Naming compounds containing benzene rings

If alkyl groups containing fewer than six carbon atoms are bonded to a benzene ring, the compound is named as an alkyl-substituted benzene. For more complex molecules, the term phenyl is named as a substituent on the parent chain of carbon atoms, as in 3-phenylheptane. 

Later in this chapter we 11 explore the criteria for aromaticity in more detail to see how they apply to cyclic polyenes of different ring sizes The next several sections intro duce us to the chemistry of compounds that contain a benzene ring as a structural unit We 11 start with how we name them... 

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... 

Our discussion of pesticides has focused primarily on insecticides. In the United States the primary use of pesticides is in the form of herbicides, those pesticides used to control weeds. Approximately 70% of the pesticides used in the United States are herbicides and 20% are insecticides. The use and development of herbicides parallels that of insecticides. The first herbicides were inorganic metal compounds and salts. During World War II organic herbicides were synthesized and their use increased dramatically. One of the first major classes of herbicides synthesized in the mid-1940s was phenoxyaliphatic acids. As this name implies, the phenoxyaliphatic acids contain the benzene ring, oxygen, and an aliphatic acid. The two most common phenoxyaliphatic acids are 2,4 dichlorophenoxyacetic acid, called 2,4-D and 2,4,5 trichlorophenoxyacetic acid, known as 2,4,5-T (Figure 18.10). The numbers in these... 

In certain polyfunctional compounds, an aldehyde or ketone group can also be named as a substituent on a molecule with another functional group as its root. The aldehyde carbonyl is given the prefix formyl-, and the ketone group is named 0x0- with a number to show its position in the molecule. Compounds with both an aldehyde and ketone are named as aldehydes, because aldehydes have functional group priority over ketones. A ketone containing a benzene ring is named as a -phenone. 

Aromatic The name originally given to cyclical compounds containing the benzene "ring" because the first benzene-type compounds isolated smelled "good". 

Unfortunately, a completely systematic method of naming aromatic compounds is not in use. The system used is a combination of trivial names and the IUPAC system. Sometimes- compounds that contain benzene rings are considered to be substituted benzenes, in which case the word benzene appears in the name of the compound along with the name of the substituent. 

Phenol(s) Aromatic molecules in which one or more hydroxyl groups (-OH) are directly attached to a benzene ring. Phenols are powerful antibacterial compounds and essential oils containing phenols need to be used with caution. Examples of phenols in essential oils include thymol, carvacrol and eugenol. Phenol is the name for the parent compound, the simplest of the phenols (C6H5OH). 

Di-azo Compounds.—Contrasted with the azo compounds we have another group known as the di-azo compounds. As the name indicates these also contain two nitrogen atoms and these nitrogens are also directly linked to each other, but only one nitrogen atom is linked to a benzene ring. ... 

Hydrocarbons. The hydrocarbons, as the name implies, are compounds containing carbon and hydrogen. If the carbon atoms lie in the same plane they are known as open-chain, or aliphatic hydrocarbons. If the carbon atoms form a ring structure they are known as cyclic hydrocarbons. The cyclic hydrocarbons are further differentiated into benzene benzenoid, or aromatic) and alicydic hydrocarbons. If there is another element present in the ring besides carbon, they are known as heterocyclic hydrocarbons. 

Description Catecholamine is the name of a group of compounds that contain a catechol nucleus (a benzene ring with two adjacent hydroxyl substituents) and an amine group. This group includes the mammalian neurotransmitters or hormones, such as dopamine, norepinephrine, and epinephrine, and nonmammalian compounds such as octopa-mine. Each compound has its own synonyms. Representative Chemical Dopamine Chemical Abstracts Service Registry Number CAS 51-61-6... 

The first transition element compound containing only carbocyclic rings as ligands was bis(ri5-cyclopentadienyl)iron, [Fe(r 5-C5H5)2], which has a sandwich structure with two parallel p5- or Ji-bonded rings. The recognition that this compound was amenable to electrophilic substitution, similar to the aromatic behaviour of benzene, led to the suggestion of the non-systematic name ferrocene and to similar names for other metallocenes . 

Aromatic polycychc compounds need not contain contain benzene rings. For example, purine, which contains two fused heterocyclic rings, is aromatic. Azulene, named for its deep blue color, is also aromatic, although one ring has five carbon atoms and the other has seven. It is not, however, as aromatic as its isomer naphthalene, which has two fused benzene rings. 

Compounds containing more than one benzene ring are nearly always named as derivatives of alkanes as can be seen in the following example ... 

So far, we have discussed families of aliphatic compounds containing different functional groups. Benzene derivatives containing the same functional groups often show very different properties when the functional group is attached directly to the benzene ring. They are also sometimes named differently from their aliphatic counterparts. 

Chemists also learned that the term aromatic was not always accurate. Many compounds that belong to the class because of chemical properties and structures are not at all fragrant. Conversely, there are many fragrant compounds that do not have aromatic compound properties or structures. Today, the old class name is used but with a different meaning. Aromatic compounds are those that contain the characteristic benzene ring or... 

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