GROUP MEMBERS :

-MUHAMAD SAHLI B MUDA-NURUL HANA BALQIS BAHAROM-NAPSIAH ABDUL RAHMAN

ALKYNESNaming and physical properties of alkynes

INTRODUCTION TO ALKYNES

Contain a C-CTriple bonds

Also called ACETYLENES bcoz

they are derivatives of acetylene, the simplest

alkyne

Hydrocarbon(only have C and H)

A triple bond gives alkynes 4 fewer H than

alkane.

Contributes two elements of unsaturation

acetylene

ethylacetylene

dimethylacetylene

DERIVATIVE OF ACETYLENES

ETHYNE

CnH2n-2

MOLECULAR FORMULA OF ALKYNES

GENERAL MOLECULAR

FORMULA

NOMENCLATUREOF ALKYNES

IUPAC names

Find longest continuous chain of carbon atoms includes the triple bond

Change the –ane ending of parent alkane to -yne

Chain is numbered from end closest to

triple bond

Substituents are given numbers to indicate

their locations

When additional func. Group present, suffix combined to produce compound names.

EXAMPLES

H3C C

CH3

C C CH2 C CH3

Br

H H

2-butyne

Ethyne (acetylene)

6-bromo-2-methyl-3-heptyne

IUP

AC

NA

ME

OF

AL

KY

NE

S

1-butyne or but-1-yne

5-methyl-2-hexyne or5-methylhex-2-yne 

3-methyl-1-butyne

cyclohexylethyne

1-penten-4-yne

3-butyn-2-ol

NAMING ALKYNES WHEN ADDITIONAL FUNCTIONAL GROUP ARE PRESENT

COMMON NAME

Describe alkynes as derivatives of

acetylene

Can be named as molecule of acetylene with one or

two alkyl substituents

examples

acetylene

dimethylacetylene

diphenylacetylene

COMMON NAME OF ALKYNES

Terminal alkynes Internal alkynes

TYPE OF ALKYNES

1-butyne 2-butyne

VISUAL OF NAMING ALKYNES

EXERCISEnomenclature

Click on the diagram to watch animation

PHYSICAL PROPERTIESOF ALKYNES

CONTINUE

PHYSICAL PROPERTIES OF ALKYNES

alkynes are non-polar and are insoluble in water but soluble in non-polar organic solvents.

Boiling PointsCompared to alkanes and

alkenes, alkynes have a slightly higher boiling point.

AcidityThe acidity of terminal alkynes

compared to alkenes and alkanes are stronger. 

PHYSICAL PROPERTIES OF

ALKYNES

Alkynes are colorless

Acetylene possesses a pleasant odor when

pure.

liquid acetylene is highly explosive.

LET’S THINK AND ANSWER

THE QUIZ!!

CLICK HERE TO ANSWER QUIZ