ch. 13 hydrocarbons milbank high school. objectives 1. what is organic chemistry? in general, how do...

Ch. 13Hydrocarbons

Milbank High School

Objectives

1. What is organic chemistry? In general, how do organic compounds differ from inorganic compounds?

2. Why are there so many more organic compounds than inorganic compounds?

3. What are hydrocarbons? What structural features identify alkanes? Alkenes? Alkynes? Aromatic hydrocarbons?

4. How are alkanes, alkenes, alkynes, and aromatic hydrocarbons named using IUPAC nomenclature?

5. What are the physical and chemical properties of alkanes, alkenes, alkynes, and aromatic hydrocarbons?

Objectives

6. What is an alkyl group?

7. What are some products from reactions of alkanes? How are they formed?

8. What are the major reactions of alkenes? What are the products of those reactions?

9. What are polymers? How are they formed and utilized?

10. What is petroleum and how is it utilized?

Organic Chemistry

• Chemistry of compounds that contain carbon– Combine mainly with hydrogen, oxygen, and

nitrogen– Over 10 million compounds made with these 4

elements

• 95% of compounds contain carbon– Form stable, covalent bonds with each other

Properties

• Organic (Benzene)– Low melting pts– Low boiling pts– Low solubility in water– Highly flammable– Nonconductive– Covalent bonds

• Inorganic (NaCl)– High melting pts– High boiling pts– Soluble in water– Nonflammable– Conductive– Ionic bonds

Hydrocarbons

• Compounds containing only two elements– Carbon and hydrogen

Sec. 13.1Alkanes: Structures and Names

• Objectives– Identify an alkane– Determine what an isomer of an alkane is– Identify different types of alkanes

Alkanes

• Saturated Hydrocarbons

• Called saturated because each carbon is bonded to four other atoms

• Only single bonds

• Methane

• Ethane

• Propane

Homology

• Related compounds

• Homologs– Have properties that vary in a regular and

predictable manner– A manner of organization– Similar to P.T.

Isomers

• Different compounds having the same molecular formula

• Butane

• Isobutane (isolated branched chain)

Isomers

• Pentane

• Isopentane

• Neopentane

Alkanes

• CnH2n+2

• Representation– Structural Formulas– Condensed Structural Formulas– Butane

Alkyl Group

• A group of atoms that results when one hydrogen atom is removed from an alkane

• CnH2n+1

• Change –ane ending to –yl

• Methyl

• Ethyl

• Propyl

Sec. 13.2IUPAC Nomenclature

• Define IUPAC

• Examine the rules for IUPAC naming

• Determine the correct names of alkanes

IUPAC Nomenclature

• Geneva, Switzerland 1892

• International Union of Pure and Applied Chemistry

• IUPAC System of Nomenclature– (isobutane, isopentane are common names)

IUPAC Rules

• 1. Name the longest chain in the parent compound. End in –ane. (Root name)– Number each carbon– See Example

• 2. Note the alkyl groups attached

• 3. Number the carbon that the group is attached to.– Must use the lowest number possible.– See Example

IUPAC Rules Con’t

• 4. Use prefixes to indicate the amount of attached groups– See Example

• 5. If there are more than two or more different substituents, list them in alphabetical order. If at equal points, lower alphabetical order given lowest number– See Example

IUPAC Rules Con’t

• 6. Prefixes not included in alphabetizing– See Example

Name each of the following

Name each of the following

A. B.

C.

D.

a. 3-ethylhexaneb. 2,4-dimethylpentanec. c. 3-methylhexaned. 4-isopropylheptane

Answers

Draw the structural formulas for each of the following

• 4-propylheptane

• 3-ethyl-2-methylpentane

• 3-isopropyl-3-methyloctane

Answers

•

Sec. 13.3Properties of Alkanes

• Objectives– Determine the physical and physiological

properties of alkanes

Physical Properties

• Nonpolar– Insoluble in water

• Less dense than water– Less than 1.0g/ml

• Related to one another– See chart

• Boiling points– Increase with higher molar mass

Physiological Properties

• Gases serve as anesthetics

• Liquid alkanes– Light liquids– Harmful to lungs

– Heavy liquids• Mineral oil• Petroleum jelly

Sec. 13.4Chemical Properties: Reactions

of Alkanes

• Objectives– Determine the chemical properties of alkanes

Chemical Properties

• Do not react with many laboratory agents

• Usually very flammable– Undergo combustion reactions

CH4 + 2 O2 CO2 + 2 H2O + Heat

2 CH4 + 3 O2 2 CO + 4 H2O

(Harmful carbon monoxide reaction)

