this Organic Chemistry II class notes builds on the foundations of Organic I, diving deeper into complex reactions and mechanisms, such as aromatic substitution, carbonyl chemistry, and reactions involving carboxylic acids and their derivatives. The course emphasizes multi-step synthesis, advanced ...
, 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
(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
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