
- Acyl - Acyl [7]
- Benzoyl - Bz [4] [6] [8]
- Benzyloxycarbonyl - Cbz [6]
- Glycoloyl (hydroxyacetyl) - Gc [7]
- Carbamoyl - Cbm [4]
- Propionyl - Pp [7]
- tert-butoxycarbonyl - Boc [6] [8]
- Formil - Fo ( ) [7]
Sometimes between the designation of the nature of the radical (t, i, s, etc.) and the rest of the name there is no hyphen: iPr , tBu [7] .
The structural formulas of some examples are depicted here:
Benzyl
Benzoyl
Trifluorosulfonyl
Application
The trivial, non-nomenclature names of many organic compounds consist of the name of the hydrocarbon radical and the name of atoms or groups of atoms that replace hydrogen , for example: CH 3 Cl - methyl chloride , C 2 H 5 Br - ethyl bromide , etc.
Primary, secondary, tertiary and quaternary carbon atoms
The trivial names of radicals, as already mentioned above, are often based on the nature of carbon atoms in the radical. The nature of the atom is defined as follows: the primary atom is associated with one carbon atom, the secondary one with two, and so on. In the name of radicals, Latin ( sec- , tert- ) or Russian ( second- , third- ) prefixes are used. Primary atoms are not designated in any way. If at the very end of the radical there is a tertiary atom, add the prefix iso- . Radicals with quaternary atoms have the prefix neo- . The separation of carbon atoms according to such criteria is extremely important in determining the stability of reacting organic particles ( carbocations , carbanions, and radicals ). Sometimes this sign is denoted by the symbols 1 0 , 2 0 , 3 0 and 4 0, respectively.
Notes
- ↑ See the IUPAC rules on the website
- ↑ The old name for benzene is “hair dryer” (from Greek phain to light )
- ↑ From lat. vinum ( vini ) - wine; Vinyl is genetically related to wine alcohol - ethanol C 2 H 5 OH
- ↑ 1 2 3 4 5 6 7 8 9 10 11 Instructions to authors (Eng.) // Chem. Heterocycl. Comp .. - 2008. - February ( vol. 44 , no. 2 ). - P. 235–241 . - DOI : 10.1007 / s10593-008-0019-3 .
- ↑ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Marvin Charton. Chapter 7. Effects of structural variations on organolithium сompounds // The Chemistry of Organolithium Compounds / Ed. by Z. Rappoport and I. Marek. - John Wiley & Sons, Ltd., 2004. - T. 1. - p. 268. - 1400 p. - ISBN 0-470-84339-X .
- ↑ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Guidelines for Authors (English) . pubs.acs.org . The Journal of Organic Chemistry (2016). The appeal date is December 24, 2016.
- ↑ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Nomenclature of Lipids. Appendixes AC (English) . http://www.chem.qmul.ac.uk . Iupac . The appeal date is December 24, 2016.
- ↑ 1 2 3 4 5 6 7 8 9 ML Waters, WD Wulff. Chapter 2. The Synthesis of Phenols and Quinones via Fischer Carbene // Organic Reactions / LE Overman (Editor-in-Chief). - John Wiley & Sons, Inc., 2008. - T. 70. - p. 226. - 656 p. - ISBN 978-0-470-25453-0 .
See also
- Free radicals