Organic Chemistry

1
Organic Chemistry
the study of carbon and most carbon
compounds
2
Organic Chemistry - Hydrocarbons

• as a class of organic compounds
• structural features and properties
• importance of their combustion reactions
• How can we represent them? Molecular formulas,
  structural formulas, use of models, 3D
  representations, and names
• Structures and nomenclature decoding chemical
  names

• Resources
• POGILS
• Fractional distillation of crude oil
• organic reactions
• Molecular Models Activity
• Our TB online resources and practice quiz
• AP chemistry study cards for organic chemistry
• http//www.chemmybear.com/apch23sc.pdf

3
Bonding of Carbon Atoms

• Carbon atoms have a tendency to covalently bond
  with other carbon atoms and form chains.
• ?Straight chains
• ?Branched chains
• ?Ring chains
• Carbon atoms are able to form up to four covalent
  bonds
• Remember Carbon has 4 valence electrons.
• Carbon atoms can engage in single, double, or
  triple
• covalent bonds
• ?saturated compounds contain only single
  bonds
• ?unsaturated compounds contain at least 1
  double or
• 
  triple bond

4
Organic Molecules - Hydrocarbons

• contain H and C atoms.
• may be acyclic molecules (linear or branched) or
  cyclic molecules.
• each C atom has a total of 4 bonds and each H has
  one bond
• all C-H bonds are single covalent bonds ( ?
  bonds) but carbon-carbon covalent bonds may be
  single ( ? bonds) , double ( ? bond and a ? bond)
  or triple ( ? bond and two ? bonds) .

5
Molecular vs. Structural Formulas
Molecular Formulas Structural Formulas
Molecular Formula Structural Formula
Condensed Structural Formula
CH4 CH4 C2H6
CH3CH3
6
Hydrocarbons

• organic compounds that contain only atoms of
  hydrogen and carbon
• Homologous series of hydrocarbons
• (a) Alkanes contain only single covalant
  bonds
• - General formula
• (b) Alkenes contain one double covalent bond
• - General formula
• (c) Alkynes contain one triple covalent bond
• - General
  formula

7
First 10 Alkanes in Series
Hydrocarbon Molecular Formula Methane CH4 Et
hane C2H6 Propane C3H8 Butane C4H10
Pentane C5H12 Hexane C6H14 Heptane C7
H16 Octane C8H18 Nonane C9H20 Decane
C10H22
8
Separation of hydrocarbons by distillation?
(ex fractional distillation of crude
oil)Animation http//www.wwnorton.com/college/
chemistry/gilbert2/(Chem tours chapter 12
Fractional distillation)POGIL activity on
Fractional Distillation

• Hexane (bp 69 OC)
• Heptane (bp 98 OC)
• Octane (bp 126 OC)
• Nonane (bp 151 OC)
• Decane (bp 174 OC)

• Methane (bp -162 OC)
• Ethane (bp -88.5 OC)
• Propane (bp -42 OC)
• Butane (bp 0 OC)
• Pentane (bp 36 OC
• )

9
First 10 Alkenes in Series
Hydrocarbon Molecular Formula Ethene C2H4 P
ropene C3H6 Butene C4H8 Pentene C5H10
Hexene C6H12 Heptene C7H14 Octene C
8H16 Nonene C9H18 Decene C10H20
Notice There is no alkene corresponding to the
methane of the alkane series. That is b/c there
must be at least 2 carbon atoms to form a double
bond.
10
First 10 Alkynes in Series
Hydrocarbon Molecular Formula Ethyne C2H2 P
ropyne C3H4 Butyne C4H6 Pentyne C5H8
Hexyne C6H10 Heptyne C7H12 Octyne C8
H14 Nonyne C9H16 Decyne C10H18
Notice There is no alkyne corresponding to the
methane of the alkane series. That is b/c there
must be at least 2 carbon atoms to form a triple
bond.
11
This double bond between the two carbon atoms
makes this an unsaturated fatty acid.
12
Saturated and unsaturated fatty acids

• Saturated fatty acid

• Unsaturated fatty acid

• stearic acid
• See Jmol files (Interactive molecular animations)
  
