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Chapter 2 Hydrocarbon Frameworks: Alkanes

Chapter 2 Hydrocarbon Frameworks: Alkanes. Chapter 2; Hydrocarbon Frameworks; Alkanes. Classification of Organic Compounds Hydrocarbons vs. Functional Groups Constitutional Isomers Alkane Nomenclature Physical Properties of Alkanes Water Solubility Boiling Point Trends

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Chapter 2 Hydrocarbon Frameworks: Alkanes

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  1. Chapter 2Hydrocarbon Frameworks:Alkanes

  2. Chapter 2; Hydrocarbon Frameworks; Alkanes • Classification of Organic Compounds • Hydrocarbons vs. Functional Groups • Constitutional Isomers • Alkane Nomenclature • Physical Properties of Alkanes • Water Solubility • Boiling Point Trends • Chemical Reactions of Alkanes

  3. Chapter 2; Hydrocarbon Frameworks; Alkanes • Chemical Reactions of Alkanes • Using DH combustion to determine molecule stability • Redox Reactions

  4. Classes of Organic Compounds Organic Compounds Hydrocarbons Functional Groups

  5. H H H H H H Hydrocarbons Aliphatic Aromatic Alkanes Alkenes Alkynes CycloAlkanes

  6. Aliphatic Hydrocarbons H H H H C C H H C C H H H H HC CH Alkene; Contains a Double Bond CnH2n Alkane; All Single Bonds CnH2n+2 CnH2n Alkyne; Contains a Triple Bond CnH2n-2 Cycloalkane; C atoms are in a ring

  7. Halogens; Elements in Groups VII -F, Cl, Br, I R-I R-F

  8. R CH3OCH2 CH3 H OH C R-O-R H

  9. O O H O O CH3CH2CCH2CH2CH3 R C H R-C-R

  10. O O RCOR' R-C-OH O CH3CH2COCH3 O CH3COH

  11. O O O O RCOCR' CH3COCCH3 O O C6H5COC(CH2)5CH3 Functional Groups with Three Oxygens Acid Anhydride

  12. O RC N RCNH2 O Amide (CH3)2CHCH2CNH2 CH3CHCH3 Nitrile C N Nitrogen Containing Functional Groups CH3CH2NH2 Amines RNH2 Amide

  13. CH3CHCH2CH2SH CH3 Sulfur Containing Functional Groups R-S-H Thiol

  14. RC N Summary of Functional Groups Nitriles

  15. O O O O O RCNH2 RCOR' RCOCR' C H Summary of Carbonyl Containing Functional Groups O R-C-OH R Carboxylic Acid Aldehyde Acid Anhydride O R-C-R Amide Ester Ketone

  16. 2.5Introduction to Alkanes:Methane, Ethane, and Propane CnH2n+2 • Methane (CH4) CH4 • Ethane (C2H6) CH3CH3 • Propane (C3H8) CH3CH2CH3 The Simplest Alkanes

  17. Isomeric Alkanes: The Butanes (C4H10) n-Butane CH3CH2CH2CH3 Isobutane (CH3)3CH bp -10.2°C bp -0.4°C

  18. C5H12 (CH3)2CHCH2CH3 CH3CH2CH2CH2CH3 Isopentane n-Pentane (CH3)4C Neopentane

  19. Table 2.1 Number of Constitutionally Isomeric Alkanes CH4 1 C8H18 18 C2H6 1 C9H20 35 C3H8 1 C10H22 75 C4H10 2 C15H32 4,347 C5H12 3 C20H42 366,319 C6H14 5 C40H82 62,491,178,805,831 C7H16 9 There is no simple way to predict how many isomers there are for a particular molecular formula.

  20. IUPAC Nomenclature ofUnbranched Alkanes Alkane parent-suffix Alk ; states # C in parent chain ane; suffix; states if single, double or triple bonds For molecules with no substituents

  21. Table 2.4IUPAC Names of Unbranched Alkanes • Retained: • methane CH4 • ethane CH3CH3 • propane CH3CH2CH3 • butane CH3CH2CH2CH3

  22. IUPAC Names of Unbranched Alkanes • Note:n-prefix is not part of IUPAC name of any alkane. • For example: n-butane is "common name" for CH3CH2CH2CH3;butane is "IUPAC name."

  23. Table 2.2IUPAC Names of Unbranched Alkanes • Number of carbons Name Structure • 5 pentane CH3(CH2)3CH3 • 6 hexane CH3(CH2)4CH3 • 7 heptane CH3(CH2)5CH3 • 8 octane CH3(CH2)6CH3 • 9 nonane CH3(CH2)7CH3 • 10 decane CH3(CH2)8CH3

  24. Name the C6H14 Isomers CH3CH2CH2CH2CH2CH3 (CH3)2CHCH2CH2CH3 (CH3CH2)2CHCH3 (CH3)2CHCH(CH3)2 (CH3)3CCH2CH3

  25. CH3CH2CH2CH2CH2CH3 Hexane or n-hexane The C6H14 Isomers • Octane or normal-octane

  26. IUPAC Nomenclature of Branched Alkanesprefix-parent-suffix Step 1) Find the longest continuous carbonchain and use the IUPAC name of theunbranched alkane as the basis. Step 2) Number the chain from the end nearestthe substituent, and identify the carbon to which the substituent is attached by number. Step 3) Add name of substituent as a prefix. Name unbranched alkyl substituent by taking root name of # of carbons and adding –yl suffix

  27. H CH3 H C H H H H CH3CH2 C C H H Methyl and Ethyl Groups or Methyl or Ethyl

  28. The C6H14 Isomers (CH3)2CHCH2CH2CH3 2-Methylpentane (CH3CH2)2CHCH3 3-Methylpentane Another example; • 4-Ethyloctane

  29. IUPAC Nomenclature of Branched Alkanes • 3b. If there is more than one branch; # chain to give lowest possible combination of numbers and use the greek prefix to describe total number of identical substituents. 2; di 3; tri 4; tetra 5; penta

  30. First Point of Difference Rule 5 3 4 6 1 8 7 2 6 2 3 7 4 5 8 • The chain is numbered in the direction that gives the lower locant to the substituent at the first point of difference in the names. • Don't add locants! 1 What is correct name? 2,3,3,7,7-Pentamethyloctane? 2,2,6,6,7-Pentamethyloctane?

  31. IUPAC Nomenclature of Branched Alkanes • 4. If there are different substituents coming off the main chain; list them alphabetically by name of substituent –(not by Greek prefix or number) • 4-Ethyl-3-methyloctane

  32. Branched alkanes • 4-Ethyl-3,5-dimethyloctane List substituents in alphabetical order. But don't alphabetize di-, tri-, tetra-, etc.

  33. IUPAC Nomenclature of Branched Alkanes • 5. If a molecule has 2 chains of equal lengths; the chain with the largest number of substituents is the parent chain.

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