How To Draw The Structure Of The Majo Organic Product Formed In The Reaction Of 1-pentene

Chapter 20. Organic Chemical science

20.1 Hydrocarbons

Learning Objectives

Past the end of this section, you volition be able to:

• Explain the importance of hydrocarbons and the reason for their diversity
• Name saturated and unsaturated hydrocarbons, and molecules derived from them
• Depict the reactions characteristic of saturated and unsaturated hydrocarbons
• Identify structural and geometric isomers of hydrocarbons

The largest database^[ane] of organic compounds lists well-nigh x million substances, which include compounds originating from living organisms and those synthesized by chemists. The number of potential organic compounds has been estimated^[ii] at 10^threescore—an astronomically high number. The existence of so many organic molecules is a event of the ability of carbon atoms to class up to four strong bonds to other carbon atoms, resulting in chains and rings of many unlike sizes, shapes, and complexities.

The simplest organic compounds contain simply the elements carbon and hydrogen, and are chosen hydrocarbons. Even though they are composed of only two types of atoms, there is a wide variety of hydrocarbons because they may consist of varying lengths of chains, branched chains, and rings of carbon atoms, or combinations of these structures. In add-on, hydrocarbons may differ in the types of carbon-carbon bonds present in their molecules. Many hydrocarbons are found in plants, animals, and their fossils; other hydrocarbons accept been prepared in the laboratory. We apply hydrocarbons every day, mainly every bit fuels, such as natural gas, acetylene, propane, butane, and the principal components of gasoline, diesel fuel, and heating oil. The familiar plastics polyethylene, polypropylene, and polystyrene are also hydrocarbons. We can distinguish several types of hydrocarbons by differences in the bonding between carbon atoms. This leads to differences in geometries and in the hybridization of the carbon orbitals.

Alkanes

Alkanes, or saturated hydrocarbons, contain simply single covalent bonds between carbon atoms. Each of the carbon atoms in an alkane has sp ⁱⁱⁱ hybrid orbitals and is bonded to iv other atoms, each of which is either carbon or hydrogen. The Lewis structures and models of methane, ethane, and pentane are illustrated in Effigy one. Carbon chains are usually drawn as straight lines in Lewis structures, merely one has to retrieve that Lewis structures are not intended to indicate the geometry of molecules. Notice that the carbon atoms in the structural models (the ball-and-stick and space-filling models) of the pentane molecule practice non prevarication in a directly line. Considering of the sp ³ hybridization, the bond angles in carbon chains are close to 109.5°, giving such chains in an alkane a zigzag shape.

The structures of alkanes and other organic molecules may too exist represented in a less detailed manner by condensed structural formulas (or simply, condensed formulas). Instead of the usual format for chemical formulas in which each element symbol appears simply once, a condensed formula is written to propose the bonding in the molecule. These formulas have the appearance of a Lewis structure from which most or all of the bond symbols have been removed. Condensed structural formulas for ethane and pentane are shown at the bottom of Figure 1, and several additional examples are provided in the exercises at the end of this affiliate.

Figure 1. Pictured are the Lewis structures, brawl-and-stick models, and space-filling models for molecules of methane, ethane, and pentane.

A common method used by organic chemists to simplify the drawings of larger molecules is to use a skeletal structure (also chosen a line-angle structure). In this type of structure, carbon atoms are not symbolized with a C, but represented by each cease of a line or bend in a line. Hydrogen atoms are not drawn if they are attached to a carbon. Other atoms besides carbon and hydrogen are represented by their elemental symbols. Effigy 2 shows iii different ways to depict the aforementioned structure.

Effigy two. The same structure can exist represented three dissimilar ways: an expanded formula, a condensed formula, and a skeletal structure.

Example ane

Cartoon Skeletal Structures
Depict the skeletal structures for these 2 molecules:

Solution
Each carbon cantlet is converted into the stop of a line or the place where lines intersect. All hydrogen atoms attached to the carbon atoms are left out of the structure (although nosotros still need to recognize they are there):

Check Your Learning
Draw the skeletal structures for these 2 molecules:

Answer:

Example ii

Interpreting Skeletal Structures
Identify the chemic formula of the molecule represented here:

Solution
At that place are eight places where lines intersect or end, meaning that in that location are eight carbon atoms in the molecule. Since we know that carbon atoms tend to make four bonds, each carbon atom volition have the number of hydrogen atoms that are required for 4 bonds. This chemical compound contains 16 hydrogen atoms for a molecular formula of C_eightH₁₆.

