Alkanes
Alkanes are a family of hydrocarbons consisting of carbon and hydrogen atoms linked by single bonds. They are known for their saturated structure, meaning they contain the maximum number of hydrogen atoms possible. Alkanes are commonly used as fuels and are important in organic chemistry due to their stability and lack of reactivity.
8 Key excerpts on "Alkanes"
eBook - ePub- James G. Speight(Author)
- 2010(Publication Date)
- Gulf Professional Publishing(Publisher)
...Alkanes can have straight or branched chains, but without any ring structure. 2. Alkenes (olefins) are unsaturated hydrocarbons insofar as not all of the carbon valencies are satisfied by another atom and have a double bond (C=C) between carbon atoms. Alkenes have the general formula C n H 2 n, assuming no ring structures in the molecule. Alkenes may have more than one double bond between carbon atoms, in which case the formula is reduced by two hydrogen atoms for each additional double bond. For example, an alkene with two double bonds in the molecule has the general formula C n H 2 n – 2. Because of their reactivity and the time involved in crude oil maturation, alkenes do not usually occur in petroleum. 3. Alkynes (acetylenes) are hydrocarbons which contain a triple bond (C≡C) and have the general formula C n H 2 n – 2. Acetylene hydrocarbons are highly reactive and, as a consequence, are very rare in crude oil. 4. CycloAlkanes (naphthenes) are saturated hydrocarbons containing one or more rings, each of which may have one or more paraffinic side chains (more correctly known as alicyclic hydrocarbons). The general formula for a saturated hydrocarbon containing one ring is C n H 2 n. 5. Aromatic hydrocarbons (arenes) are hydrocarbons containing one or more aromatic nuclei, such as benzene, naphthalene, and phenanthrene ring systems, which may be linked up with (substituted) naphthene rings and/or paraffinic side chains. 5.1. Bonding in hydrocarbons Since carbon adopts the tetrahedral geometry when there are four σ bonds, only two bonds can occupy a plane simultaneously. The other two bonds are directed to the rear or to the front of the plane...
eBook - ePub- Graham Patrick(Author)
- 2004(Publication Date)
- Taylor & Francis(Publisher)
...SECTION B — Alkanes AND CYCLOAlkanes B1 Definition Key Notes Alkanes Alkanes are organic molecules consisting solely of carbon and hydrogen atoms linked by single σ bonds. All the carbon atoms are tetrahedral and sp 3 hybridized. Alkanes are stable molecules and unreactive to most chemical reagents. They have the general formula C n H 2 n +2 CycloAlkanes CycloAlkanes are cyclic alkane structures. They have the general formula C n H 2 n. Most cycloAlkanes are unreactive to chemical reagents. However, three- and four-membered rings are reactive due to ring strain and behave like alkenes. Related topics (A3) sp 3 Hybridization (D4) Conformational isomers Alkanes Alkanes are organic molecules with the general formula C n H 2 n +2, which consist of carbon and hydrogen atoms linked together by C–C and C–H single bonds. They are often referred to as saturated hydrocarbons — saturated because all the bonds are single bonds, hydrocarbons because the only atoms present are carbon and hydrogen. All the carbon atoms in an alkane are sp 3 hybridized and tetrahedral in shape. The C–C and C–H bonds are strong σ bonds, and so Alkanes are unreactive to most chemical reagents. Alkanes are sometimes referred to as straight chain or acyclic Alkanes to distinguish them from cycloAlkanes or alicyclic compounds. CycloAlkanes CycloAlkanes are cyclic Alkanes (alicyclic compounds) having the general formula C n H 2 n where the carbon atoms have been linked together to form a ring. All sizes of ring are possible. However, the most commonly encountered cycloalkane in organic chemistry is the six-membered ring (cyclohexane). Most cycloAlkanes are unreactive to chemical reagents. However, small three- and four-membered rings are reactive and behave like alkenes...
