Nomenclature of organic compounds(有机化合物英文命名)

Nomenclature of organic compounds (for fundamental organic chemistry) Functional groupIn organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction(s) regardless of the size of the molecule it is a part of. However, its relative reactivity can be modified by nearby functional groups.The word moiety is often used synonymously to "functional group," but, according to the IUPAC definition,a moiety is a part of a molecule that may include functional groups as substructures. For example, an ester is divided into an alcohol moiety and an acyl moiety, but has an ester functional group. Also, it may be divided into carboxylate and alkyl moieties. Each moiety may carry any number of functional groups, for example methyl parahydroxybenzoate carries a phenol functional group in the acyl moiety.Combining the names of functional groups with the names of the parent alkanes generates a powerful systematic nomenclature for naming organic compounds.The atoms of functional groups are linked to each other and to the rest of the molecule by covalent bonds. When the group of atoms is associated with the rest of the molecule primarily by ionic forces, the group is referred to more properly as a polyatomic ion or complex ion. And all of these are called radicals, by a meaning of the term radical that predates the free radical.The first carbon atom after the carbon that attaches to the functional group is called the alpha carbon; the second, beta carbon, the third, gamma carbon, etc. If there is another functional group at a carbon, it may be named with the Greek letter, e.g. the gamma-amine in gamma-aminobutanoic acid is on the third carbon of the carbon chain attached to the carboxylic acid group.Examples to Rule A-2.2Examples to Rule A-2.3(i)ethyl is cited before methyl, thus 4-Ethyl-3,3-dimethylheptaneExamples to Rule A-2.3(ii)dimethylpentyl (as complete single substituent) is alphabetized under "d", thus 7-(1,2-Dimethylpentyl)-5-ethyltridecaneExamples to Rule A-2.3(iii)Examples: to Rule A-2.4Examples to Rule A-3.12-Hexene1,4-HexadieneExamples to Rule A-3.31,3-Hexadien-5-yne3-Penten-1-yne1-Penten-4-yneAlcoholIn the IUPAC system, the name of the alkane chain loses the terminal "e" and adds "ol", e.g. "methanol" and "ethanol".When necessary, the position of the hydroxyl group is indicated by a number between the alkane nameand the "ol": propan-1-ol for CH3CH2CH2OH, propan-2-ol for CH3CH(OH)CH3.Sometimes, the position number is written before the IUPAC name:1-propanol and 2-propanol. If a higher priority group is present (such as an aldehyde, ketone or carboxylic acid), then it is necessary to use the prefix "hydroxy".EtherIn the IUPAC nomenclature system, ethers are named using the general formula "alkoxyalkane", for example CH3-CH2-O-CH3is methoxyethane. If the ether is part of a more complex molecule, it is described as an alkoxy substituent, so -OCH3would be considered a "methoxy-"group. The simpleralkyl radical is written in front, so CH3-O-CH2CH3would be given asmethoxy(CH3O)ethane(CH2CH3). The nomenclature of describing the two alkyl groups and appending "ether", e.g. "ethyl methyl ether" is a trivial usage.Methyl ethyl ether (CH3OC2H5), diphenylether (C6H5OC6H5). IUPAC rules areoften not followed for simple ethers. As for other organic compounds, very common ethers acquired names before rules for nomenclature were formalized. Diethyl ether is simply called "ether".Aldehyde1.Acyclic aliphatic aldehydes are named as derivatives of the longestcarbon chain containing the aldehyde group. Thus, HCHO is named asa derivative of methane, and CH3CH2CH2CHO is named as a derivativeof butane. The name is formed by changing the suffix -e of the parent alkane to -al, so that HCHO is named methanal, and CH3CH2CH2CHO is named butanal.2.In other cases, such as when a -CHO group is attached to a ring,the suffix -carbaldehyde may be used. Thus, C6H11CHO is known as cyclohexanecarbaldehyde. If the presence of another functional group demands the use of a suffix, the aldehyde group is named with the prefix formyl-. This prefix is preferred to methanoyl-. 3.If the compound is a natural product or a carboxylic acid, the prefixoxo- may be used to indicate which carbon atom is part of the aldehyde group; for example, CHOCH2COOH is named 3-oxopropanoic acid.Example of aldehydes:1.methanal (formaldehyde), , ,2.ethanal (acetaldehyde), , , ,3.propanal (propionaldehyde), , ,,4.2-methylpropanal (2 not strictly needed but advisable, 2-methypropionaldehyde),o, ,5.butanal (butyraldehyde), , ,6.2-methylbutanal (2-methylbutyraldehyde), ,7.3-methylbutanal (3-methylbutyraldehyde), ,8.pentanal (old name 'valeraldehyde'),,9.benzaldehyde (benzenecarbaldehyde), and2-hydroxybenzaldehydeKetoneAccording to the rules of IUPAC nomenclature, ketones are named by changing the suffix -e of the parent alkane to -one. For the most important ketones, however, traditional nonsystematic names are still generally used, for example acetone and benzophenone. These nonsystematic names are considered retained IUPAC names, although some introductory chemistry textbooks use names such as 2-propanone