Location of the hydrogen atoms:

Cheque Your Learning
Identify the chemic formula of the molecule represented here:

All alkanes are composed of carbon and hydrogen atoms, and take similar bonds, structures, and formulas; noncyclic alkanes all have a formula of C_nH_2n+2. The number of carbon atoms present in an paraffin has no limit. Greater numbers of atoms in the molecules will lead to stronger intermolecular attractions (dispersion forces) and correspondingly different physical properties of the molecules. Backdrop such as melting betoken and humid point (Tabular array one) usually change smoothly and predictably as the number of carbon and hydrogen atoms in the molecules alter.

Alkane	Molecular Formula	Melting Point (°C)	Humid Bespeak (°C)	Phase at STP[3]	Number of Structural Isomers
methyl hydride	CH4	–182.5	–161.v	gas	1
ethane	CtwoHsix	–183.3	–88.half-dozen	gas	1
propane	C3H8	–187.7	–42.1	gas	1
butane	C4H10	–138.3	–0.5	gas	2
pentane	C5H12	–129.seven	36.1	liquid	3
hexane	Chalf-dozenH14	–95.3	68.7	liquid	five
heptane	CsevenH16	–90.half-dozen	98.4	liquid	9
octane	CeightH18	–56.viii	125.7	liquid	xviii
nonane	C9H20	–53.6	150.8	liquid	35
decane	CtenH22	–29.seven	174.0	liquid	75
tetradecane	C14H30	5.nine	253.5	solid	1858
octadecane	CxviiiH38	28.2	316.1	solid	threescore,523
Table 1. Properties of Some Alkanes[4]

Hydrocarbons with the aforementioned formula, including alkanes, can take different structures. For example, two alkanes have the formula C₄H₁₀: They are chosen n-butane and 2-methylpropane (or isobutane), and take the following Lewis structures:

The compounds north-butane and 2-methylpropane are structural isomers (the term constitutional isomers is also unremarkably used). Ramble isomers take the same molecular formula but different spatial arrangements of the atoms in their molecules. The n-butane molecule contains an unbranched chain, pregnant that no carbon cantlet is bonded to more than than 2 other carbon atoms. We use the term normal, or the prefix northward, to refer to a chain of carbon atoms without branching. The compound ii–methylpropane has a branched chain (the carbon cantlet in the eye of the Lewis construction is bonded to three other carbon atoms)

Identifying isomers from Lewis structures is not as piece of cake as information technology looks. Lewis structures that look different may actually stand for the same isomers. For example, the three structures in Effigy iii all stand for the same molecule, northward-butane, and hence are non different isomers. They are identical because each contains an unbranched chain of 4 carbon atoms.

Effigy three. These three representations of the construction of n-butane are not isomers because they all contain the same arrangement of atoms and bonds.

The Basics of Organic Classification: Naming Alkanes

The International Wedlock of Pure and Applied Chemical science (IUPAC) has devised a system of nomenclature that begins with the names of the alkanes and can be adapted from there to account for more complicated structures. The classification for alkanes is based on two rules:

1. To name an alkane, first identify the longest chain of carbon atoms in its structure. A two-carbon concatenation is called ethane; a three-carbon chain, propane; and a 4-carbon concatenation, butane. Longer chains are named as follows: pentane (v-carbon chain), hexane (six), heptane (7), octane (8), nonane (9), and decane (x). These prefixes tin can be seen in the names of the alkanes described in Table i.
2. Add prefixes to the proper name of the longest chain to indicate the positions and names of substituents. Substituents are branches or functional groups that replace hydrogen atoms on a chain. The position of a substituent or branch is identified by the number of the carbon cantlet it is bonded to in the chain. We number the carbon atoms in the concatenation past counting from the end of the concatenation nearest the substituents. Multiple substituents are named individually and placed in alphabetical order at the front of the name.

When more i substituent is present, either on the same carbon atom or on different carbon atoms, the substituents are listed alphabetically. Because the carbon cantlet numbering begins at the end closest to a substituent, the longest chain of carbon atoms is numbered in such a way equally to produce the lowest number for the substituents. The catastrophe -o replaces -ide at the end of the name of an electronegative substituent (in ionic compounds, the negatively charged ion ends with -ide similar chloride; in organic compounds, such atoms are treated as substituents and the -o ending is used). The number of substituents of the aforementioned type is indicated past the prefixes di- (two), tri- (three), tetra- (four), then on (for case, difluoro- indicates two fluoride substituents).

