review alkena alkuna
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Alkena
Qorry Dinnia Fatma (1118103010--)
Ardine Kumalasari (121810301017)
Nora Dwi Saputri (121810301021)
Zuni Dihliziah (121810301023)
Dewi Adriana Putri (121810301053)
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Hidrokarbon yang mengandung ikatan rangkap
C C
ALKENA
ikatan rangkap sebagai pusat reaktifitas
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Alkena Alifatik
Cn
H2n
Rumus Molekul Alkena
Alkena Siklik
CnH2n2
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TATA NAMA aLKENA
1. TRIVIAL (UMUM)
2. SISTEM IUPAC
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Common Name
Nama trivial adalah nama umum yang diberikan kepada beberapa
alkena. Sebagai contoh, etena mempunyai nama trivial etilena; promempunyai nama trivial propilena; dan 2-metilpropena mempunyaiisobutilena.
CH2 = CH2 CH3 CH=CH2 CH3 C=CH2
PropyleneEthyleneCommon:IUPAC: 2-MethylpropenePropeneEthene
Isobutylene
CH3
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Nama Sistematik Alkena
1. Temukan rantai terpanjang yang mengandung ikatan rangkap
beri nama seperti menamai alkana tetapi digunakan akhiraena.
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Nama Sistematik Alkena
3. Tandai posisi ikatan rangkap menggunakan nomor karbon ikatan rangkap yang
kecil. Tempatkan nomor tersebut sebelum menulis nama induk alkena. Jika te
lebih dari satu ikatan rangkap, gunakan akhiran diena, triena, dst.
1,4-Pentadiene 2-Methyl-1,3-butadiene
1,3-Cyclope
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Tata Nama Sikloalkena
Pada sikloalkena, ikatan rangkap dianggap menempati posisC2. Untuk substituen pertama harus memiliki penomoranmungkin
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Isomer Cis-Trans
Cis: hidrogen pada ikatan rangkap terletak pada satu sisi
Trans : hidrogen pada ikatan rangkap terletak pada sisi berlawanan
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Aturan Penandaan
Substituen dengan prioritas yang sama berposisi sama ma
tanda Z sedangkan jika posisinya berlawana diberi tanda E
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Aturan Penandaan E dan Z
Aturan yang digmemberikan urutan
aturan Cahn-Ingold-p
Aturan 1: Lihat ato
langsung pada karbon
lalu urutkan subs
berdasarkan nomor at
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Aturan Penandaan E dan Z
Aturan 2: Jika kedua gug
yang terikat langsung
sp2 sama (disebut tie)
digunakan sebagai d
atom yang terikat berik
diperoleh perbedaan pr
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Aturan Penandaan E d
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Aturan Penan
Aturarangk
samaikatandengdeng
rangk
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H2/PtO2
X2HX
H2
O
x2
H2O
1. OsO42. NaHSO3
1. O32. Zn, H3O+
1. Cl2, H2O2. Zn, H3O+
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Sintesis Alkena
Reaksi eliminasi pembentukan alkena yang paling umum adalahdehidrohalogenasi, lepasnya HX dari alkil halida, dan dehidrasi, le
dari alkohol. Dehidrohalogenasi biasanya terjadi pada alkil halida yang diperla
dengan basa kuat seperti kalium hidroksida. Contohnya ketikabromosikloheksana ditreatmen dengan KOH dalam larutan alkoho
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Reaksi Alkena
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I. Hidrogenasi pada alkena = reduksi dari ikatanp
C C + Y Z C C
Y ZReaksi adisi
C C + C C
H H
H2Pt, Pd,or Ni
catalyst
OH
O
OH
OH2, Ni
Asam (tak je
Asam s
(jen
REAKSI PADA ALKENA
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2. Addit Step 1: proton transfer from H3O
+to the alkene
++
+
intermediateA 2o carbocation
+O
H
HOH
H
CH3CH=CH2 CH3CHCH3
slow, ratedetermining ::
:
:
:+
+
+
An oxonium ion
H O HH
CH3CHCH3 O-H CH3CHCH3fast
:
:
:
++
+OH H
OH
H
H
H O HCH3 CHCH3 CH3 CHCH 3fast
OH:
:
:
:
Step 2: reaction of the carbocation (an electrophile) with water (anucleophile) gives an oxonium ion
Step 3: proton transfer to water gives the alcohol
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3. Addition of C
carried out with either the pure reagents or in an inert solven
addition of bromine or chlorine to a cycloalkene gives a trandihalocycloalkane
addition occurs with anti stereoselectivity; halogen atoms adopposite face of the double bond
Br2CH2 Cl2
Br
Br
Br
Br+
trans-1,2-Dibromocyclohexane(a racemic mixture)
Cyclohexene
+
CH3 CH=CHCH3 Br2 CH2Cl2 CH3CH-CHCH3
