Plastic recycling is the process of recovering waste, scrap, or used plastics, and reprocessing the material into useful products. For example, polyethylene terephthalate soft drink bottles can be melted down and used for plastic furniture, in carpets, or for other applications.
Other plastics, like polyethylene bags and polypropylene cups, plastic food containers , can be recycled or reprocessed to be used again. Many areas of the country have recycling programs that focus on one or more of the commodity plastics that have been assigned a recycling code see Figure 8. These operations have been in effect since the s and have made the production of some plastics among the most efficient industrial operations today. The name of an alkene is derived from the name of the alkane with the same number of carbon atoms.
The presence of the double bond is signified by replacing the suffix -ane with the suffix -ene. The location of the double bond is identified by naming the smaller of the numbers of the carbon atoms participating in the double bond:. Molecules of 1-butene and 2-butene are structural isomers; the arrangement of the atoms in these two molecules differs.
As an example of arrangement differences, the first carbon atom in 1-butene is bonded to two hydrogen atoms; the first carbon atom in 2-butene is bonded to three hydrogen atoms. The compound 2-butene and some other alkenes also form a second type of isomer called a geometric isomer. In a set of geometric isomers, the same types of atoms are attached to each other in the same order, but the geometries of the two molecules differ.
Carbon atoms are free to rotate around a single bond but not around a double bond; a double bond is rigid. This makes it possible to have two isomers of 2-butene, one with both methyl groups on the same side of the double bond and one with the methyl groups on opposite sides. The 2-butene isomer in which the two methyl groups are on the same side is called a cis -isomer; the one in which the two methyl groups are on opposite sides is called a trans -isomer Figure 9. The different geometries produce different physical properties, such as boiling point, that may make separation of the isomers possible:.
This reaction is called an addition reaction. The hybridization of the carbon atoms in the double bond in an alkene changes from sp 2 to sp 3 during an addition reaction. For example, halogens add to the double bond in an alkene instead of replacing hydrogen, as occurs in an alkane:. Solution The reactant is a five-carbon chain that contains a carbon-carbon double bond, so the base name will be pentene.
We begin counting at the end of the chain closest to the double bond—in this case, from the left—the double bond spans carbons 2 and 3, so the name becomes 2-pentene.
Since there are two carbon-containing groups attached to the two carbon atoms in the double bond—and they are on the same side of the double bond—this molecule is the cis- isomer, making the name of the starting alkene cis pentene. The product of the halogenation reaction will have two chlorine atoms attached to the carbon atoms that were a part of the carbon-carbon double bond:. This molecule is now a substituted alkane and will be named as such.
The base of the name will be pentane. We will count from the end that numbers the carbon atoms where the chlorine atoms are attached as 2 and 3, making the name of the product 2,3-dichloropentane. Check Your Learning Provide names for the reactant and product of the reaction shown:. Hydrocarbon molecules with one or more triple bonds are called alkynes ; they make up another series of unsaturated hydrocarbons.
The simplest member of the alkyne series is ethyne, C 2 H 2 , commonly called acetylene. The Lewis structure for ethyne, a linear molecule, is:.
The IUPAC nomenclature for alkynes is similar to that for alkenes except that the suffix -yne is used to indicate a triple bond in the chain. Structure of Alkynes Describe the geometry and hybridization of the carbon atoms in the following molecule:.
Solution Carbon atoms 1 and 4 have four single bonds and are thus tetrahedral with sp 3 hybridization. Carbon atoms 2 and 3 are involved in the triple bond, so they have linear geometries and would be classified as sp hybrids.
Check Your Learning Identify the hybridization and bond angles at the carbon atoms in the molecule shown:. Chemically, the alkynes are similar to the alkenes.
The reaction of acetylene with bromine is a typical example:. Acetylene and the other alkynes also burn readily. An acetylene torch takes advantage of the high heat of combustion for acetylene. Benzene, C 6 H 6 , is the simplest member of a large family of hydrocarbons, called aromatic hydrocarbons. These compounds contain ring structures and exhibit bonding that must be described using the resonance hybrid concept of valence bond theory or the delocalization concept of molecular orbital theory.
To review these concepts, refer to the earlier chapters on chemical bonding. The resonance structures for benzene, C 6 H 6 , are:. Valence bond theory describes the benzene molecule and other planar aromatic hydrocarbon molecules as hexagonal rings of sp 2 -hybridized carbon atoms with the unhybridized p orbital of each carbon atom perpendicular to the plane of the ring.
Benzene does not, however, exhibit the characteristics typical of an alkene. To represent this unique bonding, structural formulas for benzene and its derivatives are typically drawn with single bonds between the carbon atoms and a circle within the ring as shown in Figure There are many derivatives of benzene.
The hydrogen atoms can be replaced by many different substituents. Aromatic compounds more readily undergo substitution reactions than addition reactions; replacement of one of the hydrogen atoms with another substituent will leave the delocalized double bonds intact. The following are typical examples of substituted benzene derivatives:. Toluene and xylene are important solvents and raw materials in the chemical industry.
Styrene is used to produce the polymer polystyrene. Structure of Aromatic Hydrocarbons One possible isomer created by a substitution reaction that replaces a hydrogen atom attached to the aromatic ring of toluene with a chlorine atom is shown here. Draw two other possible isomers in which the chlorine atom replaces a different hydrogen atom attached to the aromatic ring:. Solution Since the six-carbon ring with alternating double bonds is necessary for the molecule to be classified as aromatic, appropriate isomers can be produced only by changing the positions of the chloro-substituent relative to the methyl-substituent:.
