Suffixes organic compound groups

Organic compounds are named according to their functional group. Generally, the suffix of a compound s name indicates the most important functional group in the molecule. For example, the suffix -ene indicates the presence of a double bond, and the suffix -ol indicates the presence of a hydroxyl group. 

The use of suffixes and prefixes. The groups that are typical of the various classes of organic compound, such as... 

In general, organic compounds are given systematic names by using the order prefix-parent-suffix, where prefix indicates how many branching groups are present, parent indicates how many carbons are in the longest chain and suffix indicates the name of the family. Common names as weU as systematic names are used for alkanes and their derivatives. However, it is advisable to use systematic names or the lUPAC (International Union of Pure and Applied Chemistry) nomenclature, which can be derived from a simple set of rules. 

Another important class of organic compounds that we shall meet frequently, even in the early chapters of the text, are the carboxylic acids. These compounds are characterized by the carboxyl group, — COOH (7). As their names suggest, these compounds are acids. The most common example is acetic acid, CH3COOH (8 formally, ethanoic acid), the acid that gives vinegar its sharp taste. Another simple carboxylic acid is formic acid, HCOOH (9 formally, methanoic acid), the acid of ant venom. Note how the systematic (formal) names of the carboxylic acids are derived from the parent hydrocarbons (ethane and methane, respectively) by adding -anoic acid as a suffix to the stems eth- and meth-. 

Ketones have the carbonyl group attached to an interior carbon atom of an organic compound. The carbonyl group gives the molecular polarity, thus many ketones are used as solvents. In the naming of ketones, you need to replace the ending of the molecule with the suffix -one. A number is used to indicate the position of the carbonyl group in the molecule. 

Many simple common compounds are known by both a trivial and a systematic name. The systematic names are helpful in learning the structures of organic compounds, but the trivial names are often simpler and can reflect the source or dominant reactivity of the compound concerned. The systematic name for a compound has a stem that describes the carbon skeleton, prefixes and suffixes that indicate the functional groups, and numbers (locants) that define their position. Prefixes may also be added to indicate modifications to the carbon skeleton and to define the stereochemistry. A list of the more common prefixes, suffixes and stems is given in Table 1.2. 

Because the longest chain consists of three carbon atoms, the name for this compound is based on propane. From Table i, you can see that the presence of the —OH functional group classifies this compound as an alcohol. Therefore, as indicated by Table 4, the name for this compound is propanol, whose suffix -ol indicates that this molecule is an alcohol. Because the functional group is attached to the second carbon atom, the correct name for this compound is 2-propanol. A number of organic compounds are often referred to by their common names, even by chemists. The common name for 2-propanol is isopropyl alcohol. 

Suffix The suffix tells the type of organic compound the molecule represents that is, it identifies the key functional group the molecule possesses. The suffix is placed after the root. 

Aldehydes are formally named by changing the final -e of the name of the alkane with the same number of carbon atoms to the suffix -a/. Thus, the formal name of the compound methanal, shown in Table 22.7, is based on the one-carbon alkane methane. Because the carbonyl group in an aldehyde always occurs at the end of a carbon chain, no numbers are used in the name unless branches or additional functional groups are present. Methanal is also commonly called formaldehyde. Ethanal has the common name acetaldehyde. Scientists often use the common names of organic compounds because they are familiar to chemists. 

Most of the hydrocarbon-derivative functional groups in organic compounds are designated by either a sufQx or a prefix, as shown in Table B. Rules regarding whether a prefix or a suffix designation is used are as follows ... 

M acid or acyl halides these are organic compounds containing die group —CO.X, where X is a halogen. Acyl chlorides, have the general formula R.CO.Cl. In systemi-caily naming acyl halides the names end with the suffix -oyl, e.g. ethanoyi chloride CH3COCI. 

Alcohols are a group of organic compounds that contain the -OH functional group. In fact, alcohols are often generalized as R-OH, where the R stands for the Rest of the molecule (like that radio newscaster s rest of the story . Alcohols are named using the -o/ suffix replacing the -ane of the corresponding alkane. 

Hydrocarbons contain only C and H atoms, so their physical properties depend on the strength of their dispersion forces. The names of organic compounds have a root for the longest chain, a prefix for any attached group, and a suffix for the type of compound. Alkanes (CnHan+a) have only single bonds. Cycloalkanes (C Hp ) have ring structures that are typically nonplanar. Alkenes (CnHpn) have at least one C=C bond. Alkynes (CnHpn-p) have at least one C=C bond. Aromatic hydrocarbons have at least one planar ring with delocalized tt electrons. 

Nitriles. Organic compounds that contain the -ON function are, as a group, called nitriles. The lUPAC nomenclature for this group is based on simply adding the suffix nitrile to the appropriate hydrocarbon chain name. The number of carbons used in deciding upon the appropriate hydrocarbon name includes the carbon of the nitrile itself. Examples are the following ... 

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