Suffixes naming alkenes

To name alkenes, we follow the basic IUPAC rules, but add the suffix -ene to indicate the main functional group is an alkene. The location of the double bond is given by a locant number, which identifies the first carbon in the double bond. The main functional group always gets the lowest number. Figure 11.9 illustrates some example alkene structures and names. 

In naming alkynes the usual lUPAC rules for hydrocarbons are followed and the suffix ane is replaced by yne Both acetylene and ethyne are acceptable lUPAC names for HC=CH The position of the triple bond along the chain is specified by number m a manner analogous to alkene nomenclature... 

Alkynes aie named m much the same way as alkenes using the suffix yne instead of ene... 

Alkenes are named using a series of rules similar to those for alkanes (Section 3.4), with the suffix -ene used instead of -one to identify the family. There are three steps. 

Step 3 Write the full name. Number the substituents according to their positions in the chain, and list them alphabetically. Indicate the position of the double bond by giving the number of the first alkene carbon and placing that number directly before the parent name. If more than one double bond is present, indicate the position of each and use one of the suffixes -diene, -triene, and so on. 

Cycloalkenes are named similarly to open-chain alkenes but, because there is no chain end to begin from, we number the cycloalkene so that the double bond is between Cl and C2 and the first substituent has as low a number as possible. Note that it s not necessary to indicate the position of the double bond in the name because it is always between Cl and C2. As with open-chain alkenes, newer but not yet widely accepted naming rules place the locant immediately before the suffix in a diene. 

Rule 3 Number the substituents according to their position on the chain, and write the name listing the substituents in alphabetical order and identifying the position to which the -OH is bonded. Note that in naming ns-l,4-cyclohexanediol, the final -e of cyclohexane is not deleted because the next letter, d. is not a vowel, that is, cyclohexanediol rather than cyclohexandiol. Also, as with alkenes (Section 6.3), newer IUPAC naming recommendations place the locant immediately before the suffix rather than before the parent. 

Ketones are named by replacing the terminal -e of the corresponding alkane name with -one. The parent chain is the longest one that contains the ketone group, and the numbering begins at the end nearer the carbonyl carbon. As with alkenes (Section 6.3) and alcohols (Section 17.1), the locant is placed before the parent name in older rules but before the suffix in newer IUPAC recommendations. For example ... 

The IUPAC names of alkynes are derived from those of the corresponding alkenes by replacing the suffix -ene with -yne. Thus we have... 

The alkynes are hydrocarbons that have at least one carbon-carbon triple bond. The simplest is ethyne, FIO CH, which is commonly called acetylene (20). Alkynes are named like the alkenes but with the suffix -yne. 

This number indicates the number of the first carbon atom that is part of the double/triple bond. (2) The name of longest carbon chain is formed by taking the alkane name, dropping the -ane suffix and replace it by -ene for an alkene or -yne for an alkyne. 

Alkenes hydrocarbons that contain carbon-carbon donble bonds. The chemical name indicates the number of carbon atoms and ends with the suffix ene. 

When the suffixes a7nea.nd -eneshow up in a compound name like decane or decene they are usually consistent with the alkane and alkene definitions, but not always. Benzene is a cyclic aromatic hydrocarbon, not a straight chain molecule naphthenes are cyclic compounds. 

Alcohols with double or triple bonds are named using the -ol suffix on the alkene or aUcyne name. Numbering gives the hydroxyl group the lowest possible number. When numbers are also given for the multiple bond position, the position of the hydroxyl can be written immediately before the -ol prefix. If the hydroxyl group is only a minor part of the structure, it may be named as a hydroxy- substituent. 

The names of the alkenes are formed with the same prefixes used in naming the alkanes. These prefixes correspond to the number of carbon atoms in the compound. The suffix is -ene, which indicates that the compound belongs to the alkene family. Thus the simplest member of the alkene family, C2H4, should be called ethene. Ethene is commonly known as ethylene, Figure 1-8. The next larger member of the family, propene, commonly is called propylene. 

The IUPAC Rules are exactly the same for naming alkynes as for naming of alkenes except that die suffix -yne replaces -ene. 

Alkynes are named in much the same way as alkenes, using the suffix -yne instead of -ene. 

A few very common alkenes also are called alkylenes by appending the suffix -ene to the name of the hydrocarbon radical with the same carbon skeleton. Examples are shown below with their alkylene names in parentheses. We shall continue to use the IUPAC names whenever possible. 