eBook - ePub- Jay Cheng, Jay Cheng(Authors)
- 2017(Publication Date)
- CRC Press(Publisher)
...They are called saturated hydrocarbons because of the absence of double or triple bonds. Saturated acyclic hydrocarbons have the general empirical formula C n H 2n+2. The simplest Alkanes are methane (n = 1), ethane (n = 2), and propane (n = 3) whose structures are shown in Figure 2.1. When n ≥ 4, more than one compound is possible for the same empirical formula. These compounds are called structural isomers and differ in their arrangement of the carbon atoms (straight chain or branched). When n = 4, there are two distinct compounds with the empirical formula of C 4 H 10 : normal butane (n -butane) and iso-butane (Figure 2.2). Similarly, when n = 5 (pentane), there are three structural isomers with the empirical formula of C 5 H 12. The number of structural isomers rapidly increases as the number of carbon atoms increases. For example, C 7 H 16 has 9 structural isomers and C 10 H 22 has 75 structural isomers. FIGURE 2.1 Structures of simple Alkanes. FIGURE 2.2 Structural isomers of butane (C 4 H 10). FIGURE 2.3 Simplified representations of the structural isomers of butane (C 4 H 10) and pentane (C 5 H 12). Since including every carbon and hydrogen atom in structures can be cumbersome, representations of organic compounds are simplified by using chains of carbon atoms with hydrogen atoms assumed implicit. Figure 2.3 shows the simplified representations of the structures of n -butane and iso-butane, along with the three structural isomers of pentane (n -pentane, isopentane, and neopentane). Note the use of wedged bonds in the case of isopentane. These bonds are often used in place of plain lines to provide a 3-D perspective of substituent groups attached to a central atom. 2.2.2 Alkenes Alkenes are hydrocarbons that contain at least one double bond between adjacent carbon atoms. The simplest acyclic alkenes contain only one such double bond and have the general formula empirical C n H 2n...
eBook - ePub- Jeffrey Gaffney, Nancy Marley(Authors)
- 2017(Publication Date)
- Elsevier(Publisher)
...There are three basic types of hydrocarbon structures: straight chain hydrocarbons, branched hydrocarbons, and cyclic hydrocarbons. The straight chain hydrocarbons form one continuous chain of carbon atoms bonded together in a straight line where each carbon atom is bonded to no more than two other carbon atoms. Branched hydrocarbons have one or more of the carbon atoms in the chain bonded to three or four carbon atoms creating a branch in the straight carbon chain. Cyclic hydrocarbons are hydrocarbons in which the carbon chain joins to itself forming a ring. The simplest of the hydrocarbons are the Alkanes. Alkanes are a class of hydrocarbons that contain only sp 3 hybridized carbon atoms. They have the general formula C n H 2 n + 2 and tetrahedral geometries. The Alkanes are sometimes referred to as saturated hydrocarbons, meaning that all carbon bonds in the molecule are sp 3 hybridized and all the bonds are σ single bonds. Each carbon is bonded to the maximum number of four neighboring carbon or hydrogen atoms. They are nonpolar and very chemically stable since they contain only C C and C H bonds. The larger Alkanes are sometimes referred to as paraffin hydrocarbons because they appear waxy in the solid phase. Petroleum and natural gas are primarily composed of mixtures of Alkanes. The simple Alkanes are known as normal Alkanes or straight chain Alkanes. They are named according to the number of carbon atoms in the molecule. The names of the first 10 Alkanes are listed in Table 13.1. We have already looked at the simplest alkane, which is methane (CH 4), containing only one carbon atom and four hydrogen atoms. The second alkane is ethane (C 2 H 6) containing two carbon atoms and six hydrogen atoms. The structure of ethane can be viewed as two CH 3 groups bonded together or it can be viewed as a substituted methane with one hydrogen replaced by a CH 3 group. The third compound, called propane, contains three carbon atoms and eight hydrogen atoms (C 3 H 8)...
