review alkena alkuna

8/11/2019 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 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 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


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 .

review alkena alkuna

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