Jessica Zha
Period 1
April 11, 2005
Chapter 22: Organic Chemistry
definition: the study of carbon-containing compounds and their properties
 alkanes: composed of saturated hydrocarbons
o hydrocarbons are compounds composed of only carbon and hydrogen
o in saturated hydrocarbons all carbons are bonded to 4 atoms (unsaturated hydrocarbons have carbon-carbon
multiple bonds)
o carbons in alkanes have sp3 hybridization
o normal/straight-chain/unbranched hydrocarbons- alkanes in which carbons form long chains (not straight
since C-C-C has a 109.5 degree bond angle
o general formula denoted by CH3—(CH2)n—CH3
o first ten alkanes:
# of Carbons
1
2
3
4
5
6
7
8
9
10
o
Name
Methane
Ethane
Propane
Butane
Pentane
Hexane
Heptane
Octane
Nonane
Decane
Formula (CnH2n+2)
CH4
C2H6
C3H8
C4H10
C5H12
C6 H14
C7H16
C8H18
C9H20
C10H22
Molar mass
16
30
44
58
72
86
100
114
128
142
isomers- two molecules have the same atoms but different bond orientation; isomers exhibit different
properties
o nomenclature- rules for naming alkanes:
1. for a branched hydrocarbon, the longest continuous chain of carbon atoms gives the root name for the
hydrocarbon
2. when alkane groups appear as substituents, they are named by dropping the -ane and adding -yl
3. the positions of substituent groups are specified by numbering the longest chain of carbon atoms
sequentially, starting at the end closest to the branching
4. the location and name of each substituent are followed by the root alkane name; the substituents are
listed in alphabetical order (irrespective of any prefix), and the prefixes di-, tri-, etc. are used to
indicate multiple identical substituents
o fairly unreactive because C-C and C-H bonds are relatively strong; do not react at room temp with acids,
bases, or strong oxidizing agents
o combustion reactions
2C4H10 (g) + 13O2 (g)  8CO2 (g) + 10H2O(g)
substitution reactions
CH4 + Cl2 –hv CH3Cl (chloromethane) + HCl
dehydrogenation reactions (yields unsaturated hydrocarbons)
CH3CH3 –Cr2O3/500°C CH2=CH2 (ethylene) + H2
o cyclic alkanes- rings of saturated hydrocarbons with prefix cyclo- ; weaker bonds than straight-chain
 alkenes and alkynes
o alkene- (CnH2n) contains a carbon-carbon double bond
o naming system resembles that for alkanes except with suffix -ene
o pi bonds prevent rotation of the CH2 and CH groups, allowing alkenes to exhibit cis-trans isomerism
o alkynes- contains a carbon-carbon triple bond
o names contain suffix –yne
o alkenes and alkynes also have ringed structures (ie. cyclohexene)
o
reactions: because they are unsaturated, they undergo addition reactions in which pi bonds are broken and
new sigma bonds formed:
CH2=CHCH3 (propene) + H2 –catalyst CH3CH2CH3 (propane)
(hydrogenation reaction)
halogenation reaction: addition of halogen atoms
CH2=CHCH2CH2CH3 (1-pentene) +Br2  CH2BrCHBrCH2CH2CH3 (1,2-dibromopentane)
o polymerization- process in which many small molecules are joined together to form a large molecule
 aromatic hydrocarbons- hydrocarbons with six-membered carbon rings and delocalized electrons
o simplest is benzene: C6H6
o
o
undergoes substitution reactions where hydrogen atoms are replaced by other atoms
benzene + Cl2 –FeCl3 chlorobenzene + HCl
nomenclature: similar to that for saturated ring systems; if more than one substituent is present, numbers
are used to indicate positions, the smallest numbers associated to the substituents (can also system of
prefixes: ortho- [2 adjacent substituents], meta- [2 substituents with one carbon in between], and para- [2
substituents opposite each other])
o-dichlorobenzene
m-dichlorobenzene
p-dichlorobenzene
o phenyl group- benzene is used as a substituent
o benzene is simplest- more complex forms made with rings fused together
 the petrochemical industry
o petroleum contains molecules of hydrocarbons of various lengths; shorter lengths attained in order to
maximize output of products in the burning of petroleum—process called “cracking”
 hydrocarbon derivatives- hydrocarbons with functional groups (additional atoms or groups of atoms)
o alcohol- characterized by presence of hydroxyl group (–OH); classified according to the number of
hydrocarbon fragments bonded to the carbon where the –OH group is located:
primary
secondary
tertiary
R
R
\
|
R—CH2OH
CHOH
R’—COH
/
|
R
R”
o aldehydes and ketones- contain carbonyl groups:
aldehyde:
ketone:
o
carboxylic acids: characterized by the presence of the carboxyl group:
o
generally are weak acids w/ general formula RCOOH
esters: formed when carboxylic acids react with alcohols
has a sweet, fruity odor such as that of bananas and oranges
aspirin has an ester group
o amines: contains a N—C bond; primary contains one N—C bond, secondary contains 2, tertiary contains 3
has an unpleasant “fishlike” smell
 polymers
o large, usually chainlike molecules built from small molecules called monomers
o basis for synthetic fibers, rubbers, and plastics
o simplest and most common is formed from ethylene monomers: polyethylene- a tough and flexible plastic
o other examples: Teflon (from tetrafluoroetheylene)
o types of polymerization:
-addition polymerization- monomers simply add together, caused by irritation of a free radical
(species with an unparie electron)
-condensation polymerization- a small molecule is formed for each extension of the polymer
o copolymer- chain formed by 2 different types of monomers (ie. nylon)
o homopolymer- results from a singer type of monomer
o dimer- two monomers joined
Multiple Choice Questions
How many sigma bonds does a molecule of ethene have?
a) 1
b) 4
c) 5
d) 7
What is the oxidation product of a primary alcohol?
a) aldehyde
b) alkene
c) ester
d) ketone
Which of these compounds have cis- and trans- isomers?
a) dichlorobenzene
b) 1-chloropropene
c) 1,2-dichloropropane
d) dichloroethyne
If a certain polymer has the formula (–CH2CCl2CH2CCl2–)n, from which monomer is it made?
a) HC CCl
b) ClHC=CClH
c) Cl2C=CH2
d) H2C=CClH
What is the position of the bromine atom relative
methyl group in 3-bromotoluene?
a) meta
b) ortho
c) para
d) trans
Free Response Question
Compound Name
Compound Formula
ΔH°vap (kJ mol-1)
Propane
CH3CH2CH3
19.0
Propanone
CH3COCH3
32.0
1-propanol
CH3CH2CH2OH
47.3
Using the information in the table above, answer the following questions about organic compounds.
a) For propanone
i) draw the complete structural formula (showing all atoms and bonds);
ii) predict the approximate carbon-to-carbon bond angle
b) For each pair of compounds below, explain why they do not have the same value for their standard heat of
vaporization, ΔH°vap. (You must include specific information about both compounds in each pair.)
i) propane and propanone
ii) propanone and 1-propanol
c) Draw the complete structural formula for an isomer of the molecule you drew in part a) i).
d) Given the structural formula for propyne below,
H
|
h—C—C≡C—H
|
H
i) indicate the hybridization of the carbon atom indicated by the arrow in the structure above;
ii) indicate the total number of sigma (σ) bonds and the total number of pi (π) bonds in the molecule.