Alkenes are named by counting the longest chain of carbons that contains the double bond and adding the suffix -ene. Thus, ethylene, the simplest alkene, is followed by propene, butene, pentene, hexene, and so on. Note that ethylene should properly be called ethene, but the name ethylene has been used for so long that it is universally accepted. Similarly, the name propylene is often used for propene. 

Alkynes are similar in many respects to alkenes and are named using the suffix -yne. The simplest alkyne, HC = CH, is often called by its alternative name acetylene rather than by its systematic name ethyne. 

In a hydrocarbon name, the prefix tells how many carbon atoms are in the molecule, and the suffix tells how many carbon and hydrogen atoms are in the molecule. The general formula for alkanes is CnH2n+2, the general formula for alkenes is C H2n, and the general formula for the alkynes is C H2n,2. 

The naming system is extended to include alkenes by changing the suffix from -ane to -ene, and to alkynes by the suffix -yne. A number before the suffix gives the location of the multiple bond. The terminal carbon is that closest to the multiple bond it has priority over branching of the carbon skeleton. 

The names of alkenes and alkynes contain the suffixes -ene and -yne, respectively. With some alkenes it is necessary to define the stereochemistry of the double bond ... 

Alkenes contain one or more double bonds. Alkenes are also called olefins. The suffix used in the naming of alkenes is -ene, and the number roots are those used for alkanes of the same length. 

Alkynes contain one or more triple bonds. They are named in a similar way to alkenes. The suffix used for alkynes is -yne. Ethyne is often called acetylene. Alkynes with one triple bond have the general formula Cn 2n-2-Multiple triple bonds are named using -diyne, -triyne, etc. The infix -ynyl- is used for functional groups composed of alkynes after the removal of a hydrogen atom. 

In the tables on the following pages, the symbols R and R represent hydrocarbons in covalent linkage to the functional group. Many derivatives are named in a similar manner to alkenes and alkynes, but the location and suffix of the functional group is used in place of -ene and -yne. 

The suffix used for an alkene is -ene. Names for compounds with more than one double bond use the suffixes -diene, -triene. and so on. 

Alkynes are named in a manner nearly identical to the naming of alkenes except that the suffix is -yne. The same rules for numbering apply. Compounds with several triple bonds use the suffixes -diyne, -triyne, and so on. For compounds that contain both a double bond and a triple bond, both suffixes are used, as in -enyne. Some examples follow ... 

Alkenes are hydrocarbons that contain carbon-carbon double bonds. A carbon-carbon double bond is the most reactive part of an alkene, so we say that the double bond is the functional group of the alkene. Alkene names end in the -ene suffix. If the double bond might be in more than one position, then the chain is numbered and the lower number of the two double-bonded carbons is added to the name to indicate the position of the double bond. 

The names of alkenes follow the same format as the names of alkanes prefix + root + suffix. The prefixes and the steps for locating and identifying branches are the same, too. The greatest difference involves the double bond. The suffix -ene immediately tells you that a compound has at least one double bond. The rest of the necessary information—the location of the double bond, and the number of carbon atoms in the main chain—is communicated in the root. Follow the steps below to find out how to name the compound in Figure 13.20. 

Both double and triple bonds are multiple bonds. Therefore alkynes are unsaturated hydrocarbons, just as alkenes are. To name alkynes and draw their structures, you follow the same rules that you used for alkenes. The only difference is the suffix -yne, which you need to use when naming alkyne compounds. Also, remember to count the number of bonds for each carbon. An alkyne bond counts as three bonds. 

An alkene is a hydrocarbon which has only one double bond in its structure. Because of the one double bond, they are also called as monoalkenes. Alkenes having two double bonds in their structures are known as "alkadienes". While naming these, instead of the -ene suffix, -diene is used, and carbon atoms having the double bonds are indicated. Some examples of alkadienes and polyenes are shown as follows. 

Compounds with two double bonds are named as dienes by changing the -ane ending of the parent alkane to the suffix -adiene. Compounds with three double bonds are named as trienes, and so forth. Always choose the longest chain that contains both atoms of the double bond. In Figure 10.1, the alkene is named as a derivative of heptene because the seven-carbon chain contains both atoms of the double bond, but the eight-carbon chain does not. 

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