Propyne is a colorless gas with the chemical formula C3H4. It has a sweet odor and exists as a triple bonded alkyne. The document discusses propyne's physical properties such as its molar mass, boiling point, and density. It also examines propyne's chemical properties including its addition, substitution, oxidation and combustion reactions. Propyne undergoes addition reactions through halogenation and hydrohalogenation. It is prepared through the separation of dihalogen in a basic alcohol solution or by dehydrogenating propane twice. Finally, the document notes propyne's applications as a less toxic rocket fuel and in organic synthesis reactions.

1. Propyne
By Lê Hà Minh Châu,Tô Phạm
Quỳnh Mai
I. Introduction
II. Physical properties
III.Chemical properties
IV. Preparation
V. Applications

2. Introduction

3. Introduction
• Chemical formula: C3H4
• Structure:
• Name:
+ IUPAC name: Prop-1-yne
+ Common names: Propyne,
Methylacetylene.

4. Physical
properties

5. Physical properties
Title Properties
Molar mass 40.0639 g/mol
Appearance Colorless gas
Odor Sweet
Density 0.53 g/cm3
Melting point −102.7 °C (170.5 K)
Boiling point −23.2 °C (250.0 K)

6. Chemical
properties

7. 1. Addition reaction
• A triple bond adition reaction can
take place in two stages
• Markovnikov’s law: The rich get
richer.
• Similar to addition reaction of
alkenes
• 1 pi bond becomes 2 sigma bonds.
• Usually exothermic

8. a) Halogenation (X2)
• Cl2 and Br2 add to alkynes to form
vinyl dihalides.
• May add syn or anti, so product is
mixture of cis and trans isomers.
• Difficult to stop the reaction at
dihalide.

9. b) Hydrohalogenation (HX)
•Markovnikov’s law:H atoms of hydrogen
halides into atoms C
double bind more H atoms.
•HCl, HBr, and HI add to alkynes to form
vinyl halides.
•If two moles of HX is added, product is a
geminal dihalide.

10. c) Hydrogenation (H2)

11. d) Hydration (H2O)
• Mercuric sulfate in aqueous sulfuric
acid adds H-OH to one pi bond with a
Markovnikov orientation, forming a
vinyl alcohol (enol) that rearranges to
a ketone.
• Hydroboration-oxidation adds H-OH
with an anti-Markovnikov orientation,
and rearranges to an aldehyde.

12. 3. Substitution reaction
• Substitution on the alkyne reaction involves the
release of H atoms bound to the C C bond at the
end of the chain of alkyne
CH≡C-CH3 + AgNO3/NH3 → Ag-C≡-C-CH3↓ + NH4NO3
silver asetilide

13. 4. Oxidation reaction
a, KMnO4
• Dilute, neutral solution of KMnO4
• Oxidizes alkynes to a diketone.
• Warm, basic KMnO4 cleaves the
triple bond.
• Ozonolysis, followed by hydrolysis
cleaves the triple bond.

14. 4. Oxidation reaction
b, Combustion reaction
• Combustion propyne with a limited amount
of O2, CO or C will result in:
C3H4(g) + 4O2(g) 3CO2(g) + 2H2O(g)

15. Preparation

16. Preparation
• The separation reaction of dihalogen in
the solution of base and alcol
• Two times dehydrogenation of propane

17. Applications

18. Applications
a, Use as a rocket fuel
• Less toxic
• Advantageous for craft intended
for low Earth orbital operations
b, Organic chemistry
• Organic synthesis
• Used to synthesize vitamin E

19. Thank you
for listening!