• http//wps.prenhall.com/esm_brown_chemistry_11/86/
  22103/5658536.cw/index.html

• oleic acid
• See Jmol files (Interactive molecular animations)
  
• http//wps.prenhall.com/esm_brown_chemistry_11/86/
  22103/5658536.cw/index.html

13
Aromatic Hydrocarbons

• Simple Examples

• Aromatics contain cyclic arrangements of carbon
  atoms bonded through both s and delocalized p
  bonds.
• example - benzene and toluene

14
Naming Organic Compounds

• Naming straight-chained hydrocarbons
• ? Use Reference Table P (Organic Prefixes) and
  Table Q (Homologous Series of Hydrocarbons)
  to name write the formulas.
• ? When naming alkenes alkynes, indicate where
  the double/triple bond is located in
  the molecule.

The carbons are numbered so as to keep the
number for the double bond as low as possible
The triple bond is located on the 1st carbonso
its name would be 1-butyne
The double bond is located on the 1st carbonso
its name would be 1-butene
Both compounds have four carbons (use prefix
but-) and a double bond (use ending ene)
Both compounds have four carbons (use prefix
but-) and a triple bond (use ending yne)
The double bond is located on the 2nd carbonso
its name would be 2-butene
The triple bond is located on the 2nd carbonso
its name would be 2-butyne
15
AP and Class Exams you will need to memorize
the root names, functional groups and the naming
rules associated with simple organic molecules

• Memory aids for the first 5 in the series
• mary eats peanut butter pancakes
• (methyl-, ethyl-, propyl-, butyl-, pentyl-

16
Naming Organic Compounds

• Naming branched hydrocarbons
• 1) Find the longest carbon chain which contains
  the functional group or multiple bond if present
  and name it (using Tables P Q to find correct
  prefix ending).
• 2) Number the longest chain (left to right or
  right to left) so that the functional
  group/multiple bond/longest side chain (branch)
  is on the lowest numbered carbon possible.
• 3) Name each side group but change the ending to
  -yl.
• 4) Use a prefix di-, tri-, tetra-, etc. to
  denote how many side groups of each length are
  present.
• 5) Before naming the side group give the number
  of the carbon to which the side group is
  attached.
• 6) Arrange the side groups in alphabetical order
  ignoring the prefixes di-,tri-, etc.

17
Examples
3.) The side group has only one carbon, so use
the prefix meth- and add the ending yl methyl.
1.) The longest chain has 5 carbons, so the
prefix pent- must be used.
2.) There are only single bonds, so the ending
ane must be used.
4.) Since the side group is right in the middle,
the carbons can be numbered from either side.
The methyl group is located on the 3rd carbon.
Name 3-methyl pentane
3.) Each side group has only one carbon, so use
the prefix meth- and add the ending yl methyl.
Since there are 3 methyl groups, use the prefix
tri- trimethyl.
1.) The longest chain has 4 carbons, so the
prefix but- must be used.
2.) There are only single bonds, so the ending
ane must be used.
4.) Count carbons so that the longest side chain
has the lowest . The first 2 methyl groups are
located on carbon 2, and the next methyl group is
located on carbon 3.
Name 2,2,3-trimethyl butane
18
Isomers

• As the of carbon atoms in a compounds
  increases, the of possible isomers also
  increases.

Example of Isomers All of these compounds have
the molecular formula C5H12
19
Cis and Trans Isomers

• Alkenes exhibit not only structural isomerism but
  geometric (cis-trans) isomerism as well. In
  geometric isomers the bonds are the same, but the
  molecules have different geometries. Geometric
  isomerism is possible in alkenes because rotation
  about the CC double bond is restricted.