eBook - ePub- James G. Speight(Author)
- 2019(Publication Date)
- Gulf Professional Publishing(Publisher)
...Such differences in molecular structure, even though the empirical formula can remain the same, cause significant difference in the properties and behavior of hydrocarbon derivatives and fuels that are predominantly composed of hydrocarbon derivatives. A hydrocarbon is any chemical compound that consists only of the elements carbon (C) and hydrogen (H) (Chapter 1). With the exception of methane (CH 4), all hydrocarbon derivatives contain a carbon-chain skeleton and have hydrogen atoms attached to the carbon skeleton. Most hydrocarbon derivatives are readily combustible (Chapter 10). Almost all usable supplies of hydrocarbon derivatives are currently obtained from crude oil and natural as. Hydrocarbon derivatives are the simplest organic compounds and contain only carbon and hydrogen but they can be straight-chain or branched-chain (Stoker, 2008 ; Klein, 2013) with the same empirical formula but showing difference in properties. The hydrocarbon derivatives can be divided into various homologous series (Chapter 1) and each member of such a series shows a definite relationship in its structural formula to the members preceding and following it, and there is generally some regularity in changes in physical properties of successive members of a series. The alkane derivatives are a homologous series of saturated aliphatic hydrocarbon derivatives. The first and simplest member of this series is methane, CH 4 ; the series is sometimes called the methane series. Each successive member of a homologous series of hydrocarbon derivatives has one more carbon and two more hydrogen atoms in its molecule than the preceding member. The second alkane is ethane, C 2 H 6, and the third is propane, C 3 H 8. Alkane derivatives have the general formula C n H 2n+2 (where n is an integer greater than or equal to 1)...
eBook - ePub- Tony Farine, Mark A. Foss(Authors)
- 2013(Publication Date)
- Routledge(Publisher)
...In this section, we concentrate on other important organic molecules, such as alcohols. Let us first clarify how organic molecules are named. The names of organic molecules usually begin with a prefix that indicates the length of the carbon atom chain. Table 3.4 identifies the first ten carbon atom prefixes. In each case, an example is given from a group of compounds called Alkanes. You may be unfamiliar with many of these, but if you have ever used a camping stove, you may be familiar with propane and butane as fuels. Petrol is a mixture of organic molecules, including Alkanes. Chemical groups that are attached to a carbon-atom chain are called substituents. The simplest organic molecules result when carbon forms compounds with the substituent hydrogen alone. The resultant compounds are collectively referred to as hydrocarbons. Alkanes are examples of hydrocarbons, since they consist of hydrogen and carbon alone. Hydrocarbons Organic molecules that contain only single bonds between carbon atoms are said to be saturated. The group of aliphatic hydrocarbons (compounds containing only hydrogen and carbon in a straight chain) that are saturated are called Alkanes, and they are named by adding the suffix –ane to the appropriate prefix. The simplest alkane is, therefore, methane. How many carbon atoms does methane possess? Remember those prefixes? If you do, you will have worked out that methane contains only one carbon atom (CH 4). Its structural formula is given in Figure 3.10. Perhaps you are already familiar with methane, since it is the main component of natural gas. You may also have used propane (C 3 H 8) and butane (C 4 H 10) as fuels in portable heaters and cookers. Take a moment to draw the structures of butane and propane. Now check your diagrams against Figure 3.10. Figure 3.10 The structural formulae of methane, butane and propane. Hydrocarbons that contain double or triple bonds are said to be unsaturated...