instead of acetone, the simplestketone (CH3-C O-CH3). The position of the carbonyl group is usually denotedby a number.Oxo is the IUPAC nomenclature for a ketone functional group. Other prefixes, however, are also used. For some common chemicals (mainly in biochemistry), "keto" or "oxo" is the term that describes the ketone functional group. The term "oxo" is used widely through chemistry, for example it also refers to a single oxygen atom coordinated to a transition metal (a metal oxo).Examples of ketones1.propanone (acetone, dimethyl ketone, DMK), , ,,2.butanone (or butan-2-one, but 2 not strictly needed, methyl ethyl ketone, MEK,2-butanone),o, , ,3.3-methylbutan-2-one (2 and 3 not strictly needed BUT advisable,3-methyl-2-butanone),o,4.pentan-2-one (2-pentanone), ,,5.pentan-3-one (3-pentanone), ,,6.1-phenylethanone7.2-hydroxyphenylethanoneCarboxylic acid1a. methanoic Acid (formic acid), ,,,1b. methanamide (formamide), ,,,1c. methyl methanoate (methyl formate), ,,,1d. ethyl methanoate , ,,,1e. propyl methanoate , ,,2a. ethanoic acid (acetic acid), ,,,2b. ethanoyl chloride (acetyl chloride), ,,,2c. ethanamide (acetamide), ,,,2d. methyl ethanoate (methyl acetate), ,,,EsterThe names for esters are derived from the names of the parent alcohol and the carboxylic acid. For esters derived from the simplest carboxylic acids, the traditional names are used, such as formate, acetate, propionate, and butyrate. For esters from more complex carboxylic acids, the systematic name for the acid is used, followed by the suffix -oate. For example, hexyl octanoate, also called hexyl caprylate, has the formula CH3(CH2)6CO2(CH2)5CH3.IUPAC names of Aromatic CompoundsCompounds containing one or more of benzene rings are known as aromatic family. Naming aromatic compounds isn’t quite so straightforward as naming chain compounds. Often, more than one name is acceptable and it’s not uncommon to find the old names still in use as well.If only one hydrogen atom of the benzene ring is replaced by another atom or group of atoms, a monovalent substituted derivative is formed. It can exist only in one form as all the six hydrogen atoms in benzene are equivalent. For example.Substituent names:Examples:Di-Substituted Benzene DerivativesIf two or more hydrogen atoms of the benzene ring are replaced by other atoms or group of atoms, these are indicated by Arabic numerals i.e., 1, 2, 3....... etc. In case of disubstituted compounds, it is also indicated by the following method.(a) Ortho. The compound is termed as ortho if the two substituents are on the adjacent carbon atoms. In IUPAC system to indicate these positions are 1, 2.(b) Meta.The compound is termed as meta if the two substituents are on alternate carbon atom. In IUPAC system to indicate these position are 1, 3. (c) Para. The compound is termed as para if the two substituents are present on diagonally opposite carbon atoms. In IUPAC system to indicate these positions are 1, 4.Examples:Poly-Substituted Benzene DerivativesBenzene derivatives with more than two substituents are named by numbering the position of each substituent. List the substituents alphabetically, with the numbers having the lowest possible sum.Examples:Common NamesSince aromatic compounds have been known since antiquity, many of these compounds have common names. The common names for several important aromatic compounds are listed below:Aromatic compounds with only one group attached to the benzene ringCases where the name is based on benzenechlorobenzeneThis is a simple example of a halogen attached to the benzene ring. The name is self-obvious.The simplified formula for this is C6H5Cl. You could therefore (although you never do!) call it phenyl chloride. Whenever you draw a benzene ring with one other thing attached to it, you are in fact drawing a phenyl group. In order to attach something else, you have to remove one of the existing hydrogen atoms, and so automatically make a phenyl group.nitrobenzeneThe nitro group, NO2, is attached to a benzene ring.The simplified formula for this is C6H5NO2.methylbenzeneAnother obvious name - the benzene ring has a methyl group attached. Other alkyl side-chains would be named similarly - for example, ethylbenzene. The old name for methylbenzene is toluene, and you may still meet that.The simplified formula for this is C6H5CH3.(chloromethyl)benzeneA variant on this which you may need to know about is where one of the hydrogens on the CH3 group is replaced by a chlorine atom. Notice the brackets around the (chloromethyl) in the name. This is so that you are sure that the chlorine is part of the methyl group and not somewhere else on thering.If more than one of the hydrogens had been replaced by chlorine, the names would be (dichloromethyl)benzene or (trichloromethyl)benzene. Again, notice the importance of the brackets in showing that the chlorines are part of the side group and not directly attached to the ring.benzoic acid (benzenecarboxylic acid)Benzoic acid is the older name, but is still in common use - it's a lot easier to say and write than the modern alternative! Whatever you call it, it has a carboxylic acid group, -COOH, attached to the