To avoid long and tedious names in normal communication, the official IUPAC naming recommendations are not always followed in practice, except when it is necessary to give an unambiguous and absolute definition to a compound. IUPAC names can sometimes be simpler than older names, as with ethanol, instead of ethyl alcohol. For relatively simple molecules they can be more easily understood than non-systematic names, which must be learnt or looked over. However, the common or trivial name is often substantially shorter and clearer, and so preferred. These non-systematic names are often derived from an original source of the compound. Also, very long names may be less clear than structural formulas.
Basic principles
This article needs to be updated. The reason given is: According to current nomenclature, rings are senior to chains and chain length is senior to number of multiple bonds, the list should be revisited and updated as a whole. Please help update this article to reflect recent events or newly available information.(February 2020)
Identification of the ring or chain with the maximum number of senior groups.
Identification of the ring or chain with the most senior elements (In order: N, P, Si, B, O, S, C).
Identification of the parent compound. Rings are senior to chains if composed of the same elements.
For cyclic systems: Identification of the parent cyclic ring. The cyclic system must obey these rules, in order of precedence:
It should have the most senior heteroatom (in order: N, O, S, P, Si, B).
It should have the maximum number of rings.
It should have the maximum number of atoms.
It should have the maximum number of heteroatoms.
It should have the maximum number of senior heteroatoms (in order: O, S, N, P, Si, B).
For chains: Identification of the parent hydrocarbon chain. This chain must obey the following rules, in order of precedence:
It should have the maximum length.
It should have the maximum number of heteroatoms.
It should have the maximum number of senior heteroatoms (in order: O, S, N, P, Si, B).
For cyclic systems and chains after previous rules:
It should have the maximum number of multiple, then double bonds.
It should have the maximum number of substituents of the suffix functional group. By suffix, it is meant that the parent functional group should have a suffix, unlike halogen substituents. If more than one functional group is present, the one with highest group precedence should be used.
Identification of the side-chains. Side chains are the carbon chains that are not in the parent chain, but are branched off from it.
Identification of the remaining functional groups, if any, and naming them by their ionic prefixes (such as hydroxy for −OH, oxy for =O, oxyalkane for O−R, etc.). Different side-chains and functional groups will be grouped together in alphabetical order. (The multiplier prefixes di-, tri-, etc. are not taken into consideration for grouping alphabetically. For example, ethyl comes before dihydroxy or dimethyl, as the "e" in "ethyl" precedes the "h" in "dihydroxy" and the "m" in "dimethyl" alphabetically. The "di" is not considered in either case). When both side chains and secondary functional groups are present, they should be written mixed together in one group rather than in two separate groups.
Identification of double/triple bonds.
Numbering of the chain. This is done by first numbering the chain in both directions (left to right and right to left), and then choosing the numbering which follows these rules, in order of precedence. Not every rule will apply to every compound, rules can be skipped if they do not apply.
Has the lowest-numbered locant (or locants) for heteroatoms. Locants are the numbers on the carbons to which the substituent is directly attached.
Has the lowest-numbered locants for the indicated hydrogen. The indicated hydrogen is for some unsaturated heterocyclic compounds. It refers to the hydrogen atoms not attached to atoms with double bonds in the ring system.
Has the lowest-numbered locants for the suffix functional group.
Has the lowest-numbered locants for multiple bonds ('ene', 'yne'), and hydro prefixes. (The locant of a multiple bond is the number of the adjacent carbon with a lower number).
Has the lowest-numbered locants for all substituents cited by prefixes.
Has the lowest-numbered locants for substituents in order of citation (for example: in a cyclic ring with only bromine and chlorine functional groups, alphabetically bromo- is cited before chloro- and would receive the lower locant).
Numbering of the various substituents and bonds with their locants. If there is more than one of the same type of substituent/double bond, a prefix is added showing how many there are (di – 2, tri – 3, tetra – 4, then as for the number of carbons below with 'a' added at the end)
The numbers for that type of side chain will be grouped in ascending order and written before the name of the side-chain. If there are two side-chains with the same alpha carbon, the number will be written twice. Example: 2,2,3-trimethyl- . If there are both double bonds and triple bonds, "en" (double bond) is written before "yne" (triple bond). When the main functional group is a terminal functional group (a group which can exist only at the end of a chain, like formyl and carboxyl groups), there is no need to number it.
