Suffixes alkanes

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... 

Diols are almost always given substitutive lUPAC names As the name of the prod uct m the example indicates the substitutive nomenclature of diols is similar to that of alcohols The suffix dwl replaces ol and two locants one for each hydroxyl group are required Note that the final e of the parent alkane name is retained when the suffix begins with a consonant ( diol) but dropped when the suffix begins with a vowel ( ol)... 

The e ending of an alkane name is dropped before a suffix beginning with a vowel ( a/) and retained before one beginning with a consonant ( dial)... 

Compounds with two carboxyl groups as illustrated by entries 10 through 12 are distinguished by the suffix dioic acid or dicarboxylic acid as appropnafe The final e m fhe base name of fhe alkane is refamed... 

Compounds with two ammo groups are named by adding the suffix diamine to the name of the corresponding alkane or arene The final e of the parent hydrocarbon IS retained... 

Compounds with two car boxyl groups, as illustrated by entries 10 through 12, are distinguished by the suffix -dioic acid or -dicarboxylic acid as appropriate. The final -e in the base nane of the alkane is retained. 

Straight-chain alkanes are named according to the number of carbon atoms they contain, as shown in Table 3.3. With the exception of the first four compounds—methane, ethane, propane, and butane—whose names have historical roots, the alkanes are named based on Greek numbers. The suffix -one is added to the end of each name to indicate that the molecule identified is an alkane. Thus, pentane is the five-carbon alkane, hexeme is the six-carbon alkane, and so on. We ll soon see that these alkane names form the basis for naming all other organic compounds, so at least the first ten should be memorized. 

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. 

Simple alcohols are named by the IUPAC system as derivatives of the parent alkane, using the suffix -ol. 

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 ... 

Compounds containing the -C=N functional group are called nitriles and undergo some chemistry similar to that of carboxylic acids. Simple open-chain nitriles are named by adding -nitrile as a suffix to the alkane name, with the nitrile carbon numbered Cl. 

Normal alkane (Section 3.2) A straight-chain alkane, as opposed to a branched alkane. Normal alkanes are denoted by the suffix n. as in //-C4H10 (//-butane). 

As usual, R is a hydrocarbon group or, in the simplest case, a hydrogen atom. The acidic hydrogen atom is the one bonded to oxygen. The IUPAC name of a carboxylic add can be obtained by substituting the suffix -oic acid for the final e in the name of the corresponding alkane. In practice, such names are seldom used. For example, the first two members of the series are commonly referred to as formic add and acetic add. 

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. 

One of the major organizing principles in organic chemistry is the presence of special arrangements of atoms. These so-called functional groups convey particular chemical properties. For example, a substance that contains an —OH group is called an alcohol. The systematic name of an alcohol is obtained by adding the suffix -ol to the name of the alkane with the same carbon framework. Thus, CH3 OH has the carbon framework of methane and is called methanol, whereas C2 H5 OH has the carbon framework of efhane and is called ethanol. 

Change the name of the alkane corresponding to this chain by dropping the final -e and adding the suffix -ol. 

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. 

When naming an alkane, what suffix must be present ... 

The suffix indicates the type of compound, according to the functional groups present. (See Table 1.4 on page 22.) As you progress through this chapter, you will learn the suffixes for different chemical families. In your previous chemistry course, you learned the suffixes -one for alkanes, -ene for alkenes, and -yne for alkynes. Thus, an alkane composed of six carbon atoms in a chain is called hexane. An alkene with three carbons is called propene. 

Step 2 Find the suffix If the hydrocarbon is an alkane, use the suffix -ane. Use -ene if the hydrocarbon is an alkene. Use -yne if the hydrocarbon is an alkyne. If more than one double or triple bond is present, use the prefix di- (2) or tri- (3) before the suffix to indicate the number of multiple bonds. 

Step 3 Add a position number before the root of the name to indicate the location of the —OH group. (Remember to number the main chain of the hydrocarbon so that the hydroxyl group has the lowest possible position number.) If there is more than one —OH group, leave the -e in the name of the parent alkane, and put the appropriate prefix (di-, tri-, or tetra-) before the suffix -ol. 

Step 3 Put the prefix and suffix together alkoxy group + parent alkane. 

Step 2 If there is one ketone group, replace the -e at the end of the name of the parent alkane with -one. If there is more than one ketone group, keep the -e suffix and add a suffix such as -dione or -trione. 

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. 

The common names of primary amines consist of the name of the alkyl branch followed by the name amine. The systematic (lUPAC) name of primary amines consists of the name of the alkane with the -e replaced by the suffix -amine. Some examples of primary amines appear in Figure 13-1. If more than one amine group is present, you need to use the appropriate prefix. 

To name a straight-chain alkane, simply match the appropriate chemical prefix with the suffix -ane. The prefixes, which relate to the number of Ccirbons in the continuous chain, are listed in Table 64. 

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