Chemistry
Unsaturated Hydrocarbons
Unsaturated hydrocarbons are organic compounds that contain carbon-carbon double or triple bonds. They are more reactive than saturated hydrocarbons due to the presence of these double or triple bonds. Unsaturated hydrocarbons include alkenes, alkynes, and aromatic compounds, and are important in various industrial processes and in the production of plastics, fuels, and other chemicals.
Written by Perlego with AI-assistance
Related key terms
1 of 5
12 Key excerpts on "Unsaturated Hydrocarbons"
eBook - PDFIntroductory Chemistry
An Active Learning Approach
- Mark Cracolice, Edward Peters, Mark Cracolice(Authors)
- 2020(Publication Date)
- Cengage Learning EMEA(Publisher)
Hydrocarbons in which two or more carbon atoms are (1) connected by a double or triple bond and (2) bonded to fewer than four other atoms are unsaturated. If one hydrogen atom, complete with its electron, is removed from each of two adjacent carbon atoms in an alkane (diagram [a] in the middle of this paragraph), each carbon is left with a single unpaired electron (diagram [b]). These electrons may then form a second bond between the two carbon atoms (diagram [c]) : C H C H H H H H 22 H C C H H H H C C H H H H a b c Each carbon atom is now bonded to three other atoms. An aliphatic hydrocar- bon that contains at least one carbon–carbon double bond is called an alkene. Figure 21.11(a) illustrates the simplest alkene, which has the common name ethylene (eth- 5 2 carbon atoms 1 -ylene 5 alkene). Removal of another hydrogen atom from each of the double-bonded carbon atoms in an alkene yields a triple bond: C C H H 22 H C C H H H H C C H H Each carbon atom is now bonded to two other atoms. An aliphatic hydrocarbon in which two carbon atoms are triple-bonded to each other is called an alkyne. Words or chemical symbols are sometimes placed above or above and below the arrow of an equa- tion to indicate a substance whose presence or removal is necessary for a reaction to proceed or to identify a reaction condition. Copyright 2021 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 829 21.5 Unsaturated Hydrocarbons: The Alkenes and Alkynes Acetylene, the common name for the most common alkyne, is illustrated in Figure 21.11(b).
eBook - PDF- H. Stephen Stoker(Author)
- 2015(Publication Date)
- Cengage Learning EMEA(Publisher)
In general, saturated and Unsaturated Hydrocarbons undergo distinctly different chemical reactions. ◀ Saturated hydrocarbons are the subject of this chapter. Unsaturated Hydrocarbons are considered in the next chapter. Figure 1-2 summarizes the terminology presented in this section. ▶ The term saturated has the general meaning that there is no more room for something. Its use with hydrocarbons comes from early studies in which chemists tried to add hydrogen atoms to various hydrocarbon molecules. Compounds to which no more hydrogen atoms could be added (because they already contained the maximum number) were called saturated, and those to which hydrogen could be added were called unsaturated. Copyright 2016 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 4 CHAPTER 1 Saturated Hydrocarbons Two categories of saturated hydrocarbons exist, those with acyclic carbon atom arrangements and those with cyclic carbon atom arrangements. The term acy-clic means “not cyclic.” The following notations contrast simple acyclic and cyclic arrangements of six-carbon atoms. C O C O C O C O C O C C C C C C C Cyclic Acyclic Sections 1-4 through 1-11 of this chapter treat the subject of saturated hydrocarbons with acyclic carbon atom arrangements. ◀ A discussion of saturated hydrocarbons with cyclic carbon atom arrangements follows in Sections 1-12 through 1-14.
