ALKYNES
Pharm 122L-Preliminary Term
Prepared by: Mary Grace S. Biagtan, RP h, MS P harm
TABLE OF 01
CONTENTS INTRODUCTION
02
PHYSICAL PROPERTIES
03
APPLICATION
ALKYNE a hydrocarbon that contains a
carbon–carbon triple bond
Diyne: two triple bonds
e..g.: 6-methylhepta-1,4-diyne
Alkyne: CnH2n-2
GENERAL FORMULA
Ethyne: C2H2 & Propyne C3H4
Cycloalkyne: CnH2n-2
Cyclooctyne: C8H14
non-polar colorless gas: 3 carbons
insoluble in water liquid: 4-8 carbons
density lower than water solid: 9 carbons and more
ethyne lighter than air
boiling point increases with mass
highest BP among the HC due to the presence of triple bond
Application
1. Ethyne
2. Terbinafine
3. Efavirenz
4. Synthetic Alkynes for Parkinson’s Disease
5. Synthetic Alkynes as Birth Control
1. Ethyne
• AKA: Acetylene
• “oxyacetylene torch” that gives an extremely hot
flame (about 3000°C)
• stored in maroon-coloured cylinders
Preparation of Acetylene
CaC2 + 2H2O → Ca(OH)2 + C2H2
• colourless gas with a garlic like odour
• Specific gravity: 0.9
• ignition temperature: 325 °C
2. Terbinafine
• BN: Lamisil
• Classification: Anti-fungal
• Indications: for superficial skin infections such as jock itch,
athlete's foot, and ringworm
3. Efavirenz
• antiviral medicine that prevents human immunodeficiency
virus (HIV) from multiplying in the body
• CNS effects (confusion, depersonalization, abnormal dreams)
usually seen on day 1
4. Synthetic Alkynes For Parkinson’s Disease
• Parkinson’s disease is a degenerative condition characterized
by tremors
• Etiology: destruction of brain cells producing dopamine
Selegiline & Rasagiline
• MOA: inhibiting an enzyme that oxidizes dopamine and
thereby increasing its availability in the brain
• Selegiline metabolite: similar structure to methamphetamine
• psychiatric and cardiac effects
5. Synthetic Alkynes as Birth Control
• Natural hormones: Estradiol and Progesterone
• Estradiol: secondary sex characteristics in
women
• Progesterone: continuation of pregnancy
4. Synthetic Alkynes as Birth Control
• Ethinyl estradiol: prevents ovulation
• Norethindrone: makes it difficult for a fertilized egg
to attach to the wall of the uterus.
• Mifepristone: abortifacient
• Levonorgestrel/Morning-After Pill: an emergency
contraceptive pill; prevents pregnancy if taken within
a few days of conception
Thank you for your time
and attention!
ALKYNES
Pharm 122L-Preliminary Term
Prepared by: Mary Grace S. Biagtan, RP h, MS P harm
Chemical Reactions
1.Combustion
2.Hydrogenation
3.Hydrohalogenation
4.Halogenation
5.Hydration
6.Oxidation
7.Formation of Metal Acetylides
8.Alkylation
1. Combustion
●oxy-acetylene produces a flame temperature of 3150 °C,
making it the hottest of all the fuel gases and the only
fuel gas that can weld steel
2C2H2 + 2O2 → 4CO2 + 2H2O
2. Hydrogenation
●dihydrogen (H2) is added to alkynes in the presence of catalysts
such as Pt, Pd or Ni, alkenes are first formed which react further
with another molecule of dihydrogen to form alkane
Prop-1-yne Prop-1-ene Propane
CH≡CH + H2 → CH2=CH2 → CH3-CH3
Ethyne Ethene Ethane
3. Hydrohalogenation
●addition of hydrogen halide to produce halogenated
alkene
●apply Markovnikov rule
Prop-1-yne 2-bromoprop-1-ene
4. Halogenation
●addition reaction with halides to produce dihalogenated
alkene
Ethyne 1, 2-dibromoethane 1,1,2,2-tetrabromoethane
5. Hydration
●addition of water in the presence of catalysts
●catalysts: HgSO4 (mercury bisulphate) and H2SO4
●OH group adds to the more highly substituted carbon
and the -H attaches to the less highly substituted one
But-1-yne Butan-2-one
5. Hydration
●Products: enol-carbon–carbon double bond with an OH group
bonded to one carbon converted to ketone-contains a carbonyl
group (C=O) bonded to 2 HC
●Keto–enol interconversion or Tautomerization: Interconversion of
the tautomers
●Tautomers: constitutional isomerism differ only in the location of
double bond and a hydrogen.
5. Hydration
Hex-1-yne Enol Tautomerization Hexan-2-one
6. Oxidation
●cleaved by reaction with powerful oxidizing agents such as ozone
or KMnO4
●Internal: 2 carboxylic acids(C=OOH)
●External: carboxylic acid (C=OOH) + Carbon dioxide
Visual Chemical Tests for Alkenes and Alkynes
●Hexene or Hexyne?
●presence of terminal acetylene (one in which the
triple bond is on the end of the hydrocarbon chain)
●form an insoluble precipitate when treated with
certain metal ions, particularly Silver and copper in
basic solution (aqueous ammonia)
●Product: Metal Acetylide
Visual Chemical Tests for Alkenes and Alkynes
7. Formation of Acetylides
Formation of Copper Acetylide
C2H2 + 2NH4OH + 2CuCl → C2Cu2 (red ppt.)+ 2NH4Cl + H2O
Formation of Silver Acetylide
C2H2 + 2NH4OH + AgNO3 → C2Ag2 (silver ppt.) + 2NH4NO3 + 2H2O
8. Synthesis using Acetylide Ions
●forms a carbon–carbon bond is the reaction of an
acetylide ion with an alkyl halide or;
●Alkylation reaction: attaches an alkyl group to a species
Acetylide Alkyl Halide Hept-3-yne
8. Synthesis using Acetylide Ions: Alkylation
Hex-1-yne Bromobutane Dec-5-yne
But-1-yne Chloropropane Hept-3-yne
Thank you for your time
and attention!
