Cyclo- prefix

As you can see cycloalkanes are named under the lUPAC system by adding the prefix cyclo to the name of the unbranched alkane with the same number of carbons as the ring Substituent groups are identified m fhe usual way Their posifions are specified by numbering fhe carbon atoms of fhe ring m fhe direction fhaf gives fhe lowesf num ber to fhe subsfifuenfs af fhe firsf pomf of difference... 

Monocyclic Aliphatic Hydrocarbons. Monocyclic aliphatic hydrocarbons (with no side chains) are named by prefixing cyclo- to the name of the corresponding open-chain hydrocarbon having the same number of carbon atoms as the ring. Radicals are formed as with the alkanes, alkenes, and alkynes. Examples ... 

The chain and branched chain saturated hydrocarbons make up a family called the alkanes. Some saturated hydrocarbons with five carbon atoms are shown in Figure 18-11. The first example, containing no branches, is called normal-pentane or, briefly, n-pentane. The second example has a single branch at the end of the chain. Such a structural type is commonly identified by the prefix iso- . Hence this isomer is called /50-pentane. The third example in Figure 18-11 also contains five carbon atoms but it contains the distinctive feature of a cyclic carbon structure. Such a compound is identified by the prefix cyclo in its name—in the case shown, cyclopentane. 

The prefix cyclo- may be used for a single-bond bridge [14]. 

Cyclic oligosaccharides composed of a single type of oligosaccharide unit may be named semisystematically by citing the prefix cyclo , followed by terms indicating the type of linkage [e.g. malto for a-(l—>4)-linked glucose units], the number of units (e.g. hexa for six) and the termination -ose . The trivial names a-cyclodex-trin (a-CD) for cyclomaltohexaose, (i-cyclodextrin ((i-CD) for cyclomaltoheptaose and y-cyclodextrin (y-CD) for cyclomaltooctaose are well established. 

Step 1 Find tbe root Identify the longest chain or ring in the hydrocarbon. If the hydrocarbon is an alkene or an alkyne, make sure that you include any multiple bonds in the main chain. Remember that the chain does not have to be in a straight line. Count the number of carbon atoms in the main chain to obtain the root. If it is a cyclic compound, add the prefix -cyclo- before the root. 

If there is a ring, it is usually taken as the main chain. Follow the same rules to name cyclic compounds that have branches attached. Include the prefix -cyclo-afterthe names and position numbers of the branches, directly before the root for example, 2-methyl-1-cyclohexene. 

The nomenclature of cycloalkanes is almost the same as that for alkanes, with the exception that the prefix cyclo- is to be added to the name of the alkane. When a substituent is present on the ring, the name of the substituent is added as a prefix to the name of the cycloalkane. No number is required for rings with only one substituent. 

A cyclic alkene is named by a prefix cyclo- to the name of the acyclic alkene. Double bonded carbons are considered to occupy positions 1 and 2. 

AUcyclic Hydrocarbons. Saturated monocyclic hydrocarbons, or, 4cy do-alkanes, are named by attaching the prefix cyclo to the name of the acydic unbranched alkane. 

The prefix cyclo- is used to name cycloalkanes. Cyclopropane is planar, but larger carbon rings are puckered. Cyclohexane exists mainly in a chair conformation with all bonds on adjacent carbons staggered. One bond on each carbon is axial (perpendicular to the mean carbon plane) the other is equatorial (roughly in that plane). The conformations can be interconverted by flipping the ring, which requires only bond rotation and occurs rapidly at room temperature for cyclohexane. Ring substituents usually prefer the less crowded, equatorial position. 

The prefix cyclo- appears before the root of the name in ring compounds, except for those involving the benzene ring (Problem 9.9). The benzene compounds form a special category of compounds referred to as aromatic compounds. The opposite of aromatic is aliphatic. Further modifications of the system, such as those when elements other than carbon and hydrogen are involved, will be noted when functional groups are discussed. 

Cycloalkanes A chain of carbon atoms can form ring structures. To name a cycloalkane, we simply add the prefix cyclo- to the parent name. Some examples of cycloalkanes are given in Figure 11.7. Cyclopropane has been used as an anesthetic gas. 

The procedure used to name a cycloalkane by the IUPAC method is very similar to that used for alkanes. Here, the root designates the number of carbons in the ring and the prefix cyclo- is attached to indicate that the compound contains a ring. The rules for numbering the ring carbons are as follows ... 

In addition to branched chains, alkanes can also form rings. The two terminal carbons bond together to complete a ring. The nomenclature is very similar except the prefix cyclo- is added before the name of the alkane. For instance, when the two terminal carbon atoms in hexane connect together, a six-sided ring is formed, called cyclohexane. A five-sided ring would be called cyclopentane. Each of these molecules is shown in Figure 19.7 ... 

Students accidentally draw cyclic structures when acyclic structures are intended, and vice versa. Always verify whether the name contains the prefix cyclo-. 

Cyclic alcohols are named using the prefix cyclo- the hydroxyl group is assumed to be on Cl. 

When the structural prefixes cyclo, iso, neo, and spiro are integral parts of chemical names, close them up to the rest of the name (without hyphens) and do not italicize them. 

Cycloalkanes are named by adding the prefix cyclo - to the names of the alkanes. For example, the cycloalkane with three carbon atoms is called cyclopropane. 

The nomenclature for cycloalkanes follows the same rules as for the other alkanes except that the root name is preceded by the prefix cyclo-. The ring is numbered to yield the smallest substituent numbers possible. 

Cycloalkanes are named by using similar rules, but the prefix cyclo- immediately precedes the name of the parent. 

Count the number of carbon atoms in the ring and use the parent name for that number of carbons. Add the prefix cyclo- and the suffix -ane to the parent name. 

The Naphthene Hydrocarbons. The naphthene hydrocarboiis are also called cycloparaffins and, as this name implies, they are saturated hydrocarbons in which the carbon chains form closed rings. The general formula for this aeries is C Ha and consequently they are isomeric with the olefins. They are named fay placing the prefix cyclo- before the name of the corresponding parato hydrocarbon. The first member of this series is cyclopropane and has the structure shown. The... 

Most of the chains mentioned with three or more carbons can be bent around and formed into a ring. Such ring compounds are named similarly to the straight chains, except that their name starts with the prefix cyclo. Cyclopropane and cyclohexane are shown in Figure 1.11. 

Notice that the prefix cyclo- is added to the name of the alkane to indicate that it has a ring structure. 

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