Question

the answers i circled are incorrect except for 19. can you please tell me why this is correct. can you give me the correct answers and explain why?

actions usually proceed with amounts of inversion and retention at the center undergoing sustitution more inversion than retention at the center undergoing substitution y more retention then in version at the center undergoing substitution lete inversion at the center undergoing sostituti plete retention at the center undergoing substitution Which of the following carbocations is likely to undergo a hydride shi? A) B) IT DIV E) II and IV 19) Consider the three-step mechanism for the reaction of A through intermediates B and C to produce D shown below. A B B-C C-D Ea - 10 kcal/mol, AH-7 kcal/mol Ea = 15 kcal/mol, AH = -6 kcal/mol Ea -2 kcal/mol, AH° = -20 kcal/mol Which of the three steps is rate-limiting? A) The reaction of A to B. B) The reaction of B to C. C) The reaction of C to D. D) All three steps occur at the same rate: there is no rate-limiting step. E) The most exothermic step is rate-limiting. 20-21) Predict the two products of the following reactions. 20) NBS 21) Br CH,OH

Answer 1

(17) SN' reactions usually proceeds with. # CDI complete inversion at the center undergoing. Substitution, Example Rate I HORI RL H SN? inversion of (18.). Hydride Shift Configuratim. will occure a in optim. . Reason: it is a primary Carbocation so a least stable and always want to recently rearrenge into a or tertiary. Carbocatin. secondery H shift

19. At B. Fw= 10 Kcal/mo! B+C Fa = 15 kcal/mol C+D. Eu = 2 kcal/mo! Since, Fam. Btc. Ea is highest (ię 15 kcal/mol). So, the reactim will proveeds slowly. and this is why it is rate limiting step. NBS Br Dr pote element les con CH2OH OCH3 3 sta festa kot