Example 3

Naming Element of group vii-substituted Alkanes
Name the molecule whose structure is shown hither:

Solution

The four-carbon chain is numbered from the terminate with the chlorine cantlet. This puts the substituents on positions i and 2 (numbering from the other terminate would put the substituents on positions 3 and iv). Iv carbon atoms means that the base of operations name of this compound will exist butane. The bromine at position two volition exist described by adding 2-bromo-; this volition come at the beginning of the name, since bromo- comes before chloro- alphabetically. The chlorine at position 1 will exist described past adding 1-chloro-, resulting in the name of the molecule being 2-bromo-1-chlorobutane.

Check Your Learning
Name the following molecule:

Answer:

3,3-dibromo-2-iodopentane

Nosotros call a substituent that contains one less hydrogen than the respective alkane series an alkyl grouping. The proper noun of an alkyl group is obtained by dropping the suffix -ane of the alkane proper noun and adding -yl:

The open bonds in the methyl and ethyl groups bespeak that these alkyl groups are bonded to another atom.

Example iv

Naming Substituted Alkanes
Name the molecule whose structure is shown here:

Solution
The longest carbon chain runs horizontally across the page and contains six carbon atoms (this makes the base of the proper noun hexane, just we will too need to comprise the name of the branch). In this instance, we want to number from right to left (as shown by the blueish numbers) then the branch is connected to carbon iii (imagine the numbers from left to right—this would put the co-operative on carbon 4, violating our rules). The branch attached to position three of our chain contains two carbon atoms (numbered in ruby-red)—and then we take our name for two carbons eth- and attach -yl at the end to signify we are describing a branch. Putting all the pieces together, this molecule is 3-ethylhexane.

Bank check Your Learning
Name the post-obit molecule:

Some hydrocarbons can form more than than one type of alkyl group when the hydrogen atoms that would be removed have different "environments" in the molecule. This diversity of possible alkyl groups can exist identified in the following mode: The four hydrogen atoms in a methyl hydride molecule are equivalent; they all have the same environment. They are equivalent because each is bonded to a carbon atom (the same carbon atom) that is bonded to iii hydrogen atoms. (Information technology may be easier to see the equivalency in the ball and stick models in Figure 1. Removal of any ane of the 4 hydrogen atoms from marsh gas forms a methyl group. Too, the six hydrogen atoms in ethane are equivalent (Effigy 1) and removing any one of these hydrogen atoms produces an ethyl group. Each of the half dozen hydrogen atoms is bonded to a carbon atom that is bonded to two other hydrogen atoms and a carbon atom. Withal, in both propane and two–methylpropane, there are hydrogen atoms in 2 different environments, distinguished by the side by side atoms or groups of atoms:

Each of the half-dozen equivalent hydrogen atoms of the starting time type in propane and each of the nine equivalent hydrogen atoms of that type in 2-methylpropane (all shown in black) are bonded to a carbon atom that is bonded to simply one other carbon cantlet. The two purple hydrogen atoms in propane are of a second type. They differ from the six hydrogen atoms of the first blazon in that they are bonded to a carbon atom bonded to two other carbon atoms. The dark-green hydrogen atom in two-methylpropane differs from the other nine hydrogen atoms in that molecule and from the royal hydrogen atoms in propane. The green hydrogen cantlet in ii-methylpropane is bonded to a carbon atom bonded to three other carbon atoms. Two different alkyl groups tin be formed from each of these molecules, depending on which hydrogen atom is removed. The names and structures of these and several other alkyl groups are listed in Effigy four.

Figure four. This listing gives the names and formulas for diverse alkyl groups formed by the removal of hydrogen atoms from different locations.

