Ch. 22: Organic
Chemistry
22.1 Alkanes
Alkanes
 saturated
hydrocarbons
 only single bonds
 each C has 4 atoms bonded to it
 all C have tetrahedral
arrangement
 sp3 hybridization
 straight-chained, normal,
unbranched hydrocarbons
with no substituent groups
are long chain alkanes
Alkanes
 really
a zigzag
shape because of
109.5° in C-C-C
bond
 structural isomers


different molecules
with same atoms
(formula)
different bonding
have different
properties
C4H10
C4H10
Naming
Find the longest chain of carbons



If there are substituent groups, number
the carbons in the chain from one end to
the other



count the number and find the prefix
name is prefix and –ane ending for alkanes
make the #s for groups as small as can
Name the groups by taking the prefix for
the number of carbons in the group and
add -yl
Naming
 the
positions of each group are given
by the #s of the carbon they are
attached to

put hyphen between # and group and a
comma between #s
 For
more than 1 group, list then in
alphabetical order

add prefix (di, tri, etc) if there are more
than one of the same type
Practice Naming
 longest

1

chain is 3
name: propane
C group: methyl group
off of #2 carbon
 2-methylpropane
 longest
chain is 3
 2- methyl groups
 2,2-dimethylpropane
Practice Naming
Reactions with Alkanes
 fairly
unreactive
 combustion


always added to O2
always makes CO2 and H2O
 substitution


when a halogen is added to it, one halogen
may replace one hydrogen
CH4 + Cl2  CH3Cl + HCl
 dehydrogenation


2H atom are removed to form unsaturated
CH3CH3  CH2=CH2 + H2
 cyclopropane

planar unstable
 cyclobutane

planar and unstable
 cyclopentane

planar and stable
 cyclohexane

puckered and stable
Cyclic Alkanes
Unsaturated: Alkenes and Alkynes
 alkenes:
contain at least one double bond
 alkynes: contain at least one triple bond
 change the ending of name to –ene or –yne
 add a # telling the starting position of the
special bond
Unsaturated: Alkenes and Alkynes
 can
also have
unsaturated rings

cyclohexene
 double
bonds prevent
rotation
 cis-trans isomerism:


cis- identical groups on
same side of bond
trans – identical groups
on opp side of bond
Reactions: Alkenes and Alkynes
 Addition
Reactions
 Hydrogenation:


add hydrogen pair to remove special bond
CH2=CHCH3 + H2  CH3-CH2-CH3
 Halogenation:


add halogen pair to remove special bond
CH2=CHCH3 + Br2  CH2Br-CHBr-CH3
Aromatic Hydrocarbons
 cyclic
unsaturated
hydrocarbons
 benzene
 phenyl group:
when attached to
a chain
functional
groups