Check Your Learning Draw three isomers of a six-membered aromatic ring compound substituted with two bromines. Strong, stable bonds between carbon atoms produce complex molecules containing chains, branches, and rings. The chemistry of these compounds is called organic chemistry. Hydrocarbons are organic compounds composed of only carbon and hydrogen. The alkanes are saturated hydrocarbons—that is, hydrocarbons that contain only single bonds.
Alkenes contain one or more carbon-carbon double bonds. Alkynes contain one or more carbon-carbon triple bonds.
Draw Lewis structures for these compounds, with resonance structures as appropriate, and determine the hybridization of the carbon atoms in each. Write the formula of the compound showing the acetylide ion. How many kilograms of ethylene is produced by the pyrolysis of 1.
Both reactions result in bromine being incorporated into the structure of the product. The difference is the way in which that incorporation takes place. In the saturated hydrocarbon, an existing C—H bond is broken, and a bond between the C and the Br can then be formed. Unbranched alkanes have free rotation about the C—C bonds, yielding all orientations of the substituents about these bonds equivalent, interchangeable by rotation.
Since these concepts pertain to phenomena at the molecular level, this explanation involves the microscopic domain.
They are the same compound because each is a saturated hydrocarbon containing an unbranched chain of six carbon atoms. In the following, the carbon backbone and the appropriate number of hydrogen atoms are shown in condensed form:. In acetylene, the bonding uses sp hybrids on carbon atoms and s orbitals on hydrogen atoms. In benzene, the carbon atoms are sp 2 hybridized.
Skip to content Chapter Organic Chemistry. Learning Objectives By the end of this section, you will be able to: Explain the importance of hydrocarbons and the reason for their diversity Name saturated and unsaturated hydrocarbons, and molecules derived from them Describe the reactions characteristic of saturated and unsaturated hydrocarbons Identify structural and geometric isomers of hydrocarbons.
Example 1 Drawing Skeletal Structures Draw the skeletal structures for these two molecules: Solution Each carbon atom is converted into the end of a line or the place where lines intersect. All hydrogen atoms attached to the carbon atoms are left out of the structure although we still need to recognize they are there : Check Your Learning Draw the skeletal structures for these two molecules: Answer:. Example 2 Interpreting Skeletal Structures Identify the chemical formula of the molecule represented here: Solution There are eight places where lines intersect or end, meaning that there are eight carbon atoms in the molecule.
Example 3 Naming Halogen-substituted Alkanes Name the molecule whose structure is shown here: Solution The four-carbon chain is numbered from the end with the chlorine atom. Check Your Learning Name the following molecule: Answer: 3,3-dibromoiodopentane. Learn more about phase transformations and chemical reactions. Carbon can form a double bond with itself.
Instead of sharing one pair of electrons, it shares two pairs of electrons—four electrons shared between two carbon atoms. Imagine two Cs connected by an equal sign. In this case, two hydrogens for each carbon. That leads to the compound C 2 H 4 , or ethane, which is the simplest member of the alkene series.
Now, all the variations described above—chains, branches, rings—can also feature double bonds. The formulas differ from alkanes in that for each carbon-carbon double bond, there are two fewer hydrogens. Carbon can also form a triple bond with itself. In this case, sharing three pairs of electrons, a total of six electrons are shared between the two carbons, and in that case, each carbon only needs one additional hydrogen. The reason society values hydrocarbons so much is because of their unique and valuable properties.
All of these chemicals burn. They burn with intense heat and flame. They produce carbon dioxide and hydrogen oxide— that is, water—as by-products.
The smallest of these molecules are typically gases or liquids, so propane and butane, for example, are fluids and, therefore, can be destroyed very easily as fuels. Learn more about states of matter and changes of state. If you look at the way a candle behaves, you actually see a very interesting phenomenon taking place. In the lighted candle, you have the solid portion of the candle, which is at room temperature. Near the base of the flame, at temperatures above about a hundred degrees, you have a puddle of liquid.
Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. Your Money.
Personal Finance. Your Practice. Popular Courses. Commodities Oil. Oil Guide to Investing in Oil Markets. Table of Contents Expand. What Is a Hydrocarbon? Understanding Hydrocarbons. Some Hydrocarbon Companies. Special Considerations. Alternatives to Hydrocarbons. Hydrocarbon FAQs.
The Bottom Line. Key Takeaways Hydrocarbons are chemical compounds that are utilized as the basis of the vast majority of global energy production. A variety of complex technologies and techniques have been developed for extracting hydrocarbons from deep within the earth. Some of the world's largest companies are hydrocarbon companies, primarily oil and gas companies. The use of hydrocarbons as an energy source has negatively impacted the world's climate in a significant way, resulting in climate change.
Because of the serious environmental cost of using hydrocarbons as a primary source of energy, attempts to move away from them towards alternative energy sources, such as solar, nuclear, wind, and geothermal power have increased significantly.
Article Sources. Investopedia requires writers to use primary sources to support their work. These include white papers, government data, original reporting, and interviews with industry experts. We also reference original research from other reputable publishers where appropriate. You can learn more about the standards we follow in producing accurate, unbiased content in our editorial policy.
Compare Accounts. The offers that appear in this table are from partnerships from which Investopedia receives compensation. This compensation may impact how and where listings appear. Investopedia does not include all offers available in the marketplace.
A nonrenewable resource is a natural substance that is not replenished with the speed at which it is consumed. Its supply is finite. Petroleum Petroleum is a fluid found in the earth that can be refined into fuel and plastics. Read about the types of petroleum, its uses, and environmental impacts.
What Is Shale Oil? Shale oil is a type of oil found in shale rock formations that must be hydraulically fractured to extract.
0コメント