CHEM 261 1st Edition Lecture 14Outline of Last Lecture: I. Classes of Organic ReactionsII. Equilibrium, Rates, and Energy ChangesIII. Enthalpy and EntropyOutline of Current Lecture:I. Review of Last LectureII. Reaction GraphsIII. Reaction MechanismsIV. Polar ReactionsReview of Last Lecture:-Getting reactions to go: Use the equation to predict if ΔG will be positive or negativeΔG = ΔH – TΔS**ΔG < 0 is favorable for reaction to proceed**ΔH = energy heat (ΔH < 0 = exothermic, NOT favorable. ΔH >0 = endothermic)Reaction Graphs:(above graph = exothermic, products have LESS energy than reactants)ΔG = the difference in energy from starting materials (reactants) and the transition state (peak of the hill)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-The transition state determines the kinetics of the reaction (bigger transition state = slower reaction)(above graph is endothermic, products have MORE energy than reactants)-Not all reactions proceed in one step, they can have intermediates. The transition state represents the reaction intermediate. Reaction graphs can have multiple transition states. Indicating Steps in Reaction Mechanisms:-Arrows= indicate the movement of electrons(single arrow) = electron pair movementFish hook arrow (only half) = movement of one electron** conservation of electrons, cannot lose or gain electrons in a reactionReaction Mechanisms:1. Radicals ( half arrow, 1 electron)-Symmetrical bond breaking (homo-lytic = symmetrical bond breaking, homo-genic = symmetrical bond creating) 2. Polar Reaction-nonsymmetrical bond breaking (hetero-lytic = nonsymmetrical breaking bond, hetero-genic = nonsymmetrical making bond)**Radical = VERY reactive!!Propagation- Continue the reactionTermination: Multiple waysPolar Reactions: Electrophiles and NucleophilesN = nucleophile, “donator of electron”E = electrophile, “ electron-borrowing”**Arrow goes nvc:- electrophile**nucleophile can be – or neutral, electrophile can be + or
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