Organic Reaction Intermediates Simplified

Explore the reagents and short-lived reaction intermediates that drive organic reactions, including bond breaking and making, ionic species, free radicals, carbocations, and carbanions.

Identify electrophiles as electron-deficient, electron-loving species that attack negative centers. Identify nucleophiles as electron-rich, electron-donor species that attack positive centers; examples include ammonia, water, and alcohols.

Learn how neutral, electron-deficient molecules such as boron-based species, aluminum, SO3, zinc chloride, zinc fluoride, and FeCl3 act as electrophiles by accepting electrons and behaving as lewis acids.

Classify species as electrophiles or nucleophiles and identify dual roles, using resonance to predict nucleophilic sites and reactive patterns.

This lecture explains ambident nucleophiles, using nitrite as example with nitrogen and oxygen both acting as nucleophiles through resonance, and discusses lithium aluminum hydride as a nucleophile.

Explain homolytic and heterolytic bond fission in organic reactions, detailing how homolysis forms free radicals while heterolysis yields ions, driven by heat, light, peroxides, and polarity.

Learn how carbocations, or carbonium ions, form by bond shifting to create a positively charged carbon with three sigma bonds, sp2 hybridization, and a planar 120-degree geometry, as reactive intermediates.

Explore how resonance and inductive effects stabilize carbocations, illustrated by benzylic and other carbocation examples, and explain why tertiary alkyl carbocations are most stable due to hyperconjugation and electron donation.

explains the stability order of carbocations, highlighting triphenylmethyl cation as most stable due to resonance with phenyl rings, then diaryl, benzyl, and alkyl cations, guided by hyperconjugation and inductive effects.

Carbanions are negatively charged carbon species with a lone pair; in conjugated systems, the charge delocalizes by resonance into the benzene ring, making the carbon highly reactive and planar sp2.

Explore how resonance and inductive effects determine carbanion stability, including benzyl carbanions with aromatic delocalization. Note how electron withdrawing groups stabilize, while electron donating groups and alkyl substitution affect stability.

Explore free radicals as highly reactive intermediates with unpaired electrons formed by homiletic bond cleavage. Distinguish simple alkyl free radicals, resonance-stabilized radicals, and fluorinated derivatives.

This lecture explains that free radical stability comes from hyperconjugation and resonance, with primary, secondary, and tertiary radicals in order; alpha hydrogens yield hyperconjugated structures, and benzene resonance enhances stability.

Discover how carbenes are neutral, electron-deficient reactive intermediates with two nonbonding electrons on carbon, often sp2-hybridized and planar at about 120°, existing as singlet or triplet states.

Examine carbene stability, comparing triplet and singlet states, and show how electron-donor groups like halogens stabilize singlet carbenes via orbital overlap and resonance.

The stability order of singlet dihalocarbene places difluorocarbene as most stable, then chlorocarbene, then dibromocarbene, due to extensive 2p-2p overlap between carbon and fluorine in the same period.

Solve practice problems on reaction intermediates by identifying the most and least stable carbonyls, explaining resonance stabilization and inductive effects, and noting geometry of the ions.

Analyze practice problems on ordering reaction intermediates by increasing stability, using resonance and hyperconjugation in benzylic, primary, secondary, and tertiary cases.

Learn curved arrows in organic reactions, showing electron movement from donors to acceptors, correct arrow starts, single-headed arrows for single electrons, and homolytic cleavage forming radicals.

Practice problems reinforce using gloved arrows to show how electron donors and acceptors drive hydrogen transfer and bond movement, yielding resonance forms and the product in organic reactions.

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