, Book notes 07/6/2024 Chapter 14 :
Conjugated compounds and ultraviolet spectroscopy
Conjugated compounds Compounds :
with alternating double and single bonds
if different independently but if
sat. are far from each other , they react
, they're closer
together they
,
can interact
Exy(
H # H
H
- I
H
H -yay
-
2
I I H Conjugated dienes can be made by using base-
H H
H induced elimination
it of HX from an allylic halide
Conjugated
diene
non
conjugated HA Br
diene +
NBS k JC (CH3) z
hr
* because more substituted alkenes ,
24 HOC(2Hzbe
are more stable and produce less heat Cyclohexene S-Bremocyclohexene 1,
3-Cyclohexadiene (76 %)
they also release less heat when thus
PH3
+H H
A3) 0 , - ↑
are added to water H
-
stability due to orbital hybridizati
&
c -
x ↑ Hexcc2
i
is OH
H
12 Hit H
It
one
thing that separates conjugated and non conjugated diens is that in
a conjugated diene the central (middle) single bond is shorter than a non
Conjugated one
i C Hy CH CHz
CH3-CH2CHe-CHa
. .
= -
CH =
T
There are differences between 147PPm 153 ppm
13 butadiene
Conjugated dienes and alkenes in
Butane
electrophilic addition runs when you add HC
O to an alkene adds the Cl
is this a cony-clone
to the mose Subst
Carbon .
So
2-methyl propere becomes
2-chloro-2-methyl Instead at
1-chloro-2methyl
Sometimes dienes two products , and
conjugated can get one will have the alkone
on the central carbon Br
↑ ↓
~
CyrH 3-Bromo-l-butene
H
=
-
+
H 11 % 1 2-
addition
j = c +=
- H #Y ,
H
H
it H LBY H
1-Bromo-2-butene
C-
c
=
-
yH 20
H %, 1-4-addition
1 , 3-butadiene ↓ it
, B
H
H H ↑* Br
BI H ↑
Y=c -
,
- H
C-
-
c
=
-
yH
H H
ItH ↓ Br
(example) give structures of the likely products from uyn of 1 equinent HCI with
2-methyl-1 3-cyclohexdiene ,
. Show both 1 , 2 and 1 , 4 adducts
Is 4 1 , 26 1 , 4
s HCI
-
> x
L
+
[T *
132 di
Imagine a run that can
give either or both Products of Band C
rxn at low temp (4GB(GFC)
Ax
B forms faster than 1 butcis
,
more stable than
L
B C B(4G ° (GB) Kinetic control
Because B forms faster than ( (lower temp : irreversable)
A
Bis the
Major
Product It doesn't matter If Cis more (faster) L ↳ (slower)
B
,
Stable than B at an irreversible reacti
C
. Product
The
depends on relative rates ,
not stability . Such rans are said
to be under Kinetic control
If we do the same reaction at a
higher temperature ,
both Processes
ore somewhat reversable
and reached Because
Cis It does not
equilibrium is .
more Stable than B ,
C is the
major Product ,
Matter that B bas the two one
(is slower than in equilibum
. The Product of a readily reversable xn
depends on
Stability ,
not relative rates . Such rans are said to be under equilibrum control =
thermo
dynam contine
A Thermodyname contral
↑ X
B , (higher temp ; reversable)
Summary : When we have lower temps and an Irreversable run. the
major product will
be determind by relative rates depend
.
When we higher temps and a reverssbe ran. the major product will
on
stability .
Kinetic control = Lower temp and irreversable ·
Thermodynamic control-higher temp and
Reversable
, The diel-alder Cycloaddition reaction
conjugated diens undergo an addition run with alkenes to yield subst
cyclohexene products
H
i P
H =
c -
H
#Y
-
H - -
CH3
i
CHS
-
c Tolere
+ ,
Il heat
H
- H
H -c -
3-Cyclohexenyl
3-butadiene 3-buten-2-one
methyl kotone (96 %)
1.
This process called the dies alder
↳
is -
Cycloaddation reaction
not polar or radical
(diene Lover
The dienophile : alkene part of the dids Alder xn
diels alder An occurs quicker when the cherephile has an electron with drawing substituent
group.
also act as
alkynes can
dienophing
·
Stereospecific : a
single Product Stereoisomer is formed
P
endo :
Syn(cis)
iAn i
It
[Ychz
anti (trans)
a
exo :
t >
-
/j CO2CHy
-
H
Cis product
P It
H--achs
* t
Htz(
/
i &
H
-
CH3
Trans Product
Predict the following diels-alder vxn
i
"
draw the diene so that the
2nds at its 2 double bands are near the dienophile double bond ,
then form 2 single
bonds btwn the Partners Convert the 3 double bond , into
single bonds , and convert the former
Single bond of the diene into a double bond because the deenophile double bond is Cis to begin with the 2 attached
.
