Transcript Organic Chemistry

Organic Chemistry
= the study of carbon and
most carbon compounds
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
(a) Fractional distillation
of crude oil
(b) organic reactions
Molecular Models Activity
Our TB online resources
and practice quiz
AP chemistry study cards
for organic chemistry
http://www.chemmybear.c
om/apch23sc.pdf
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
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) .
Molecular vs. Structural
Formulas
Molecular Formulas –
Structural Formulas –
Molecular Formula
Structural Formula
Condensed Structural Formula
CH4
CH4
C2H6
CH3CH3
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:
First 10 Alkanes in Series
Hydrocarbon
Molecular Formula
Methane
CH4
Ethane
C 2H 6
Propane
C 3H 8
Butane
C4H10
Pentane
C5H12
Hexane
C6H14
Heptane
C7H16
Octane
C8H18
Nonane
C9H20
Decane
C10H22
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
Methane (bp: -162 OC)
Ethane (bp: -88.5 OC)
Propane (bp: -42 OC)
Butane (bp: 0 OC)
Pentane (bp: 36 OC
Hexane (bp: 69 OC)
Heptane (bp: 98 OC)
Octane (bp: 126 OC)
Nonane (bp: 151 OC)
Decane (bp: 174 OC)
First 10 Alkenes in Series
Hydrocarbon
Molecular Formula
Ethene
C 2H 4
Propene
C 3H 6
Butene
C 4H 8
Pentene
Hexene
Heptene
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.
C5H10
C6H12
C7H14
Octene
C8H16
Nonene
C9H18
Decene
C10H20
First 10 Alkynes in Series
Hydrocarbon
Molecular Formula
Ethyne
C 2H 2
Propyne
C 3H 4
Butyne
C 4H 6
Pentyne
Hexyne
Heptyne
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.
C5H8
C6H10
C7H12
Octyne
C8H14
Nonyne
C9H16
Decyne
C10H18
This double bond between the two
carbon atoms makes this an
unsaturated fatty acid.
Saturated and unsaturated fatty
acids
Saturated fatty acid
Unsaturated fatty acid
• stearic acid
• See Jmol files (Interactive
molecular animations)
• oleic acid
• See Jmol files (Interactive
molecular animations)
• http://wps.prenhall.com/e
sm_brown_chemistry_11/
86/22103/5658536.cw/ind
ex.html
• http://wps.prenhall.com/e
sm_brown_chemistry_11/
86/22103/5658536.cw/ind
ex.html
Aromatic
Hydrocarbons
Aromatics –contain
cyclic arrangements
of carbon atoms
bonded through both
σ and delocalized π
bonds.
example - benzene
and toluene
Simple Examples
Toluene
Benzene
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 double bond is
located on the 1st
carbon…so its name
would be: 1-butene
**The carbons are numbered so as to keep the
number for the double bond as low as possible**
Both compounds
have four carbons
(use prefix but-)
and a double bond
(use ending –ene)
The double bond is
located on the 2nd
carbon…so its name
would be: 2-butene
Both compounds
have four carbons
(use prefix but-)
and a triple bond
(use ending –yne)
The triple bond is located
on the 2nd carbon…so its
name would be: 2-butyne
The triple bond is located
on the 1st carbon…so its
name would be: 1-butyne
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-
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.
Examples:
3.) The side group has only one
carbon, so use the prefix methand 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.
Name: 3-methyl pentane
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.
3.) Each side group has only one
carbon, so use the prefix methand 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 butmust be used.
2.) There are only single
bonds, so the ending –ane
must be used.
Name: 2,2,3-trimethyl butane
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.
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
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 C=C double bond is
restricted.
c
trans 1,2-dichloroethene
cis 1,2-dichloroethene
Functional Groups
=
(1) 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!
(2) Alcohols:
= one or more hydrogen atoms of a hydrocarbon are replaced by
an –OH group (called a hydroxyl group)
Note: The –OH group does not
dissociate, and therefore alcohols
- named by citing the location of the –OH
are not bases/electrolytes.
However, the –OH group does make
group and changing the ending to –ol.
alcohols polar molecules.
- Classifying alcohols:
Monohydroxy alcohol:
one –OH group
Dihydroxy alcohol:
Trihydroxy alcohol:
two –OH groups
three –OH groups
- 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.
(3) Aldehydes:
= the carbonyl group (-C=O) is found on the end carbon
- named by substituting –al in place of the final –e of the
corresponding alkane name
(4) Ketones:
= the carbonyl group (-C=O) 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.
(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-)
(6) Organic Acids:
= contain the carboxyl functional group (-COOH)
- named by replacing the –e in the corresponding alkane name
with –oic acid
(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 alcoholsee Esterification)
- named for the alcohol and organic acid that make up the ester
(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
(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
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.**
(1)
Combustion:
=
(2) Substitution:
=
(3) Addition:
=
Ethene
Ethene
(4) Esterification:
=
Organic Acid + Alcohol  Ester + Water
(5) Saponification:
=
(6) Fermentation:
=
(7) Polymerization:
=
Polymers = organic compounds
make up of chains of smaller units
covalently bonded to each other
(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
Addition Polymerization:
Condensation Polymerization:
Polymerization
• Animations for
polymerization reactions
• http://www.wwnorton.com
/college/chemistry/gilbert
2/
• Chem tours chapter 12
Animations for
– Polymerization
• Lab Activity: Esterification
• POGIL – organic reactions (group work)
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
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
Many drugs of importance in human
medicine are chiral, and the enantiomers
may produce very different biochemical
effects.
R-Albuterol used as a bronchodialator
S-Albuterol ineffective as a bronchodialator
and can counter the effects of the R-enantiomer
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 problems:25.1-25.6
• End of chapter exercises for now: 25.7,.8, .9, .12, .17,
.21, .23, .25, .31a, .43, .44, .47