ypes of Reactions, Heterolytic Mechanisms, Nucleophiles and Electrophiles, and Energies of Organic Reactions Flashcards
What is an addition reaction?
Two reactants combining to form a single product
What is the result of an addition reaction?
Decrease in the # of pi bonds, increase in the # of sigma bonds
What is an elimination reaction?
Single reactant splits into two products
What is the result of an elimination reaction?
Increase in the # of pi bonds, Decrease in the # of sigma bonds
What is a substitution reaction?
Two reactants exchanging parts to form two new products
What is the result of an substitution reaction?
No change in the # of pi bonds but groups were exchanged
What is a Rearrangement reaction?
Single reactant yielding a constitutional isomer as product
What is the result of a rearrangement reaction?
No change in the # of pi bonds but groups, bonds and atoms were reorganized
What is a heterolytic mechanism?
Unsymmetrical breaking and making of bonds
What is an unsymmetrical bond breaking?
Two bonding electrons remain with one product fragment, leaving the other with a vacant orbital after bond breaking
What are nucleophiles?
Electron rich species that donate electron pairs to electrophiles in a polar bond forming reaction; lewis base
What are electrophiles?
Substances that accept electron pairs from a nucleophile; lewis acid
What are the rules writing organic molecules using curved arrow?
- Electron moves from a nucleophilic source to an electrophilic sink
- The octet rule should be followed when pushing electrons. This may cause formal charges
What is gibbs free energy?
Change in energy that occur during a chemical reaction
What happens when Delta G is <0
Reaction is exergonic; spontaneous
What happens when Delta G is >0
Reaction is endergonic; non spontaneous
Which side is favored if Delta G is < 0
Product
Which side is favored if Delta G is > 0
Reactant
What happens when a reaction is exothermic
Heat is released; Delta H < 1
What happens when a reaction is endothermic
Heat is absorbed; Delta H > 1
What happens when Delta S > 1
Entropy increase; more disordered system
What happens when Delta S < 1
Entropy decrease; Less disordered system
What does the number of hills in an energy diagram indicate?
The number of steps in a reaction
What does the steepness/height of the hill in an energy diagram indicate?
Rate of reaction
Compare a “tall” hill and a “short” hill
Tall hill has a slower reaction rate than short hill
What is a transition state?
The point at which the compound is in the process of transformation
Where is the transition state located on an energy diagram
Top of the hill
What is activation energy?
Energy required to go from reactant to transition state
What is a reaction intermediate?
Species that are neither reactant nor the final product
