Faculty of Allied Medical Sciences
Organic chemistry
(MGOC-101)
Alkenes
Supervision:
Prof.Dr.Shehata El-Sewedy
Dr. Fatma Ahmed
Outcomes
By the end of this lecture, the students
will be able to
1-Recognize formula of alkenes
2-Known nomenclature of alkenes
3- learn to preparation of alkenes
4-Differentiate between reaction of alkenes
Alkenes
1-Alkenes are fully unsaturated hydrocarbons
2-General formula C2H2n
3-Double bonds (-C=C-)
4-Straight or branched chain.
Nomenclature
1-Common name
Alkyl +ene
(Prefix)
2-IUPAC name
1-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=c
3-Priority of numbering must be considered
4-The position of C=C must write
5-The name& position of substituent must write
6-For similar substituent add di, tri or tetra
EX:
√√√
XXX
√√√
xxx
Preparation of alkene
Dehydration of alcohol
Reaction of alkene
(1) Addition of Hydrogen Halides to
Alkenes
C
C
+ HX
C C
H
X
Eample
CH3CH CHCH3 + HCl
2-Butene
CH3CH2CHCH3
Cl
2-Chlorobutane
Addition to an Unsymmetrically substituted alkenes according for
Markovnikov’s
CH3CH
CH2 + HBr
CH3 CH CH2 + CH3 CH CH2
H Br
Br H
(80%)
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.
(20%)
CH3
H3C C + >
CH3
CH3
CH3
+
+
+
> CH3
H3C C > H C
H
H
Tertiary(3 ) > Secondary(2 ) > primary(1 ) > Methyl
Explanation for “Markovnikov’s rule”
CH3
CH3
C
CH2 + HCl
CH3 +
C
CH3
CH3
The stabilities of
carbocation:
(I) > (II)
CH3
CH2
H
(I) +
C CH2
H
Cl
CH3
CH3
Cl
CH3
CH3
C
CH2
Cl H
C
CH2
H
Cl
(II)
Electrophilic addition to an unsymmetrically substituted alkene give the more highly
substituted carbocation.
(2) Addition of Halogen to Alkenes
(CH3)2CHCH
CHCH3
+ Br2
CCl4
(CH3)2CHCH
Br
CHCH3
Br
Vicinal dihalide
(3) Oxidative cleavage of alkenes:
Ozonolysis of Alkenes
CH3
CH3
C
CHCH3
1) O3
2) H2O, Zn
CH3
CH3
C O+O C H
CH3
Quiz time
Complete
How can you prepare the following compound?
, 2-Chlorobutane ,Vicinal dihalide
Write the chemical formula for the following compounds?
Write the nomenclature for the following compounds?
Show more stable compound of (I) & (II) and why?
Student Question
Write the nomenclature for the following compounds?
How can you prepare the following compound?
, 2-Chlorobutane ,Vicinal dihalide
Write the chemical formula for the following compounds?
Complete
Assignments
Group A and Group B
Application of Alkenes in plastic
synthesis
Aya Salah- Omnia Gamal- Hanan Farg-Sarah
Fasal Hashem
Uses of propene in industry
Mohamad El Saber
Saad Mohamad El-sawi
Mohamad Ahmad Fouad
Mohamad Moawad
El hussein Mohsen -Adel Ahmed
Mahmoud Abd El- Mageed
carbocations
Mana Allah Gamal- Malak Atef-Yasmine Abd
ElHameed
Effect of Benzene on human Health
Haidy Adel- Ali Hassan
Hossam Hassan- Yehia Hamdy
Youssef Ali
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