eBook - ePub- George A. Olah, Arpad Molnar, G. K. Surya Prakash(Authors)
- 2017(Publication Date)
- Wiley(Publisher)
1 Introduction and General AspectsHydrocarbon chemistry is essentially abiological organic chemistry although methane and fossil fuels and derivatives have biological origin.1.1 Hydrocarbons and Their Classes
Hydrocarbons, as their name indicates, are molecular compounds of carbon and hydrogen. As such, they represent one of the most significant classes of organic compounds (i.e., of carbon compounds).1 In methane (CH4 ), the simplest saturated alkane, a single carbon atom is bonded to four hydrogen atoms. In the higher homologs of methane (of the general formula Cn H2n+2), all atoms are bound to each other by single [(sigma (σ), two-electron, two-center] bonds with carbon displaying its tendency to form C–C bonds. Whereas in CH4 the H/C ratio is 4, in C2 H6 (ethane) it is decreased to 3, in C3 H8 (propane) to 2.67, and so on. Alkanes can be straight chain (each carbon attached to not more than two other carbon atoms) or branched (in which at least one of the carbon is attached to either three or four other carbon atoms). Carbon atoms can be aligned in open chains (acyclic hydrocarbons) or can form rings (cyclic hydrocarbons).Cycloalkanes are cyclic saturated hydrocarbons containing a single ring. Bridged cycloalkanes contain one (or more) pair(s) of carbon atoms common to two (or more) rings. In bicycloalkanes, there are two carbon atoms common to both rings. In tricycloalkanes, there are four carbon atoms common to three rings such as in adamantane (tricyclo[3.3.1.13,7 ]decane) giving a caged hydrocarbon structure.Carbon can also form multiple bonds with other carbon atoms. This results in Unsaturated Hydrocarbons such as olefins (alkenes, Cn H2n), specifically, hydrocarbons containing a carbon–carbon double bond or acetylenes (alkynes, Cn Hn
eBook - PDFChemistry for Today
General, Organic, and Biochemistry
- Spencer Seager, Michael Slabaugh, Maren Hansen, , Spencer Seager, Spencer Seager, Michael Slabaugh, Maren Hansen(Authors)
- 2021(Publication Date)
- Cengage Learning EMEA(Publisher)
polyunsaturated A term usually applied to molecules with several double bonds. George Doyle/Stockbyte/Getty Images FIGURE 12.11 Margarines are prepared by the hydrogenation of vegetable oils. Copyright 2022 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Unsaturated Hydrocarbons 383 b. The carbon–carbon double bond becomes a carbon–carbon single bond with two hy- drogen atoms attached. CH 3 CH CH 3 CH 3 CH 3 C CH 2 CH 3 H H CH 3 C CH 2 CH 3 H H condensed to ✔ LEARNING CHECK 12.5 Write the structural formula for the product of each of the following reactions: a. C CH 3 CH CH 3 Pt CH 3 1H 2 b. H 2 1 Pt CH 3 A number of acidic compounds, such as the hydrogen halides—HF, HCl, HBr, and HI—also add to alkenes to give the corresponding alkyl halide. The reaction with HCl is illustrated as follows: General reaction: C C H 1 Cl C C H Cl (12.6) Specific example: H Cl CH 3 CH CHCH 3 H 1 Cl CH 3 CHCHCH 3 (12.7) The addition reactions involving H 2 , Cl 2 , and Br 2 yield only one product because the same group (H and H or Br and Br) adds to each double-bonded carbon. However, with HiX, a different group adds to each carbon, and for certain alkenes, there are two pos- sible products. For example, in the reaction of HBr with propene, two products might be expected: 1-bromopropane or 2-bromopropane, CH CH CH 2 CH 3 1H Br CH 2 CH 3 Br H CH CH 2 CH 3 H Br or 1-bromopropane 2-bromopropane (12.8) It turns out that only one product, 2-bromopropane, is formed in significant amounts.
eBook - ePubOrganic Chemistry
Concepts and Applications
- Allan D. Headley(Author)
- 2019(Publication Date)
- Wiley(Publisher)
4 ) are considered to be asphyxiants (in that they will not support respiration with insufficient oxygen.). Inhalation of higher molecular weight alkanes may cause central nervous system depression, dizziness, and loss of coordination. Also, higher molecular weight alkanes will dissolve fatty substances around the nerve. As a result, extreme care must be exercised in the industrial workplace to minimize the exposure to workers. For some insects, hydrocarbons provide a waterproof layer to prevent desiccation. Some alkanes also serve as pheromones for some insects and in some cases act as recognition cues to protect insects from parasites and other undesired invasions.DID YOU KNOW?
