University:
Amherst College
Course:
CHEM 221 | Organic Chemistry I
Academic year:

2024
Views:

84

Pages:

4
Author:

espiranza2242r

Chem 21 Homework set 8 End-of-chapter problems from Hornback: Ch 8: 22, 24, 27a,d-g,j,k,m, 31, 37, 41, 42, 45, 49, 52, 55, 56. Ch 9: 17a,c,e-l, 20, 23-25, 27. 1. Draw the organic products of the following SN2 reactions, showing stereochemistry clearly where necessary. (Note that in some cases E2 can occur as well, but let's just focus on SN2 for now.) Cl (a) + Cl (b) HCO2Na I (c) EtO– Na+ (excess) OCH3 TsO (d) + CH3CH2NH– CH3I O Cl (e) NH2 + (f) O EtSNa OMs (g) Br C CH3C (h) Br Cl CH3OK 2. Draw the organic products of the following SN2 reactions, showing stereochemistry where necessary. For the first two parts, draw out the structures of the nucleophiles so that the bonding and charge placement are clear. Also draw the products so that their structures are clear — i.e., do not write, for example, "something–CO2–something". Draw out the structure. If you're not sure what the structure of that "–CO2–" part is, figure it out. Which atom of cyanide is more nucleophilic? Draw the structure and it will be clear. (And no more breaks for carrying an alkali metal along as if it were covalently bonded — you need to recognize ionic compounds at this point every time, without exception, or you're just wasting your time.) (a) CO2 (CH3)2CH–I (b) Cl KCN (c) O Cs+ Br (this reactant only) (d) (1S,3R)-1-chloro-3-(iodomethyl)cyclopentane + excess NaOEt (e) Same rxn as in part c, but with 1 equivalent of NaOEt (just draw the product.) 3. For each reaction below, draw all the alkene products formed by the E2 mechanism. If more than one alkene is produced, indicate which is the major product. (a) (b) EtO Cl Br Ph EtO EtOH EtOH (Note that syn/anti stereochem is not an issue for the next two — E2 rxns on cyclopentane rings go via both syn and slightly-misaligned-anti, so Hs cis and trans to the l.g. are lost.) (c) (d) OTs EtO EtOH (e) In which of these reactions can SN2 also occur? Br CH3 CH3 EtO EtOH Chem 21 Fall 2009 HW set 8 25 points; due Wed, Nov 4 Name _________________________________________ 1. Draw the products of these SN2 reactions. Same instructions as for #1 and 2 of the nongraded portion. Make sure all structures are clear. (a) O iPr–NH2 Br O DMF (b) F SNa CH3CH2Br DMSO (c) Br NaCN (1 equiv) I acetone CH3O (d) Same rxn as in part c, but with excess sodium cyanide. (e) Cl CH3CO2K Ph O SO2 CF3 CH3CN 2. A key experiment that established 100% inversion of configuration in the SN2 reaction was the finding that an optically active iodoalkane, upon treatment with radioactive iodide, lost optical activity twice as fast as the radioactive iodine was incorporated. Suppose that the result had been instead that the radioactive iodide had been incorporated twice as fast as the optical activity was lost. What would you conclude about the ratio of inversion to retention in this case? Show your reasoning. 3. The following reactions go via E2 mechanisms. Draw the products, showing structures and stereochemistry clearly. (a) NaOCH3 OEt Cl CH3OH (b) Br OLi iPrOH (c) OK tBu–OTs acetone (d) In which of these cases might SN2 also occur?

Chemistry 21 Homework set 8

Related Documents

Description

Related Documents

Free up your schedule!

Take 5 seconds to unlock