Alkanes Hydrocarbons with Only Single Bonds

Alkanes Hydrocarbons with Only Single Bonds 

A hydrocarbon that contains only single bonds is an alkane (general formula C H2 +2, where n is a positive integer). For example, if n = 5, the formula is C5H[(2x5)+2] or C5H12. The alkanes comprise a homologous series, one in which each member differs from the next by a —CH2— (methylene) group. In an alkane, each C is sp hybridized. Because each C is bonded to the maximum number of other atoms (C or H), alkanes are referred to as saturated hydrocarbons. 

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  

For example, in the name 2-methylbutane, 2-methyl- is the prefix (a one-carbon branch is attached to C-2 of the main chain), -but- is the root (the main chain has four C atoms), and -ane is the suffix (the compound is an alkane). 

CHAPTER 1 5 Organic Compounds and the Atomic Properties of Carbon 

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Alkanes Hydrocarbons with Only Single Bonds... 

Carbon Skeletons and Hydrogen Skins 462 Alkanes Hydrocarbons with Only Single Bonds 464... 

Hydrocarbons with only single bonds are called alkanes, and all of their names end with -ane. Methane (CH ), the simplest alkane, consists of one carhon atom bonded to four hydrogen atoms. Each of the four hydrogen atoms has one electron. These electrons pair with carbon s four outer electrons to create four single bonds. 

Our discussion has centered around hydrocarbon molecules that consist of carbon atoms bonded to each other in long chains. These chains are called normal, straight, or unbranched. The chains may have only single bonds (alkanes), double bonds (alkenes), or triple bonds (alkynes). Hydrocarbons with only single bonds are called saturated hydrocarbons with double or triple bonds are called unsaturated. Not all hydrocarbons want to form straight chains. After all, who among us wants to be straight and serious all the time Some of us will always be comedians. In the world of hydrocarbon molecules, the comedians are the branched and cyclic molecules. 

Alkanes (hydrocarbons containing only single bonds) are often referred to as saturated hydrocarbons because they are saturated (loaded to capacity) with hydrogen. The simplest hydrocarbons are methane (CH4), the main component of natural gas ethane (C2H5), a minority component in natural gas and propane (CjHg), the main component of Uquid petroleum (LP) gas. 

Modem chemists can explain the results of the chemists of 170 years ago. Hydrocarbons that reacted with bromine had double or triple covalent bonds. Those that took up no bromine had only single covalent bonds. Today, a saturated hydrocarbon is defined as a hydrocarbon having only single bonds— in other words, an alkane. An unsaturated hydrocarbon is a hydrocarbon that has at least one double or triple bond between carbon atoms. You will learn more about unsaturated hydrocarbons in Section 22.3. 

The alkanes, also called saturated hydrocarbons, have only single bonds. The bonds are described by sp hybridization of the carbon atoms. When the carbon atoms are not bonded in a linear sequence, cases can occur in which two molecules with the same formula can have different structures, called geometrical isomers, with quite distinct properties. 

INTRODUCTION TO HYDROCARBONS We consider hydrocarbons, compounds containing only C and H, including the hydrocarbons called alkanes, which contain only single bonds. We also look at isomers, compounds with identical compositions but different molecular structures. 

The alkanes, also known as paraffins or saturated hydrocarbons, are straight- or branched-chain hydrocarbons with only single covalent bonds between the carbon atoms. We will study the alkanes in some detail because many other classes of organic compounds are derivatives of these substances. Be sure to learn the names of the first 10 members of the alkane series, because they are the basis for naming other classes of compounds. 

Alkenes — Also known as olefins, and denoted as C H2 the compounds are unsaturated hydrocarbons with a single carbon-to-carbon double bond per molecule. The alkenes are very similar to the alkanes in boiling point, specific gravity, and other physical characteristics. Like alkanes, alkenes are at most only weakly polar. Alkenes are insoluble in water but quite soluble in nonpolar solvents like benzene. Because alkenes are mostly insoluble liquids that are lighter than water and flammable as well, water is not used to suppress fires involving these materials. Because of the double bond, alkenes are more reactive than alkanes. 

An alkane is a hydrocarbon that has only single bonds. Alkanes that do not contain rings have the formula C H2n + 2 An alkane in the shape of a ring is called a cycloalkane. Cycloalkanes have the formula CnH2n- An alkene is a compound that has at least one double bond. Straight-chain alkenes with one double bond have the same formula as cycloalkanes, Cj,H22,. 

Alkanes are open-chain (acyclic) hydrocarbons constituting the homologous series with the general formula where n is an integer. They have only single bonds and therefore are said to be... 

Alkanes A family of saturated hydrocarbons with the general formula C H2n+2. The term saturated, in this context, is used to describe molecules that have only single bonds. The alkanes can only undergo substitution reactions in which there is replacement of one atom in the molecule by another atom. 

Alkanes are hydrocarbons that contain only single bonds. Alkane names generally have the -ane suffix, and the first part of the name indicates the number of carbon atoms. Table 2-2 shows how the prefixes in the names correspond with the number of carbon atoms. 

We classify hydrocarbons according to their bonding (Section 2-12), as shown in Table 3-1. Alkanes have only single bonds. A hydrocarbon with a carbon-carbon double bond (such as ethylene) is an alkene. If a hydrocarbon has a carbon-carbon triple bond (like acetylene), it is an alkyne. Hydrocarbons with aromatic rings (resembling benzene) are called aromatic hydrocarbons. 

Because alkanes have only single bonds, they contain the largest possible number of hydrogen atoms per carbon atom. As a result, they are called saturated hydrocarbons. Alkenes, alkynes, and aromatic hydrocarbons contain multiple bonds (double, triple, or delocalized tr bonds). As a result, they contain less hydrogen than an alkane with the... 

Generally speaking, compounds such as alkanes, whose molecules contain only single bonds, are referred to as saturated compounds because these compounds contain the maximum number of hydrogen atoms that the carbon compound can possess. Compounds with multiple bonds, such as alkenes, alkynes, and aromatic hydrocarbons, are called unsaturated compounds because they possess fewer than the maximum number of hydrogen atoms, and they are capable of reacting with hydrogen under the proper conditions. We shall have more to say about this in Chapter 7. 

Hydrocarbons contain only C and H atoms, so their physical properties depend on the strength of their dispersion forces. The names of organic compounds have a root for the longest chain, a prefix for any attached group, and a suffix for the type of compound. Alkanes (CnHan+a) have only single bonds. Cycloalkanes (C Hp ) have ring structures that are typically nonplanar. Alkenes (CnHpn) have at least one C=C bond. Alkynes (CnHpn-p) have at least one C=C bond. Aromatic hydrocarbons have at least one planar ring with delocalized tt electrons. 

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