Note that alkyl groups do non exist as stable independent entities. They are e'er a part of some larger molecule. The location of an alkyl grouping on a hydrocarbon concatenation is indicated in the same way as whatsoever other substituent:

Alkanes are relatively stable molecules, simply heat or light volition activate reactions that involve the breaking of C–H or C–C single bonds. Combustion is ane such reaction:

[latex]\text{CH}_4(yard)\;+\;two\text{O}_2(thou)\;{\longrightarrow}\;\text{CO}_2(g)\;+\;ii\text{H}_2\text{O}(1000)[/latex]

Alkanes burn in the presence of oxygen, a highly exothermic oxidation-reduction reaction that produces carbon dioxide and water. As a outcome, alkanes are excellent fuels. For instance, methane, CH₄, is the master component of natural gas. Butane, C₄H_x, used in camping ground stoves and lighters is an methane series. Gasoline is a liquid mixture of continuous- and branched-chain alkanes, each containing from five to nine carbon atoms, plus various additives to improve its operation as a fuel. Kerosene, diesel oil, and fuel oil are primarily mixtures of alkanes with college molecular masses. The chief source of these liquid paraffin fuels is crude oil, a complex mixture that is separated by partial distillation. Fractional distillation takes reward of differences in the humid points of the components of the mixture (see Figure 5). You may recall that humid point is a function of intermolecular interactions, which was discussed in the chapter on solutions and colloids.

Figure five. In a column for the fractional distillation of rough oil, oil heated to about 425 °C in the furnace vaporizes when information technology enters the base of the tower. The vapors rise through bubble caps in a serial of trays in the tower. Every bit the vapors gradually cool, fractions of higher, and then of lower, boiling points condense to liquids and are drawn off. (credit left: modification of piece of work by Luigi Chiesa)

In a substitution reaction, another typical reaction of alkanes, i or more of the alkane'southward hydrogen atoms is replaced with a different atom or grouping of atoms. No carbon-carbon bonds are broken in these reactions, and the hybridization of the carbon atoms does not change. For example, the reaction betwixt ethane and molecular chlorine depicted here is a exchange reaction:

The C–Cl portion of the chloroethane molecule is an example of a functional grouping, the part or moiety of a molecule that imparts a specific chemical reactivity. The types of functional groups present in an organic molecule are major determinants of its chemical backdrop and are used as a means of classifying organic compounds every bit detailed in the remaining sections of this chapter.

Want more than practise naming alkanes? Lookout this brief video tutorial to review the classification procedure.

Alkenes

Organic compounds that contain ane or more double or triple bonds betwixt carbon atoms are described as unsaturated. You lot take probable heard of unsaturated fats. These are circuitous organic molecules with long bondage of carbon atoms, which contain at least ane double bail between carbon atoms. Unsaturated hydrocarbon molecules that contain one or more double bonds are chosen alkenes. Carbon atoms linked by a double bail are leap together past two bonds, one σ bond and one π bond. Double and triple bonds give rise to a different geometry around the carbon atom that participates in them, leading to important differences in molecular shape and backdrop. The differing geometries are responsible for the unlike backdrop of unsaturated versus saturated fats.

Ethene, C₂H₄, is the simplest alkene. Each carbon atom in ethene, unremarkably chosen ethylene, has a trigonal planar construction. The second member of the series is propene (propylene) (Figure 6); the butene isomers follow in the series. Four carbon atoms in the chain of butene allows for the formation of isomers based on the position of the double bond, besides as a new form of isomerism.

Figure vi. Expanded structures, ball-and-stick structures, and space-filling models for the alkenes ethene, propene, and one-butene are shown.

Ethylene (the common industrial proper name for ethene) is a bones raw fabric in the production of polyethylene and other important compounds. Over 135 million tons of ethylene were produced worldwide in 2022 for use in the polymer, petrochemical, and plastic industries. Ethylene is produced industrially in a process called groovy, in which the long hydrocarbon chains in a petroleum mixture are broken into smaller molecules.

Recycling Plastics

Polymers (from Greek words poly significant "many" and mer meaning "parts") are large molecules made up of repeating units, referred to as monomers. Polymers can be natural (starch is a polymer of sugar residues and proteins are polymers of amino acids) or synthetic [similar polyethylene, polyvinyl chloride (PVC), and polystyrene]. The variety of structures of polymers translates into a broad range of properties and uses that brand them integral parts of our everyday lives. Adding functional groups to the structure of a polymer can result in significantly different properties (see the discussion about Kevlar later in this chapter).

An instance of a polymerization reaction is shown in Figure 7. The monomer ethylene (C_iiH_four) is a gas at room temperature, but when polymerized, using a transition metal catalyst, it is transformed into a solid textile made upward of long chains of –CH₂– units called polyethylene. Polyethylene is a commodity plastic used primarily for packaging (bags and films).

Figure seven. The reaction for the polymerization of ethylene to polyethylene is shown.