Arrangement in this form: Group of side chains and secondary functional groups with numbers made in step 6 + prefix of parent hydrocarbon chain (eth, meth) + double/triple bonds with numbers (or "ane") + primary functional group suffix with numbers. Wherever it says "with numbers", it is understood that between the word and the numbers, the prefix (di-, tri-) is used.
Adding of punctuation:
Commas are put between numbers (2 5 5 becomes 2,5,5)
Hyphens are put between a number and a letter (2 5 5 trimethylheptane becomes 2,5,5-trimethylheptane)
Successive words are merged into one word (trimethyl heptane becomes trimethylheptane) Note: IUPAC uses one-word names throughout. This is why all parts are connected.
The resulting name appears as:
#,#-di<side chain>-#-<secondary functional group>-#-<side chain>-#,#,#-tri<secondary functional group><parent chain prefix><If all bonds are single bonds, use "ane">-#,#-di<double bonds>-#-<triple bonds>-#-<primary functional group>
where each "#" represents a number. The group secondary functional groups and side chains may not look the same as shown here, as the side chains and secondary functional groups are arranged alphabetically. The di- and tri- have been used just to show their usage. (di- after #,#, tri- after #,#,#, etc.)
Example
Here is a sample molecule with the parent carbons numbered:
For simplicity, here is an image of the same molecule, where the hydrogens in the parent chain are removed and the carbons are shown by their numbers:
Now, following the above steps:
The parent hydrocarbon chain has 23 carbons. It is called tricosa-.
The functional groups with the highest precedence are the two ketone groups.
The groups are on carbon atoms 3 and 9. As there are two, we write 3,9-dione.
The numbering of the molecule is based on the ketone groups. When numbering from left to right, the ketone groups are numbered 3 and 9. When numbering from right to left, the ketone groups are numbered 15 and 21. 3 is less than 15, therefore the ketones are numbered 3 and 9. The smaller number is always used, not the sum of the constituents numbers.
The side chains are: an ethyl- at carbon 4, an ethyl- at carbon 8, and a butyl- at carbon 12. Note: the −O−CH3 at carbon atom 15 is not a side chain, but it is a methoxy functional group.
There are two ethyl- groups. They are combined to create, 4,8-diethyl.
The side chains are grouped like this: 12-butyl-4,8-diethyl. (But this is not necessarily the final grouping, as functional groups may be added in between to ensure all groups are listed alphabetically.)
The secondary functional groups are: a hydroxy- at carbon 5, a chloro- at carbon 11, a methoxy- at carbon 15, and a bromo- at carbon 18. Grouped with the side chains, this gives 18-bromo-12-butyl-11-chloro-4,8-diethyl-5-hydroxy-15-methoxy.
There are two double bonds: one between carbons 6 and 7, and one between carbons 13 and 14. They would be called "6,13-diene", but the presence of alkynes switches it to 6,13-dien. There is one triple bond between carbon atoms 19 and 20. It will be called 19-yne.
The arrangement (with punctuation) is: 18-bromo-12-butyl-11-chloro-4,8-diethyl-5-hydroxy-15-methoxytricosa-6,13-dien-19-yne-3,9-dione
Finally, due to cis-trans isomerism, we have to specify the relative orientation of functional groups around each double bond. For this example, both double bonds are trans isomers, so we have (6E,13E)
The final name is (6E,13E)-18-bromo-12-butyl-11-chloro-4,8-diethyl-5-hydroxy-15-methoxytricosa-6,13-dien-19-yne-3,9-dione.
Straight-chain alkanes take the suffix "-ane" and are prefixed depending on the number of carbon atoms in the chain, following standard rules. The first few are:
Numberofcarbons
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Prefix
Meth
Eth
Prop
But
Pent
Hex
Hept
Oct
Non
Dec
Undec
Dodec
Tridec
Tetradec
Pentadec
Hexadec
Heptadec
Octadec
Nonadec
Icos
For example, the simplest alkane is CH4 methane, and the nine-carbon alkane CH3(CH2)7CH3 is named nonane. The names of the first four alkanes were derived from methanol, ether, propionic acid and butyric acid, respectively. The rest are named with a Greek numeric prefix, with the exceptions of nonane which has a Latin prefix, and undecane which has mixed-language prefixes.
