Naming compounds alkanes

As organic chemistry developed, it became apparent that some systematic way of naming compounds was needed. About 70 years ago, the International Union of Pure and Applied Chemistry (IUPAC) devised a system that could be used for all organic compounds. To illustrate this system, we will show how it works with alkanes. 

The International Union of Pure and Applied Chemistry (lUPAC) has set standard rules for naming organic compounds. The systematic (or lUPAC) names of alkanes and most other organic compounds follow the same pattern, shown below. 

Continuing in the alkane series (also called the paraffin series because the first solid hydrocarbon in the series is paraffin, or candle wax), the next compound is pentane. This name is derived from the Greek word penta, for five. As its name implies, it has five carbon atoms, and its molecular formula is C,H12. From pentane on, the Greek prefix for the numbers five, six, seven, eight, nine, ten, and so on are used to name the alkanes, the Greek prefix corresponding to the number of carbon atoms in the molecule. The first four members of the alkane series do not use the Greek... 

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. 

Keep in mind that alkyl groups themselves are not stable compounds and that the "removal" of a hydrogen from an alkane is just a useful way of looking at things, not a chemical reaction. Alkyl groups are simply parts of molecules that help us to name compounds. 

The IUPAC system works consistently to name many different families of compounds. We will consider the naming of alkanes in detail, and later extend these rules to other kinds of compounds as we encounter them. The IUPAC system uses the longest chain of carbon atoms as the main chain, which is numbered to give the locations of side chains. Four rules govern this process. 

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. 

Some systematic method for naming compounds is necessary. The system in use today is prescribed by the International Union of Pure and Applied Chemistry (TUPAC). The names of the first 20 straight-chain alkanes are listed in Table 27-2. You should become familiar with at least the first ten. The names of the alkanes starting with pentane have prefixes (from Greek) that give the number of carbon atoms in the molecules. All alkane names have the -ane ending. 

We ll begin the chapter with a brief survey of various kinds of hydrocarbons— compounds that contain only carbon and hydrogen—introduce some functional groups, then return to hydrocarbons to discuss alkanes in some detail. The names of alkanes may seem strange at first, but they form the foundation for the most widely accepted system of organic nomenclature. The fundamentals of this nomenclature system, the lUPAC rules, constitute one of the main topics of this chapter. 

An older name for alkanes is paraffin hydrocarbons. Paraffin is derived from the Latin words parum affinis ( with little affinity ) and testifies to the low level of reactivity of alkanes. Like most other organic compounds, however, alkanes bum readily in air. This combination with oxygen is known as combustion and is quite exothermic. All hydrocarbons yield carbon dioxide and water as the products of their combustion. 

Names of compounds containing C=C bonds end with -yne. Again the name of the parent compound is determined by the nnmber of carbon atoms in the longest chain (see Table 24.1 for names of alkane counterparts). As in the case of alkenes, the names of alkynes indicate the position of the carbon-carbon triple bond, as, for example, in... 

Naming Alkanes You learned how to name simple alkanes in Section 2.8. Here we discuss general rules for naming any alkane and, by extension, other organic compounds as well. The key point is that each chain, branch, or ring has a name based on the number of C atoms. The name of a compound has three portions ... 

The number of constitutional isomers increases rapidly as the number of carbons in an alkane increases. For example, there are 75 alkanes with molecular formula C10H22 and 4347 alkanes with molecular formula C15H32. To avoid having to memorize the names of thousands of stmctural units, chemists have devised rules that name compounds on the basis of their structures. That way, only the rules have to be learned. Because the name is based on the structure, these rules make it possible to deduce the structure of a compound from its name. 

This is a two carbon alkane. A chain of two carbon atoms is given the root eth. The parent names of alkanes are formed by adding the suffix ane to the root name of the longest carbon chain. This compound is called ethane. 

In geologic conditions nonpolar, hydrophobic substances under consideration, depending on pressure and temperature are capable of changing their phase state and can be gaseous, liquid or even solid. In gas state they form underground gas whose composition is dominated by such components as CH, more rarely and very rarely CO. Liquid nonpolar substances are mobile solutions (crude oil, oil products, residual oil, etc.,) whose composition is dominated by complex non-volatile organic compounds, namely, liquid alkanes (from pentane to heptadecane), almost all naphthenes, numerous aromatic hydrocarbons (benzene, toluene, isopropyl benzene, etc.), which in pure form may have melting temperature below 0 °C. 

Identify organic compounds and name simple alkanes and alcohols. (Section 2.9)... 

We have just seen that the three C5H12 isomers all incorporate pentane in their names and are differentiated by the prefixes n- iso , and neo. Extending this approach to alkanes beyond C5H12 fails because we run out of descriptive prefixes before all the isomers have unique names. As difficult as it would be to invent different names for the 18 constitutional isomers of CgHjg, for example, it would be even harder to remember which structure corresponded to which name. For this and other reasons, organic chemists have developed systematic ways to name compounds based on their structure. The most widely used approach is called the lUPAC rules lUPAC stands for the International Union of Pure and Applied Chemistry. (See the boxed essay. What s in a Name Organic Nomenclature,)... 

Alkyl groups are the groups that we identify for purposes of naming compounds. They are groups that would be obtained by removing a hydrogen atom from an alkane ... 

The lUPAC system for naming alkanes is not difficuit to iearn, and the principies invoived are used in naming compounds in other famiiies as weii. For these reasons we begin our study of the iUPAC system with the ruies for naming aikanes and then study the ruies for aikyi haiides and aicohois. 

Systematically naming all the various types of organic compounds would probably take another book, lUPAC Nomenclature For Dummies. Here, I just show you the rules for naming simple alkanes (even the naming of alkanes can get complicated, so it s important to use the KISS Rule — Keep It Simple, Silly) ... 

The naming of alkanes and cycloalkanes in Sections 3.3 and 3.4 illustrates the application of the lUPAC system of nomenclature to these two specific classes of organic compounds. Now let us describe the general approach of the lUPAC system. The name we give to any compound with a chain of carbon atoms consists of three parts a prefix, an infix (a modifying element inserted into a word), and a suffix. Each part provides specific information about the structural formula of the compound. 

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