Polyethylene is a member of one subset of synthetic polymers classified as plastics. Plastics are synthetic organic solids that tin be molded; they are typically organic polymers with high molecular masses. Most of the monomers that become into common plastics (ethylene, propylene, vinyl chloride, styrene, and ethylene terephthalate) are derived from petrochemicals and are not very biodegradable, making them candidate materials for recycling. Recycling plastics helps minimize the need for using more of the petrochemical supplies and also minimizes the ecology damage caused by throwing away these nonbiodegradable materials.

Plastic recycling is the procedure of recovering waste product, scrap, or used plastics, and reprocessing the material into useful products. For example, polyethylene terephthalate (soft potable bottles) can be melted down and used for plastic article of 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 accept recycling programs that focus on one or more of the commodity plastics that take been assigned a recycling code (run into Figure 8). These operations accept been in effect since the 1970s and take made the production of some plastics among the most efficient industrial operations today.

Figure 8. Each blazon of recyclable plastic is imprinted with a lawmaking for easy identification.

The proper noun of an alkene is derived from the name of the alkane with the aforementioned number of carbon atoms. The presence of the double bail is signified by replacing the suffix -ane with the suffix -ene. The location of the double bail is identified by naming the smaller of the numbers of the carbon atoms participating in the double bond:

Isomers of Alkenes

Molecules of i-butene and ii-butene are structural isomers; the arrangement of the atoms in these two molecules differs. Every bit an example of arrangement differences, the first carbon cantlet in 1-butene is bonded to two hydrogen atoms; the first carbon atom in two-butene is bonded to iii hydrogen atoms.

The compound 2-butene and some other alkenes besides form a 2nd type of isomer called a geometric isomer. In a ready of geometric isomers, the same types of atoms are attached to each other in the aforementioned gild, but the geometries of the two molecules differ. Geometric isomers of alkenes differ in the orientation of the groups on either side of a [latex]\text{C}\;=\;\text{C}[/latex] bond.

Carbon atoms are free to rotate around a unmarried bail but not around a double bond; a double bail is rigid. This makes it possible to accept two isomers of 2-butene, one with both methyl groups on the same side of the double bail and one with the methyl groups on opposite sides. When structures of butene are drawn with 120° bond angles around the sp ²-hybridized carbon atoms participating in the double bond, the isomers are apparent. 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 unlike geometries produce different physical properties, such as boiling point, that may make separation of the isomers possible:

Figure 9. These molecular models show the structural and geometric isomers of butene.

Alkenes are much more reactive than alkanes considering the [latex]\text{C}\;=\;\text{C}[/latex] moiety is a reactive functional group. A π bond, being a weaker bond, is disrupted much more than easily than a σ bond. Thus, alkenes undergo a characteristic reaction in which the π bond is broken and replaced by two σ bonds. This reaction is called an addition reaction. The hybridization of the carbon atoms in the double bail in an alkene changes from sp ^two to sp ³ during an addition reaction. For case, halogens add to the double bail in an alkene instead of replacing hydrogen, equally occurs in an alkane series:

Instance 5

Alkene Reactivity and Naming
Provide the IUPAC names for the reactant and production of the halogenation reaction shown here:

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 example, from the left—the double bond spans carbons 2 and 3, and then the proper name becomes 2-pentene. Since at that place are 2 carbon-containing groups attached to the 2 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-2-pentene. The product of the halogenation reaction volition have two chlorine atoms attached to the carbon atoms that were a part of the carbon-carbon double bond:

This molecule is at present a substituted alkane and will be named as such. The base of the proper name volition be pentane. We volition count from the terminate that numbers the carbon atoms where the chlorine atoms are fastened as 2 and 3, making the name of the production 2,3-dichloropentane.

Check Your Learning
Provide names for the reactant and product of the reaction shown:

Reply:

reactant: cis-iii-hexene product: 3,four-dichlorohexane

Alkynes

Hydrocarbon molecules with ane or more triple bonds are called alkynes; they brand upwards another series of unsaturated hydrocarbons. Two carbon atoms joined by a triple bond are leap together past one σ bond and two π bonds. The sp-hybridized carbons involved in the triple bond have bond angles of 180°, giving these types of bonds a linear, rod-like shape.

The simplest fellow member of the alkyne series is ethyne, C_twoH₂, 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. For example, [latex]\text{CH}_3\text{CH}_2\text{C}\;{\equiv}\;\text{CH}[/latex] is chosen 1-butyne.

