Chapter 2a (PowerPoint download) by hedongchenchen

VIEWS: 8 PAGES: 36

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

5. Chemical Reactions of Alkanes

  1. Using DH combustion to determine molecule
     stability
  2. Redox Reactions
Classes of Organic Compounds

           Organic Compounds




  Hydrocarbons           Functional Groups
            Hydrocarbons
                                         H
                                     H       H

                                     H       H
                                         H
Aliphatic                     Aromatic



Alkanes      Alkenes       Alkynes   CycloAlkanes
        Aliphatic Hydrocarbons
        H     H
                                       H             H
   H    C     C    H
                                           C     C
         H    H                        H             H
   Alkane; All Single Bonds    Alkene; Contains a Double Bond
           CnH2n+2                         CnH2n


       HC    CH                                          CnH2n

Alkyne; Contains a Triple Bond
           CnH2n-2             Cycloalkane; C atoms are in a ring
Functional Groups; Replace H in Hydrocarbons


                              Halogens

                              Oxygen
                             Containing

                                          Single Bonds

                                      Double Bonds

                              Nitrogen
                             Containing

                              Sulfur
                             Containing
    Functional Groups

                  Halogens



Halogens; Elements in Groups VII
           -F, Cl, Br, I
                                CH3

                             CH3 C CH3
CH3 CH2 CH2 CH2    I
                                 F
   R-I
                                 R-F
Oxygen Containing Functional Group
                        Single Bonds
                                   One Oxygen

                        Double Bonds
                                    One Oxygen


                   Single and Double Bonds
                                   Two Oxygens

                                   Three Oxygens
 Oxygen Containing Functional Group

           Single Bonds;
           One Oxygen

   Ether              Alcohols

                           R
CH3OCH2 CH3
                     H     C     OH
  R-O-R
                           H
Oxygen Containing Functional Group

             Double Bonds;
              One Oxygen



Aldehyde                     Ketone
    O                          O

R    C                       R-C-R
           H
                                O
         O
                        CH3CH2CCH2CH2CH3
               H
     Oxygen Containing Functional Group

                   Two Oxygens


Carboxylic Acids                 Esters

      O                           O
   R-C-OH                        RCOR'

      O                            O

   CH3COH                   CH3CH2COCH3
    Functional Groups with
       Three Oxygens

             O O
                     Acid Anhydride
            RCOCR'

  O O                 O O
CH3COCCH3          C6H5COC(CH2)5CH3
Functional Groups

              Halogens

               Oxygen
              Containing

                    Single Bonds
                    Double Bonds

               Nitrogen
              Containing

               Sulfur
              Containing
Nitrogen Containing Functional
           Groups

RNH2       CH3CH2NH2         Amines



 O                     O
                             Amide
RCNH2      (CH3)2CHCH2CNH2


               CH3CHCH3
                              Nitrile
RC     N          C    N
Sulfur Containing Functional
          Groups

          R-S-H


       CH3CHCH2CH2SH

          CH3


          Thiol
Summary of Functional Groups
        R-X ; Halogens
        R-OH; Alcohols

        R-O-R; Ethers

        R-NH2; Amines

            R-SH; Thiols

       RC     N      Nitriles
Summary of Carbonyl Containing
     Functional Groups

                        O
     O                                    O O
R    C               R-C-OH
             H                        RCOCR'
                 Carboxylic Acid   Acid Anhydride
Aldehyd
   e                                  O
     O                 O
    R-C-R            RCOR'          RCNH2
    Ketone           Ester           Amide
          CnH2n+2

             2.5
  Introduction to Alkanes:
Methane, Ethane, and Propane

     The Simplest Alkanes


•Methane (CH4) CH4
•Ethane (C2H6) CH3CH3
•Propane (C3H8) CH3CH2CH3
Isomeric Alkanes: The Butanes (C4H10)

    n-Butane      CH3CH2CH2CH3
    Isobutane     (CH3)3CH




     bp -0.4°C        bp -10.2°C
                  C5H12


CH3CH2CH2CH2CH3             (CH3)2CHCH2CH3
   n-Pentane                  Isopentane




                  (CH3)4C

               Neopentane
                    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.
      IUPAC Nomenclature of
       Unbranched Alkanes
                      Alkane

                   parent-suffix

         Alk ; states # C in parent chain
ane; suffix; states if single, double or triple bonds


             For molecules with no substituents
           Table 2.4
IUPAC Names of Unbranched Alkanes

 •Retained:
   –methane      CH4

   –ethane       CH3CH3

   –propane      CH3CH2CH3

   –butane       CH3CH2CH2CH3
   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."
               Table 2.2
    IUPAC Names of Unbranched Alkanes

•Number of carbons        NameStructure
•      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
Name the C6H14 Isomers
       CH3CH2CH2CH2CH2CH3

       (CH3)2CHCH2CH2CH3

       (CH3CH2)2CHCH3


       (CH3)2CHCH(CH3)2


       (CH3)3CCH2CH3
    The C6H14 Isomers

             CH3CH2CH2CH2CH2CH3

Hexane or n-hexane




                     • Octane or normal-
                            octane
IUPAC Nomenclature of Branched Alkanes
         prefix-parent-suffix
Step 1) Find the longest continuous carbon
        chain and use the IUPAC name of the
        unbranched alkane as the basis.
Step 2) Number the chain from the end nearest
        the 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
         Methyl and Ethyl Groups

                     H

Methyl       H       C       or   CH3

                     H

                 H       H

Ethyl    H       C       C   or   CH3CH2

                 H       H
          The C6H14 Isomers
                   (CH3)2CHCH2CH2CH3

 2-Methylpentane

                   (CH3CH2)2CHCH3

 3-Methylpentane


Another example;
                              • 4-Ethyloctane
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
                    First Point of Difference Rule


        2       4       6       8              7       5       3       1
            3       5       7                      6       4       2
1                                          8


                            What is correct name?
                    2,3,3,7,7-Pentamethyloctane?
                    2,2,6,6,7-Pentamethyloctane?
    •      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!
     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
        Branched alkanes




       • 4-Ethyl-3,5-dimethyloctane


List substituents in alphabetical order.
But don't alphabetize di-, tri-, tetra-, etc.
        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.

								
To top