Cyclic alkanes are simply prefixed with "cyclo-": for example, C4H8 is cyclobutane (not to be confused with butene) and C6H12 is cyclohexane (not to be confused with hexene).
Branched alkanes are named as a straight-chain alkane with attached alkyl groups. They are prefixed with a number indicating the carbon the group is attached to, counting from the end of the alkane chain. For example, (CH3)2CHCH3, commonly known as isobutane, is treated as a propane chain with a methyl group bonded to the middle (2) carbon, and given the systematic name 2-methylpropane. However, although the name 2-methylpropane could be used, it is easier and more logical to call it simply methylpropane – the methyl group could not possibly occur on any of the other carbon atoms (that would lengthen the chain and result in butane, not propane) and therefore the use of the number "2" is unnecessary.
If there is ambiguity in the position of the substituent, depending on which end of the alkane chain is counted as "1", then numbering is chosen so that the smaller number is used. For example, (CH3)2CHCH2CH3 (isopentane) is named 2-methylbutane, not 3-methylbutane.
If there are multiple side-branches of the same size alkyl group, their positions are separated by commas and the group prefixed with multiplier prefixes depending on the number of branches. For example, C(CH3)4 (neopentane) is named 2,2-dimethylpropane. If there are different groups, they are added in alphabetical order, separated by commas or hyphens. The longest possible main alkane chain is used; therefore 3-ethyl-4-methylhexane instead of 2,3-diethylpentane, even though these describe equivalent structures. The di-, tri- etc. prefixes are ignored for the purpose of alphabetical ordering of side chains (e.g. 3-ethyl-2,4-dimethylpentane, not 2,4-dimethyl-3-ethylpentane).
Alkenes are named for their parent alkane chain with the suffix "-ene" and a numerical root indicating the position of the carbon with the lower number for each double bond in the chain: CH2=CHCH2CH3 is but-1-ene. Multiple double bonds take the form -diene, -triene, etc., with the size prefix of the chain taking an extra "a": CH2=CHCH=CH2 is buta-1,3-diene. Simple cis and transisomers may be indicated with a prefixed cis- or trans-: cis-but-2-ene, trans-but-2-ene. However, cis- and trans- are relative descriptors. It is IUPAC convention to describe all alkenes using absolute descriptors of Z- (same side) and E- (opposite) with the Cahn–Ingold–Prelog priority rules (see alse E–Z notation).
In haloalkanes and haloarenes (R−X), Halogen functional groups are prefixed with the bonding position and take the form of fluoro-, chloro-, bromo-, iodo-, etc., depending on the halogen. Multiple groups are dichloro-, trichloro-, etc., and dissimilar groups are ordered alphabetically as before. For example, CHCl3 (chloroform) is trichloromethane. The anesthetic halothane (CF3CHBrCl) is 2-bromo-2-chloro-1,1,1-trifluoroethane.
Alcohols (R−OH) take the suffix "-ol" with a numerical suffix indicating the bonding position: CH3CH2CH2OH is propan-1-ol. The suffixes -diol, -triol, -tetraol, etc., are used for multiple −OH groups: Ethylene glycolCH2OHCH2OH is ethane-1,2-diol.
If higher precedence functional groups are present (see order of precedence, below), the prefix "hydroxy" is used with the bonding position: CH3CHOHCOOH is 2-hydroxypropanoic acid.
Ethers (R−O−R) consist of an oxygen atom between the two attached carbon chains. The shorter of the two chains becomes the first part of the name with the -ane suffix changed to -oxy, and the longer alkane chain becomes the suffix of the name of the ether. Thus, CH3OCH3 is methoxymethane, and CH3OCH2CH3 is methoxyethane (not ethoxymethane). If the oxygen is not attached to the end of the main alkane chain, then the whole shorter alkyl-plus-ether group is treated as a side-chain and prefixed with its bonding position on the main chain. Thus CH3OCH(CH3)2 is 2-methoxypropane.
