CHEM 232 Final Exam with Complete
Solutions
3 steps in each radical mechanism - ANSWER-1. Initation
2. propagation
3. termination
Homolytic fragmentation - ANSWER-electrons in bonding pair move together. Creates
anion with missing pair and cation with complete octet
Heterolytic fragmentation - ANSWER-electrons in bond move independently. highly
reactive. creates 2 radical products
Sn2 - ANSWER-1. One Step
2. transition state of RDS has 2 species coming together
3. nucleophile does backside attack in coaxial way: inversion of stereochemistry
4. n---> sigma*, sigma type interaction
5. less substituted carbon = more accessible
Sn1 - ANSWER-1. two steps
2. transition state of RDS has 1 species
3. proceeds without stereospecificity or selectivity (racemic)
the transition state of an exothermic rxn will be more like the products or reactants? -
ANSWER-reactants
Late transition state will resemble products or reactants more? - ANSWER-products
stereospecific rxn - ANSWER-rxn when stereochemistry of reactant determines
stereochemistry of product w/o any other option
Hammond's Postulate - ANSWER-in moving between two states at different energies,
the critical "transition state" point most resembles the high energy state.
kinetic stability - ANSWER-lower deltaG standard=more kinetically favored
thermodynamic stability - ANSWER-lower energy level=more stable
factors that contribute to chemical potential - ANSWER-1. bond energy change
2. strength (reactivity) of electrophiles and/or acids
Solutions
3 steps in each radical mechanism - ANSWER-1. Initation
2. propagation
3. termination
Homolytic fragmentation - ANSWER-electrons in bonding pair move together. Creates
anion with missing pair and cation with complete octet
Heterolytic fragmentation - ANSWER-electrons in bond move independently. highly
reactive. creates 2 radical products
Sn2 - ANSWER-1. One Step
2. transition state of RDS has 2 species coming together
3. nucleophile does backside attack in coaxial way: inversion of stereochemistry
4. n---> sigma*, sigma type interaction
5. less substituted carbon = more accessible
Sn1 - ANSWER-1. two steps
2. transition state of RDS has 1 species
3. proceeds without stereospecificity or selectivity (racemic)
the transition state of an exothermic rxn will be more like the products or reactants? -
ANSWER-reactants
Late transition state will resemble products or reactants more? - ANSWER-products
stereospecific rxn - ANSWER-rxn when stereochemistry of reactant determines
stereochemistry of product w/o any other option
Hammond's Postulate - ANSWER-in moving between two states at different energies,
the critical "transition state" point most resembles the high energy state.
kinetic stability - ANSWER-lower deltaG standard=more kinetically favored
thermodynamic stability - ANSWER-lower energy level=more stable
factors that contribute to chemical potential - ANSWER-1. bond energy change
2. strength (reactivity) of electrophiles and/or acids