Example 6

Construction of Alkynes
Describe the geometry and hybridization of the carbon atoms in the post-obit molecule:

Solution
Carbon atoms 1 and 4 have four unmarried 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:

Answer:

carbon 1: sp, 180°; carbon 2: sp, 180°; carbon 3: sp ^two, 120°; carbon iv: sp ², 120°; carbon 5: sp ³, 109.5°

Chemically, the alkynes are like to the alkenes. Since the [latex]\text{C}\;{\equiv}\;\text{C}[/latex] functional group has two π bonds, alkynes typically react even more readily, and react with twice as much reagent in addition reactions. The reaction of acetylene with bromine is a typical example:

Acetylene and the other alkynes also burn readily. An acetylene torch takes reward of the high heat of combustion for acetylene.

Aromatic Hydrocarbons

Benzene, C_{half dozen}H₆, is the simplest member of a large family of hydrocarbons, called effluvious 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_{half dozen}H_half-dozen, 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 aeroplane of the band. Three valence electrons in the sp ^two hybrid orbitals of each carbon atom and the valence electron of each hydrogen atom form the framework of σ bonds in the benzene molecule. The fourth valence electron of each carbon atom is shared with an adjacent carbon cantlet in their unhybridized p orbitals to yield the π bonds. Benzene does not, however, exhibit the characteristics typical of an alkene. Each of the six bonds between its carbon atoms is equivalent and exhibits backdrop that are intermediate betwixt those of a C–C unmarried bond and a [latex]\text{C}\;=\;\text{C}[/latex] double bond. To stand for 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 band as shown in Effigy ten.

Effigy 10. This condensed formula shows the unique bonding structure of benzene.

At that place are many derivatives of benzene. The hydrogen atoms can be replaced past many different substituents. Aromatic compounds more than readily undergo substitution reactions than addition reactions; replacement of one of the hydrogen atoms with some other substituent volition leave the delocalized double bonds intact. The following are typical examples of substituted benzene derivatives:

Toluene and xylene are of import solvents and raw materials in the chemical manufacture. Styrene is used to produce the polymer polystyrene.

Example 7

Structure of Aromatic Hydrocarbons
One possible isomer created by a exchange 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 effluvious ring:

Solution
Since the half dozen-carbon band with alternating double bonds is necessary for the molecule to exist classified as aromatic, appropriate isomers can exist produced but past changing the positions of the chloro-substituent relative to the methyl-substituent:

Check Your Learning
Draw iii isomers of a six-membered aromatic ring chemical compound substituted with ii bromines.

Answer:

Central Concepts and Summary

Stiff, stable bonds betwixt 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 1 or more carbon-carbon double bonds. Alkynes comprise one or more than carbon-carbon triple bonds. Aromatic hydrocarbons contain band structures with delocalized π electron systems.

Chemistry End of Chapter Exercises

1. Write the chemic formula and Lewis structure of the following, each of which contains v carbon atoms:

   (a) an alkane

   (b) an alkene

   (c) an alkyne

2. What is the divergence betwixt the hybridization of carbon atoms' valence orbitals in saturated and unsaturated hydrocarbons?
3. On a microscopic level, how does the reaction of bromine with a saturated hydrocarbon differ from its reaction with an unsaturated hydrocarbon? How are they like?
4. On a microscopic level, how does the reaction of bromine with an alkene differ from its reaction with an alkyne? How are they like?
5. Explain why unbranched alkenes tin can form geometric isomers while unbranched alkanes cannot. Does this explanation involve the macroscopic domain or the microscopic domain?
6. Explicate why these two molecules are not isomers:
   
7. Explain why these two molecules are not isomers:
   
8. How does the carbon-cantlet hybridization modify when polyethylene is prepared from ethylene?
9. Write the Lewis structure and molecular formula for each of the following hydrocarbons:

   (a) hexane

   (b) 3-methylpentane

   (c) cis-3-hexene

   (d) 4-methyl-1-pentene

   (e) 3-hexyne

   (f) 4-methyl-2-pentyne

10. Write the chemical formula, condensed formula, and Lewis construction for each of the following hydrocarbons:

    (a) heptane

    (b) 3-methylhexane

    (c) trans-iii-heptene

    (d) 4-methyl-i-hexene

    (e) 2-heptyne

    (f) 3,iv-dimethyl-1-pentyne

11. Requite the complete IUPAC proper noun for each of the following compounds:

    (a) [latex]\text{CH}_3\text{CH}_2\text{CBr}_2\text{CH}_3[/latex]

