Page 2-12 Organic Chemistry

• Hydrocarbons


  • Saturated
  • Unsaturated
• Saturated hydrocarbons


  Every carbon atom is bonded to four atoms (the maximum bonding), these are single bonds
• Saturated hydrocarbons


  • Ethane, CH4
• Unsaturated hydrocarbons


  Containing double or triple bonds (and fewer carbon atoms)
• Unsaturated hydrocarbons


  • Ethene, CH2=CH2
  • Ethyne, CH≡CH
• Ethane vs ethene


  Ethene will have a greater molar mass
• Crude oil contains a wide variety of hydrocarbons that can be taken out of oil (refined) by applying different temperatures because boiling point increases with increased molar masses
• Alkanes


  The simplest hydrocarbon alkane is methane, CH4
• Methane


  • Has a 3-dimensional tetrahedral shape, this shape places the hydrogens as far apart as possible
  • All carbons in alkanes actually have this tetrahedral shape, we draw them flat with structural formulas only for convenience
• Drawing structural formulas


  1. Molecular formula shows only the number of atoms

  2. Structural formula shows the arrangement of atoms

  3. Condensed structural formula shows the arrangement but each carbon and its attachments are written together with C-H bonds understood
• Alkanes have the formula 2n+2, where n is the number of carbon atoms
• Structural isomers


  Compounds with the same molecular formula but different structural formulas, they have different physical and chemical properties
• To draw structural isomers, you must add branches to carbons inside the chain, not to carbons on the ends of the chain
• We don't have isomers if we just flip the compound around
• IUPAC naming of organic compounds

  • The stem tells the number of carbons in the longest chain
  • The suffix describes the family of the compound
• Alkyl group


  • Derived from an alkane by removing a hydrogen, the 'ane' ending becomes 'yl'
  • Alkyl groups do not exist alone, they are always attached to a carbon chain
• Rules for naming branched-chain alkanes

  1. Start backwards

  2. Follow the steps on pages 334-336
• 2,3-dimethylhexane has 6 carbons in the parent chain, two identical methyl (CH3) groups on carbons 2 and 3
• Structural formula shows the full arrangement of atoms, condensed structural formula shows the arrangement but each carbon and its attachments are written together
• Ethane and ethene have the same molecular formula (C2H6) but different structural formulas
• Common substituents


  NH2 (amino), Br (bromo), Cl (chloro), F (fluoro), NO2 (nitro)
• Formation of nylon


  1. Sebacoyl chloride dissolved in hexane in the top layer

  2. 1,6-diaminohexane dissolved in aqueous NaOH in the bottom layer

  3. The strand will continue to form at the interface as long as both solutions contain reactants
• Cycloalkanes


  Carbon atoms form rings by losing hydrogens
• Cycloalkanes have the formula 2n, where n is the number of carbon atoms
• Haloalkanes


  Have one or more hydrogen replaced by a halogen (F, Cl, Br, I)
• CFC stands for chlorofluorocarbons
• Common CFCs include refrigerants and propellants in aerosol cans
• The first four alkanes (methane, ethane) are gases at STP and act as anesthetics if inhaled, alkanes with 5-17 carbons are liquids at STP
• Halogen


  Numbered and named in front of the parent alkane
• Halogens


  • Fluoro
  • Chloro
  • Bromo
  • Indo
• Older method of naming haloalkanes

  Naming by the alkyl group attached to the halogen atom
• Do NOT use the older method of naming haloalkanes unless the book tells you to
• Write out the condensed structural formula for 3-Bromo-2-chloro-4-methylpentane


  CH3-CH(Br)-CH(Cl)-CH(CH3)-CH3
• Read the Health Note on page 345
• Read the Environmental Notes on pages 345 & 346
• Write four isomers of C2H2Cl2

  1. H2C=CCl2

  2. ClCH=CHCl

  3. CH2Cl-CH2Cl

  4. CH3-CCl2
• Alkanes


  • First four are gases at STP and act as anesthetics if inhaled
  • 5-17 carbons are liquids at room temperature
  • 18 or more carbons are waxy solids
• Alkanes are nonpolar, so they don't dissolve in water and instead float on it
• Alkanes are the least reactive of any organic compounds because their single bonds are hard to break
• Alkanes burn readily in oxygen, which is why we use them as fuels