Prefixes organic compound groups

In the petroleum industry the International Union of Pure and Applied Chemistry (lUPAC) system is in widespread use for naming organic compounds. Two points, however, regarding group names and the prefix, iso, call for comment. 

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. 

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. 

Dioxy—. A German prefix indicating the presence of two hydroxyl groups (OH) in an organic compound... 

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 ... 

Uns- unsym-) adj. Abbreviation for un-symmetrical, a prefix denoting unsyrmnet-rical disposition of substituents of organic compounds with respect to the carbon skeleton or a functional group. It is usually ignored in alphabetization of compound names. 

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. 

The prefix "1" in Ihe name of 1-propanol indicates that the replacement of H with OH has occurred at one of Ihe "outer" carbon atoms rather tlian the "middle" carbon atom a different compound called 2-propanol (also known as isopropyl alcohol) is obtained if Ihe OH functional group is attached to the middle carbon atom. Ball-and-stick models of 1-propanol and 2-propanol are presented in Figure 2.28 . As you will learn in Cliapter 25, the nomenclature of organic compounds provides ways in which we can unambiguously define which atoms are bonded to one another. 

---