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					Essentials of Organic Chemistry



           Chemistry 304

       Thomas J. Wiese, Ph.D.
   Associate Professor of Chemistry
      Fort Hays State University
                 Introduction

•   Roll Call
•   Syllabus
•   Tests and Grading
•   Approximate grading scale: 90-80-70-60
              Course Overview
Ch. 1-9, 18?
The way to study:
• scan assigned reading material before class
• listen during class and take notes
• read assigned material (SQ3R) and supplement class
  notes
• review the weeks notes every weekend
• begin good study habits early!
• pay attention to details I point out
Introduction to Organic
      Chemistry
(Review of Freshman Chemistry)
                  Element

Element- pure substance composed of only one
  type of atom
H vs. He vs. Unh
                    Atom

Atom- the smallest particle of matter
Composed of protons, neutrons and electrons
       Compound vs. molecule

Compound- atoms of two or more elements
  bonded together
Molecule has two meanings
• Atoms of the same element bonded together
• A single compound moiety
            Atomic Structure

A nucleus containing protons and neutrons,
  surrounded by a cloud of electrons
s-electrons
p-electrons (px, py, and pz)
(d-electrons and f-electrons)
        Electron Configurations
Two electrons (e–) per orbital
Principle energy levels and the Aufbau principle
  1 contains only s e–
  2 contains s and p e–
  3 contains s, p and d e–
  4 contains s, p, d and f e–
Spin-pair rule
Hunds rule
6/9/04
                    Bonds

Ionic bond- electrostatic interaction when metal
  and nonmetal interact (NaCl as an example)
Covalent bond-A chemical bond that involves
  sharing of electron pairs (not all same)
Two shared electrons = 1 bond (H2)
          Molecular Properties
Ionic compounds     vs. Covalent compounds
  solid                solid or liquid or gas
  high mp/bp           low mp/bp
  conductors           insulators
           Other Bond Issues

Polar covalent bond (O—H)
Double bond (O2) and triple bond (N2)
Coordinate covalent bond (NH4+ formation)
      Charge and Formal Charge

• There is a formal charge for each atom of a
  compound
                   group        unshared       half of the
    Formalcharge                            minus           
                     number
                             minus
                                electrons
                                                   shared e- 
               Review Questions
 • Are the following bonds
   polar or nonpolar?
        C-C
        C-H
        C-O
        C-N
What are the formal charges
for the carbonate ion, CO32-?
        Intermolecular Forces

London forces (AKA van der Waals)
Dipole-dipole interactions
Hydrogen bond
6
            Forces between Molecules
                I. London Forces
    • all particles have
      London forces           Ne          Ne 



    • larger particles have
    larger London forces           .
    • only force between noble             Ar
    gases and nonpolar                            .
    compounds
    • about 1/1000 as strong as
    a covalent bond
7
          Forces between Molecules
        II. Dipole-Dipole Interactions
    • different from London
      forces only in
      permanence               .
    • somewhat stronger than
      London forces because            O
      permanent
    • occurs in all polar              C
      molecules
    • weaker than ionic bond
                                   H       H.
      because only + or 
8
           Forces between Molecules
             III. Hydrogen Bonds
    • rare
    • occur between one H
      which is covalently       .
      bonded to an N, O, or F           O               O
      atom and a second N, O,       H       H       H       H
      or F atom                                 O
                                            H       H
    • strongest of three
      intermolecular forces             O               O
                                    H       H       H       H .
6/10/04
                    Solubility

•   ―Like dissolves like‖
•   Solvent-
•   Solute-
•   4C
            Shapes of Molecules

•   Linear
•   Bent
•   Pyramidal
•   Tetrahedral
•   Triangular
•   others
           Organic Chemistry

Organic chemistry- the chemistry of carbon-
 containing compounds
      Forms of Elemental Carbon
• Graphite
• Diamond
• Buckminsterfullerene -
   Nobel prize 1996
• ―Amorphous‖
                        Carbon
• Atomic structure
   – 6p
   – Predominately 6 neutrons
   – 6 e–
• group IVA                      C
   –4 valence electrons
   –oxidation state ―±4‖
   –form 4 bonds in reactions
   –tetrahedral
6/14/04
             Atomic Orbitals

electron configuration of C
   1s2,2s2,2p2
We might expect C to form two bonds ( the 2
   unpaired p electrons)
          We know that C forms 4 bonds 
We might expect that CH4 would have 1 s-s
   bonds and 3 s-p bonds.
   We know that all C–H bonds are equivalent 
        Hybrid Atomic Orbitals

