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OCR organic reaction mechanisms

OCR organic reaction mechanisms. Click here for advice. Click a box below to go to the mechanism. AS. Free Radical Substitution. Electrophilic Addition. Nucleophilic Substitution. Electrophilic Substitution. A2. Nucleophilic Addition. Free radical substitution. chlorination of methane.

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OCR organic reaction mechanisms

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  1. OCR organic reaction mechanisms Click here for advice Click a box below to go to the mechanism AS Free Radical Substitution Electrophilic Addition Nucleophilic Substitution Electrophilic Substitution A2 Nucleophilic Addition

  2. Free radical substitution chlorination of methane i.e. homolytic breaking of covalent bonds Overall reaction equation CH4 + Cl2 CH3Cl + HCl Conditions ultra violet light excess methane to reduce further substitution

  3. Free radical substitution mechanism Cl + Cl CH4 + Cl CH3 + HCl CH3 + Cl2 CH3Cl + Cl CH3 + Cl CH3 + CH3 ultra-violet Cl2 initiation step two propagation steps termination step CH3Cl minor termination step CH3CH3

  4. Further free radical substitutions Overall reaction equations CH3Cl + Cl2 CH2Cl2 + HCl CH2Cl2 + Cl2 CHCl3 + HCl CHCl3 + Cl2 CCl4 + HCl Conditions ultra-violet light excess chlorine

  5. Electrophilic addition bromine with ethene Overall reaction equation CH2=CH2 + Br2 CH2BrCH2Br 1,2-dibromoethane mechanism

  6. bromine with ethene H H C C H H H H C C H H + Br - Br Br Br + Br Br H H - C C H H Br Br Electrophilic addition mechanism carbocation 1,2-dibromoethane reaction equation

  7. Nucleophilic substitution water with bromoethane mechanism CH3CH2Br + H2O CH3CH2OH + HBr ethanol hydroxide ion with bromoethane mechanism CH3CH2Br + OH- (aqueous) CH3CH2OH + Br- ethanol

  8. water with bromoethane H - + OH C CH3 H + H O H C H CH3 Br C H CH3 H H O - Br H H H Br Nucleophilic substitution mechanism ethanol reaction equation

  9. hydroxide ion with bromoethane H - + OH C CH3 H H - Br Br C CH3 - H OH Nucleophilic substitution mechanism ethanol reaction equation

  10. Electrophilic Substitution Nitration of benzene C6H6 + HNO3 C6H5NO2 + H2O Conditions / Reagents concentrated HNO3 and concentrated H2SO4 50oC mechanism

  11. electrophilic substitution mechanism (nitration) NO2 + 1. Formation of NO2 H + + NO2 O SO3H- + NO2 NO2 H O SO3H the nitronium ion HNO3 + 2H2SO4 + H3O+ + 2HSO4- 2. Electrophilic attack on benzene 3. Forming the product and re-forming the catalyst reaction equation

  12. Nucleophilic Addition HCN + OH- addition of hydrogen cyanide to carbonyls to form hydroxynitriles + HCN RCOR RC(OH)(CN)R RCH(OH)CN + HCN RCHO Conditions / Reagents HCN (aq) andNaOH(aq) to form the CN- nucleophile CN- + H2O Room temperature and pressure

  13. Nucleophilic Addition Mechanism C N - O + O O H H CN CN C CH3 C CN CH3 C CN CH3 CH3 CH3 CH3 CN hydrogen cyanide with propanone + HCN CH3COCH3 CH3C(OH)(CN)CH3 HCN / NaOH (aq) is a source of cyanide ions 2-hydroxy-2-methylpropanenitrile

  14. Advice To get back to the mechanism links page from anywhere in the presentation, click the button at the top right corner of the screen. This version provides the organic mechanisms specified (2002/3) by the OCR exam board. Each stage of a reaction equation, its conditions and mechanism are revealed in turn on a mouse click or keyboard stroke. Note that there is another version available where each reaction and mechanism play automatically after an initiating click or key stroke. The number of ways of navigating through this presentation may depend on the version of PowerPoint being used and how it is configured. Some possible ways of advancing: left mouse click or return key or right arrow key or up arrow key. Some possible ways of reversing: backspace key or left arrow key or down arrow key.

  15. References Steve Lewis for the Royal Society of Chemistry

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