Br Br
2,3-Dibromobutane2-Butene
+
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Step 1: formation of a bridged bromonium ion interm
C C
Br
Br
C C
Br
C C
Br
C
B
The bridgeion retains
These carbocations are majorcontribu ting s tructures
3. Addition of C
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Step 2: attack of halide ion (a nucleophile) from the oppositethe bromonium ion (an electrophile) opens the three-memb
give the product
Anti (coplanar) orientation
of added bromine atoms
C C
Br
Br
B
B
N ewman p
of the p
C C
Br
Br-
Anti (coplanar) orientation
of added bromine atoms
C C
Br
Br-
CC
Br
BrB
B
New man p
of the p
3. Addition of C
4 ddi i f OCl
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Treatment of an alkene with Br2or Cl2in water forms a halohy
Halohydrin:a compound containing -OH and -X on adjacen
CH3CH=CH2 Cl2 H2O CH3CH-CH2
ClHO
HCl
1-Chloro-2-propanol (a chlorohydrin)
Propene
+++
4. Addition of HOCl a
4 Additi f HOCl
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reaction is both regiospecific (OH adds to the more substituted carbon) and
stereoselective both selectivities are illustrated by the addition of HOBr to 1-methylcyclopent
to account for the regioselectivity and the anti stereoselectivity, chemists pro
step mechanism in the next screen
2-Bromo-1-methylcyclopentanol
( a racemic mixture )
Br2/ H2O OH
1-Methylcyclopentene
+ H+
HBr
OH
HBr
4. Addition of HOCl a
4 Additi f HOCl
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Step 1: formation of a bridged halonium ion intermediate
Step 2: attack of H2O on the more substituted carbon opensmembered ring
C C
Br
O H
H
HR
OH
H H H
+
C C
Br
R HH H
::
:
:
:
:::
C C
Br
R HH H
C C
Br
R HH
C CR H
H H -Br-
bridge d bromoniumion
minor contribustructure
Br
Br:
:
:
:
:
:
:: :::
4. Addition of HOCl a
4 Additi f HOCl
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Step 3: proton transfer to H2O completes the reaction
H3 O+
+C C
Br
O H
H
H
R
H H
+
O H
H
C C
Br
O
H
H
H
R
H
4. Addition of HOCl a
5 O ti /R
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Oxymercuration followed by reduction results in hydration of a carb
carbon double bond oxymercuration
reduction
OH
HgOAc
NaBH4
OH
H
CH3COH
O
H
2-Pentanol
+
Acetic acid
+
Hg(OAc) 2 H2O
OH
HgOAc
CH
A
a
An o rganomercury
compound
Mercury(II)
acetate
1-Pentene
++ +
5. Oxymercuration/R
5 O ti /R
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Step 1: dissociation of mercury(II) acetate
Step 2: formation of a bridged mercurinium ion intermediate; a two-atom thre
center bond
5. Oxymercuration/R
5 Oxymercuration/R
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Step 3: regioselective attack of H2O (a nucleophile) on the bridged intermedopens the three-membered ring
Step 4: reduction of the C-HgOAc bond
5. Oxymercuration/R
5 Hydroboration/Ox
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Hydroboration:the addition of borane, BH3, to an alkene to form atrialkylborane
Borane dimerizes to diborane, B2H6
Borane
H BH
H
3CH2=CH2 CH3CH2 BCH2CH3
CH2CH3
Triethylborane(a trialkylborane)
+
Borane D iborane
2BH3 B2H6
5. Hydroboration/Ox
22
Tetrahydrofuran (THF)
-++O O BH3B2 H6
BH3 THF
:::
5 Hydroboration/Ox
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Hydrogen peroxide oxidation of a trialkylborane
step 1: hydroperoxide ion (a nucleophile) donates a pair of electrons to boron (an
step 2: rearrangement of an R group with its pair of bonding electrons to an adjacatom
B
R
R
R O O H B
R
R O
R
O-H-
+
B
R
R
R B
R
R
R O-O-H B
R
R
R O O HB
R
R
R O O H+
A trialkylborane
(an electroph ile)
Hydroperoxide ion(a nucleophile)
5. Hydroboration/Ox
5 Hydroboration/Ox
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step 3: reaction of the trialkylborane with aqueous NaOH gives thsodium borate
( RO)3 B 3NaOH 3ROH + Na3 BO3
A trialkylborate Sodiu m borate
+
5. Hydroboration/Ox
6 Oxidation/Reduct
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three balanced half-reactions
CH3 CH=CH2 CH3 CHCH3+ H2 O
Propene 2-Propanol
OH
CH3 CH=CH2 CH3 CHCH2+ 2 H2 O + 2 H+ + 2 e -
Propene 1,2-Propane diol
HO OH
CH3 CH2 CH3+ 2 H+ + 2 e -
Propene
CH3 CH=CH2
Propane
6. Oxidation/Reduct
7 Oxidation with OsO
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OsO4oxidizes an alkene to a glycol, a compoOH groups on adjacent carbons
oxidation is syn stereoselective
OsO4
O
Os
O O
O
NaHSO3H2O
cis-1,2-Cy (a c
A cyclic osmate
