:Functional group

The following is a list of common functional groups.{{cite book |last= Brown |first= Theodore |title= Chemistry: the central science |publisher= Prentice Hall |location= Upper Saddle River, NJ |year= 2002 |isbn= 0130669970 |page=1001}} In the formulas, the symbols R and R' usually denote an attached hydrogen, or a hydrocarbon side chain of any length, but may sometimes refer to any group of atoms.

Hydrocarbons are a class of molecule that is defined by functional groups called hydrocarbyls that contain only carbon and hydrogen, but vary in the number and order of double bonds. Each one differs in type (and scope) of reactivity.

There are also a large number of branched or ring alkanes that have specific names, e.g., tert-butyl, bornyl, cyclohexyl, etc. There are several functional groups that contain an alkene such as vinyl group, allyl group, or acrylic group. Hydrocarbons may form charged structures: positively charged carbocations or negative carbanions. Carbocations are often named -um. Examples are tropylium and triphenylmethyl cations and the cyclopentadienyl anion.

Haloalkanes are a class of molecule that is defined by a carbon–halogen bond. This bond can be relatively weak (in the case of an iodoalkane) or quite stable (as in the case of a fluoroalkane). In general, with the exception of fluorinated compounds, haloalkanes readily undergo nucleophilic substitution reactions or elimination reactions. The substitution on the carbon, the acidity of an adjacent proton, the solvent conditions, etc. all can influence the outcome of the reactivity.

Compounds that contain C–O bonds each possess differing reactivity based upon the location and hybridization of the C–O bond, owing to the electron-withdrawing effect of sp-hybridized oxygen (carbonyl groups) and the donating effects of sp²-hybridized oxygen (alcohol groups).

Compounds that contain nitrogen in this category may contain C-O bonds, such as in the case of amides.

Compounds that contain sulfur exhibit unique chemistry due to sulfur's ability to form more bonds than oxygen, its lighter analogue on the periodic table. Substitutive nomenclature (marked as prefix in table) is preferred over functional class nomenclature (marked as suffix in table) for sulfides, disulfides, sulfoxides and sulfones.

Compounds that contain phosphorus exhibit unique chemistry due to the ability of phosphorus to form more bonds than nitrogen, its lighter analogue on the periodic table.

Compounds containing boron exhibit unique chemistry due to their having partially filled octets and therefore acting as Lewis acids.

{{Note label|halogen|note 1|note 1}} Fluorine is too electronegative to be bonded to magnesium; it becomes an ionic salt instead.

These names are used to refer to the moieties themselves or to radical species, and also to form the names of halides and substituents in larger molecules.

When the parent hydrocarbon is unsaturated, the suffix ("-yl", "-ylidene", or "-ylidyne") replaces "-ane" (e.g. "ethane" becomes "ethyl"); otherwise, the suffix replaces only the final "-e" (e.g. "ethyne" becomes "ethynyl").

When used to refer to moieties, multiple single bonds differ from a single multiple bond. For example, a methylene bridge (methanediyl) has two single bonds, whereas a methylidene group (methylidene) has one double bond. Suffixes can be combined, as in methylidyne (triple bond) vs. methylylidene (single bond and double bond) vs. methanetriyl (three double bonds).

There are some retained names, such as methylene for methanediyl, 1,x-phenylene for phenyl-1,x-diyl (where x is 2, 3, or 4),{{cite web|url=https://www.acdlabs.com/iupac/nomenclature/93/r93_271.htm|title=R-2. 5 Substituent Prefix Names Derived from Parent Hydrides|publisher=IUPAC|year=1993|access-date=2018-12-15|archive-date=2019-03-22|archive-url=https://web.archive.org/web/20190322061930/https://www.acdlabs.com/iupac/nomenclature/93/r93_271.htm|url-status=live}} section P-56.2.1 carbyne for methylidyne, and trityl for triphenylmethyl.

• :Category:Functional groups
• Group contribution method

{{Reflist|refs=

{{cite web |url=http://www.chem.qmul.ac.uk/iupac/ions/RC811.html#p11|title=RC-81.1.1. Monovalent radical centers in saturated acyclic and monocyclic hydrocarbons, and the mononuclear EH4 parent hydrides of the carbon family |last=Moss |first=G. P. |author2=W.H. Powell |work=IUPAC Recommendations 1993 |publisher=Department of Chemistry, Queen Mary University of London|access-date=25 February 2015 |archive-url=https://web.archive.org/web/20150209155729/http://www.chem.qmul.ac.uk/iupac/ions/RC811.html|archive-date=9 February 2015}}

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{{Commons|Functional groups}}

• [https://www.acdlabs.com/iupac/nomenclature/ IUPAC Blue Book (organic nomenclature)]
• {{cite web|url=http://www.iupac.org/reports/provisional/abstract04/RB-prs310804/TableVII-3.04.pdf|title=IUPAC ligand abbreviations|date=2 April 2004|publisher=IUPAC|access-date=25 February 2015 |archive-url= https://web.archive.org/web/20070927121055/http://www.iupac.org/reports/provisional/abstract04/RB-prs310804/TableVII-3.04.pdf |archive-date=27 September 2007}}
• [https://www.pearson.com/channels/organic-chemistry/learn/johnny/molecular-representations/functional-groups Functional group video]

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Category:Organic chemistry