Question

need help with last hw problems, please explain and the answers thank you

O Rank the substituents below from hiahest priority to lowest using the Cann-ingold, Prelog sequence rules. B. -OH A. A>D>C>B B. B>D>A>C A.-CEN C. A>B>D>C D. D>B>A>C C.-CECH D. C.CH 7. The regiochemistry of hydroboration/oxidation of alkenesis A. Markovnikov. B. Anti-Markovnikov. C. Subject to solvent effects. D. Unrelated to alkene structure. 8. Assign the correct E or Z. cis or trans configuration to the following structure. OH A. E B. Z C. cis D. trans 9. The Hammond Postulate A. Predicts that in electrophilic additions to alkenes, the more stable carbocation intermediate is formed. B. Predicts that the transition state of an exothermic reaction step structurally resembles the reactant. C. Predicts that the transition state of an exothermic reaction step structurally resembles the products. D. Predicts that in the addition of HX to alkenes, the Hadds to the less substituted alkene carbon and the X adds to the more substituted carbon 10. Markovnikov's Rule A Predicts that in electrophilic additions to alkenes, the more stable carbocation intermediate is formed. B. Predicts that the transition state of an exothermic reaction step structurally resembles the reactant. C. Predicts that in the addition of HX to alkenes, the H adds to the less substituted alkene carbon and the X adds to the more substituted carbon D. Predicts that in the addition of HX to alkenes, the H adds to the more substituted alkene carbon and the X adds to the less substituted carbon.

Answer 1

Cahn-Ingold-Prelog Rules Since most of the chiral stereogenic centers that we will find are asymmetric carbons, the four different substituents must be ordered in this way. 1. The higher the atomic number of the immediate substituent atom, the higher the priority. 2. If two substituents have the same immediate substituent atom, Evaluate atoms progressively farther from the chiral center until a difference is found. 3) If double or triple bond groups are found as substituents, they are treated as an equivalent set of single bond atoms. A. —CAN B. –OH C. -CECH D._ 5– 4 1 the highest priority sequence and 4 the lowest. CH3 32m Z So: B>D>A>C Option B

Markovnikov's rule

Highest priority groups on opposite sides so: The correct assignment is: E (German, entgegen for opposite) Option A

Hammond's postulate Exothermic reaction Transition state The energy of the transition state is closer to the energy of the reagent than that of the intermediate or that of the product, therefore the structure of the transition state also resembles that of the reagent. Reaction coordinate So: Option B

Electrophilic Addition 10. The H atom adds to the C with the most H atoms already present. X adds to the more substituted carbon. So: Optionc