hydroging
Must remain Cis in the product
Conjugated compounds and ultraviolet spectroscopy
Conjugated compounds Compounds :
with alternating double and single bonds
if different independently but if
sat. are far from each other , they react
, they're closer
together they
,
can interact
Exy(
H # H
H
- I
H
H -yay
-
2
I I H Conjugated dienes can be made by using base-
H H
H induced elimination
it of HX from an allylic halide
Conjugated
diene
non
conjugated HA Br
diene +
NBS k JC (CH3) z
hr
* because more substituted alkenes ,
24 HOC(2Hzbe
are more stable and produce less heat Cyclohexene S-Bremocyclohexene 1,
3-Cyclohexadiene (76 %)
they also release less heat when thus
PH3
+H H
A3) 0 , - ↑
are added to water H
-
stability due to orbital hybridizati
&
c -
x ↑ Hexcc2
i
is OH
H
12 Hit H
It
one
thing that separates conjugated and non conjugated diens is that in
a conjugated diene the central (middle) single bond is shorter than a non
Conjugated one
i C Hy CH CHz
CH3-CH2CHe-CHa
. .
= -
CH =
T
There are differences between 147PPm 153 ppm
13 butadiene
Conjugated dienes and alkenes in
Butane
electrophilic addition runs when you add HC
O to an alkene adds the Cl
is this a cony-clone
to the mose Subst
Carbon .
So
2-methyl propere becomes
2-chloro-2-methyl Instead at
1-chloro-2methyl
Sometimes dienes two products , and
conjugated can get one will have the alkone
on the central carbon Br
↑ ↓
~
CyrH 3-Bromo-l-butene
H
=
-
+
H 11 % 1 2-
addition
j = c +=
- H #Y ,
H
H
it H LBY H
1-Bromo-2-butene
C-
c
=
-
yH 20
H %, 1-4-addition
1 , 3-butadiene ↓ it
, B
H
H H ↑* Br
BI H ↑
Y=c -
,
- H
C-
-
c
=
-
yH
H H
ItH ↓ Br
(example) give structures of the likely products from uyn of 1 equinent HCI with
2-methyl-1 3-cyclohexdiene ,
. Show both 1 , 2 and 1 , 4 adducts
Is 4 1 , 26 1 , 4
s HCI
-
> x
L
+
[T *
132 di
Imagine a run that can
give either or both Products of Band C
rxn at low temp (4GB(GFC)
Ax
B forms faster than 1 butcis
,
more stable than
L
B C B(4G ° (GB) Kinetic control
Because B forms faster than ( (lower temp : irreversable)
A
Bis the
Major
Product It doesn't matter If Cis more (faster) L ↳ (slower)
B
,
Stable than B at an irreversible reacti
C
. Product
The
depends on relative rates ,
not stability . Such rans are said
to be under Kinetic control
If we do the same reaction at a
higher temperature ,
both Processes
ore somewhat reversable
and reached Because
Cis It does not
equilibrium is .
more Stable than B ,
C is the
major Product ,
Matter that B bas the two one
(is slower than in equilibum
. The Product of a readily reversable xn
depends on
Stability ,
not relative rates . Such rans are said to be under equilibrum control =
thermo
dynam contine
A Thermodyname contral
↑ X
B , (higher temp ; reversable)
Summary : When we have lower temps and an Irreversable run. the
major product will
be determind by relative rates depend
.
When we higher temps and a reverssbe ran. the major product will
on
stability .
Kinetic control = Lower temp and irreversable ·
Thermodynamic control-higher temp and
Reversable
, The diel-alder Cycloaddition reaction
conjugated diens undergo an addition run with alkenes to yield subst
cyclohexene products
H
i P
H =
c -
H
#Y
-
H - -
CH3
i
CHS
-
c Tolere
+ ,
Il heat
H
- H
H -c -
3-Cyclohexenyl
3-butadiene 3-buten-2-one
methyl kotone (96 %)
1.
This process called the dies alder
↳
is -
Cycloaddation reaction
not polar or radical
(diene Lover
The dienophile : alkene part of the dids Alder xn
diels alder An occurs quicker when the cherephile has an electron with drawing substituent
group.
also act as
alkynes can
dienophing
·
Stereospecific : a
single Product Stereoisomer is formed
P
endo :
Syn(cis)
iAn i
It
[Ychz
anti (trans)
a
exo :
t >
-
/j CO2CHy
-
H
Cis product
P It
H--achs
* t
Htz(
/
i &
H
-
CH3
Trans Product
Predict the following diels-alder vxn
i
"
draw the diene so that the
2nds at its 2 double bands are near the dienophile double bond ,
then form 2 single
bonds btwn the Partners Convert the 3 double bond , into
single bonds , and convert the former
Single bond of the diene into a double bond because the deenophile double bond is Cis to begin with the 2 attached
.
hydroging
Must remain Cis in the product
