Organic chemistry

Faculty of Allied Medical Sciences

(MGOC-101)

Supervision:Prof.Dr.Shehata El-Sewedy

Dr. Fatma Ahmed

Alkenes

Outcomes By the end of this lecture, the

students will be able to1-Recognize formula of alkenes

2-Known nomenclature of alkenes 3 -learn to preparation of alkenes

4-Differentiate between reaction of alkenes

Alkenes

2-General formula C2H2n 3-Double bonds (-C=C-) 4-Straight or branched chain.

1-Alkenes are fully unsaturated hydrocarbons

Nomenclature

H2C CH2

Ethylene

CH3CH CH2

Propylene

CH3C CH2

CH3

Iso-butylene

1-Common name Alkyl +ene

(Prefix)

2-IUPAC name1-Select the long continuous chain which contain

c=c as parent name (alkyl+ene) or (prefix+ene)2-Number the chain from side which give lowest

number for c=c3-Priority of numbering must be considered

-oic -al -one -ol -ene -yneCOOH>CHO>CO>OH>C=C>C C >RX

4-The position of C=C must write5-The name& position of substituent must

write6-For similar substituent add di, tri or tetra

EX:

H2C CHCH2CH31 2 3 4

1-Butene

H2C CHCH2CH31234

3-Butene √√√XXX

CH3CH CHCH2Cl1234

1-Chloro-2-butene

CH3C CHCHCH3

CH3

OH

CH3C CHCHCH3

CH3

OH

12345

4-Methyl-3-penten-2-ol

1 2 3 4 5

2-Methyl-3-penten-4-ol √√√xxx

1

2

3

4

5

6

3-Hexene

1 23

45

6

4-Ethyl-2-methyl-1-hexene

Preparation of alkeneDehydration of alcohol

C

OH

D C

C B

H

AH2SO4

-H2OCD C

C B

A

EX:

CH3-CH-CH2

HOH

H2SO4

-H2OCH3-CH CH2

Propene

Reaction of alkene(1 )Addition of Hydrogen Halides

to Alkenes C C + HX C C

H X

+ HClCH3CH CHCH3 CH3CH2CHCH3

Cl2-Butene 2-Chlorobutane

Eample

CH3CH CH2 + HBr CH3 CH CH2HBr

+ CH3 CH CH2H Br

Markovnikov’s Rule: In the addition of HX to an

alkene, the H attaches to the carbon with fewer alkyl groups and X attaches to the carbon

with more alkyl groups.

Addition to an Unsymmetrically substituted alkenes according for Markovnikov’s

(80%) (20%)

H3C

CH3

CH3

C+ H3C

CH3

H

C+ H

CH3

H

C+ CH3+

> > >

Tertiary(3 ) > Secondary(2 ) > primary(1 ) > Methyl

C CH2CH3

CH3H

+

C CH2CH3

CH3

+

H

Explanation for “Markovnikov’s rule”

C CH2 + HClCH3

CH3

Cl-

C CH2CH3

CH3HCl

Cl-

C CH2CH3

CH3 H Cl

(I)

(II)

The stabilities of carbocation:

(I( > )II)Electrophilic addition to an unsymmetri-

cally substituted alkene give the more highly substituted carbocation.

(2 )Addition of Halogen to Alkenes(CH3)2CHCH CHCH3 + Br2

CCl4 (CH3)2CHCH CHCH3

Br Br

Vicinal dihalide

(3 )Oxidative cleavage of alkenes:Ozonolysis of Alkenes

CCH3

CH3CHCH3

1) O3

2) H2O, ZnC

CH3

CH3O + O C

CH3H

Quiz time

CompleteH2SO4

-H2OCH3-CH CH2.....................

How can you prepare the following compound?Propene ,2-Chlorobutane ,Vicinal dihalide

+ HClCH3CH CHCH3 .......................

+ Br2CCl4 (CH3)2CHCH CHCH3

Br Br

............................

Write the chemical formula for the following compounds? 4-Ethyl-2-methyl-1-hexene4-Methyl-3-penten-2-olIso-butylene

Write the nomenclature for the following compounds?

CH3C CHCHCH3

CH3

OH

CH3CH CHCH2ClCH3C CH2

CH3

C CH2 + HClCH3

CH3

C CH2CH3

CH3HCl

C CH2CH3

CH3 H Cl

(I)

(II)

Show more stable compound of (I) & (II) and why ?

Student Question

Write the nomenclature for the following compounds?

CH3C CHCHCH3

CH3

OH

CH3CH CHCH2ClCH3C CH2

CH3

CH3CH CH2 H2C CHCH2CH3

CH3CH2CHCH3

Cl

CompleteH2SO4

-H2OCH3-CH CH2.....................

How can you prepare the following compound?Propene ,2-Chlorobutane ,Vicinal dihalide

+ HClCH3CH CHCH3 .......................+ Br2

CCl4 (CH3)2CHCH CHCH3

Br Br

............................

Write the chemical formula for the following compounds?4-Ethyl-2-methyl-1-hexene

4-Methyl-3-penten-2-olIso-butylene

AssignmentsGroup A and Group B

Aya Salah- Omnia Gamal- Hanan Farg-Sarah Fasal Hashem

Application of Alkenes in plastic synthesis

Mohamad El SaberSaad Mohamad El-sawiMohamad Ahmad FouadMohamad MoawadEl hussein Mohsen -Adel AhmedMahmoud Abd El- Mageed

Uses of propene in industry

Mana Allah Gamal- Malak Atef-Yasmine Abd ElHameed

carbocations

Haidy Adel- Ali HassanHossam Hassan- Yehia HamdyYoussef Ali

Effect of Benzene on human Health

Recommended textbooks:1-Raymond Chang. Chemistry: An introduction to organic chemistry. 10th ed. 2009 2008

2-Zumdehl. Organic Chemistry; study guide and solution manual. 2008