13_all_ - 13.1(a What product(s would you expect to obtain if propene labeled with subject to allylic chlorination or bromination(b Explain your

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
13.1 (a) What product(s) would you expect to obtain if propene labeled with 14 C at C1 were subject to allylic chlorination or bromination? (b) Explain your answer. H 2 14 C CHCH 3 + X 2 high temperature or low conc. of X 2 ? (c) If more than one product would be obtained, what relative proportions would you expect? Answer: (a) It will obtain H 2 14 C CHCH 2 Br and H 2 C CH 14 CH 2 Br . (b) high temperature H 2 14 C CHCH 2 Br H 2 C CH CH 2 Br 2 2Br + H 2 14 C CHCH 3 HBr + H 2 CC H CH 2 H 2 H CH 2 H 2 H CH 2 Br Br 14 14 14 (c) 50% to 50% 13.2 (a) Write structures corresponding to D, E and F for the carbocation shown. H 3 C H C C H CH 2 (b) This carbocation appears to be even more stable than a tertiary carbocation; how can you expect this? (c) What product do you expect to be formed if this carbocation reacted with a chloride ion? Answer: (a) H 3 C C C CH 2 H H H 3 C C C H H CH 2 E D H 3 C C CH CH 2 H H 1/2 1/2 F (b) Because the positive charge has been dispersed on two carbons, so it is more stable than tertiary carbocation. (c) H 3 C CH C CH 2 Cl H H 3 C C C H H H 2 C Cl and
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
13.3 Give the important resonance structures for each of the following: (a) H 2 C C CH 3 CH 2 (b) H 2 CC H H C C H CH 2 (c) (d) (e) H 3 CHC C H C H OH (f) H 2 H Br (g) CH 2 (h) H 2 CH 3 O (i) H 3 CS CH 2 (j) H 3 CN O 2 Answer: (a) H 2 C C CH 3 CH 2 H 2 CH 3 CH 2 (b) H 2 H H C C H CH 2 H 2 H C H C H CH 2 H 2 H C H C H CH 2 (c)
Background image of page 2
(d) (e) H 3 CHC C H C H OH H 3 CHC C H H C OH H 3 CHC C H C H OH (f) H 2 CC H Br H 2 H Br (g) CH 2 CH 2 CH 2 CH 2 (h) H 2 CH 3 O H 2 C C CH 3 O (i) H 3 CS CH 2 H 3 CH 2 (j) H 3 CN O O H 3 O O 13.4 From each set of resonance structures that follow, designate the one that would contribute most to the hybrid and explain your choice. (a) H 3 CH 2 CC C H CH 2 CH 3 H 3 CH 2 CC C H CH 2 CH 3 (b)
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
CH 2 CH 2 (c) H 2 CN ( C H 3 ) 2 H 2 ( C H 3 ) 2 (d) H 3 CC O H O H 3 O H O (e) H 2 CHC CHCH CH 2 H 2 C CHCHCH CH 2 H 2 C CHCH CHCH 2 (f) H 2 NC N H 2 N Answer: (a) H 3 CH 2 CC C H CH 2 CH 3 because the positive charge is on a tertiary carbon. (b) CH 2 because the positive charge is on the secondary carbon (c) H 2 ( C H 3 ) 2 The more covalent bonds a structure has, the more stable it is. (d) H 3 O H O (e) H 2 C CHCHCH CH 2 because the radical is a secondary carbon. (f) H 2 N because there is no charge separation. 13.5 The following keto and enol forms differ in the position for their electrons, but they are not resonance structures. Explain why they are not.
Background image of page 4
CC H H H O H Enol form C C O H H H H Keto form They are not resonance structures because a hydrogen atom has been moved. 13.6 (a) Which other compounds in Section 13.6 are conjugated dienes? (b) Which other compound is an isolated diene? (c) Which compound is an isolated enyne? (a) etc (b) (c) HC C H 2 C C H CH 2 13.7 Two compounds, A and B, have the same molecular formula, C 6 H 8 . Both A and B react with two molar equivalents of hydrogen in the presence of platinum to yield cyclohexane. Compound A shows three signals in its broadband decoupled 13 C NMR spectrum. Compound B shows only two 13 C NMR signals. Compound A shows an absorption maximum at 256 nm, whereas B shows no absorption maximum at wavelengths longer than 200nm. What are the structures of A and B?
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/23/2010 for the course CHEM 101 taught by Professor Smith during the Spring '10 term at Duke.

Page1 / 24

13_all_ - 13.1(a What product(s would you expect to obtain if propene labeled with subject to allylic chlorination or bromination(b Explain your

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online