20
Functional Groups

• Halides
• when any of the halogens
• (F, Cl, Br, or I) replaces a hydrogen
• atom in an alkane
• - named by citing the location of the
• halogen attached to the chain and
• adding the appropriate prefix
• (fluoro-, chloro-, bromo-, or
• iodo-)

Note Table R provides examples on how to
recognize and name compounds w/ each of the
functional groups!
21

• (2) Alcohols
• one or more hydrogen atoms of a hydrocarbon
  are replaced by an OH group
  (called a hydroxyl group)
• - named by citing the location of the OH
• group and changing the ending to
  ol.
• - Classifying alcohols

Note The OH group does not dissociate, and
therefore alcohols are not bases/electrolytes.
However, the OH group does make alcohols polar
molecules.
Monohydroxy alcohol one OH group
Dihydroxy alcohol two OH groups
Trihydroxy alcohol three OH
groups
22

• - Alcohols can also be classified according to
  the position of their OH group

PRIMARY (1o) the functional group is bonded to
a carbon that is on the end of the
chain. SECONDARY (2o) The functional group is
bonded to a carbon in the middle of the
chain. TERTIARY (3o) The functional group is
bonded to a carbon that is itself directly bonded
to three other carbons.
23

• (3) Aldehydes
• the carbonyl group (-CO) is found on the end
  carbon
• - named by substituting al in place of the
  final e of the corresponding alkane name

24

• (4) Ketones
• the carbonyl group (-CO) is found on an
  interior carbon atom that is attached to
  two other carbon atoms
• - named by replacing the final e from the
  corresponding alkane with one if necessary,
  cite which carbon atom the carbonyl group
  is attached to.

25

• (5) Ethers
• two carbon chains are joined together by an
  oxygen atom bonded between two carbon atoms
• - named by first naming the two methyl groups,
  followed by the word ether (when both R
  groups are the same, use prefix di-)

26

• (6) Organic Acids
• contain the carboxyl functional group (-COOH)
• - named by replacing the e in the
  corresponding alkane name with oic acid

27

• (7) Esters
• have the type formula R-CO-OR (R-CO-O- part
  of formula comes from an organic acid the
  R part comes from an alcohol- see
  Esterification)
• - named for the alcohol and organic acid that
  make up the ester

28

• (8) Amines
• formed when one or more of the hydrogen atoms
  of ammonia are replaced by an alkyl group
• - named by changing the alkane ending of e to
  amine and then numbering the alkane chain to
  show the location of the amine group

29

• (9) Amides
• a compound formed by the combination of two
  amino acids
• (See Condensation reaction)
• - named by changing the carboxylic acid
• acid reactant ending oic acid with
• -amide

30
Organic Reactions

• Note Generally occur more slowly than
  inorganic reactions. When covalently bonded
  substances react, they must first break
  relatively strong existing bonds before making
  new bonds.
• Combustion

31

• (2) Substitution
• (3) Addition

Ethene
Ethene
32

• (4) Esterification
• (5) Saponification

Organic Acid Alcohol ? Ester Water
33

• (6) Fermentation
• (7) Polymerization
• (a) Addition polymerization
• involves the joining of monomers of
  unsaturated compounds
• (b) Condensation polymerization
• involves the joining of monomers by
  removing water from hydroxyl groups and
  joining the monomers by an ether or ester
  linkage

Polymers organic compounds make up of chains of
smaller units covalently bonded to each other
34
Addition Polymerization
Condensation Polymerization
35
Polymerization

• Animations for polymerization reactions
• http//www.wwnorton.com/college/chemistry/gilbert2
  /
• Chem tours chapter 12 Animations for
• Polymerization

36

• Lab Activity Esterification
• POGIL organic reactions (group work)

37
Molecules that possess nonsuperimposable mirror
images are termed _________._______________ are
stereoisomers that are mirror images of one
another that are not superimposable.

• Resources
• Molecular models
• Video clip (our TB online resources for chapter
  25)

www.chm.bris.ac.uk
38
Many of the molecules occurring in living
systems, such as the amino acids, are chiral and
exist in nature in only one enantiomeric form.

• Example Alanine

www.rikenresearch.riken.jp
39

• Many drugs of importance in human medicine are
  chiral, and the enantiomers may produce very
  different biochemical effects.

40
eTextbook problems - Problem Set 4

• Chapter 25 (in part)
• GIST problems p. 1056, 1059 1063, 1069
• VC problems 25.1-25.3, 25.6 (p. 1096-1097)
• Within chapter 25, Study the sample exercises and
  then do practice problems25.1-25.6
• End of chapter exercises for now 25.7,.8, .9,
  .12, .17, .21, .23, .25, .31a, .43, .44, .47