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Chapter 11 Introduction to Organic Chemistry: Alkanes

Chapter 11 Introduction to Organic Chemistry: Alkanes. 11.2 Alkanes. Names of Alkanes. The names of alkanes are determined by the IUPAC (International Union of Pure and Applied Chemistry) system use a prefix to indicate the number of carbons in a chain end in - ane.

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Chapter 11 Introduction to Organic Chemistry: Alkanes

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  1. Chapter 11 Introduction to Organic Chemistry: Alkanes 11.2Alkanes

  2. Names of Alkanes The names of alkanes • are determined by the IUPAC (International Union of Pure and Applied Chemistry) system • use a prefix to indicate the number of carbons in a chain • end in -ane

  3. IUPAC Names for Alkanes

  4. Learning Check A. Give the name of each compound: 1) CH3—CH3 2) CH3—CH2—CH3 3) CH3—CH2—CH2—CH2—CH2—CH3 B. Write the condensed structural formula of pentane.

  5. Solution A. Give the name of each compound: 1) CH3—CH3 ethane 2) CH3—CH2—CH3 propane 3) CH3—CH2—CH2—CH2—CH2—CH3 hexane B. Write the condensed structural formula of pentane. CH3—CH2—CH2—CH2—CH3

  6. Structural Formulas Alkanes are written with structural formulas that are • expanded toshow each bond • condensed to show each carbon atom and the attached hydrogen atoms

  7. Line-Bond Formulas • Because each C atom has a tetrahedral arrangement, the order of atoms is not a straight line, but a zigzag pattern. • A line-bond formula abbreviates the carbon atoms and shows only the zigzag pattern of bonds from carbon atom to carbon atom.

  8. Types of Structural Formulas

  9. Rotation Around a CC Single Bond The groups attached to a C—C single bond • rotate around the bond • give different relative structural arrangements called conformations

  10. Writing Structural Formulas Carbon atoms in a chain • maintain their tetrahedral shape • are connected in a zigzag pattern • are drawn as two-dimensional • can be written in several conformations

  11. Structural Arrangements of Butane • Rotation of the end CH3-groups provides different structural arrangements for butane.

  12. Hexane has Six Carbon Atoms Hexane • is an alkane with 6 carbon atoms in a continuous chain • has a “zigzag” look because each carbon atom is at the center of a tetrahedron • is represented by a ball-and-stick model as

  13. Learning Check A. Draw the condensed structural formula of B. What is its molecular formula? C. What is its name?

  14. Solution A. Draw the condensed structural formula: CH3─CH2─CH2─CH2─CH3 B. What is its molecular formula? C5H12 C. What is its name? pentane

  15. Learning Check Draw the condensed structural formula for: A. Ethane B. Heptane

  16. Solution Draw the condensed structural formula for: A. Ethane CH3─CH3 B. Heptane CH3─CH2─CH2─CH2─CH2─CH2─CH3

  17. Cycloalkanes Cycloalkanes • are cyclic alkanes • have 2H fewer than the alkane • are named by using the prefix cyclo- before the name of the alkane chain with the same number of carbon atoms

  18. Cycloalkanes (continued) The structural formulas of cycloalkanes • are often shown as geometric figures

  19. Cycloalkanes (continued)

  20. Learning Check Name the following: A. CH3─CH2─CH2─CH3 B. C. CH3─CH2─CH2─CH2─CH2─CH2─CH2─CH3 D.

  21. Solution Name the following: A. CH3─CH2─CH2─CH3 butane B. cyclopropane C. CH3─CH2─CH2─CH2─CH2─CH2─CH2─CH3 octane D. cyclohexane

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