Chapter 12 Introduction to Organic Chemistry and Alkanes by dffhrtcv3

VIEWS: 10 PAGES: 38

									 Chapter 12: Introduction to
Organic Chemistry and Alkanes
               CH234
         Bruce A. Hathaway
  Southeast Missouri State University

                                        1
     What is Organic Chemistry?
• The chemistry of Carbon and its compounds.
• There are over 18 million known compounds.
• Over 95% of all known molecules are organic –
  Why?
• Carbon can form stable covalent bonds with
  other carbons and other atoms, since it is
  intermediate in electronegativity.


                                              2
The Periodic Table




                     3
              Ionic Bonds
• Ionic bonds: an attraction between atoms
  with opposite charges.
• Examples?
• NaCl                             Na Cl
                                   +     -




• Why is Na positive?
• Why is Cl negative?
• Look at the periodic table.

                                             4
The Periodic Table




                     5
              The Octet Rule
• Atoms can gain stability if they have a filled
  outer shell of electrons.
• Na: 1s22s22p63s1 Cl: 1s22s22p63s23p5
• If Na gives up its 3s electron to become Na+,
  its outer shell has 8 electrons – Na+: 1s22s22p6
• If Cl gains an electron to become Cl-, its outer
  shell has 8 electrons – Cl-: 1s22s22p63s23p6
• Hydrogen’s filled outer shell has only 2
  electrons – why?
                                                     6
            Covalent Bonds
• A covalent bond is the sharing of one or
  more pairs of electrons between two
  atoms.                                  H H
• A simple example is H2, molecular
                                           H H
                                         -   -




  hydrogen.
• The shared pair of electrons can be shown
  as a pair of dots between the two atoms,
  or as a line between the two atoms.

                                                 7
  Examples of Covalent Molecules
• CO2                          O    C   O
• C shares 4 pairs of
  electrons: why?
• O shares 2 pairs of   2 shared pairs of electrons:
  electrons: why?            a "double bond"
• HCN
• N shares 3 pairs of          H    C   N
  electrons: why?
• H only makes 1
  bond: why?            3 shared pairs of electrons:
                              a "triple bond"
                                                   8
    Drawing Structures of Covalent
    Molecules from Formulas: C2H6
• Carbon has 4 valence electrons, (C: 1s22s22p2),
  and Hydrogen has 1.
• Therefore, we have 14 electrons to account
  for.
• How do we bond the atoms together? Answer




                                                9
    Drawing Structures of Covalent
    Molecules from Formulas: C2H4
• Carbon has 4 valence electrons, (C: 1s22s22p2),
  and Hydrogen has 1.
• Therefore, we have 12 electrons to account
  for.
• How do we bond the atoms together? Answer




                                                10
    Drawing Structures of Covalent
    Molecules from Formulas: C3H4
• Carbon has 4 valence electrons, (C: 1s22s22p2),
  and Hydrogen has 1.
• Therefore, we have 16 electrons to account
  for.
• How do we bond the atoms together? Answer




                                                11
 Organization of Organic Compounds
• When you look at
  an animal, you can
  often classify it as
  some type on the
  basis of certain
  characteristics,
  even if you can’t
  define them well.

                                     12
           Functional Groups
• Organic compounds are classified on the basis
  of their functional groups.
• A functional group is a group of atoms in a
  molecule that imparts a characteristic
  chemical reactivity.
• See table 12.1 on page 329 of your book, or
  the functional group handout.


                                              13
      Functional Groups Containing
              only C and H
• Alkane                         • Alkene
• C and H with only single       • One or more C=C.
  bonds
             C C                           C   C


• Specific example is            • Specific example is
  ethane H           H             ethene or ethylene
         H       C   C       H         H        H

             H           H                 C   C
                                       H           H     14
      Functional Groups Containing
              only C and H
• Alkyne                • Aromatic Ring
• One or more CΞC.      • Generally, a six-
                          membered ring with
      C    C              alternating C=C and C-C.
• Specific example is   • Specific example is
  ethyne or acetylene     benzene
                                     H           H
                                         C   C
 H    C    C    H
                                 H   C           C   H
                                         C   C
                                     H           H
                                                         15
      Functional Groups Containing
            C-O single bonds
• Alcohol                   • Ether
• One or more C-OH.         • Contains C-O-C.
          O                             O
      C       H                     C       C