Alternatively, an ether chain can be named as an alkane in which one carbon is replaced by an oxygen, a replacement denoted by the prefix "oxa". For example, CH3OCH2CH3 could also be called 2-oxabutane, and an epoxide could be called oxacyclopropane. This method is especially useful when both groups attached to the oxygen atom are complex.[4]
Aldehydes (R−CH=O) take the suffix "-al". If other functional groups are present, the chain is numbered such that the aldehyde carbon is in the "1" position, unless functional groups of higher precedence are present.
If a prefix form is required, "oxo-" is used (as for ketones), with the position number indicating the end of a chain: CHOCH2COOH is 3-oxopropanoic acid. If the carbon in the carbonyl group cannot be included in the attached chain (for instance in the case of cyclic aldehydes), the prefix "formyl-" or the suffix "-carbaldehyde" is used: C6H11CHO is cyclohexanecarbaldehyde. If an aldehyde is attached to a benzene and is the main functional group, the suffix becomes benzaldehyde.
In general ketones (R2C=O) take the suffix "-one" (pronounced own, not won) with a suffixed position number: CH3CH2CH2COCH3 is pentan-2-one. If a higher precedence suffix is in use, the prefix "oxo-" is used: CH3CH2CH2COCH2CHO is 3-oxohexanal.
In general, carboxylic acids (R−C(=O)OH) are named with the suffix -oic acid (etymologically a back-formation from benzoic acid). As with aldehydes, the carboxyl functional group must take the "1" position on the main chain and so the locant need not be stated. For example, CH3−CH(OH)−COOH (lactic acid) is named 2-hydroxypropanoic acid with no "1" stated. Some traditional names for common carboxylic acids (such as acetic acid) are in such widespread use that they are retained in IUPAC nomenclature,[5] though systematic names like ethanoic acid are also used. Carboxylic acids attached to a benzene ring are structural analogs of benzoic acid (Ph−COOH) and are named as one of its derivatives.
Citric acid
If there are multiple carboxyl groups on the same parent chain, multiplying prefixes are used: Malonic acid, CH2(COOH)2, is systematically named propanedioic acid. Alternatively, the suffix "-carboxylic acid" can be used in place of "oic acid", combined with a multiplying prefix if necessary –mellitic acid is benzenehexacarboxylic acid, for example. In the latter case, the carbon atoms in the carboxyl groups do not count as being part of the main chain, a rule that also applies to the prefix form "carboxy-". Citric acid serves as an example: it is formally named 2-hydroxypropane-1,2,3-tricarboxylic acid rather than 3-carboxy-3-hydroxypentanedioic acid.
Salts of carboxylic acids are named following the usual cation-then-anion conventions used for ionic compounds in both IUPAC and common nomenclature systems. The name of the carboxylate anion (R−C(=O)O−) is derived from that of the parent acid by replacing the "–oic acid" ending with "–oate" or "carboxylate." For example, NaC6H5CO2, the sodium salt of benzoic acid (C6H5COOH), is called sodium benzoate. Where an acid has both a systematic and a common name (like CH3COOH, for example, which is known as both acetic acid and as ethanoic acid), its salts can be named from either parent name. Thus, KCH3CO2 can be named as potassium acetate or as potassium ethanoate. The prefix form, is "carboxylato-".
Esters (R−C(=O)O−R') are named as alkyl derivatives of carboxylic acids. The alkyl (R') group is named first. The R−C(=O)O part is then named as a separate word based on the carboxylic acid name, with the ending changed from "-oic acid" to "-oate" or "-carboxylate" For example, CH3CH2CH2CH2COOCH3 is methyl pentanoate, and (CH3)2CHCH2CH2COOCH2CH3 is ethyl 4-methylpentanoate. For esters such as ethyl acetate (CH3COOCH2CH3), ethyl formate (HCOOCH2CH3) or dimethyl phthalate that are based on common acids, IUPAC recommends use of these established names, called retained names. The "-oate" changes to "-ate." Some simple examples, named both ways, are shown in the figure above.