Hybrid atomic orbitals is a theory used to
  reconcile the discrepancy between what atomic
  orbital theory predicts, and what is seen
  experimentally.
• Fig 1.12: C has 4 sp3 hybrid orbitals
  – called sigma bonds
• pi bonds: sp2 hybrid orbitals
          Hybrid Atomic Orbitals

hybrid     bonding     shape      rotation bond
sp3()     head-head   tetrahedral free    single
sp2 ()    sideways    triangular rigid   double
sp ()     sideways    linear     rigid     triple
     There are a Huge Number of
         Organic Molecules
• 100 new ones described every week
• It is estimated that there could be 5  1020
  different organic molecules
  How Can So Many Molecules be
   Made From So Few Elements?
• different number of C atoms
• Functional groups (later)
• Isomers
  – iso means…
Empirical formula- C6H14 (molecular formula)
Structural formula
           Drawing Molecules

As you can see already, drawing all these C-H
  bonds is tedious. We will use shortcuts most of
  the time.
Condensed formula
Line formula
Drawing Molecules on Paper Does
not Show the 3-Dimensional Shape
The geometry around each C atom is tetrahedral
 (sp3 hybrid)
             Hydrocarbons

Hydrocarbon- Compounds which contain only
 carbon and hydrogen.
    Alkanes
    Alkenes
    Alkynes
    Cycloalkanes
    (Aromatics)
                Alkanes
meth-   1 carbon
eth-    2 carbons
prop-   3 carbons
but-    4 carbons
pent-   5 carbons
hex-    6 carbons
hept-   7 carbons
oct-    8 carbons
non-    9 carbons
dec-    10 carbons
                 Nomenclature

•   Primary
•   Secondary
•   Tertiary
•   Quaternary
6/15/04
               IUPAC Nomenclature
1. Find the longest continuous carbon chain and use the name for the
   alkane with that number of carbon atoms.
2. Number the carbons in the longest continuous carbon chain from the
   end nearer the first R group.
3. Identify R groups by name.
4. Identify by number the carbon atom in the chain to which each
   substituent bonds. If the same substituent occurs more than once,
   identify each carbon number for that substituent, separate the
   numbers to commas, and use the appropriate prefix to identify how
   many occur in the compound.
5. Name the compound by listing the substituents preceded by a number
   and a hyphen, followed by the base name for the C chain. If more
   than one type R group, arrange in alphabetical order, ignoring
   prefixes except iso- and cyclo-. Connect all numbers and prefixes by
   hyphens.
               R-groups by name
.
                        CH2CH2CHCH3     isopentyl
    CH2CH2H3   propyl        CH3


                        CH2CHCH2CH3      secpentyl
      CH3                  CH3
     CH   isopropyl
      CH3                  CH3
                        CH2CCH3    neopentyl
                                   (tertpentyl)
                           CH3




                                                     .
                 Cycloalkanes
Whether the ring or chain
 is considered the parent
 compound depends on
 which is larger.           .


                                CH3CH2


                                         .
           Functional Groups

Functional group- An atom or group of atoms that
  imparts on a molecule a distinctive chemistry
1. Alkane- not considered a functional group
2. Alkyl halide
3. Alkene
4. Alkyne
                   Alkanes

Only sigma bonds in molecules
General formula CnH2n+2
Molecular formula
Structural formula
Condensed formula
Isomers- same formula, different structure
  functional isomers
  structural isomers
6/16/04
      Conformation of Molecules

• Important because of free rotation about the -
  bond
• Eclipsed-
• Staggered-
• Important because of size of groups (can
  overlap)
     Practice Conformation Problems
• Draw ―all possible‖              .


  Newman projections for
  the compound
  CH3CH2CH2CH3
  (butane)                                                               .


 .

                       H                                   H
         H
         H                                 CH3
                   H         H                        H          H
                                       H         H

             CH3   H         CH3                     CH3         H
     H
     H       CH3                       H         H
                       CH3                                 CH3
                                           CH3
                                                                     .
   Practice Conformation Problems
• What would the most
  stable conformation of                             CH3CH2                              CH2CH3
  the following molecule
  be?

                                                                 CH3CH2
CH3CH2          CH2CH3



                                                     CH2CH3
                                            CH2CH3                                        CH2CH3
         boat                                          diaxial   CH3CH2

                         CH2CH3
                                                                          diequitorial
                         axial-equitorial
    Physical Properties of Alkanes

1. Solubility
2. mp/bp
3. Density

				
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posted:9/22/2011
language:English
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