The saturated hydrocarbon shown below is a sex pheromone used by female tiger moths.2.3.1 Classification of the Carbons of Saturated Hydrocarbons
Owing to the numerous different possible saturated hydrocarbons, a system of classification has been devised. This classification is based on the number of alkyl groups that are bonded to the carbons. For example, if a carbon in a hydrocarbon is bonded to one alkyl group, that carbon is classified as a primary carbon, or sometimes the symbol 1° is used. Since carbons of saturated hydrocarbon have four single bonds, the classifications are primary (1°), secondary (2°), and tertiary (3°), as illustrated below.This method of classification will be used throughout our course to describe different organic compounds that contain these types of carbons.Problem 2.3
Label the starred carbon atoms in the following compounds as primary (1°), secondary (2°), or tertiary (3°).2.4 Organic Nomenclature
Around the middle of the nineteenth century, many compounds were synthesized or isolated from natural sources and there had to be a systematic way of communicating the names and the structures of these compounds within the scientific community. The system of naming chemical compounds used at that time was not based on a scientific method. For example, barbituric acid, which is the parent compound for barbiturate drugs, it is believed that the name was derived from a woman's name, Barbara. Adolph von Baeyer, a German chemist, synthesized a new compound from urea and malonic acid and he did not have a name for this new compound, so he decided to name it after St. Barbara’s Day because he was celebrating both the discovery of this new compound and Saint Barbara’s birthday that day.
eBook - ePub- James G. Speight(Author)
- 2010(Publication Date)
- Gulf Professional Publishing(Publisher)
Chapter 9. Chemical and Physical Properties of HydrocarbonsContents1. Introduction3252. Stereochemistry3263. Molecular weight3294. Chemical properties3305. Physical properties3355.1. Boiling points and melting points3355.2. Density and specific gravity3435.3. Vapor density3475.4. Flash point and ignition temperature3485.5. Dew point350References3521. IntroductionHydrocarbons, the principal compounds of oil and natural gas, have to be chemically altered to make useful products and materials. This is carried out by changes in the chemical and physical structure. Such differences in molecular structure, even though the empirical formula can remain the same, cause significant differences in the properties and behavior of hydrocarbons and hydrocarbon fuels.Hydrocarbons are the simplest organic compounds and contain only carbon and hydrogen but they can be straight chain or branched chain (Stoker, 2008 ) with the same empirical formula but showing differences in properties.A hydrocarbon is any chemical compound that consists only of the elements carbon (C) and hydrogen (H) (Chapter 1 ). All hydrocarbons contain a carbon-chain skeleton and have hydrogen atoms attached to the carbon skeleton. Most hydrocarbons are readily combustible (Chapter 10 ). Almost all usable supplies of hydrocarbons are currently obtained from petroleum and natural gas.The hydrocarbons can be divided into various homologous series (Chapter 1 ). 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 alkanes are a homologous series of saturated aliphatic hydrocarbons. The first and simplest member of this series is methane, CH4 ; the series is sometimes called the methane series. Each successive member of a homologous series of hydrocarbons has one more carbon and two more hydrogen atoms in its molecule than the preceding member. The second alkane is ethane, C2 H6 , and the third is propane, C3 H8 . Alkanes have the general formula Cn H2n+2(where n is an integer greater than or equal to 1). Other homologous series of hydrocarbons include the alkenes and the alkynes (Chapter 1
- Morris Hein, Scott Pattison, Susan Arena, Leo R. Best(Authors)
- 2014(Publication Date)
- Wiley(Publisher)
Hydrocarbons are compounds that are composed entirely of carbon and hydrogen atoms bonded to each other by covalent bonds. Hydrocarbons are classified into two major categories, aliphatic and aromatic. The term aromatic refers to compounds that contain benzene rings. All hydrocarbons that are not aromatic are often described as aliphatic (from the Greek word aleiphar, meaning “fat”). The aliphatic hydrocarbons include the alkanes, alkenes, alkynes, cycloalkenes, and cycloalkanes. (See Figure 19.5.) Fossil fuels—natural gas, petroleum, and coal—are the principal sources of hydrocarbons. Natural gas is primarily methane with small amounts of ethane, propane, and butane. Petroleum is a mixture of hydrocarbons from which gasoline, kerosene, fuel oil, lubricating oil, paraffin KEY TERMS hydrocarbon aliphatic Coal tar–containing shampoos are used to treat dandruff. LEARNING OBJECTIVE Fossil fuels are mined from many sources: an oil exploration rig in Alaska, a coal mine in Pennsylvania, and a natural gas operation in Washington (left to right). Ken Graham/Age Fotostock America, Inc. Larry Mangino/The Image Works Chris Knapton/Science Source Images 450 CHAPTER 19 • Organic Chemistry: Saturated Hydrocarbons wax, and petrolatum (themselves mixtures of hydrocarbons) are separated. Coal tar, a volatile by-product of making coke from coal for use in the steel industry, is the source of many valuable chemicals, including the aromatic hydrocarbons benzene, toluene, and naphthalene. The fossil fuels provide a rich resource of hydrocarbons for human society. In the past, these resources have been used primarily as a source of heat (via combustion). We now see that extensive combustion can have severe environmental consequences (e.g., air pollution and global warming). Fossil fuels also serve as the raw materials for much of today’s chemical industry.
