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Overview of Key Organic Chemistry Reactions

May 9, 2025

Organic Chemistry Reactions Overview

Reactions with Alkenes

1-Butene and Hydrobromic Acid

  • Reaction: 1-butene reacts with HBr.
  • Process: Alkene is a nucleophile, reacts with electrophile (HBr).
  • Outcome: H attaches to primary carbon, more stable secondary carbocation forms, Br attacks forming racemic mixture.

Alkenes with HBr vs. HBr and Peroxides

  • HBr alone: Bromine attaches to more substituted carbon (Markovnikov's rule).
  • HBr with peroxides: Bromine attaches to less substituted carbon (anti-Markovnikov).

Cyclohexene and Bromine

  • Reaction: Cyclohexene with Br2 in dichloromethane.
  • Outcome: Anti-addition, forms two stereoisomers (racemic).

Allylic Bromination with NBS

  • Reaction: Cyclohexene with NBS.
  • Outcome: Bromine replaces allylic hydrogen, double bond remains.

Radical Reactions

Alkanes with Bromine and UV Light

  • Reaction: Radical substitution, bromine replaces tertiary hydrogen.
  • Note: More stable tertiary radicals.

Alkanes with Chlorine

  • Reaction: Non-selective, forms multiple products.

Acid-Catalyzed Hydration

  • Reaction: Alkene with water and HCl.
  • Process: Alkene forms carbocation, rearranges for stability, forms alcohol.

Hydrogenation of Alkenes

  • Reaction: Cyclohexene with H2 and metal catalyst.
  • Outcome: Alkene to alkane, cis addition with deuterium.

Hydroboration-Oxidation

  • Reaction: Alkene with BH3, THF, H2O2, OH-.
  • Outcome: OH on less substituted carbon, syn addition.

Oxymercuration-Demercuration

  • Reaction: Alkene with Hg(OAc)2, NaBH4.
  • Outcome: OH on more substituted carbon.

Epoxidation and Diols Formation

  • Reaction: Cyclohexene with mCPBA, H2O/H+.
  • Outcome: Epoxide to trans-1,2-diol.

Cis-Diol Formation

  • Reaction: Alkene with OsO4, NaHSO3.
  • Outcome: Syn addition, forms cis-diol.

Reactions with Alkynes

Hydrogenation

  • Reaction: Alkyne with H2/metal catalyst.
  • Outcome: Alkyne to alkane.

Sodium Metal and Ammonia

  • Reaction: Alkyne to trans-alkene.

Lindlar's Catalyst

  • Reaction: Alkyne to cis-alkene.

Hydroboration of Terminal Alkynes

  • Reaction: Alkyne with R2BH, THF, H2O2, OH-.
  • Outcome: Forms aldehyde.

Oxymercuration of Alkynes

  • Reaction: Alkyne with HgSO4, H2O, H2SO4.
  • Outcome: Forms ketone.

SN2 and SN1 Reactions

SN2

  • Example: Secondary alkyl halide with KI, acetone.
  • Outcome: Inversion of configuration.

SN1

  • Example: Secondary alkyl halide with water.
  • Outcome: Racemic mixture, retention and inversion possible.

E1 and E2 Reactions

E1

  • Reaction: Secondary alcohol with acid, heat.
  • Outcome: Dehydration, carbocation rearrangement.

E2

  • Reaction: Strong base with alkyl halide.
  • Outcome: Formation of stable alkene.

Alcohol Transformations

Conversion to Alkyl Halides

  • SN1: Tertiary alcohol with HBr.
  • SN2: Primary alcohol with HI.

Oxidation

  • Primary Alcohols: PCC to aldehyde, CrO3 to carboxylic acid.
  • Secondary Alcohols: Oxidized to ketones.

Reduction

  • NaBH4: Reduces aldehydes/ketones to alcohols.
  • LiAlH4: Reduces esters/carboxylic acids to alcohols.

Grignard Reagents

  • Reaction: Addition to carbonyls.
  • Outcome: Alcohol formation by addition of alkyl group.

These notes cover important organic chemistry reactions pertinent for exam preparations, providing a broad overview of reaction mechanisms, conditions, and outcomes.

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