Alkanes, Alkenes, and Alkynes *NOTES for Class 11th (NEET-UG) ✨🎀

If you're preparing for NEET 🗿 , it's crucial to delve even deeper into the concepts of alkanes, alkenes, and alkynes. Let's expand on each class with additional details and example:

1. Alkanes:

   Alkanes, also known as saturated hydrocarbons, exhibit unique properties that stem from their single bond structure. Understanding these properties is essential for NEET preparation.

   - Isomerism: Alkanes exhibit structural isomerism, where molecules with the same molecular formula have different structures. For example, butane (C4H10) can exist as n-butane and iso-butane.

 - Conformational Isomers: Due to rotation around single bonds, alkanes can have different conformations. Take ethane (C2H6) as an example, where the staggered and eclipsed conformations result from rotation around the C-C single bond.

   - Combustion Reaction: Alkanes undergo combustion reactions in the presence of oxygen, producing carbon dioxide and water. The balanced equation for methane combustion is CH4+2O2---> C02+2H2O

2. Alkenes:

   Alkenes, with their double bond structure, introduce additional concepts like geometrical isomerism and electrophilic addition reactions.

 - Geometrical Isomerism: Alkenes may exhibit cis-trans isomerism due to the restricted rotation around the carbon-carbon double bond. For instance, consider cis-2-butene and trans-2-butene.

   - Addition Reactions: Alkenes readily undergo addition reactions. One classic example is the addition of hydrogen (hydrogenation) to form an alkane. Ethene's hydrogenation reaction is c2h4+h2---->c2h6

   - Polymerization: Alkenes can undergo polymerization to form polymers. Ethene polymerizes to form polyethylene, a widely used plastic.

3. Alkynes:

  Alkynes, with their triple bond structure, bring in unique characteristics such as acidity and versatility in organic synthesis.

   - Acidity of Alkynes: Terminal alkynes are acidic and can undergo deprotonation. For example, acetylene (ethyne) reacts with a strong base to form the acetylide ion.

   - Addition Reactions: Alkynes undergo addition reactions similar to alkenes. The hydrogenation of ethyne is represented as C2h2+2h2---->c2h6

   - Synthetic Applications: Alkynes find extensive use in organic synthesis. The Sonogashira coupling, involving a palladium-catalyzed cross-coupling of an alkyne and an aryl or vinyl halide, is a notable example.