Alkenes
Chapter Name : Hydrocarbons |
Sub Topic Code : 102_11_13_03_04 |
Topic Name : Alkenes |
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Sub Topic Name : Preparation From Alkynes |
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Introduction
In organic chemistry, an alkene is an unsaturated chemical compound containing at least one carbon–carbon double bond. The simplest acyclic alkenes, with only one double bond and no other functional groups, known as mono-enes, form a homologous series of hydrocarbons with the general formula CnH2n.
Pre-Requisites:
Alkenes
Activity:
Raincoats.
Real Life Question:
What are alkenes?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| alkyne | an unsaturated hydrocarbon which has at least one carbon—carbon triple bond between two carbon atoms. The simplest acyclic alkynes with only one triple bond and no other functional groups form a homologous series with the general chemical formula CnH2n-2. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| alkenes | Alkenes are used for artificial ripening of fruits, as a general anesthetic, for making poisonous mustard gas (War gas) and ethylene-oxygen flame. |
Real life uses :
Making industrial ethanol and further oxidation to ethanoic acid.
Places to visit :
Chemistry laboratory.
Practical examples around us
| Examples | Explainations |
|---|---|
| Propene | Propene, also known as propylene or methyl ethylene, is an unsaturated organic compound having the chemical formula C3H6. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. |
What you learn in Theory:
Reduction of alkynes is a useful method for the stereo selective synthesis of disubstituted alkenes. If the cis-alkene is desired, hydrogenation in the presence of Lindlar's catalyst (a heterogeneous catalyst that consists of palladium deposited on calcium carbonate and treated with various forms of lead) is commonly used, though hydroboration followed by hydrolysis provides an alternative approach. Reduction of the alkyne by sodium metal in liquid ammonia gives the trans-alkene.
What you learn in Practice:
The natural sources of alkenes are natural gas and petroleum.