Sec. 13.5Halogenated Hydrocarbons

• Objectives– Define what halogenated hydrocarbons are– Name halogenated hydrocarbons using

common and IUPAC names

Halogenated Hydrocarbons

• Have one or more hydrogen atoms replaced by halogen atoms– Usually these are formed under UV light or

very high temps

– Results in an alkyl halide

Common Names

• First part of name is alkyl group

• Second part is the halogen, ending in –ide

• Name these:– CH3CH2Br

– (CH3)2CHCl

– CH3I

– CH3CH2CH2F

Answers

• Ethyl bromide

• Isopropyl chloride

• Methyl iodide

• Propyl flouride

IUPAC Names

• Rules similar to those used for naming alkanes

• Substitute in the prefixes fluoro-, chloro-, bromo-, and iodo-

Give the IUPAC name for each of the following compounds

Answers

• 2-chloropentane

• 4-bromo-2-methylhexane

• 2-chloro-3-methylbutane

• 1-bromo-3-chloro-4-methylpentane

Sec. 13.6Cycloalkanes

• Define what a cycloalkane is

• Name and draw cycloalkanes

Cycloalkanes

• Carbon atoms that are joined in a ring or circle

• Simplest: cyclopropane

• Another: cyclohexane

Naming

• Add cyclo-

• Otherwise fairly similar to regular naming

• Draw structures for the following compounds– Cyclooctane– Ethylcyclohexane– 1,1,2-trimethylcyclobutane

Answers

• A.

• B.

C.

Draw these structures

• Cyclopentane

• 1-ethyl-2-methylcyclopentane

• 1-ethyl-1,2,5,5-tetramethylcycloheptane

Answers

• A.

• B.

• C.

Sec. 13.7Alkenes

• Objectives– Define alkene– Name alkenes using IUPAC rules

Alkenes

• End in -ene

• Unsaturated hydrocarbons

• Have a double bond (CH3=CH2)

IUPAC Rules

1. Name the longest chain.2. Indicate the position of the double bond

with the lowest number possible.3. Substituent groups named like alkanes

5-methyl-2-hexene

Name each of the following

Answers

• 6-dimethyl-2-heptene

• 2-ethyl-1-butene

• 4-ethyl-2-methyl-2-hexene

• 1-methylcyclohexene

• 2,4,4-trimethyl-2-pentene

Draw the structure for the following

• 3,4-dimethyl-2-pentene

• 3-ethyl-2-methyl-1-hexene

• 3-isopropylcyclopentene

Answers

• A.

• B.

• C.

Sec. 13.8Properties of Alkenes

• Objectives– Determine the properties of alkenes

Properties of Alkenes

• Similar to alkanes

• Occur widely in nature• Ethylene

– Triggers fruit ripening– Can be used artifically

• Others– Carotene

• Vitamin A

– Fruit coloring

Sec. 13.9Chemical Properties: Reactions

of Alkenes• Define addition reactions

• Discuss hydrogenation and hydration

• Write equations for reactions between alkenes and other substances

Addition Reactions

• One of the bonds in the double bond is broken and each of the involved carbon atoms then bonds to another atom or group

• Hydrogenation—addition of hydrogen to an unsaturated molecule

Halogen addition

• Alkenes readily add halogen molecules

Hydration

• Addition of water to an alkene

Equations

• Write equations for the reaction between CH3CH=CHCH3 and each of the following

• H2

• Br2

• H2O (H2SO4 catalyst)

Answers

• Write equations for the reaction of with each of the following.

• H2 (Ni catalyst)

• Cl2

• H2O (H2SO4 catalyst)

Answers.

Sec. 13.11Alkynes

• Define alkyne

• Name alkynes using IUPAC naming rules

Alkynes

• Carbon atoms share 3 pairs of electrons, forming a triple bond

• Acetylene

• Alkynes have similar properties to those of alkanes and alkenes

• Naming is the same, except they end in

-yne

Sec. 13.12 Benzene

• Objectives– Recognize the versatile structure of a

benzene ring

Benzene

• Recognized by Michael Faraday in 1825

• Six sided structure with single and double mobile bonds

• Resonance—a word used to describe the phenomenon in which no single Lewis structure can be used

Figure 13.13    

Sec. 13.13Structure and Nomenclature of

Aromatic Compounds

• Define and name aromatic hydrocarbons and aliphatic compounds

• Determine the difference between ortho, meta, and para distribution

Aromatic Compounds

• Benzene

• Named because thought to have strong aroma

• Now define as anything that has a benzene ring

• Aliphatic compounds—nonaromatic

Naming

• One substituent…easy

Naming

• 2 substituents…2 different ways

• One way…same as before

• Other way…uses the terms ortho, meta, and para– Ortho (1,2 distribution)– Meta (1,3 distribution)– Para (1,4 distribution)

Examples

Aryl Groups

• Sometimes Benzene rings attach to alkanes or alkenes

• Known as aryl groups

• Most common one is phenyl

Sec. 13.14Uses of Benzene and Benzene

Derivatives• Objectives

– Discuss some of the uses of benzene

Uses of Benzene

• Most comes from petroleum• Used as a starting material• Added to fuels to improve octane rating• Cigarette smoke• Very toxic• In Nature..

– Tryptophan– Vitamin K– Folic acid– Many drugs…Table 13.12