Cyclic hydrocarbons
• Important for proper working order of human
body (examples: steroids – testosterone and
estrone, cholesterol)
3. Cholesterol
• Important medicinal uses – ex. Budesonide
(asthma treatment)
• In some hydrocarbons the carbons at the ends
of the chain join together to form a ring and
are called cyclic hydrocarbons.
Naming Cyclic Hydrocarbons
Cycloalkanes are named using the alkane parent
with the prefix cyclo.
cyclopropane
cyclohexane
cyclobutane
cyclopentane
cycloheptane
• The general formula for the cycloalkanes is CnH2n.
• With what homologous series are cycloalkanes
isomeric?
• Alkene
Naming Branched Cycloalkanes
• If there is only one branch, no number is
needed.
CH2–CH3
ethylcyclohexane
methylcyclopentane
• If there are two branches, the # 1 carbon
would be the one with substituent listed first
in the alphabet.
• Number toward the second branch in the
direction which yields the lower number for
the carbon bearing that second branch.
CH3
CH3
CH3 – CH2
1-ethyl-3-methylcyclohexane
CH3
1,1-dimethylcyclopropane
• When more than two branches are resent,
each must have the lowest possible position
number.
CH2–CH3
3-ethyl-6-methyl-1-propylcycloheptane
1-ethyl-5-methyl-3-propylcycloheptane
CH3–CH2–CH2
CH3
Naming Cycloalkenes
• If double bond is present in the ring structure,
you must follow the same rules as for alkenes.
• DOUBLE BOND GETS PRIORITY FOR THE
LOWEST NUMBER!!!
CH3
CH3
CH3 – CH2
3-methyl-1-cyclohexene
5-ethyl-3-methyl-1-cyclohexene
Sample problem 1
Name the following structures
c)
CH3 – CH2
CH3
Sample problem 1
Name the following structures
b) Ethylcyclopropane
a) 1,3-dimethylcyclohexane
c)
CH3
CH3 – CH2
c) 1-ethyl-2-methyl-1-cyclopentene
d) 1-methyl-3-propylcyclohexane
Sample Problem 2
Draw a condensed structural diagram for
following compounds:
a) 1,1-dimethylcyclobutane
b) ethylcyclopentane
c) 1-bromo-3-ethylcyclobutane
d) 3-bromo-1-ethyl-1-cyclobutene
CH3
CH3
a)
CH2–CH3
c)
Br
b)
CH2–CH3
CH2–CH3
d)
Br
Complete questions p.358 #30,31