• Specific example is       • Specific example is
  ethanol or ethyl alcohol.   diethyl ether.
      H   O   H                 H   H           H   H

  H   C   C   H             H   C   C   O       C   C   H

      H   H                     H   H           H   H

                                                            16
          Functional Groups Containing
           C-Other atom Single Bonds
• Amine                   • Alkyl Halide
• One or more C-N.        • Contains C-X (X = F, Cl,
                            Br, or I).
          N
      C
                          • Specific example is
• Specific example is       chloroethane or ethyl
  ethanamine.               chloride.
                                   H   H
      H       H
                              H    C   C    Cl
  H   C       C   N   H
                                   H   H
      H       H   H
                                                       17
      Functional Groups Containing
           C=O Double Bonds
• Aldehyde                        • Ketone
                      O                                O

• Contains    G       C   H       • Contains       C   C   C
              (G = H or C)

• Specific example is             • Specific example is
  benzaldehyde (cherry              acetone (nail polish
  odor). H     H                    remover).
              C   C           O            H   O   H
      H   C           C   C
                                       H   C   C   C   H
              C   C           H
          H           H                    H       H
                                                               18
      Functional Groups Containing
           C=O Double Bonds
• Carboxylic Acid                • Anhydride
                       O                            O           O
• Contains         C   C    OH   • Contains         C           C
                                                            O

• Specific example is            • Specific example is
  ethanoic acid or acetic          acetic anhydride.
  acid. H      O                            O       O
       H       C   C   OH                   C           C
                                      H3C       O           CH3
           H

                                                                    19
       Functional Groups Containing
            C=O Double Bonds
• Ester                      • Amide
• Contains       O           • Contains         O

             C   C   O   C                  C   C   N


• Specific example is ethyl • Specific example is
  acetate (nail-polish        acetaminophen.
  remover).                       O
       O                      H3C   C   N               OH

 H3C    C    O   CH2 CH3                H

                                                         20
            Note the Differences
• Alcohol                • Carboxylic Acid
                                                O
             C   OH
                                        C       C       OH

• Ether          O       • Ester            O
            C        C              C       C       O


• Amine                  • Amide            O
             C   N                  C       C       N


                                                             21
     Find the Functional Groups

                                        OH O
               HO                 CH3
                            CH2         C     C   CH2   O
                      CH          C
                CH3                         CH2    O    C   CH3
          CH2         CH          CH
    H2C         C           CH          CH2

     C          C           CH2
O         CH          CH2



                                                                  22
      Naming Organic Compounds
• When organic compounds were discovered, often the people
  who discovered them named them randomly.
• Morphine, was named after Morpheus, the Greek god of
  sleep.
• Acetic acid was named after “Acetum”, which is Latin for
  vinegar.
• When people began to figure out the structures, they started
  naming compounds systematically, so that the name would
  tell others what the structure of the compound was.
• This is now overseen by the International Union of Pure and
  Applied Chemistry (IUPAC).

                                                                 23
               IUPAC Naming
            Prefix-Parent-Suffix
• Suffix: tells the highest priority functional
  group.
• Parent: tells the longest continuous chain of
  carbons.
• Prefix: tells what other stuff is attached to the
  longest carbon chain. There may be more than
  one prefix.

                                                  24
              Naming Alkanes
• Alkanes: Contain only C   • The parents for 1-4 carbons
  and H, and only have        were “grandfathered in”
                              from older naming systems.
  single bonds.
                            •   5 = pent
• Suffix is “ane”
                            •   6 = hex
• Parent part
                            •   7 = hept
• 1 = meth
                            •   8 = oct
• 2 = eth
                            •   9 = non
• 3 = prop
                            •   10 = dec
• 4 = but
                                                        25
             Naming Examples
• CH4                        •   CH3-CH2-CH2-CH3
• The longest carbon chain   •   Parent is?
  is one, so parent is?      •   But
• Meth                       •   Name is?
• Suffix is?                 •   Butane
• ane
• So the name is?
• Methane


