In organic chemistry and biochemistry, substituents are atoms or groups of atoms that replace one or more hydrogen atoms in the hydrocarbon parent chain, becoming part of the newly generated molecule. The terms substituents and functional groups, as well as others (eg side chains, pendant groups) are used almost interchangeably to describe the branches of the parent structure, although certain differences are made in the context of polymer chemistry. In polymers, the side chain extends from the backbone structure. In proteins, side chains are attached to alpha carbon atoms from the backbone of amino acids.
The suffix -il is used when naming an organic compound containing a single bond which replaces one hydrogen; -ylidene and -ylidyne are used with double bonds and triplicate bonds, respectively. Additionally, when naming a substituent-containing hydrocarbon, a positional number is used to indicate which carbon atom is attached to the substituent when the information is required to distinguish between isomers. The polar effect given by the substituent is a combination of inductive and mesomeric effects. The additional steric effect is generated from the volume occupied by the substituent.
Substituted and subtitles are most commonly used to describe molecules and predict their products. In this terminology, methane is used as a reference comparison. Using methane as a reference, for every hydrogen atom that is replaced or "substituted" by something else, the molecule can be said to be more substituted. As an example:
- The Markovnikov rule predicts that hydrogen adds carbon from an alkene-functional group having more hydrogen atoms (less alkyl substituents).
- The Zaitsev Rule predicts that the main reaction product is an alkene with a higher (more stable) double bond.
Video Substituent
Nomenklatur
The suffix -il is used in organic chemistry to form radical names, either separate species (called free radicals ) or parts of chemically bonded molecules (called moieties ). This can be traced back to the old name methanol, "methylene" (created from the Greek word methy = "wine" and h? L? = "wood"), which is shortened to "methyl" in compound names. Some chemical nomenclature reforms eventually generalize the use of suffixes for other organic substituents.
The use of suffixes is determined by the number of hydrogen atoms that substitute the substituents in the parent compound (and also, usually, on the substituent). According to the 1993 IUPAC guidelines:
- -il means one hydrogen is replaced.
- -ylidene means two hydrogens are replaced by a double bond between the mother and the substituent.
- - ylidyne means three hydrogens are replaced by a triple bond between the parent and the substituent.
The suffix -ylidine (with "ine" instead of "yne" or "ene") is encountered sporadically, and appears to be the spelling of the "-ilidene" variant. It is not mentioned in the IUPAC guidelines.
For multiple bonds of the same type, which links the substituents to the parent group, prefixes at , tri , tetra , etc. Used: -diyl (two single bonds), -triyl (three single bonds), -tetrayl < - diylidene (two double bonds)
For some bonds of different bond types, multiple suffixes are added: - ylylidene (one single and one double), -ylylidyne (one and one triple), -diylylidene (two singles and one double)
The plural parent name can be changed in two ways.
- For many common compounds, substituents are connected at one end (1 position), which is therefore not explicitly numbered in the formula. The substituent name is modified by stripping ane (see Alkane) and adding the appropriate suffix. This is "only recommended for saturated acyclic and monocyclic hydrocarbon groups and for mononuclear parent hydrides silicon, germanium, lead, lead, and boron". Thus, if there is a carboxylic acid called " X -ic acid", the alcohol ends " X -anol" (or " X -" alcohol , "or alkanes called" X -ane ", then" X -il "usually shows the same carbon chain that does not have these groups but is modified by attachment to some other parent molecules.
- A more general method only removes the terminal "e" from the substituent name, but requires explicit numbering of each prefix yl , even at position 1 (except for -ylidyne, which as a triple bond) ending the substituent carbon chain). Pentan-1-yl is an example name with this method, and identical to Pentyl from the previous guidelines.
Note that some popular terms like "vinyl" (when used mean "polyvinyl") represent only a portion of the complete chemical name.
The suffix "-il" appears by extracting it from the word "methyl".
Maps Substituent
Methane substituents
According to the above rule, the carbon atom in the molecule, regarded as a substituent, has the following name depending on the amount of hydrogen attached to it, and the type of bond formed with the rest of the molecule:
Structure
In the formula of chemical structure, organic substituents such as methyl, ethyl, or aryl can be written as R (or R 1 , R 2 , etc.) This is a generic placeholder, R originating from radical or rest , which can replace any part of the formula as the author finds it convenient. The first to use this symbol was Charles FrÃÆ'Â © dÃÆ' Â © ric Gerhardt in 1844.
The X symbol is often used to indicate electronegative substituents such as halides.
Distribution statistics
One cheminformatics study identified 849,574 unique substituents of up to 12 large, non-hydrogen atoms containing only carbon, hydrogen, nitrogen, oxygen, sulfur, phosphorus, selenium, and halogens in a set of 3,043,941 molecules. Fifty substituents can be considered common because they are found in more than 1% of this set, and 438 are found in more than 0.1%. 64% of the substituents are found in only one molecule. The top five most common are methyl, phenyl, chlorine, methoxy, and hydroxyl substituents. The number of organic substituents in organic chemistry is estimated at 3.1 million, creating a total of 6.7ÃÆ'â € "10 23 molecules. An infinite number of substituents can be obtained only by increasing the length of the carbon chain. For example, the methyl substituent (-CH 3 ) and the pentyl (-C 5 H 11 ).
See also
- The functional group is part of the substituent
References
Source of the article : Wikipedia
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