eBook - PDFChemistry
Principles and Reactions
- William Masterton, Cecile Hurley(Authors)
- 2020(Publication Date)
- Cengage Learning EMEA(Publisher)
■ ■ the phenomenon of isomerism, which is very common among organic com-pounds. This topic is introduced in Section 22-1 but discussed more generally in Section 22-5. ■ ■ different types of organic reactions (Section 22-6). Throughout this chapter, we will represent molecules by structural formulas, which show all the bonds present. Thus we have H 9 C 9 O 9 C 9 H H H H H ethanol H 9 C 9 C 9 H H H H H H 9 C 9 C 9 O 9 H H H H H ethane dimethyl ether To save space we often write condensed structural formulas such as CH 3 CH 3 CH 3 CH 2 OH CH 3 } O } CH 3 or C 2 H 6 or C 2 H 5 OH or (CH 3 ) 2 O 22-1 Saturated Hydrocarbons: Alkanes One large and structurally simple class of hydrocarbons includes those substances in which all the carbon-carbon bonds are single bonds. These are called saturated hydrocarbons , or alkanes . In the alkanes the carbon atoms are bonded to each other in chains, which may be long or short, straight or branched. The ratio of hydrogen to carbon atoms is a maximum in alkanes, ▼ hence the term “saturated” hydrocarbon. The general formula of an alkane containing n carbon atoms is C n H 2 n 1 2 The simplest alkanes are those for which n 5 1 (CH 4 ), n 5 2 (C 2 H 6 ), or n 5 3 (C 3 H 8 ): H 9 C 9 H H H H 9 C 9 C 9 H H H H H H 9 C 9 C 9 C 9 H H H H H H H methane ethane propane Around the carbon atoms in these molecules, and indeed in any saturated hydrocarbon, there are four single bonds involving sp 3 hybrid orbitals. As would be expected from the VSEPR model, these bonds are directed toward the corners of a regular tetrahedron. The bond angles are approximately 109.5 8 , the tetrahe-dral angle. This means that in propane (C 3 H 8 ) and in the higher alkanes, the car-bon atoms are arranged in a “zigzag” pattern (Figure 22.1). The outer surfaces of these molecules contain mainly H atoms. CH 4 methane CH 3 CH 3 ethane CH 3 CH 2 CH 3 propane Figure 22.1 The three simplest alkanes.
- Barron's Educational Series, Albert S. Tarendash(Authors)
- 2021(Publication Date)
- Barrons Educational Services(Publisher)
The properties detailed in this section support the view that the existence of ions or polar covalent bonds is commonly associated with inorganic compounds. In organic compounds, however, the bonding is usually covalent with little or no polarity. Carbon has four valence electrons, and in organic compounds it forms a total of four covalent bonds. We will see that carbon atoms may form single, double, or triple bonds by sharing one, two, or three pairs of electrons.
Passage contains an image
11.3 Hydrocarbons and Homologous Series
The simplest organic compounds contain only carbon and hydrogen and are called hydrocarbons. Hydrocarbons are obtained from the refining of petroleum, a complex mixture of natural hydrocarbons. Petroleum is the starting point for the production of plastics, textiles, rubber, and detergents. The petroleum is separated into components with different boiling points by the process of fractional distillation. Another process, called cracking, is used to break the larger hydrocarbon molecules into smaller ones. This procedure increases the yield of the more important fractions with lower boiling points (such as gasoline). The simplest hydrocarbon is methane (CH4 ), which is the chief component of natural gas.Hydrocarbons with related structures and properties are usually separated into “families” known as homologous series. Each member of a series differs from the next member by a single carbon atom. With each successive member, the properties of the compounds, such as melting and boiling points, change in a regular way. This classification into series greatly simplifies the study of organic chemistry.The Alkane Series
Alkanes are hydrocarbons that contain only single bonds between carbon atoms. The first member of the alkane series is methane (CH4 ). In Chapter 9 , we discovered that methane is a tetrahedral molecule because carbon forms four sp3 hybrid orbitals—as it does in every
eBook - PDFChemistry
Structure and Dynamics
- James N. Spencer, George M. Bodner, Lyman H. Rickard(Authors)
- 2011(Publication Date)
- Wiley(Publisher)