If the alkyl group is not attached at the end of the chain, the bond position to the ester group is suffixed before "-yl": CH3CH2CH(CH3)OOCCH2CH3 may be called butan-2-yl propanoate or butan-2-yl propionate.[citation needed]. The prefix form is "oxycabonyl-" with the (R') group preceding.
Acyl groups are named by stripping the "-ic acid" of the corresponding carboxylic acid and replacing it with "-yl." For example, CH3CO−R is called ethanoyl-R.
Simply add the name of the attached halide to the end of the acyl group. For example, CH3COCl is ethanoyl chloride. An alternate suffix is "-carbonyl halide" as opposed to "-oyl halide". The prefix form is "halocarbonyl-".
Acid anhydrides (R−C(=O)−O−C(=O)−R) have two acyl groups linked by an oxygen atom. If both acyl groups are the same, then the name of the carboxylic acid with the word acid is replaced with the word anhydride and the IUPAC name consists of two words. If the acyl groups are different, then they are named in alphabetical order in the same way, with anhydride replacing acid and IUPAC name consists of three words. For example, CH3CO−O−OCCH3 is called ethanoic anhydride and CH3CO−O−OCCH2CH3 is called ethanoic propanoic anhydride.
Amines (R−NH2) are named for the attached alkane chain with the suffix "-amine" (e.g., CH3NH2 methanamine). If necessary, the bonding position is suffixed: CH3CH2CH2NH2 propan-1-amine, CH3CHNH2CH3 propan-2-amine. The prefix form is "amino-".
For secondary amines (of the form R−NH−R), the longest carbon chain attached to the nitrogen atom becomes the primary name of the amine; the other chain is prefixed as an alkyl group with location prefix given as an italic N: CH3NHCH2CH3 is N-methylethanamine. Tertiary amines (R−NR−R) are treated similarly: CH3CH2N(CH3)CH2CH2CH3 is N-ethyl-N-methylpropanamine. Again, the substituent groups are ordered alphabetically.
Amides (R−C(=O)NH2) take the suffix "-amide", or "-carboxamide" if the carbon in the amide group cannot be included in the main chain. The prefix form is "carbamoyl-". e.g., HCONH2 methanamide, CH3CONH2 ethanamide.
Amides that have additional substituents on the nitrogen are treated similarly to the case of amines: they are ordered alphabetically with the location prefix N: HCON(CH3)2 is N,N-dimethylmethanamide, CH3CON(CH3)2 is N,N-dimethylethanamide.
Nitriles (R−C≡N) are named by adding the suffix "-nitrile" to the longest hydrocarbon chain (including the carbon of the cyano group). It can also be named by replacing the "-oic acid" of their corresponding carboxylic acids with "-carbonitrile." The prefix form is "cyano-." Functional class IUPAC nomenclature may also be used in the form of alkyl cyanides. For example, CH3CH2CH2CH2C≡N is called pentanenitrile or butyl cyanide.
Cycloalkanes and aromatic compounds can be treated as the main parent chain of the compound, in which case the positions of substituents are numbered around the ring structure. For example, the three isomers of xyleneCH3C6H4CH3, commonly the ortho-, meta-, and para- forms, are 1,2-dimethylbenzene, 1,3-dimethylbenzene, and 1,4-dimethylbenzene. The cyclic structures can also be treated as functional groups themselves, in which case they take the prefix "cycloalkyl-" (e.g. "cyclohexyl-") or for benzene, "phenyl-".
The IUPAC nomenclature scheme becomes rapidly more elaborate for more complex cyclic structures, with notation for compounds containing conjoined rings, and many common names such as phenol being accepted as base names for compounds derived from them.
Order of precedence of group
When compounds contain more than one functional group, the order of precedence determines which groups are named with prefix or suffix forms. The table below shows common groups in decreasing order of precedence. The highest-precedence group takes the suffix, with all others taking the prefix form. However, double and triple bonds only take suffix form (-en and -yn) and are used with other suffixes.
Prefixed substituents are ordered alphabetically (excluding any modifiers such as di-, tri-, etc.), e.g. chlorofluoromethane, not fluorochloromethane. If there are multiple functional groups of the same type, either prefixed or suffixed, the position numbers are ordered numerically (thus ethane-1,2-diol, not ethane-2,1-diol.) The N position indicator for amines and amides comes before "1", e.g., CH3CH(CH3)CH2NH(CH3) is N,2-dimethylpropanamine.