benzene ring.Cases where the name is based on phenylRemember that the phenyl group is a benzene ring minus a hydrogen atom - C6H5. If you draw a benzene ring with one group attached, you have drawn a phenyl group.phenylaminePhenylamine is a primary amine and contains the -NH2 group attached to a benzene ring.The old name for phenylamine is aniline, and you could also reasonably call it aminobenzene. Phenylamine is what it is most commonly for UK-based exam purposes.phenyletheneThis is an ethene molecule with a phenyl group attached. Ethene is a two carbon chain with a carbon-carbon double bond. Phenylethene is therefore:The old name for phenylethene is styrene - the monomer from which polystyrene is made.phenylethanoneThis is a slightly awkward name - take it to pieces. It consists of a two carbon chain with no carbon-carbon double bond. The one ending shows that it is a ketone, and so has a C=O group somewhere in the middle. Attached to the carbon chain is a phenyl group. Putting that together gives:phenyl ethanoateThis is an ester based on ethanoic acid. The hydrogen atom in the -COOH group has been replaced by a phenyl group.phenolPhenol has an -OH group attached to a benzene ring and so has a formulaC6H5OH.Aromatic compounds with more than one group attached to the benzene ringNumbering the ringAny group already attached to the ring is given the number 1 position. Where you draw it on the ring (at the top or in any other position) doesn't matter - that's just a question of rotating the molecule a bit. It's much easier, though, to get in the habit of drawing your main group at the top.The other ring positions are then numbered from 2 to 6. You can number them either clockwise or anti-clockwise. As with chain compounds, you number the ring so that the name you end up with has the smallest possible numbers in it. Examples will make this clear.Some simple examplesSubstituting chlorine atoms on the ringLook at these compounds:All of these are based on methylbenzene and so the methyl group is given the number 1 position on the ring.Why is it 2-chloromethylbenzene rather than 6-chloromethylbenzene? The ring is numbered clockwise in this case because that produces a 2- in the name rather than a 6-. 2 is smaller than 6.2-hydroxybenzoic acidThis might also be called 2-hydroxybenzenecarboxylic acid. There is a -COOH group attached to the ring and, because the name is based on benzoic acid, that group is assigned the number 1 position. Next door to it in the 2 position is a hydroxy group, -OH.benzene-1,4-dicarboxylic acidThe di shows that there are two carboxylic acid groups, -COOH, one of them in the 1 position and the other opposite it in the 4 position.2,4,6-trichlorophenolThis is based on phenol - with an -OH group attached in the number 1 position on the ring. There are 3 chlorine atoms substituted onto the ring in the 2, 4 and 6 positions.methyl 3-nitrobenzoateThis is a name you might come across as a part of a practical exercise in nitrating benzene rings. It's included partly for that reason, and partly because it is a relatively complicated name to finish with!The structure of the name shows that it is an ester. You can tell that from the oate ending, and the methyl group floating separately from the rest of thename at the beginning.The ester is based on the acid, 3-nitrobenzoic acid - so start with that.There will be a benzene ring with a -COOH group in the number 1 position and a nitro group, NO2, in the 3 position. The -COOH group is modified to make an ester by replacing the hydrogen of the -COOH group by a methyl group. Methyl 3-nitrobenzoate is therefore:Table 1 Suffixes and prefixes for some important characteristic groups in substitutive nomenclature (in order of decreasing priority)Class Formula Prefix SuffixCarboxylic acids carboxy--carboxylic acid----oic acidEsters (of carboxylic acids)(R)-oxycarbonyl-(R)...carboxylate---(R)...oateAcid halides halocarbonyl--carbonyl halidecarbamoyl--carboxamideAmides----amideAldehydesoxo--alKetones oxo--oneAlcohols, Phenols hydroxy--olAmines amino--amineTable 2 Some characteristic groups cited only as prefixes in substitutive nomenclatureCharacteristic group PrefixBromo-Chloro-Iodo-Diazo-Azido-Nitroso-Nitro-(R)-oxy-Table 5 Suffixes and prefixes for some important characteristic groups in substitutive nomenclatureIn alphabetical orderClass Formula Prefix SuffixAcid halideshalocarbonyl--carbonyl halideAlcoholates, Phenolates oxido--olateAlcohols, Phenols hydroxy--olAldehydes formyl--carbaldehydeoxo--alAmides carbamoyl--carboxamide----amideAmidines carbamimidoyl--carboximidamide----imidamide Amines amino--amineCarboxylates carboxylato--carboxylate----oateCarboxylic acids carboxy--carboxylic acid----oic acidEthers(R)-oxy----Esters (of carboxylic acids)(R)-oxycarbonyl-(R)...carboxylate---(R)...oateHydroperoxideshydroperoxy----Iminesimino--imine(R)-imino----Ketones oxo--oneNitriles cyano--carbonitrile----nitrilePeroxides(R)-peroxy----Salts (of carboxylic acids)---(cation) ...carboxylate---(cation) ...oateSulfides(R)-sulfanyl----Sulfonatessulfonato--sulfonateSulfonic acidsulfo--sulfonic acid Thiolatessulfido--thiolateThiols Sulfanyl--thiol。