                                                   26
               Another Example
• What about this?    • This structure could also be
       H3C    CH2       written as:
 H3C     CH2 CH2      • CH3-CH2-CH2-CH2-CH2-CH2-CH3
       H2 C   CH2     • This is a condensed structure.
• The longest chain   • Or even as the following,
  is?                   which is a line drawing:
• Seven
• So the name is?
• Heptane             • Each corner is a CH2, and the
                        ends are CH3’s.
                                                        27
        A More Complex Example
                  CH2         CH2         CH2         CH3
            H3C         CH          CH2         CH2
             1    2   3
                        CH3

• The longest continuous             • To name a carbon group,
  carbon chain is?                     you add “yl” to the parent,
• Eight, which is?                     so the group is?
• Octane                             • Methyl
• I circled the longest chain        • You number from the end
• There is a one-carbon group          closest to the group, so the
  attached to the octane               methyl is at carbon 3
                                     • 3-methyloctane


                                                                      28
        Another Alkane Example
                               H3C                          CH3
                                          CH2    H2C

                  CH2         CH2         CH          CH2
           H3C          CH2         CH2         CH2


• The longest continuous                  • The group is located
  chain is?                                 where?



• The group is?                           • The name is?


                          Answer
                                                                   29
       More than One of a Group
• If there is more than         • Each group has to have
  one of a type of group,         its own number, even is
  a prefix is put in front of     the groups are on the
  the group name to tell          same carbon.
  how many there are.           • Numbers are separated
• 2 = di                          from each other by a
• 3 = tri                         comma.
• 4 = tetra                     • Numbers are separated
• 5 = penta                       from words with a dash.

                                                        30
                       An Example
      CH2        CH2         CH3
H3C         C          CH2         • How many methyls are
                CH3
                                     there?
      H3C
                                   • Two, which is?
• The longest carbon               • Di, so we have a
  chain is?                          dimethylhexane.
• Six, which is?                   • Where are the methyls?
• Hexane                           • 3, so the name is?
• The groups are?                  • 3,3-dimethylhexane
• Methyls

                                                          31
     Another Substituted Alkane
               H3C   CH2        H2C   CH3

         H2C     CH2 CH CH CH2 CH CH2 CH3

           CH3         H2C    CH3

• The longest continuous      • The groups are located
  chain is?                     where?

• The groups are?
                              • The name is?

• How many?
                     Answer                              32
         Naming Cyclic Alkanes
• Cyclic alkanes have the
  prefix “cyclo” before the
  alkane name.
• If a molecule has a ring • This is cyclopentane
  and a chain, the ring
  has priority if it has ≥
  the number of carbons
  as in the chain.
                            • This is cyclononane


                                                    33
          More Cyclic Examples

• Where are the most C’s:    • Where are the most C’s:
  the chain or the ring?       the chain or the ring?

• What is the group?         • What is the group?

• What is the name?          • What is the name?



                                                     34
                       Answers
    More than One Type of Group
                                                          CH2
                                         CH3    H2C             CH3
• If there is more than
                             H3C         CH          CH         CH2         CH3
  one type of group, the           CH2         CH2        CH2         CH2
  group prefixes are
  arranged alphabetically      • Groups?
  before the parent.
• The group closest to the     • Numbers?
  end of the chain gets
  the lowest number.
                               • Name?
• Longest Chain?

                      Answer                                                35
    More than One Type of Group on a Ring
• When numbering a ring,           H3C            CH2CH2CH2CH3

  start at the carbon that
  has a group, and                                CH2CH3
  number toward the          •   If we start at the arrow, the
  closest group.                 numbers are?
• The goal is to get the
  lowest numbers.
                             •   If we start at the star, the
• If we start at the smiley-     numbers are?
  face, the numbers are?

                             • Name?
                          Answer                                36
                                          CH2CH2CH2CH3
  Ring #2 Problem
• Sometimes, you can get                  CH2CH3
  the same numbers.
                              • If you start at the arrow,
• When you do, put the          what numbers do you
  lowest number closest         get?
  to the front of the
  name.
                              • Name?
• If you start at the star,
  what numbers do you
  get?

                                                         37
                          Answer
            Naming Alkyl Halides
• Halogens (F, Cl, Br, I) are                    Br
  always named as groups.           H3C CH2 CH CH CH3
• Drop the “ine” from the
                                           CH3
  halogen name and add
  “o”.                          • How do you name the
• How do you name CHCl3,          above structure?
  otherwise called
  chloroform?


                           Answer                     38

								
To top