《有机化学》课程教学资源（PPT课件讲稿）第六章、七章 有机化学反应理论

第二部分有机化学反应 第六章有机化学反应理论 第七章有机化学反应机制及研究方法

第二部分 有机化学反应 第六章 有机化学反应理论 第七章 有机化学反应机制及研究方法

有机反应总论的主要问题 ●热力学 Thermodynamics 动力学 Kinetics 反应机制 Reaction Mechanism ●反应的方向、活性与选择性 反应活泼中间体 Active Intermediates ●有机反应机制的研究方法

有机反应总论的主要问题 热力学 Thermodynamics 动力学 Kinetics 反应机制 Reaction Mechanism 反应的方向、活性与选择性 反应活泼中间体Active Intermediates 有机反应机制的研究方法

Thermodynamics e Question: 1.In what direction does the reaction proceed? 2 Does the reaction release or absorb heat? ● Thermodynamics-热力学问题 9 Equilibria, Energy changes 反应方向、平衡、能量变化

Thermodynamics Question: 1. In what direction does the reaction proceed? 2. Does the reaction release or absorb heat? Thermodynamics——热力学问题 ----- Equilibria, Energy changes ——反应方向、平衡、能量变化

Thermodynamics For the generalized reaction aa t bB cct dD e we have IProducts ICTIDI 4 Reactants「A1「B巾

Thermodynamics For the generalized reaction: we have aA + bB c C + d D Ke q = [Products] [Reactants] = [ C ]c [ D ]d [ A ]a [ B ]b

Thermodynamics ● ree Energy自由能)AG9=- REInKe ●When△G0 1s negative, the reaction is exergonic(放能的), has a favorable equilibrium constant, and can occur spontaneously. When AGo is positive the reaction is endergonic(吸能的), has an unfavorable equilibrium constant and cannot occur spontaneous ly

Thermodynamics Free Energy（自由能）△G 0 = - RTlnKeq When △G 0 is negative, the reaction is exergonic （ 放能的 ） , has a favorable equilibrium constant, and can occur spontaneously. When △G 0 is positive, the reaction is endergonic （ 吸 能 的 ） , has an unfavorable equilibrium constant, and cannot occur spontaneously

Thermodynamics e Standard -state conditions (标准状态) ●△G0=△H-T△S0 △F—焓变;△S0—熵变 e Nonstandard- state conditions ●(非标准状态) ●△G=△H-T△S

Thermodynamics Standard - state conditions: （标准状态） △G 0 = △H 0 - T△S 0 △H 0——焓变； △S 0 ——熵变 Nonstandard - state conditions: （非标准状态） △G = △H - T△S

Thermodynamics △H0 Enthalpy 焓) change e When AHO is negative, the reaction releases heat and is exothermic(放热的).When△H is positive, the reaction absorbs heat and is enderthermic(吸热的)

Thermodynamics △H 0 --- Enthalpy（焓）change When △H 0 is negative, the reaction releases heat and is exothermic（放热的）. When △H 0 is positive, the reaction absorbs heat and is enderthermic（吸热的）

Thermodynamics △S0- Entropy(熵) change sThe change in molecular disorder(无序程度) during a reaction o When ASo is negative, disorder decreases; when Aso is positive disorder increases

Thermodynamics △S 0 --- Entropy（熵）change The change in molecular disorder（无序程度） during a reaction When △S 0 is negative, disorder decreases; when △S 0 is positive, disorder increases

Thermodynamics ./Bond Dissociation Energy(D) (键的裂解能) O- defined as the amount of energy required to break a given bond to produce two radical fragments when the molecule is in gas phase at 25C. A: B A.+.B

Thermodynamics Bond Dissociation Energy (D) （键的裂解能） ---- defined as the amount of energy required to break a given bond to produce two radical fragments when the molecule is in gas phase at 250C. A:B A. + . B

Thermodynamics 已知键的裂解能,焓变是可以计算的 通过焓变可以粗略估计反应在能量上是否有利 ●但是熵变较难计算 另一个困难是多数有机反应在溶液中进行,存 在溶剂化作用,增加了计算难度 热力学能告诉我们反应是否能进行,却不能预 计反应的速度如何?也不能告诉我们反应的具 体进程是怎样的

Thermodynamics 已知键的裂解能，焓变是可以计算的 通过焓变可以粗略估计反应在能量上是否有利 但是熵变较难计算 另一个困难是多数有机反应在溶液中进行，存 在溶剂化作用，增加了计算难度 热力学能告诉我们反应是否能进行，却不能预 计反应的速度如何？也不能告诉我们反应的具 体进程是怎样的