Preparation of Alkanes, Alkynes, and Alkenes Notes of Class 11th and NEET-UG 🎨

Hydrocarbons: A Perfect Notes of Alkanes, Alkynes, and Alkenes for Class 11th and NEET-UG

Introduction:

Welcome to the exciting world of hydrocarbons, where carbon and hydrogen dance together to create a myriad of compounds. In this beginner-friendly guide, we'll explore the step-by-step process of preparing alkanes, alkynes, and alkenes, spiced up with easy-to-understand examples.

1. Alkanes: The Simple Saturations

Alkanes are like the chillers of the hydrocarbon family, keeping it simple with single carbon-carbon bonds. Imagine turning an unsaturated pal into a laid-back saturated friend - that's hydrogenation!

Example: Transforming Ethene into Ethane

${\text{C}}_2{\text{H}}_4+{\text{H}}_2\underset{\text{Pt}}{\overset{\text{Catalyst}}{\to }}{\text{C}}_2{\text{H}}_6$

Here, ethene (C₂H₄) kicks back with hydrogen (H₂) using a platinum (Pt) catalyst, becoming ethane (C₂H₆), a relaxed saturated alkane.

2. Alkynes: The Triple Action Heroes

Meet alkynes, the hydrocarbons with a bit of spice - carbon-carbon triple bonds. Let's transform a double-bonded duo into a triple-bonded trio through dehydrohalogenation!

Example: Turning Dibromoethane into Acetylene

${\text{CH}}_2\text{Br}-{\text{CH}}_2\text{Br}+2{\text{NaNH}}_2\stackrel{\text{Heat}}{\to }\text{HC}\equiv \text{CH}+2\text{NaBr}+2{\text{NH}}_3$

Heating up 1,2-dibromoethane (CH₂Br-CH₂Br) with sodium amide (NaNH₂) transforms it into acetylene (HC≡CH), bringing that triple bond swagger.

3. Alkenes: The Double Trouble Makers

Alkenes, with their carbon-carbon double bonds, add a dash of drama. Picture removing water from an alcohol - that's dehydration leading to alkene formation!

Example: Dehydrating 2-Propanol into Propene

${\text{(CH}}_3{\text{)}}_2\text{CHOH}\underset{{\text{H}}_2{\text{SO}}_4}{\overset{\text{Catalyst}}{\to }}{\text{(CH}}_3{\text{)}}_2\text{C}={\text{CH}}_2+{\text{H}}_2\text{O}$

By using sulfuric acid (H₂SO₄) as a catalyst, 2-propanol [(CH₃)₂CHOH] loses water and transforms into propene [(CH₃)₂C=CH₂], ready to stir things up