Benzene derivatives naming

Aniline is the parent lUPAC name for ammo substituted derivatives of benzene Substituted derivatives of aniline are numbered beginning at the carbon that bears the ammo group Substituents are listed m alphabetical order and the direction of number mg IS governed by the usual first point of difference rule... 

Click Coached Problems for a self-study module on naming derivatives nf benzene. 

For replacement names the parent carbocycles, apart from benzene, are all named as cycloalkanes (modified to -ene, -diene, etc., as necessary) with the heteroatom replacing /CH2, CH, or C— as appropriate to its valency. Replacement names derived from benzene are not used unless the three formal double bonds are retained otherwise names of the type oxacyclohexa-2,4-diene are appropriate [see 1-3 and 57-60 replacement names for 7-11 are thiacyclopenta-2,4-diene (7), 1,3-diazabenzene (8), l-oxa-2,5-diazacyclopenta-2,4-diene (9), l-oxa-4-azacyclohexane (10), and l,2-diazacyclopent-3-ene (11)]. 

Side chain>benzene Name Phenyl Derivative Name... 

The simplest aromatic carboxylic acid is benzoic acid. Derivatives are named by using numbers and prefixes to show the presence and location of substituents relative to the carboxyl group. Certain aromatic carboxylic acids have common names by which they are more usually known. For example, 2-hydroxybenzoic acid is more often called salicylic acid, a name derived from the fact that this aromatic carboxylic acid was finst obtained from the bark of the willow, a tree of the genus SaEx. Aromatic dicarboxylic acids are named by adding the words dicarboxylic acid to benzene. Examples are 1,2-benzenedicarboxyhc acid and 1,4-benzenedicar-boxylic acid. Each is more usually known by its common name phthahc acid and terephthalic acid, respectively. Terephthahc acid is one of the two organic components required for the synthesis of the textile fiber known as Dacron polyester (Section 16.4B). 

This special stability has come to be known as benzene s aromatic character or aromaticity, a name derived in an obvious way from the pleasant ( ) odor of many benzene derivatives. In the next few pages, we will expand on the theme of aromaticity, eventually ending up with a general method for identifying aromatic compounds. 

Alternate Names l,l -(l-propene-l,3-diyl)bis[l,l,l-trimethy-Isilane] (lE)-l-propene-l,3-diylbis[trimethylsilane] (E)-prop- 1-ene-1,3-diylbis(trimethylsilane) (IZ)- 1-propene-1,3-diylbis[trimethylsilane], CAS 141291-16-9 Bis(r-butyl-dimethylsilyl) derivative (l )-l-propene-l,3-diylbis[(l,l-dimethylethyl)dimethylsilane] Bis(dimethylphenyl) derivative [[(l )-3-dimethylphenylsilyl)-1-propen-l-yl]dimethyl-silyl]-benzene other derivatives are known but less widely used. 

Alcohols are organic compounds that have a functional hydroxyl group attached to a carbon atom of an alkyl chain. Benzene hydroxyl derivatives and aromatic hydrocarbons are called phenols, and the hydroxyl group is directly attached to a carbon atom in the benzene ring. In this case, phenol is an alcohol but not an alkyl alcohol the group QH5- is named phenyl but the CsHsOH compound is called phenol and not phenylic alcohol. 

Simple cyclobutanes do not readily undergo such reactions, but cyclobutenes do. Ben-zocyclobutene derivatives tend to open to give extremely reactive dienes, namely ortho-c]uin(xlimethanes (examples of syntheses see on p. 280, 281, and 297). Benzocyclobutenes and related compounds are obtained by high-temperature elimination reactions of bicyclic benzene derivatives such as 3-isochromanone (C.W. Spangler, 1973, 1976, 1977), or more conveniently in the laboratory, by Diels-Alder reactions (R.P. Thummel, 1974) or by cycliza-tions of silylated acetylenes with 1,5-hexadiynes in the presence of (cyclopentadienyl)dicarbo-nylcobalt (W.G, Aalbersberg, 1975 R.P. Thummel, 1980). 

