Prefixes carbon-atom chain

To name the parent hydrocarbon, add the suffix -am to the prefix oct- (for a carbon-atom chain with eight carbon atoms) to form octane. Now identify and name the alkyl groups. 

The lUPAC rules assign names to unbranched alkanes as shown m Table 2 2 Methane ethane propane and butane are retained for CH4 CH3CH3 CH3CH2CH3 and CH3CH2CH2CH3 respectively Thereafter the number of carbon atoms m the chain is specified by a Latin or Greek prefix preceding the suffix ane which identifies the com pound as a member of the alkane family Notice that the prefix n is not part of the lUPAC system The lUPAC name for CH3CH2CH2CH3 is butane not n butane... 

If the same alkyl group occurs more than once as a side chain, this is indicated by the prefixes di-, tri-, tetra-, etc. Side chains are cited in alphabetical order (before insertion of any multiplying prefix). The name of a complex radical (side chain) is considered to begin with the first letter of its complete name. Where names of complex radicals are composed of identical words, priority for citation is given to that radical which contains the lowest-numbered locant at the first cited point of difference in the radical. If two or more side chains are in equivalent positions, the one to be assigned the lowest-numbered locant is that cited first in the name. The complete expression for the side chain may be enclosed in parentheses for clarity or the carbon atoms in side chains may be indicated by primed locants. 

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 ... 

An oxygen atom directly attached to two carbon atoms already forming part of a ring system or to two carbon atoms of a chain may be indicated by the prefix epoxy-. For example, CH2—CH—CH2CI is named l-chloro-2,3-epoxypropane. 

For bicyclic structures the von Baeyer name consists of the prefix bicyclo-, followed in square brackets by the numbers of carbon atoms separating the bridgeheads on the three possible routes from one bridgehead to the other, followed in turn by the name of the alkane (or other homogeneous hydride, or repeating unit hydride) containing the same number of atoms in the chain as the whole bicyclic skeleton (examples 55-57). Replacement nomenclature can be applied to hydrocarbon names (example 58). 

The system for naming the straight-chain hydrocarbons is based on an agreed-upon method of retaining the first three or four common names, then using Greek prefixes that indicate the number of carbon atoms in the chain. For isomers, the same system is used, always using the name of the compound that is attached to the chain and the name of the chain. 

Branched-chain alkanes, also known as isoparaffins or isoalkanes, are possible when n > 4. The prefix iso is used when two methyl groups are attached to a terminal carbon atom of an otherwise straight chain and the prefix neo when three methyl groups are attached in that manner. Branched-chain alkanes are sometimes regarded as normal alkanes with attached substituent alkyl groups. An example is... 

Strategy First find the longest chain of carbon atoms. That tells you the suffix of the name, given in the far left column of Table 22.1. Then identify the prefix, or prefixes, by choosing the appropriate alkyl group from the right side of Table 22.1. Finally, number the carbon atoms as described above. 

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. 

To name an alkane in which the carbon atoms form a single chain, we combine a prefix denoting the number of carbon atoms with the suffix -ane (Table 18.1). For example, CH,—CH, (more simply, CH,CH,) is ethane and CH,—CH2—CH, (that is, CH,CH2CH,) is propane. Cyclopropane, C,H6 (15), and cyclohexane, C6H12 (16), are cycloalkanes, alkanes that contain rings of carbon atoms. 

Chart I. Trivial names (with recommended three-letter abbreviations in parentheses) and structures (in the aldehydic, acyclic form) of the aldoses with three to six carbon atoms. Only the D-forms are shown the L-forms are the mirror images. The chains of chiral atoms delineated in bold face correspond to the configurational prefixes given in italics below the names... 

Number the chain so as to include both carbon atoms of the double bond, and begin numbering at the end of the chain nearer the double bond. Designate the location of the double bond by using the number of the first atom of the double bond as a prefix ... 

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. 

Relative configurations at two contiguous carbon atoms in main chains bearing, respectively, substituents a and b (a b), are designated by the prefix erythro or threo, as appropriate, by analogy with the terminology for carbohydrate systems [6] in which the substituents are -OH. 

However, higher members of the series are named systematically by combining the ending -ane, characteristic of the first four members and implying complete saturation, with a multiplicative prefix of the series penta-, hexa-, etc. of Table 4.2, which indicates the number of carbon atoms constituting the chain. The letter a , which ends the name of the multiplicative prefix, is elided. 

C) The location of the double bond along an alkene chain is indicated by a prefix number that designates the number of the carbon atom that is part of the double bond and is nearest an end of the chain. The chain is always numbered from the end that gives the smallest number prefix. 

The name of a carbon compound shows how many carbon atoms it contains, the type(s) of chemical bonds present between the carbon atoms, and the other atoms bonded to the carbon chain. The word methane, for example, shows that the compound has one carbon atom with only single bonds. All carbon compounds with one carbon atom begin with the prefix meth. In this case, the -ane ending shows that the compound contains only single bonds. All carbon compound names follow these rules. 

The lUPAC naming of the alkanes is based on a prefix indicating the number of carbon atoms in the chain (as shown below) followed by the suffix -ane. For example, if a chain contains three carbons the parent name is propane, if four carbons the parent name is butane and so on. The remaining parts of the structure are treated as substituents on the chain. Numbers are used to indicate the positions of the substituents on the parent carbon chain. 

When more than one substituent is present, the location of each substituent should be designated by an appropriate name and number. The presence of two or more identical substituents is indicated by the prefixes di-, tri-, tetra- and so on, and the position of each substituent is indicated by a number in the prefix. A number and a word are separated by a hyphen, and numbers are separated by comma. For example, in 2,2-dimethylbutane, both methyl groups are attached to carbon atom 2 of a butane chain. The names of the substituents are arranged in alphabetical order, not numerical order, e.g. 3-ethyl-2-methyUiexane, not 2-methyl-3-ethylhexane. 

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