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Organic Chemistry

Organic Chemistry: The chemistry of carbon and carbon-based compounds. Organic Chemistry. Organic Chemistry in everyday life: Smells & tastes: fruits, chocolate, fish, mint Medications: Aspirin, Tylenol, Decongestants, Sedatives

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Organic Chemistry

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  1. Organic Chemistry: The chemistry of carbon and carbon-based compounds Organic Chemistry Organic Chemistry in everyday life: Smells & tastes: fruits, chocolate, fish, mint Medications:Aspirin, Tylenol, Decongestants, Sedatives Addictive substances: Caffeine, Nicotine, Alcohol, Narcotics Hormones/Neurotransmitters: Adrenaline, Epinephrine Food/Nutrients: Carbohydrates, Protein, Fat, Vitamins Genetics: DNA, RNA Consumer products: Plastics, Nylon, Rayon, Polyester

  2. Butane: C4H10 Drawing Organic Structures Shortcuts make structures easier & faster to draw Lewis Structure Carbon Atoms • Line Structure • Only shows bonds • C atoms assumed at each end and intersection of bonds • H atoms not shown • Assume 4 bonds to each C • Fulfill C’s 4 bonds by adding H’s Condensed Structures CH3CH2CH2CH3 CH3(CH2)2CH3

  3. Alkane Alcohol Carboxylic acid Alkene Ether Amine Alkyne Ketone Amide Haloalkane Aldehyde Amino acid Classified according to functional group Types of Organic Compounds

  4. Structure controls Function Big Idea in Organic Chemistry Each functional group has predictable reactivity

  5. All C atoms are tetrahedral and sp3 hybridized (only C-C single bonds) General formula = CnH2n+2 (CH4, C2H6, C3H8, C4H10, etc.) Can have linear or branched alkanes Alkanes or Paraffins C5H12 1° 3° 2° • Same molecular formula, different structure: structural isomers • Branches are called substituents • Primary (1°) carbon atom:bound to one other C atom • Secondary (2°) C atom: bound to 2 other C atoms • Tertiary (3°) C atom: ” 3 ” • Quaternary (4°) C atom: ” 4 ”

  6. Alkane Names of Linear Alkanes and Alkyl Substituents # of C atoms Alkyl substituents CH4 CH3CH3 CH3CH2CH3 CH3CH2CH2CH3 Methane Ethane Propane Butane Pentane Hexane Heptane Octane Nonane Decane Methyl Ethyl Propyl etc. -CH3 -CH2CH3 -CH2CH2CH3 1 2 3 4 5 6 7 8 9 10 Root: number of C atoms Suffix: functional group (-ane for alkanes) (-yl for alkyl groups)

  7. H H C H H H H H H H ? R R C H ? C C C H C H H H H H H H H H H C C C H C H H H H Methane CH4 Butane C4H10 Methyl -CH3 Butyl -C4H9 Where R = any other C atom or arrangement of C atoms

  8. First Ten Hydrocarbons: Properties Number of Carbon Atoms Molecular Formula Melting Point, oC Boiling Point, oC # of Isomers Name • -182.5 • -183.2 • -187.7 • -138.3 • -129.7 • 95.3 • 90.6 • 56.8 • 53.6 • 29.7 • -161.5 • -88.6 • -42.1 • -0.5 • 36.1 • 68.7 • 98.4 • 125.7 • 150.8 • 174.0 • 1 • 1 • 1 • 2 • 3 • 5 • 9 • 18 • 35 • 75 Methane Ethane Propane Butane Pentane Hexane Heptane Octane Nonane Decane 1 2 3 4 5 6 7 8 9 10 CH4 C2H6 C3H8 C4H10 C5H12 C6H14 C7H16 C8H18 C9H20 C10H22