(They tend to remain oily liquids when cooled.) These compounds are now called alkenes. The connection between alkanes and alkenes can be understood by think- ing about a hypothetical reaction in which we break a C¬H on both carbon atoms in ethane so that one of the electrons in these bonds ends up on each atom. We then bring the hydrogen atoms together to form an H 2 molecule and allow the electrons on the two carbon atoms to interact to form a double bond between these atoms. Although this hypothetical reaction does not occur, the opposite reaction is easy to achieve. In the presence of a suitable catalyst, such as platinum metal, we can transform an alkene into the parent alkane. The generic formula for an alkene with one double bond is C n H 2n . Alkenes are examples of Unsaturated Hydrocarbons because they have fewer hydrogen atoms than the corresponding alkanes. They were once named by adding the suffix -ene to the name of the substituent that carried the same num- ber of carbon atoms. The IUPAC nomenclature for alkenes names these compounds as derivatives of the parent alkanes. The presence of the C“C double bond is indicated by chang- ing the -ane ending on the name of the parent alkane to -ene. CH 3 OCH 2 OCH 3 Propane CH 3 OCH 3 Ethane CH 2 PCHOCH 3 Propene CH 2 PCH 2 Ethene CH 2 PCHOCH 3 Propylene H 2 CPCH 2 Ethylene C“C H 2 Pt + HOCOCOH H H H H A A A A H H H H HOCOCOH H H H H A A A A HOCOCOH H H A A HOH H T T T H T H H H H 16.5 THE Unsaturated Hydrocarbons: ALKENES AND ALKYNES 733 The location of the double bond in the skeleton structure of the compound is indicated by specifying the number of the carbon atom at which the C“C bond starts. The names of substituents are then added as prefixes to the name of the alkene. 1-Butene CH 2 PCHOCH 2 OCH 3 2-Butene CH 3 OCHPCHOCH 3 C“C 734 CHAPTER 16 / ORGANIC CHEMISTRY E x e r c i s e 1 6 .
eBook - ePub- Jeffrey Gaffney, Nancy Marley(Authors)
- 2017(Publication Date)
- Elsevier(Publisher)
Hydrocarbons are compounds that contain only hydrogen and carbon atoms. 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 Cn H2n + 2and 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 (CH4 ), containing only one carbon atom and four hydrogen atoms. The second alkane is ethane (C2 H6 ) containing two carbon atoms and six hydrogen atoms. The structure of ethane can be viewed as two CH3 groups bonded together or it can be viewed as a substituted methane with one hydrogen replaced by a CH3 group. The third compound, called propane, contains three carbon atoms and eight hydrogen atoms (C3 H8 ). Propane can also be considered to be a substituted methane, where two of the hydrogen atoms on methane are replaced by two CH3 groups. All three of these alkanes have one structural isomer possible. Structural isomers
eBook - ePubOrganic Chemistry Concepts
An EFL Approach
- Gregory Roos, Cathryn Roos(Authors)
- 2014(Publication Date)
- Academic Press(Publisher)
Chapter 2Functional Classes I, Structure and Naming
Abstract
This chapter takes an initial look at the structure and representation of functional groups. The principles of the unambiguous systematic classification and naming of organic compounds are introduced. The importance of these for accurate information transfer is highlighted. Common functional classes are detailed and, where needed, three-dimensional diagrams, oxidation states, and physical properties are introduced.Keywords
3-D drawings; Carbon oxidation states; Conjugation; Molecular diagrams; Physical properties; Systematic compound naming2.1. Drawing and Naming Molecules
To understand the chemistry of organic molecules, we need to know the types of compounds that are possible. In this chapter we look at some details of the important functional classes introduced in Chapter 1 . Each compound class is shown with structural diagrams (how to draw the compounds) and systematic naming of the compounds. This background knowledge will prepare you for the chemistry in later chapters.2.2. Saturated Hydrocarbons
Hydrocarbon means that this class of compound has only carbon and hydrogen. In this broad grouping there are both: ▪ acyclic examples called alkanes; ▪ cyclic examples called cycloalkanes.All saturated examples have only single σ-bonds between sp 3 -hybridized carbon atoms and hydrogen atoms. This class gives the parent compounds from which all other functional types come from. They also serve as the parent compounds for systematic naming.Hydrocarbons have low chemical reactivity. This is because they have no reactive functional group. They simply consist of chains of tetrahedral carbon atoms which are surrounded by hydrogen atoms. Table 2.1
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
