Naming compounds benzene derivatives

Designating a benzene compound with substituents in the 1,2 positions. The position next to a substituent is the ortho position on the benzene ring. This was used in the systematic naming of benzene derivatives. For example, orthodinitrobenzene (or o-dinitrobenzene) is 1,2-dinitroben-zene. 

The CsHs— group is known as the phenyl group (pronounced/en-i//). The name phenyl is used for compounds that cannot be easily named as benzene derivatives. For example, the following compounds are named as derivatives of alkanes ... 

Aromatic compounds that contain a benzene ring with a single substituent are usually named as benzene derivatives. However, many of these compounds have been important in chemistry for many years and still use their common names. Some widely used names such as toluene, aniline, and phenol are allowed by lUPAC rules. 

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). 

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 ... 

When applying this principle to replacement names generated from fusion nomenclature, it is essential to keep in mind that fusion names for hydrocarbons ending in -cycloalkene are for fully unsaturated skeletons the -ene ending implies whatever number of double bonds may be necessary, without a multiplier. Thus (117) has six double bonds in the twelve-membered ring, and one must add ten hydrogens to saturate it to the stage of a simple benzene derivative, compound (118). 

When the two groups in disubstituted benzenes are different, the same three isomers are possible that are possible when the substituents are the same. Compounds with two different substituents are usually named as positional derivatives of a monosubstituted (parent) compound. Above, the common (and commercial) name for methylbenzene is toluene, and the chlorinated derivatives are named as shown above. However, the same two chlorinated derivatives can also be properly named 2-chloromethylbenzene and 4-chloromethylbenzene. In this case, for naming, the parent compound is methylbenzene and it is understood that the methyl group is in the 1-position. The terms ortho- (1,2-), meta- (1,3-), and para- (1,4-) are also sometimes used for example, 2-chlorotoluene can be called ortho-c Aoioio -uene. This can be very confusing, but in the chemical industry, outside of the research labs, the common names for the parent compounds are almost always used. 

M n Part II we spend a lot of time and pages on aromatic systems, starting with benzene. You examine benzene s structure, its resonance stabilization, and its stability. Next you study benzene derivatives and heterocyclic aromatic compounds, and then we address the spectroscopy of these aromatic compounds. And in Chapters 7 and 8 we introduce you to aromatic substitution by both electrophiles and nucleophiles, and you get to see a lot of reactions and a lot of examples. In this part you also start working with many more named reactions. 

Aromatic hydrocarbons are unsaturated cyclic compounds that are resistant to addition reactions. The aromatic hydrocarbons derive their name from the distinctive odors they exhibited when discovered. Benzene is the most important aromatic compound. Because many other aromatic compounds are derived from benzene, it can be considered the parent of other aromatic compounds. Benzene molecular formula is... 

Benzene derivatives have been isolated and used as industrial reagents for well over 100 years. Many of their names are rooted in the historical traditions of chemistry. The following compounds are usually called by their historical common names, and almost never by the systematic IUPAC names ... 

Benzene.—By far the most important and most numerous of these carbo-cyclic compounds have as their mother substance the hydrocarbon benzene, and the names Benzene Series, Benzene Compounds, or Benzene Derivatives are commonly used as synonymous with carbo-cyclic compounds. This has led to the usual classification of organic... 

Tri-nitro Toluene. T.N.T.—One of the nitro toluenes is of especial interest and importance because of its use as a military high explosive. This is tri-nitro toluene, commonly known as T.N.T. Other names also used for the substance are, trotyly trinoly trilite and tritolo. The constitution of the compound is that of the symmetrical or 2-4-6-tri-nitro toluene. As a benzene derivative it is, therefore, i-methyl 2-4-6-tri-nitro benzene. 

Alcohols.—The side chain hydroxyl compounds take the class name of alcohols for they are true aromatic alcohols in formation, reaction and properties. They are neutral not acid, and are formed by methods analogous to those by which the aliphatic alcohols are prepared. They may be looked upon as benzene derivatives of aliphatic alcohols, e.g. CeHs—CH2OH, benzyl alcohol or phenyl methyl alcohol. 

If the two groups are different, and neither is a group that gives a special nanie to the molecule, we simply name the two groups successively and end the word with -benzene, as, for example, chloronitrobenzene, bronioiodobenzene, etc. If one of the two groups is the kind that gives a special name to the molecule, then the compound is named as a derivative of that special compound, as, for example, nitrotoluene, bromophenol, etc. 

When more than two groups are on a benzene ring, their positions must be numbered. If one of the groups is associated with a common name, the compound can be named as a derivative of the monosubstituted compound, numbering from the group designated in the common name. 

Solution This problem requires a knowledge of arene nomenclature. Benzene (CeHe) is the simplest aromatic hydrocarbon. Benzene compounds can be named as a derivative of benzene or as a phenyl-substituted compound. 

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