  9. Compound Methane Ethane Propane Butane Pentane Properties of Alkanes Nonpolar → only London Dispersion Forces IMF Larger molecular weight → Stronger London dispersion forces Formula CH4 C2H6 C3H8 C4H10 C5H12 MW 16 30 44 58 72 Boiling point (°C) -164 -88.6 -42.1 -0.5 +36.0 Linear Alkanes: 1 - 4 C atoms: gas at room temp 5 - 15 C atoms: liquid at room temp >15 C atoms: solid at room temp

  10. Fractional Distillation of Crude Oil Kelter, Carr, Scott, Chemistry A World of Choices 1999, page 429

  11. Root name: name of longest continuous C chain (parent chain) • 2 equally long? Choose the one with more branches • Number C atoms in chain, starting at end with first branch • Identify substituents, give each a number (C it is connected to) • Two or more identical substituents: use prefixes (di-, tri-, tetra-, etc.) • List substituents alphabetically before root name • Do not alphabetize prefixes • Punctuation: commas separate numbers from each other hyphens separate numbers from names no space between last substituent & root name Naming Branched Alkanes (IUPAC) 4-ethyl Octane 4-ethyl-3,5-dimethyloctane 2 8 5 3 6 4 1 7 = 3,5-dimethyl 3-methyl and 5-methyl

  12. Common Names of other Alkyl Substituents 3 carbons R R Tertiary carbon Secondary carbon 4 carbons R R Remember that R =any carbon chain R isopropyl alphabetized as “i” “iso” indicates symmetry R isobutyl alphabetized as “i” 2o R 2o sec-butyl alphabetized as “b” 3o 3o tert-butyl alphabetized as “b” R

  13. H H H H C C H C H C H H H C H H H Naming Practice Expanded Structure Line Structure butane 2 - methylbutane

  14. CH3 CH3 1 2 3 6 5 4 3 4 2 5 6 1 Lowest sum of numbers is correct H Naming Practice H H C C C Line Structure H H H C C H H H C H H 4,4-dimethyl hexane 3,3-dimethyl hexane

  15. Isomers The fat dog shook himself, and then rolled over on the wet rug. OR The dog shook the fat rug, then rolled over and wet on himself. These two statements use the same words... but have very different meanings! Likewise, isomers may have the same formula, but have very different structures…

  16. Structural Isomers of C4H10 2-methylpropane or

  17. On piece of your own paper, draw AND name ALL of the isomers for the following alkanes: Structural Isomer Practice # isomers Formulas C5H12 C6H14 C7H16 • Pentane • Hexane • Heptane 3 5 9 Some of your drawings may look different, but they are only different structures (isomers) if they also have different names If you complete that, try to draw and name all of the isomers for octane (C8H18). There are 18 of them!

  18. Structural Isomers: Pentane (C5H12) pentane 2-methylbutane 2,2-dimethylpropane

  19. Structural Isomers: Hexane (C6H14) hexane 2,3-dimethylbutane 2-methylpentane 2,2-dimethylbutane 3-methylpentane

  20. Structural Isomers: Heptane (C7H16) heptane 2,2-dimethylpentane 2-methylhexane 2,3-dimethylpentane 3-methylhexane

  21. Structural Isomers: Heptane (C7H16) 2,4-dimethylpentane 3-ethylpentane 3,3-dimethylpentane 2,2,3-trimethylbutane

  22. Comparing Structural Isomers C5H12 (Same formula, different structure) Structure Name Boiling point (°C) pentane 36.0 2-methylbutane 27.9 2,2-dimethylpropane 9.5 More branching → weaker London dispersion forces BP/MP of Linear alkanes > BP/MP of branched alkanes

  23. Combustion • exothermic reaction • alkanes used as fuel source Reactions of Alkanes 13/2 4 5 C4H10 + ___ O2 ___ CO2 + ___ H2O • Incomplete Combustion with insufficient O2 produces CO • Poor ventilation, cigarettes 9/2 4 5 C4H10 + ___ O2 ___ CO + ___ H2O CO is poisonous because it binds to the hemoglobin in the blood, preventing the absorption of O2

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