*Note: These suffixes, in which the carbon atom is counted as part of the preceding chain, are the most commonly used. See individual functional group articles for more details.
The order of remaining functional groups is only needed for substituted benzene and hence is not mentioned here.[clarification needed]
Common nomenclature – trivial names
Common nomenclature uses the older names for some organic compounds instead of using the prefixes for the carbon skeleton above. The pattern can be seen below.
Common names for ketones can be derived by naming the two alkyl or aryl groups bonded to the carbonyl group as separate words followed by the word ketone.
The first three of the names shown above are still considered to be acceptable IUPAC names.
Aldehydes
The common name for an aldehyde is derived from the common name of the corresponding carboxylic acid by dropping the word acid and changing the suffix from -ic or -oic to -aldehyde.
Simple cations formed by adding a hydron to a hydride of a halogen, chalcogen or pnictogen are named by adding the suffix "-onium" to the element's root: H4N+ is ammonium, H3O+ is oxonium, and H2F+ is fluoronium. Ammonium was adopted instead of nitronium, which commonly refers to NO+2.
If the cationic center of the hydride is not a halogen, chalcogen or pnictogen then the suffix "-ium" is added to the name of the neutral hydride after dropping any final 'e'. H5C+ is methanium, HO−(O+)H2 is dioxidanium (HO-OH is dioxidane), and H2N−(N+)H3 is diazanium (H2N−NH2 is diazane).
Cations and substitution
The above cations except for methanium are not, strictly speaking, organic, since they do not contain carbon. However, many organic cations are obtained by substituting another element or some functional group for a hydrogen.
The name of each substitution is prefixed to the hydride cation name. If many substitutions by the same functional group occur, then the number is indicated by prefixing with "di-", "tri-" as with halogenation. (CH3)3O+ is trimethyloxonium. CH3F3N+ is trifluoromethylammonium.
In organic chemistry, an alkane, or paraffin, is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which all the carbon–carbon bonds are single. Alkanes have the general chemical formula CnH2n+2. The alkanes range in complexity from the simplest case of methane, where n = 1, to arbitrarily large and complex molecules, like pentacontane or 6-ethyl-2-methyl-5-(1-methylethyl) octane, an isomer of tetradecane.
In chemistry, an alcohol is a type of organic compound that carries at least one hydroxyl functional group bound to a saturated carbon atom. Alcohols range from the simple, like methanol and ethanol, to complex, like sugar alcohols and cholesterol. The presence of an OH group strongly modifies the properties of hydrocarbons, conferring hydrophilic (water-loving) properties. The OH group provides a site at which many reactions can occur.
In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or in the terminal position. Terminal alkenes are also known as α-olefins.
In organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon—carbon triple bond. The simplest acyclic alkynes with only one triple bond and no other functional groups form a homologous series with the general chemical formula CnH2n−2. Alkynes are traditionally known as acetylenes, although the name acetylene also refers specifically to C2H2, known formally as ethyne using IUPAC nomenclature. Like other hydrocarbons, alkynes are generally hydrophobic.
In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group attached to an R-group. The general formula of a carboxylic acid is often written as R−COOH or R−CO2H, sometimes as R−C(O)OH with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic acids occur widely. Important examples include the amino acids and fatty acids. Deprotonation of a carboxylic acid gives a carboxylate anion.
In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two organyl groups. They have the general formula R−O−R′, where R and R′ represent organyl groups. Ethers can again be classified into two varieties: if the organyl groups are the same on both sides of the oxygen atom, then it is a simple or symmetrical ether, whereas if they are different, the ethers are called mixed or unsymmetrical ethers. A typical example of the first group is the solvent and anaesthetic diethyl ether, commonly referred to simply as "ether". Ethers are common in organic chemistry and even more prevalent in biochemistry, as they are common linkages in carbohydrates and lignin.
In chemistry, an ester is a compound derived from an acid in which the hydrogen atom (H) of at least one acidic hydroxyl group of that acid is replaced by an organyl group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well, but not according to the IUPAC.
