CHEM 2211 1st Edition Lecture 16 Outline of Last LectureI. Alkenes have double bondsII. NomenclatureOutline of Current LectureI. Curvy Arrows show flow of electrons in alkene reactionsII. Thermodynamics and KineticsCurrent LectureI. Curvy arrows show flow of electrons in alkene reactionsa. Electrophile-positive, partially positive, or an atom with an incomplete octet (Lewis ACID)b. Nucleophile-negative or partially negative atom (Lewis BASE)c. RULE: Nucleophiles always react with electrophilesd. The terms acid and base are only used when the nucleophile reacts with an H+ atom because acid/base reaction strength is a thermodynamic property and nucleophile strength is a kinetic propertye. Pi bonds are weaker than sigma bonds and are the bond most likely to break in a reactionf. The step-by-step process in which reactants are shown turning into products is called mechanisms of reactionsi. Mechanisms show the movement of electrons from the electron rich source to the electron deficient source via curvy arrowsii. We will use the following equation as an exampleiii. In the first step for the following example, the double bond is the nucleophile and the H atom attached to the bromine is the electrophileiv. In the second step the carbocation created is the electrophile and the bromide ion is the nucleophilev. This type of reaction is called an electrophilic addition reaction because the first atom added was the electrophileII. Thermodynamics and Kineticsa. Thermodynamics-how much product is formedb. Kinetics- how quickly products are formedc. Reaction coordinate diagram shows the energy change that occurs during each step of a mechanismd. The maximum energy that a reaction has is called the transition state and shows the point at which bonds are being broken and
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