eBook - ePub- Christian Vargel(Author)
- 2020(Publication Date)
- Elsevier Science(Publisher)
...C 6 H 5 C 2 H 5 ; Ethylene, C 2 H 4 ; Ethylene, oxide, (CH 2) 2 O; Fatty acids; Fresh water; Heptane, C 7 H 16 ; Hexane, C 6 H 14 ; Hydrocarbons; Isobutane, C 4 H 10 ; Isoprene; Kerosene; Lime mud; Liquid natural gas (LNG); Methane, CH 4 ; Methyl esters; Microbiologically influenced corrosion (MIC); Naphthenes; Naphthalene, C 10 H 8 ; Octane, C 8 H 18 ; Paraffins; Pentane, C 5 H 12 ; Pinene; Propane; Propylene, C 3 H 6 ; Rubber; Seawater; Styrene, C 6 H 5 C 2 H 3 ; Sulphates; Terebenthine; Terphenyl,. C 6 H 5 C 6 H 4 C 6 H 5 ; Toluene, C 6 H 5 CH 3 ; Vegetable oils; Water; Xylene, C 6 H 4 (CH 3) 2 1.1 Alkanes 1.2 Alkenes 1.3 Alkynes 1.4 Arenes or aromatic hydrocarbons 1.5 Terphenyls 1.6 Cyclic, non-benzenic hydrocarbons 1.7 Engine fuels 1.7.1 Conventional fuels 1.7.2 Biofuels 1.8 Petroleum industry 1.9 Drilling muds References Hydrocarbons are the main constituents of crude oil and natural gas. They are used as fuels and lubricants and are the raw materials for the production of plastics, solvents and industrial chemicals. Hydrocarbons are organic chemical compounds composed only of carbon and hydrogen. Depending on how the carbon atoms are bonded together, hydrocarbons can be aliphatic or cyclic. The aliphatic compounds include Alkanes (C n H 2n+2), alkenes (C n H 2n) and alkynes (C n H 2n − 2), depending on the number of unsaturated C–C bonds in the molecule. Cyclic compounds include aromatic hydrocarbons and cycloparaffins (non-benzenic hydrocarbons). Hydrocarbons are chemically relatively inert and, therefore, have no action on aluminium. They are insoluble in water. 1.1...
eBook - ePubBiobased Lubricants and Greases
Technology and Products
- Lou Honary, Erwin Richter(Authors)
- 2011(Publication Date)
- Wiley(Publisher)
...Its structural formula is shown in Figure 2.2. Figure 2.2 Structural formula for ethane A hydrocarbon consisting of a chain of three carbon atoms is referred to as propane (C 3 H 8) and has the structural formula shown in Figure 2.3. Figure 2.3 Structural formula for propane The above compounds are all compounds of carbon and hydrogen. They differ in complexity and are named differently. In order to become familiar with carbon chemistry it is important that the reader become familiar with the systematic naming system used to describe carbon compounds. The International Union of Pure and Applied Chemistry (IUPAC) has adopted a naming system based on the number of carbon atoms in a given molecule as well the atoms to which carbon is chemically bonded. Common elements other than hydrogen being bonded to carbon include oxygen, nitrogen, and sulfur. The first ten hydrocarbons in petroleum are named as follows: CH 4 Methane C 2 H 6 Ethane C 3 H 8 Propane C 4 H 10 Butane C 5 H 12 Pentane C 6 H 14 Hexane C 7 H 16 Heptane C 8 H 18 Octane C 9 H 20 Nonane C 10 H 22 Decane Notice that the name of all of these compounds ends with the suffix “ane.” The suffix of these names deal with a property known as “saturation.” The reason for this nomenclature is that carbon has the ability to share more than one valence electron with another carbon atom. When this happens, the compound is said to be “unstaturated.” An unsaturated carbon compound will end with either “ene” or “yne” as the suffix. This will be dealt with later in this chapter. The following examples will illustrate how some of the IUPAC nomenclature is used. C 3 H 8 is the empirical formula for propane. The “pro” part of the name propane is a carbon atom count and indicates three carbon atoms. The “ane” part of the name tells us that the compound is saturated, which is to say that there are no carbon atoms present in the molecule that share more than one electron with another carbon atom...