In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest of the molecule's composition. This enables systematic prediction of chemical reactions and behavior of chemical compounds and the design of chemical synthesis. The reactivity of a functional group can be modified by other functional groups nearby. Functional group interconversion can be used in retrosynthetic analysis to plan organic synthesis.
In organic chemistry, a ketone is an organic compound with the structure R−C(=O)−R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group −C(=O)−. The simplest ketone is acetone, with the formula (CH3)2CO. Many ketones are of great importance in biology and in industry. Examples include many sugars (ketoses), many steroids, and the solvent acetone.
In chemistry, a structural isomer of a compound is another compound whose molecule has the same number of atoms of each element, but with logically distinct bonds between them. The term metamer was formerly used for the same concept.
In organic chemistry, an aldehyde is an organic compound containing a functional group with the structure R−CH=O. The functional group itself can be referred to as an aldehyde but can also be classified as a formyl group. Aldehydes are a common motif in many chemicals important in technology and biology.
In chemistry, an acyl group is a moiety derived by the removal of one or more hydroxyl groups from an oxoacid, including inorganic acids. It contains a double-bonded oxygen atom and an organyl group or hydrogen in the case of formyl group. In organic chemistry, the acyl group is usually derived from a carboxylic acid, in which case it has the formula R−C(=O)−, where R represents an organyl group or hydrogen. Although the term is almost always applied to organic compounds, acyl groups can in principle be derived from other types of acids such as sulfonic acids and phosphonic acids. In the most common arrangement, acyl groups are attached to a larger molecular fragment, in which case the carbon and oxygen atoms are linked by a double bond.
In organic chemistry, the cycloalkanes are the monocyclic saturated hydrocarbons. In other words, a cycloalkane consists only of hydrogen and carbon atoms arranged in a structure containing a single ring, and all of the carbon-carbon bonds are single. The larger cycloalkanes, with more than 20 carbon atoms are typically called cycloparaffins. All cycloalkanes are isomers of alkenes.
In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term alkyl is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of −CnH2n+1. A cycloalkyl group is derived from a cycloalkane by removal of a hydrogen atom from a ring and has the general formula −CnH2n−1. Typically an alkyl is a part of a larger molecule. In structural formulae, the symbol R is used to designate a generic (unspecified) alkyl group. The smallest alkyl group is methyl, with the formula −CH3.
In organic chemistry, butyl is a four-carbon alkyl radical or substituent group with general chemical formula −C4H9, derived from either of the two isomers (n-butane and isobutane) of butane.
In organic chemistry, a substituent is one or a group of atoms that replaces atoms, thereby becoming a moiety in the resultant (new) molecule.
In the nomenclature of organic chemistry, a locant is a term to indicate the position of a functional group or substituent within a molecule.
The root alk- is used in organic chemistry to form classification names for classes of organic compounds which contain a carbon skeleton but no aromatic rings. It was extracted from the word alcohol by removing the -ol suffix. See e.g. alkyl, alkane.
IUPAC Polymer Nomenclature are standardized naming conventions for polymers set by the International Union of Pure and Applied Chemistry (IUPAC) and described in their publication "Compendium of Polymer Terminology and Nomenclature", which is also known as the "Purple Book". Both the IUPAC and Chemical Abstracts Service (CAS) make similar naming recommendations for the naming of polymers.
In chemical nomenclature, a descriptor is a notational prefix placed before the systematic substance name, which describes the configuration or the stereochemistry of the molecule. Some listed descriptors are only of historical interest and should not be used in publications anymore as they do not correspond with the modern recommendations of the IUPAC. Stereodescriptors are often used in combination with locants to clearly identify a chemical structure unambiguously.
References
↑ The Commission on the Nomenclature of Organic Chemistry Varun kedia (1971) [1958 (A: Hydrocarbons, and B: Fundamental Heterocyclic Systems), 1965 (C: Characteristic Groups)]. Nomenclature of Organic Chemistry (3rd edition combineded.). London: Butterworths. ISBN0-408-70144-7.
chemicalize.org A free web site/service that extracts IUPAC names from web pages and annotates a 'chemicalized' version with structure images. Structures from annotated pages can also be searched.
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