Ch 2 The Nature of Organic Molecules

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Ch 2 The Nature of Organic Molecules Powered By Docstoc
					Quiz 2.1
Ch 2 The Nature of Organic
        Fischer North
           Functional Groups
• which are characteristic arrangement of atoms
  which define many of the physical and
  chemical properties of a class of organic
         Carbon-carbon bonds
• The simplest of the functional groups are the
hydrocarbons, which include the alkanes,
alkenes, alkynes, and aromatic hydrocarbons.
  Carbon – (electronegative atom)
• Halides, alcohols, ethers, amines, thiols, and
• Always have a polar bond
• Carbon is always partially positive
       Carbon = oxygen (carbonyl)
•   Car-bo-neel
•   Ketones, carboxylic acids, esters, amids
•   carbon partial positive
•   Oxygen partial negative
   2.2 Alkanes and Alkyl; isomers
• Need to learn the first ten alkanes
• Meth eats peoples brains
• Methane, ethane, propane, butane, pentane,
  hexane, heptane, octane, nonane, decane
• Hydrocarbons—compounds that contain only
carbon and hydrogen.
• Saturated Hydrocarbons — contain only
  carbon carbon single bonds.
• Unsaturated Hydrocarbons —contain carbon
  carbon double or triple bonds.
                Alkyl group
• A hydrocarbon substituent, ending in –yl
  – Propyl

• Memorize figure 2.3 on p. 43
Isomers —compounds having identical
  molecular formulas, but different
  arrangements of atoms.
• constitutional Isomers —the atoms in each
  molecule are connected in a different order.
•   C7H16 9 isomers
•   C8H18 13 isomers
•   C9H20 35 isomers
•   C10H22 75 isomers
•   C20H42 366,319 isomers
•   C30H62 4,111,846,763 isomers!
•   C40H82 62,481,801,147,341 isomers!
      Primary, secondary, tertiary,
• The number of carbons branched off of a
  carbon in a molecule
Naming alkanes
1. Find the longest chain of carbons in the
2. Number the carbons in the main chain
          in sequence. Start at
  the end that will give the substituent
    groups attached to the chain the
           smallest numbers.
A hydrocarbon substituent is
         called an
       alkyl group
   (-ane changed to -yl)
3. Add numbers to the names of
    the substituent groups to
 identify their positions on the
   4. Use prefixes to indicate the
appearance of the same group more
than once in the structural formula.
  5. List the names of alkyl substituents in
       alphabetical order, ignore prefix
Ethyl is always before methyl (even dimethyl).
    6. Commas are used to separate
 numbers. Hyphens are used to separate
         numbers and words. The
entire name is written without any spaces.
      2.5 Confirmations of ethane
        Read section 2.5 #12-14
• Carbon-Carbon bonds are free to rotate in
• Staggered is the most stable confirmation with
  all bonds as far apart as possible (99% of the
• Eclipsed is the least stable confirmation with
  bond overlapped (1% of the time)
Use model set to show bonding
Draw the line bond structure for
(use dash and wedges correctly)
Draw the line bond structure for
(use dash and wedges correctly)
    Section 2.6 Drawing Structures
           Read 2.6 #15-17
• expanded structural formulas all atoms and
  bonds are shown:
 condensed structural formulas, only specific
bonds are shown; this is useful in reducing the
 number of C—H bonds that must be drawn.
   line drawings bonds are represented by
lines; everywhere lines meet or a line begins
or ends is a C atom. H’s on C’s are not shown
      H’s on other atoms must be shown.
• Draw an acceptable expanded structure and
  line drawing for the molecule CH3CH2CH2OH.
    Draw acceptable expanded structures, condensed
      structures, and line drawings for the following
•   isopropyl alcohol, CH3CH(OH)CH3
•   acetic acid, CH3COOH
•   acetaldehyde, CH3CHO
•   acetone, CH3COCH3
              2.7 Cycloalkanes
              Read 2.7 #18,19
• Add the prefix cyclo- to the parent chain
• the numbering begins at the carbon to which
  the group is attached (alphabetical order), and
  then proceeds in a direction which gives the
  lowest possible number to the next attached
Name these
Quiz ½ sheet of paper
Name these
                 Draw these
5.   2,2-dimethylbutane
6.   3-ethyl-2-methylhexane
7.   1-chloro-3-methycylcohexane
8.   1-sec-butyl-3-ethycylcohexane
         2.8 Cis-Trans Isomerism
             Read 2.8 #20-21
• stereoisomers — compounds with the same
  molecular and structural formula but different
  spatial arrangements of atoms.
   Cis = same side         trans = across
Are they geometric isomers or the same molecule?
  2.9 Conformations of Cycloalkanes
             Read 2.9
• flat cyclohexane would have bond angles of
• a “chair” or “boat” conformation with bond
  angles 109.5°.
        2.10 Axial and equatorial
             Read 2.10 #22
• Axial groups are above or below the ring

• Equatorial groups are in the rough plane of
  the ring
Quiz cycloalkanes
Name these
 Draw and give the chemical formula
1. 1-ethyl-3-propylcyclohexane
2. Sec-butylcyclohexane

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