Organic chemistry

Faculty of Allied Medical Sciences

(MGOC-101)

Supervision:Prof.Dr.Shehata El-Sewedy

Dr. Fatma Ahmed

Alkynes

Outcomes By the end of this lecture, the

students will be able to

1-Recognize formula of alkynes2-Known nomenclature of alkynes 3 -learn to preparation of alkynes

4-Differentiate between reaction of alkynes

Alkynes

2-General formula CnH2n-2

3-Triple bonds 4-Straight or branched chain.

1-Alkynes are fully unsaturated hydrocarbons

C C as function group of alkyne

Nomenclature1-Common name

C CH H Acetylene or ethyne

C CH3C H

C CH3C CH3

Methyl acetylene or propyne

Dimethyl acetylene2-IUPAC name

Position+prefix+yne

C CH3C CH2CHCH3

CH3

1 2 3 4 5 6

5-Methyl-2-hexyne

CH3C

CH3

CH3

CH2CH2 C CH

5,5-Dimethyl-1-hexyne

123456

Alkyl +yne

Synthesis of alkyne1-Dehydrohalogenation of alkyl dihalide by using

NaNH2 (sodamide)

C CR R

BrBr

H H

NaNH2NH3 + NaBr + C C

R

R

Br

H

NaNH2

R C C R

Alkyne

+ NH3 + NaBr

Vicinal dihalide

R= CH3, C2H5.......... ,

2-Dehalogenation of alkyl tetrahalide

C CR R

BrBr

Br Br

R C C R

Alkyne

+ ZnBr2

2 Zn

AcOH

R=CH3,C2H5,……..

EX:

C CH3C CH3

BrBr

Br Br

H3C C C CH3

2-Butyne

+ 2ZnBr2

2 Zn

AcOH

2,2,3,3-tetrabromobutane

Reaction of alkyne1-Addition of water (Hydration of alkyne)

C CH H + HOHdil H2SO4

HgSO4

C CH H

O

H

H

enol unstable

C CH3

O

H

Acetaldehyde

Ketoform stable

Keto-enol tautomerism

2-Addition of hydrogen

C CH3C CH3+ H2Nior Ptor Pd

HC C

HH3C CH3

2-Butene

H2 /Ni

H2C

H2CH3C CH3

n-Butane

C CH3C CH2CH3

O3 /Zn, AcOH

or

conc.KMnO4/ /OH

followed by H

CH3-C

O

OH

Acetic acid

+ CCH2CH3

O

HO

Propanoic acid

3-Oxidative cleavage of alkyne

Quiz time

Write the chemical formula for the following compounds?

How can you prepare the following compound?

5,5-Dimethyl-1-hexyne

propyne

Butyne

Butyne

AcetaldehydePropanoic acid

Acetic acid

Student Question

Complete

NaNH2NH3 + NaBr + C C

CH3

CH3

Br

H

NaNH2

+ +

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

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

C CH3C CH3

BrBr

Br Br

+2 Zn

AcOH.......................... .....................

C CH H +dil H2SO4

HgSO4

C CH3

O

H

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

C CH3C CH2CH3

O3 /Zn, AcOH

+...................... .....................

Write the nomenclature for the following compounds?

C CH3C CH2CHCH3

CH3

CH3C

CH3

CH3

CH2CH2 C CH

C CH3C CH3

AssignmentsGroup A and Group B

Mahmoud Mohamad- Amir Mohamad- Mervat Abd El-Halim- Mervat Essam – Yasmine Rabee

Applications of Alkynes

Noor El-Din AdelMohamad Abd El FatahAli Mahmoud Ahmad

Uses of Butyne in industry

Naamat Hafez Mana Allah MostafaPassant Ahmad Hamza

Applications of propanoic acid

Ashraf MohamadEl Amir Said TawfikIbrahim ShahaatAhmad Mahmoud SherifRaafat AbdAllah

Uses of alkynes in industry

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