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関連する概念動画

Radical Anti-Markovnikov Addition to Alkenes: Thermodynamics01:32

Radical Anti-Markovnikov Addition to Alkenes: Thermodynamics

The anti-Markovnikov addition of hydrogen halides to an alkene is thermodynamically feasible only with HBr. The radical addition reaction with other hydrogen halides like HCl and HI is thermodynamically unfavorable.
Radicals: Electronic Structure and Geometry01:07

Radicals: Electronic Structure and Geometry

This lesson delves into the geometry of a radical, which is influenced by the electronic structure of the molecule. The principle is similar to that of a lone pair, where the unpaired electron influences the geometry at the radical center.
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
Radical Halogenation: Thermodynamics01:34

Radical Halogenation: Thermodynamics

The thermodynamic favorability of a reaction is determined by the change in Gibbs free energy (ΔG). ΔG has two components- enthalpy (ΔH) and entropy (ΔS). The entropy component is negligible for alkane halogenation because the number of reactants and product molecules are equal. In this case, the ΔG is governed only by the enthalpy component. The most crucial factor that determines ΔH is the strength of the bonds. ΔH can be determined by comparing the energy between bonds broken and bonds...
Radical Reactivity: Steric Effects01:10

Radical Reactivity: Steric Effects

The presence of electron-donating, electron-withdrawing, or conjugating groups adjacent to a radical center, imparts electronic stabilization to the radicals. Examples of such electronically-stabilized radicals are triphenylmethyl, tetramethylpiperidine‐N‐oxide, and 2,2‐diphenyl‐1‐picrylhydrazyl. These radicals are remarkably stable and are known as persistent radicals. Some of the persistent radicals can even be isolated and purified.
Along with electronic factors, steric factors also account...
Radical Reactivity: Concentration Effects01:20

Radical Reactivity: Concentration Effects

In a radical reaction, the concentration of starting materials governs the selectivity of a radical. For example, the reaction between an alkyl halide and an alkene, in the presence of tin hydride and AIBN, begins with the generation of a tin radical. The generated radical then abstracts halogen from the alkyl halide, producing an alkyl radical. This alkyl radical can either react with tin hydride, yielding an alkane, or add to an alkene, generating a nitrile-stabilized radical, eventually...
Radical Substitution: Halogenation of Alkanes and Alkyl Substituents01:27

Radical Substitution: Halogenation of Alkanes and Alkyl Substituents

In the presence of heat or light, alkanes react with molecular halogens to form alkyl halides by a substitution reaction called radical halogenation. This reaction has three steps: initiation, propagation, and termination, as seen in the radical chlorination of methane to produce methyl chloride.
In the initiation step of the reaction, the chlorine molecule undergoes homolytic cleavage in the presence of light or heat, forming two highly reactive chlorine radicals. Propagation occurs in two...

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関連する実験動画

Updated: Jul 12, 2026

Production and Measurement of Organic Particulate Matter in the Harvard Environmental Chamber
09:46

Production and Measurement of Organic Particulate Matter in the Harvard Environmental Chamber

Published on: November 18, 2018

普通の大気:大きな激素とホルムアルデヒド濃度が予測される.

H Levy

    Science (New York, N.Y.)
    |July 9, 1971
    PubMed
    まとめ

    新しい大気モデルによると,昼間のヒドロキシル,ヒドロペロキシル,メチルペロキシルラジカルは5×10^8分子/cm3.8に達している. また,急激な連鎖反応により,一酸化炭素を素早く除去し,大気中の寿命を短くすることを提案しています.

    科学分野:

    • 大気化学 大気化学
    • 環境科学 環境科学
    • 化学的運動学 化学的運動学

    背景:

    • 地球の表面の大気には,炭素一酸化物 (CO) やホルムアルデヒドのような様々な反応性ラジカルとガスが含まれています.
    • これらの種の濃度と相互作用を理解することは,空気の質と気候モデリングに不可欠です.
    • 以前のモデルは,大気汚染物質の急速な除去経路を完全に捉えることができませんでした.

    研究 の 目的:

    • 正常で汚染されていない地表大気中のキーラジカルとホルムアルデヒドの安定状態濃度をモデル化するために.
    • 炭素一酸化物を効率的に除去するための根本的な連鎖反応機構を提案し,分析する.
    • 提案されたメカニズムに基づいて,大気中の一酸化炭素の寿命を決定する.

    主な方法:

    • 安定状態の大気モデルの開発と応用.
    • ヒドロキシル,ヒドロペロキシル,メチルペロキシル基を含む化学反応のシミュレーション.
    • 炭素一酸化物の酸化のための提案された根幹連鎖反応の運動分析.

    主要な成果:

    • ヒドロキシル,ヒドロペロキシル,メチルペロキシルラジカルの昼間の予測濃度は5×10^8分子/cm3に近い.
    • 予測されるフォーマルデヒド濃度は,約5×10^10分子/cm3 (十億分の2分) である.

    さらに関連する動画

    Combustion Chemistry of Fuels: Quantitative Speciation Data Obtained from an Atmospheric High-temperature Flow Reactor with Coupled Molecular-beam Mass Spectrometer
    07:24

    Combustion Chemistry of Fuels: Quantitative Speciation Data Obtained from an Atmospheric High-temperature Flow Reactor with Coupled Molecular-beam Mass Spectrometer

    Published on: February 19, 2018

    An Atmospheric Pressure Plasma Setup to Investigate the Reactive Species Formation
    08:36

    An Atmospheric Pressure Plasma Setup to Investigate the Reactive Species Formation

    Published on: November 3, 2016

    関連する実験動画

    Last Updated: Jul 12, 2026

    Production and Measurement of Organic Particulate Matter in the Harvard Environmental Chamber
    09:46

    Production and Measurement of Organic Particulate Matter in the Harvard Environmental Chamber

    Published on: November 18, 2018

    Combustion Chemistry of Fuels: Quantitative Speciation Data Obtained from an Atmospheric High-temperature Flow Reactor with Coupled Molecular-beam Mass Spectrometer
    07:24

    Combustion Chemistry of Fuels: Quantitative Speciation Data Obtained from an Atmospheric High-temperature Flow Reactor with Coupled Molecular-beam Mass Spectrometer

    Published on: February 19, 2018

    An Atmospheric Pressure Plasma Setup to Investigate the Reactive Species Formation
    08:36

    An Atmospheric Pressure Plasma Setup to Investigate the Reactive Species Formation

    Published on: November 3, 2016

  • 提案されている過激な連鎖反応は,一酸化炭素の寿命を大幅に短縮し,わずか0.2年になる.

    • 結論:

    • このモデルは,汚染されていない地表大気中の主要な急性物質とホルムアルデヒド濃度の推定値を提供します.
    • 根本的な連鎖反応のメカニズムは,大気中の一酸化炭素を除去するための効率的な経路を提供します.
    • この発見は,一酸化炭素の大気中の寿命が,以前に推定されたより短いことを示しており,空気の質と気候研究に影響を及ぼしている.