7. Oxidation with OsO
7 Oxidation with O
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Treatment of an alkene with ozone followed by a weak reducing ageC=C and forms two carbonyl groups in its place
Propana(an aldehy
Propanone(a ketone)
2-Methyl-2-pentene
CH3O O
CH3C=CHCH2CH31. O32. (CH3)2S
CH3CCH3 + HCCH2CH
7. Oxidation with O3
7 Oxidation with O3
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the initial product is a molozonide which rearranges to an isomeric ozonide
Acetal
2-Butene
CH3CH=CHCH3O3
(CH3)2S CH3
CH3CH-CHCH3
O OO
O O
CO
CH
CH3
H
H3C
A molozonide
An ozonide
7. Oxidation with O3
8 Reduction of Alke
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Most alkenes react with H2in the presence of a transition metal give alkanes
commonly used catalysts are Pt, Pd, Ru, and Ni
the process is called catalytic reductionor, alternatively, catalytic
hydrogenation
addition occurs with syn stereoselectivity
+ H2Pd
Cyclohexene Cyclohexane
25C, 3 atm
8. Reduction of Alke
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Bromination of cis-2-Butene
reaction of cis-2-butene with bromine forms bridged bromoniummeso and identical
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Bromination of cis-2-Butene
attack of bromide ion at carbons 2 and 3 occurs with equal probenantiomeric products as a racemic mixture
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Bromination of trans-2-Butene
reaction with bromine forms bridged bromonium ion intermediatenantiomers
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Bromination of trans-2-Butene
attack of bromide ion in either carbon of either enantiomer givedibromobutane
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Oxidation of 2-Butene
OsO4oxidation of cis-2-butene gives meso-2,3-butanediol
C CH
H3 C
H
CH3
OsO4
ROOH
CHO
COH
HCH3
H3CH
HO
C
HH3 C
C
OH
CH3
H
cis-2-Butene (achiral)
identa mecomp
(2S,3R)-2,3-Butanediol
(2R,3S)-2,3-Butanediol
2
2
2
3
3
3
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Oxidation of 2-Butene
OsO4oxidation of an alkene is stereospecific
oxidation of trans-2-butene gives the enantiomers of 2,3-butanediol amixture (optically inactive)
and oxidation of cis-2-butene gives meso 2,3-butanediol (also optica
C
H
CH3C
H3 C
H OsO4
ROOH
C CCH3
H
OH
H3 CH
HO
C
HH3 C
CH
CH3
OHHO
(2R,3R)-2,3-Butanediol
(2S,3S)-2,3-Butanediola pair oenantioa racemmixtur
trans-2-Butene
(achiral)
32
2
2
3
3
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ALKUNA
Senyawa hidrokarbon yang mengandung ikatan rangkap tigkarbon.
Rumus umum untuk senyawa alkuna adalah CnH2n-2
Tatanama Alkuna
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Tatanama adalah suatu cara sistematik untuk memberi nama susenyawa yang direkomendasikan oleh International Union of P
and Applied Chemistry (IUPAC)
Penamaan alkuna mengikuti aturan umum penamaan senyahidrokarbon . Digunakan akhiran una, dan posisi ikatan rangditandai dengan pemberian nomor di depan nama induk
Alkuna Rantai Lurus
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Dihitung jumlah atom C-nya
Dilihat posisi ikatan rangkapnya (pada nomor kecil)
Etuna 2-butuna
Contoh:CH3
CH3
Alkuna dengan Cabang
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g g
o Ditentukan rantai induk dan rantai cabangnya. Rantai indadalah rantai terpanjang yang mengandung ikatan rangk
tiga.o Diberi nomer setiap atom sehingga nomer terkecil terletak pa
atom C yang memiliki ikatan rangkap tiga
Contoh :
2,2-dimetil-3-heptuna
Alkuna Majemuk
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j
Alkuna majemuk adalah senyawa alkuna yang memiliki dua atau lebikatan rangkap tiga
1,3-diuna 1,3,5-triuna
Contoh:
Penamaan Enuna
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Senyawa yang memiliki ikatan rangkap dua dan ikatan rangkap tdisebut enuna
Penomoran rantai enuna dimulai dari ujung terdekat dengan ikarangkap, entah itu ikatan rangkap dua atau ikatan rangkap tiga.
CH2 CH
7
6
5
4
3
2
1
1-hepten-6-una
Sintesis Alkuna
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Alkuna dapat diperoleh melaluireaksi aliminasi HX dari alkil
halida dengan cara yang samadengan pembuatan alkena.
Perlakuan 1,2-dihaloalkana(vicinal dihalida) dengan basakuat seperti KOH atau NaNH2menghasilkan dua kali reaksieliminasi HX dan membentukalkuna.
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Sekian
Terimakasih .
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