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Prepared by:

Arbanah Muhammad

arbanah@micet.unikl.edu.my

CH 2_3: UNSAU!A"#H$#!%CA!&%N ' Alkyne(

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). Alkyne(

2. N*menclature %+ Alkyne(

3. Pr*pertie( %+ Alkyne(

,. Synthe(i( %+ Alkyne(-. !eacti*n( %+ Alkyne(

TOPIC COVERED:

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Alkynes

Unsaturated hydrocarbon

Contain carbon carbon triple bonds

Alkynes

General formula

Aliphatic hydrocarbons

!CC!

CnH2n2

Example:

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1. Similar to alkanes and alkenes

Density

Boilin point

!eltin point

In"rease as t#e

n$m%er o& "ar%on

in"rease.

P#ysi"al properties

'. Sol$%ility

( Sol$%le in nonpolar sol)ent

( *ot sol$%le in +ater

,. -o+ density%oilin point and meltin point

/. Properties )ary %ased on "#ain si0e

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-inear

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*amin Alkynes

Similar to Alkenes:

1. Longest chain must contain the triple bond

2. Number of carbons so that the triple bond has the lowestpossible value

. !ndicate the position of the triple bond

". Change ending to - yne

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"/erci(e:

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"/erci(e: #ra0 the (tructure +r*m the +*ll*0in1 UPAC

name:

(propyl '( o"tyne

'(trimet#yl ,( #eptyne

1(%romo#ex(,(yne

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Synt#esis o& alkynes

De#ydro#aloenation

2eminal di#alide

Vi"inal di#alide

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Synt#esis o& alkynes

De#ydro#aloenation o& di#aloalkane

'*a*3'

4

C C

4

3

3

R R5

'*3,

6 RC CR7

6

2eminal di#alide

Sodi$m amidealkyne

Ammonia

'*a4

Sodi$m #alide

6

i. eminal dihalide

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Rea"tion:

R8C C8R7

1ststep

'ndstep

43

*a*3'

4

C C

4

3

3

R R5 6

*3,

*a466

*a*3'6

*3, *a466

R8C C8R7

43

R8C C8R7

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'*a*3'

4

C C

4

3 3

R R5

'*3,

6 RC CR7

6

Vi"inal di#alide

Sodi$m amidealkyne

Ammonia

'*a4

Sodi$m #alide

6

De#ydro#aloenation o& di#aloalkane

ii. Vi"inal di#alide

Synt#esis o&alkynes

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Exer"ise:

Pro)ide a rea"tion to prod$"e o"tyne &rom

t#e rea"tion o&

19 2eminal di#aloalkane

'9 Vi"inal di#aloalkae

it# sodi$m amide

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Rea"tion o& alkynes

1. 3ydroenation'. De#ydro#aloenation

,. 3ydration

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Rea"tion o& alkynes

"atalyst ; Pt Pd *i or R#

"atRC CR7 6 '3'

1. 3ydroenation o& Alkynes

Alkyne

RC CR7"at

3'

"at3'

1ststep

'ndstep

"is alkene

R R5

3 3

CC6

6

Alkane

RC

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=ollo+ !arkoniko)5s r$le

Alkynes are sli#tly less rea"ti)e t#an alkenes

RC

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C3,>C3'9,C C3 3Br

3Br

1ststep

'ndstep

6

6

C3,>C3'9,C C3

3Br

C3,>C3'9,C C3

3Br

Rea"tion o& alkynes

Br

C3,>C3'9,C C3

''(di%romo#exane

3Br

3

Example

1(#exyne3ydroen

%romide'(%romo(1(#exene

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6 'Cl'

Cl

Cl

C3C C3,3C CC3,

,. 3aloenation o& alkynes

Rea"tion o& alkynes

"atalyst

Catalyst; AlCl,? =eCl,

tetra"#loropropane

1(propene

RC

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Rea"tion o& alkynes

RC CR7 3'O6

/. 3ydration o& alkynes

RC3'CR7

O

3'SO/

3SO/

R5 ; alkyl@ etone

R5 ; 3@ Alde#yde

C3,C3'CC3,C3,C3'C C3

O

Example

1(%$tyne '(%$tanone

3'O63'SO/

3SO/

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Exer"ise:

#at is t#e prod$"ts o& t#e rea"tion o&

#exyne +it#:

19 3ydroen

'9 3ydroen &lo$ride

,9 C#loride

/9 ater