Lecture_11

Lecture_11 - Lecture 11 Chapter 3: Alkene Structure,...

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Unformatted text preview: Lecture 11 Chapter 3: Alkene Structure, Nomenclature, and Reac:vity Thermodynamics  Thermodynamics = how much  Kine3cs = how fast Enthalpy and Entropy  Enthalpy (ΔH°) = Ebonds broken – Ebonds formed –  Exothermic and endothermic  Entropy (ΔS°) = Sproducts – Sreactants  So what does this mean about ΔG°? ΔH° Can be Predicted  DH = bond dissocia3on energy Keq and ΔG° Le Châtelier’s Principle  Equilibrium adjusts to disturbances –  What if you decreased the [prod]? –  How would you even do that?? Kine:cs: How Fast? Rate of a reac:on = number of collisions per unit of :me First ­order reac:on A rate = k[A] X frac:on with sufficient energy X frac:on with proper orienta:on Second ­order reac:on B A + B C + D rate = k[A][B] A + A B rate = k[A]2 ΔG‡ = ΔH‡  ­TΔS‡ Reac:on Coordinate Diagrams Addi:on of HBr to 2 ­butene Chapter 4: Alkene Reac:ons Carboca:on Stability  Order of stability:  Alkyl groups are electron dona3ng…why? Hammond Postulate  “ The transi3on state is more similar in structure to the species to which it is more similar in energy.” Hammond Postulate Which compound, A or C, is formed faster from B? Which is more stable, A or C? A.  A faster, A more stable B.  C faster, A more stable C.  A faster, C more stable D.  C faster, C more stable Which compound, A or C, is formed faster from B? Which is more stable, A or C? A.  A faster, A more stable B.  C faster, A more stable C.  A faster, C more stable D.  C faster, C more stable tert ­butyl Ca:on Forms Faster Than isobutyl ca:on Regioselec:vity  Regioselec:vity is the preference for one cons3tu3onal isomer over the other –  Addi3on of HCl to propene –  Addi3on of HCl to 1 ­methylcyclopentene ...
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This note was uploaded on 09/09/2011 for the course CHEM 109A taught by Professor Bruice during the Spring '07 term at UCSB.

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