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HydrocarbonsNEET Chemistry · Class 11 · NCERT Chapter 9

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2 interactive concept widgets for Hydrocarbons. Drag any slider, change any number, and watch the formula and the answer update live. Built so you understand how each NEET problem actually works, not just the final number.

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Hydrocarbon reaction mechanisms (6 reaction types)
Newman projection conformational energy (ethane and butane)

Hydrocarbon reactions and mechanisms

Six reaction tabs: Markovnikov addition, free radical substitution, Baeyer's test, ozonolysis, Friedel-Crafts, and combustion. Each tab ends with a quick MCQ.

Hydrocarbons

Hydrocarbon reactions

Explore 6 key reactions (Markovnikov, free radical, Baeyer's, ozonolysis, Friedel-Crafts, combustion). Each tab shows mechanism + 1-2 NEET questions with explanations.

Markovnikov's addition
Free radical halogenation
Baeyer's test
Ozonolysis
Friedel-Crafts alkylation
Combustion of hydrocarbons

Electrophilic addition

Markovnikov's addition

Reactant

CH₃CH=CH₂ (propene)

+

Reagent

HBr

→

Product

CH₃CHBrCH₃ (2-bromopropane)

Mechanism

H⁺ adds to the carbon with MORE H atoms (Markovnikov's rule). Br⁻ adds to the carbon with the more stable (more substituted) carbocation intermediate.

Rich get richer: H goes to the C that already has more H.

Quick questions

Addition of HBr to propene gives mainly:

1-bromopropane
2-bromopropane
propyl bromide (equal mixture)
1,2-dibromopropane

The carbocation intermediate in Markovnikov addition to propene is:

CH₃CH⁺CH₃ (secondary)
CH₃CH₂CH₂⁺ (primary)
CH₂=CHCH₃ itself
CH₃CH(Br)CH₃

Try this

  • Markovnikov vs Anti-Markovnikov: HBr with peroxides follows anti-Markovnikov (free radical, not ionic). HCl/HI don't give this even with peroxides.
  • Baeyer's test decolorizes alkaline KMnO₄. Hot concentrated KMnO₄ cleaves double bonds (different products).
  • Ozonolysis + Zn/H₂O → aldehydes/ketones. Ozonolysis + H₂O₂ → further oxidizes aldehydes to carboxylic acids.

Conformational analysis (Newman projection)

Rotate ethane and butane around the C-C bond in Newman projection. Watch the dihedral angle change and see the potential energy curve update live.

Hydrocarbons

Conformational analysis

Rotate the dihedral angle in ethane or butane. Newman projection updates live. See how staggered vs eclipsed and anti vs gauche affect relative energy.

Rotate the dihedral angle to see how conformation affects relative energy. Key: staggered conformations (60° apart) are more stable than eclipsed.

Dihedral angle

60°

Staggered

H atoms of back carbon bisect the H-H angles of front carbon (60°, 180°, 300°). Minimum energy — most stable conformation.

Relative energy:

12.0 kJ/mol

Newman projection (schematic)

H
H
H
H
H
H

Solid lines = front carbon bonds. Dashed = back carbon bonds. Dihedral = 60°

Stability order for ethane

Staggered (0 kJ) >> Eclipsed (12 kJ)
Torsional (Pitzer) strain in eclipsed = repulsion between electron clouds of C-H bonds.

Try this

  • Anti conformation of butane is the most stable because the two bulky CH₃ groups are 180° apart.
  • Eclipsed conformations have higher energy due to torsional strain (repulsion between bonding electron pairs).
  • NEET tip: conformers are the same compound (they interconvert at room temperature), not structural isomers.

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