    (b) [latex](\text{CH}_3)_3\text{CCl}[/latex]

    (c)
    

    (d) [latex]\text{CH}_3\text{CH}_2\text{C}\;{\equiv}\;\text{CH\;CH}_3\text{CH}_2\text{C}\;{\equiv}\;\text{CH}[/latex]

    (e)
    

    (f)
    

    (g) [latex](\text{CH}_3)_2\text{CHCH}_2\text{CH} = \text{CH}_2[/latex]

12. Requite the complete IUPAC name for each of the post-obit compounds:

    (a) [latex](\text{CH}_3)_2\text{CHF}[/latex]

    (b) [latex]\text{CH}_3\text{CHClCHClCH}_3[/latex]

    (c)
    

    (d) [latex]\text{CH}_3\text{CH}_2\text{CH} = \text{CHCH}_3[/latex]

    (e)
    

    (f) [latex](\text{CH}_3)_3\text{CCH}_2\text{C}{\equiv}\text{CH}[/latex]

13. Butane is used as a fuel in dispensable lighters. Write the Lewis structure for each isomer of butane.
14. Write Lewis structures and name the five structural isomers of hexane.
15. Write Lewis structures for the cis–trans isomers of [latex]\text{CH}_3\text{CH} = \text{CHCl}[/latex].
16. Write structures for the three isomers of the aromatic hydrocarbon xylene, [latex]\text{C}_6\text{H}_4(\text{CH}_3)_2[/latex].
17. Isooctane is the common proper name of the isomer of [latex]\text{C}_8\text{H}_18[/latex] used equally the standard of 100 for the gasoline octane rating:
    

    (a) What is the IUPAC name for the compound?

    (b) Name the other isomers that contain a v-carbon chain with three methyl substituents.

18. Write Lewis structures and IUPAC names for the alkyne isomers of [latex]\text{C}_4\text{H}_6[/latex].
19. Write Lewis structures and IUPAC names for all isomers of [latex]\text{C}_4\text{H}_9\text{Cl}[/latex].
20. Proper noun and write the structures of all isomers of the propyl and butyl alkyl groups.
21. Write the structures for all the isomers of the [latex]-\text{C}_5\text{H}_{11}[/latex] alkyl grouping.
22. Write Lewis structures and draw the molecular geometry at each carbon cantlet in the following compounds:

    (a) cis-iii-hexene

    (b) cis-1-chloro-2-bromoethene

    (c) 2-pentyne

    (d) trans–6-ethyl-vii-methyl-2-octene

23. Benzene is ane of the compounds used as an octane enhancer in unleaded gasoline. It is manufactured by the catalytic conversion of acetylene to benzene:[latex]3\text{C}_2\text{H}_2\;{\longrightarrow}\;\text{C}_6\text{H}_6[/latex]

    Draw Lewis structures for these compounds, with resonance structures equally advisable, and determine the hybridization of the carbon atoms in each.

24. Teflon is prepared past the polymerization of tetrafluoroethylene. Write the equation that describes the polymerization using Lewis symbols.
25. Write ii complete, counterbalanced equations for each of the following reactions, 1 using condensed formulas and one using Lewis structures.

    (a) 1 mol of ane-butyne reacts with two mol of iodine.

    (b) Pentane is burned in air.

26. Write two complete, balanced equations for each of the following reactions, one using condensed formulas and one using Lewis structures.

    (a) 2-butene reacts with chlorine.

    (b) benzene burns in air.

27. What mass of two-bromopropane could be prepared from 25.5 yard of propene? Presume a 100% yield of product.
28. Acetylene is a very weak acid; nonetheless, it will react with moist silver(I) oxide and form water and a compound composed of silvery and carbon. Addition of a solution of HCl to a 0.2352-g sample of the compound of silverish and carbon produced acetylene and 0.2822 g of AgCl.

    (a) What is the empirical formula of the compound of silver and carbon?

    (b) The production of acetylene on addition of HCl to the compound of silvery and carbon suggests that the carbon is present as the acetylide ion, [latex]\text{C}_2^{\;\;ii-}[/latex]. Write the formula of the compound showing the acetylide ion.

29. Ethylene tin can be produced by the pyrolysis of ethane:[latex]\text{C}_2\text{H}_6\;{\longrightarrow}\;\text{C}_2\text{H}_4\;+\;\text{H}_2[/latex]

    How many kilograms of ethylene is produced past the pyrolysis of i.000 × 10³ kg of ethane, assuming a 100.0% yield?

