Chapter 2 : Alkanes and cycloalkanes
G
n-bu
Three main classes of
1 .
hydrocarbons : But
-
Saturated Unsaturated, Aromatics
, see
-
non-polar (l-met
.
2 Alkanes are saturated hydrocarbons (InHan 2)+
109"
[
-
Hybridization : tetrahedral , sp3 ,
isob
-
unbranched alkanes are called n-alkanes (normal
let
-
Alkanes only differ by a
methylene group CH2 (1 , 1- d
-
Homologus : regular repetitive way-like of members in a compound
share Is
-
same
properties.
(2-m
-
Alkyl groups are alkanes -
1H atom (R-H) CnHan +1
CH3
-
neopentane : ↑
CH3 C C13
-
-
I
CH3
setroleum and natural the two important sources of
I gas are
-
alkanes , made of methane , then ethane then other higher alkanes
mostly .
-
If molecular weight is similar , alcohols have higher B .
P than alkan
-
C-C4 Gases 25-27 Liquids Co4 solids like wax
B p & weight (continuous chain)4
- .
molecular >
B Pb .
Bran
. Conformations/conformers
3 Stereo isomers
Newman projections :
H
4H °
rattached 60 rotation of the C-C bond
H- -H
toveat
↑ toton attached
it
H He H
H
staggered eclipsed of ethane
↳
, 4 cycloalkanes nomenclature
%
cyclopropane is
necessarily planar (60 angle between carbon atoms to minimiz
·
Much less than the usual 109 5 .
angle of tetrahedral sp3 .
Formula of with Cuten
a
cycloalkane one
ring :
:
examples
4
CH3
Z
3-dimethylcyc
3
63-cyclohexyl heptane ↑
I
1
sa
#
5 ,
I longest carbon chain
/ Y
>
- substituent
CU3
-
Rotating alkanes (& cyclohexane) is easier than
rotating
-
In cyclobutane and cyclopropane , puckering allows the molecu
Cleast strain energy) .
H
chair conformation cyclohexane /
↳I
of
-
I
for methyl cyclohexane methyl , group on axial is less stable tha
( Because of diaxial interaction)
1-tetr-butyl-4-methylcyclohexane (d) most sta
A
(a) least st
(2) is more s
S Ha +
/
S d 7 c7b7a
in3 A cus e
in3 A
2
=
Ring flips :
(9) (b) (C) (d)
up -up
5 Cis-trans .
(geometrical) isomerism down dow
G
n-bu
Three main classes of
1 .
hydrocarbons : But
-
Saturated Unsaturated, Aromatics
, see
-
non-polar (l-met
.
2 Alkanes are saturated hydrocarbons (InHan 2)+
109"
[
-
Hybridization : tetrahedral , sp3 ,
isob
-
unbranched alkanes are called n-alkanes (normal
let
-
Alkanes only differ by a
methylene group CH2 (1 , 1- d
-
Homologus : regular repetitive way-like of members in a compound
share Is
-
same
properties.
(2-m
-
Alkyl groups are alkanes -
1H atom (R-H) CnHan +1
CH3
-
neopentane : ↑
CH3 C C13
-
-
I
CH3
setroleum and natural the two important sources of
I gas are
-
alkanes , made of methane , then ethane then other higher alkanes
mostly .
-
If molecular weight is similar , alcohols have higher B .
P than alkan
-
C-C4 Gases 25-27 Liquids Co4 solids like wax
B p & weight (continuous chain)4
- .
molecular >
B Pb .
Bran
. Conformations/conformers
3 Stereo isomers
Newman projections :
H
4H °
rattached 60 rotation of the C-C bond
H- -H
toveat
↑ toton attached
it
H He H
H
staggered eclipsed of ethane
↳
, 4 cycloalkanes nomenclature
%
cyclopropane is
necessarily planar (60 angle between carbon atoms to minimiz
·
Much less than the usual 109 5 .
angle of tetrahedral sp3 .
Formula of with Cuten
a
cycloalkane one
ring :
:
examples
4
CH3
Z
3-dimethylcyc
3
63-cyclohexyl heptane ↑
I
1
sa
#
5 ,
I longest carbon chain
/ Y
>
- substituent
CU3
-
Rotating alkanes (& cyclohexane) is easier than
rotating
-
In cyclobutane and cyclopropane , puckering allows the molecu
Cleast strain energy) .
H
chair conformation cyclohexane /
↳I
of
-
I
for methyl cyclohexane methyl , group on axial is less stable tha
( Because of diaxial interaction)
1-tetr-butyl-4-methylcyclohexane (d) most sta
A
(a) least st
(2) is more s
S Ha +
/
S d 7 c7b7a
in3 A cus e
in3 A
2
=
Ring flips :
(9) (b) (C) (d)
up -up
5 Cis-trans .
(geometrical) isomerism down dow