Butyne trimerizes in the presence of aluminum chloride to give hexamethyl Dewar-benzene (W. Schafer, 1967). Its irradiation leads not only to aromatization but also to hexa-methylprismane (D.M. Lemal, 1966). Highly substituted prlsmanes may also be obtained from the corresponding benzene derivatives by irradiation with 254 nm light. The rather stable prismane itself was synthesized via another hydrocarbon, namely benzvalene, a labile molecule (T. J. Katz, 1971, 1972). 

Compounds related to benzene were obtained from similar plant extracts Eor example a pleasant smelling resin known as tolu balsam was obtained from the South American tolu tree In the 1840s it was discovered that distillation of tolu balsam gave a methyl derivative of benzene which not surprisingly came to be named... 

All compounds that contain a benzene ring are aromatic and substituted derivatives of benzene make up the largest class of aromatic compounds Many such compounds are named by attaching the name of the substituent as a prefix to benzene... 

Many simple monosubstituted derivatives of benzene have common names of long stand mg that have been retained m the lUPAC system Table 111 lists some of the most important ones... 

Names of Some Frequently Encountered Derivatives of Benzene... 

The prefix ortho signifies a 1 2 disubstituted benzene ring meta signifies 1 3 disubstitu tion and para signifies 1 4 disubstitution The prefixes o m and p can be used when a substance is named as a benzene derivative or when a specific base name (such as ace tophenone) is used For example... 

In these examples the base name of the benzene derivative determines the carbon at which numbering begins anisole has its methoxy group at C 1 toluene its methyl group... 

Cyclic compounds that contain at least one atom other than carbon within their ring are called heterocyclic compounds, and those that possess aromatic stability are called het erocyclic aromatic compounds Some representative heterocyclic aromatic compounds are pyridine pyrrole furan and thiophene The structures and the lUPAC numbering system used m naming their derivatives are shown In their stability and chemical behav lor all these compounds resemble benzene more than they resemble alkenes... 

Many aromatic compounds are simply substituted derivatives of benzene and are named accordingly Many others have names based on some other parent aromatic compound... 

It IS hard to find a class of compounds in which the common names of its members have influenced organic nomenclature more than carboxylic acids Not only are the common names of carboxylic acids themselves abundant and widely used but the names of many other compounds are derived from them Benzene took its name from benzoic acid and propane from propionic acid not the other way around The name butane comes from butyric acid present m rancid butter The common names of most aldehydes are derived from the common names of carboxylic acids—valeraldehyde from valeric acid for exam pie Many carboxylic acids are better known by common names than by their systematic ones and the framers of the lUPAC rules have taken a liberal view toward accepting these common names as permissible alternatives to the systematic ones Table 19 1 lists both common and systematic names for a number of important carboxylic acids... 

An old name for benzene was phene and its hydroxyl derivative came to be called phe nol This like many other entrenched common names is an acceptable lUPAC name Likewise o m and p cresol are acceptable names for the various ring substituted hydroxyl derivatives of toluene More highly substituted compounds are named as deriv atives of phenol Numbering of the ring begins at the hydroxyl substituted carbon and proceeds m the direction that gives the lower number to the next substituted carbon Sub stituents are cited m alphabetical order... 

Monocyclic Aromatic Compounds. Except for six retained names, all monocyclic substituted aromatic hydrocarbons are named systematically as derivatives of benzene. Moreover, if the substituent introduced into a compound with a retained trivial name is identical with one already present in that compound, the compound is named as a derivative of benzene. These names are retained ... 

Radicals derived from monocyclic substituted aromatic hydrocarbons and having the free valence at a ring atom (numbered 1) are named phenyl (for benzene as parent, since benzyl is used for the radical C5H5CH2—), cumenyl, mesityl, tolyl, and xylyl. All other radicals are named as substituted phenyl radicals. For radicals having a single free valence in the side chain, these trivial names are retained ... 

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