Glossary

addition reaction

reaction in which a double carbon-carbon bond forms a single carbon-carbon bond past the improver of a reactant. Typical reaction for an alkene.

alkane

molecule consisting of only carbon and hydrogen atoms connected by single (σ) bonds

alkene

molecule consisting of carbon and hydrogen containing at to the lowest degree one carbon-carbon double bail

alkyl group

substituent, consisting of an methane series missing one hydrogen cantlet, attached to a larger structure

alkyne

molecule consisting of carbon and hydrogen containing at least one carbon-carbon triple bond

aromatic hydrocarbon

cyclic molecule consisting of carbon and hydrogen with delocalized alternate carbon-carbon single and double bonds, resulting in enhanced stability

functional grouping

part of an organic molecule that imparts a specific chemical reactivity to the molecule

organic chemical compound

natural or synthetic compound that contains carbon

saturated hydrocarbon

molecule containing carbon and hydrogen that has only single bonds betwixt carbon atoms

skeletal structure

shorthand method of drawing organic molecules in which carbon atoms are represented by the ends of lines and bends in between lines, and hydrogen atoms attached to the carbon atoms are not shown (but are understood to be present by the context of the structure)

substituent

branch or functional group that replaces hydrogen atoms in a larger hydrocarbon chain

substitution reaction

reaction in which one cantlet replaces another in a molecule

Solutions

Answers to Chemical science End of Affiliate Exercises

one. There are several sets of answers; one is:

(a) [latex]\text{C}_5\text{H}_{12}[/latex]
;

(b) [latex]\text{C}_5\text{H}_{10}[/latex]
;

(c) [latex]\text{C}_5\text{H}_8[/latex]

3. Both reactions result in bromine existence 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 bail is broken, and a bail between the C and the Br tin and so exist formed. In the unsaturated hydrocarbon, the only bond broken in the hydrocarbon is the π bond whose electrons can exist used to form a bail to one of the bromine atoms in Br₂ (the electrons from the Br–Br bond form the other C–Br bail on the other carbon that was role of the π bond in the starting unsaturated hydrocarbon).

five. Unbranched alkanes take free rotation about the C–C bonds, yielding all orientations of the substituents most these bonds equivalent, interchangeable by rotation. In the unbranched alkenes, the inability to rotate about the [latex]\text{C}\;=\;\text{C}[/latex] bond results in stock-still (unchanging) substituent orientations, thus permitting dissimilar isomers. Since these concepts pertain to phenomena at the molecular level, this explanation involves the microscopic domain.

7. They are the same compound because each is a saturated hydrocarbon containing an unbranched concatenation of six carbon atoms.

9. (a) [latex]\text{C}_6\text{H}_{xiv}[/latex]
;

(b) [latex]\text{C}_6\text{H}_{fourteen}[/latex]
;

(c) [latex]\text{C}_6\text{H}_{12}[/latex]
;

(d) [latex]\text{C}_6\text{H}_{12}[/latex]
;

(e) [latex]\text{C}_6\text{H}_{10}[/latex]
;

(f) [latex]\text{C}_6\text{H}_{10}[/latex]

11. (a) ii,ii-dibromobutane; (b) ii-chloro-two-methylpropane; (c) ii-methylbutane; (d) 1-butyne; (e) 4-fluoro-iv-methyl-1-octyne; (f) trans-1-chloropropene; (g) 5-methyl-1-pentene

13.

15.

17. (a) 2,ii,4-trimethylpentane; (b) 2,two,3-trimethylpentane, 2,iii,4-trimethylpentane, and 2,3,iii-trimethylpentane:

19.

21. In the following, the carbon backbone and the appropriate number of hydrogen atoms are shown in condensed form:

23.

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.

25. (a) [latex]\text{CH}\;{\equiv}\;\text{CCH}_2\text{CH}_3\;+\;2\text{I}_2\;{\longrightarrow}\;\text{CHI}_2\text{CI}_2\text{CH}_2\text{CH}_3[/latex]

(b) [latex]\text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\text{CH}_3\;+\;8\text{O}_2\;{\longrightarrow}\;5\text{CO}_2\;+\;6\text{H}_2\text{O}[/latex]

27. 65.2 g

29. 9.328 × 10^two kg

---

Source: https://opentextbc.ca/chemistry/chapter/20-1-hydrocarbons/

Posted by: howellproself.blogspot.com

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