ORGANIC CHEMISTRY-OWL V2 ACCESS
8th Edition
ISBN: 9781305582422
Author: Brown
Publisher: CENGAGE L
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Chapter 5, Problem 5.22P
Interpretation Introduction
Interpretation:
Way in which racemization of trans-cycloalkane take place without breaking any bonds has to be determined. Also reason for trans-cyclononene racemize whereas trans-Cyclooctene does not under these conditions has to be explained.
Concept-Introduction:
Conformational isomerism is a type of stereoisomerism where isomers are able to get interconverted only by rotations about bonds that were formally single bonds.
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Students have asked these similar questions
trans-Cyclooctene has been resolved, and its enantiomers are stable at room temperature. trans-Cyclononene has also been resolved, but it racemizes with a half-life of 4 min at 0°C. How can racemization of this cycloalkene take place without breaking any bonds? Why does trans-cyclononene racemize under these conditions but trans-cyclooctene does not? You will find it especially helpful to examine the molecular models of these cycloalkenes.
Using what you know about the conformational energetics of substituted cyclohexanes, predict which of the two decalin isomers is more stable. Explain your reasoning.
Poly and B-Ryan are asked by their supervisor to synthesize (1R,3R)-1-chloro-1,3-
dimethylcyclopentane. To accomplish their syntheses, Poly chooses to start from a trisubstituted
alkene while B-Ryan chooses to start from a disubstituted alkene isomer. Poly's synthesis
provides a mixture of isomers while B-Ryan's provides two stereoisomers. Both synthetic
approaches are shown below.
Me
Me,
Me,
.CI
Me
HCI
A
B-Ryan's
Synthesis
Me
'CI
+
75%
25%
Ме
Me
Me
Me...
Me
B
Me
C
HCI
A
Poly's
Synthesis
-Me
Ме
'CI
'CI
+
+
Me..
.CI
+
a trace mixture ;
of constitutional
D
Ме
chloroalkane
isomers
Using your mechanistic knowledge of alkene reactions:
(a) Explain the selectivity (regio and stereo) observed in B-Ryan's synthesis.
(b) Propose a mechanism that accounts the formation of isomer C in Poly's synthesis.
(c) Draw the major stereoisomer(s) formed in the "trace mixture of constitutional isomers" isolated
in Poly's synthesis.
9.
Chapter 5 Solutions
ORGANIC CHEMISTRY-OWL V2 ACCESS
Ch. 5.1 - Calculate the index of hydrogen deficiency for...Ch. 5.1 - Prob. 5.2PCh. 5.2 - Write the IUPAC name of each alkene. (a) (b)Ch. 5.2 - Prob. 5.4PCh. 5.2 - Prob. 5.5PCh. 5.2 - Prob. 5.6PCh. 5.2 - Prob. 5.7PCh. 5.2 - Prob. 5.8PCh. 5 - Predict all approximate bond angles about each...Ch. 5 - Prob. 5.10P
Ch. 5 - The structure of 1,2-propadiene (allene) is shown...Ch. 5 - Prob. 5.12PCh. 5 - Draw structural formulas for these alkenes. (a)...Ch. 5 - Name these alkenes and cycloalkenes.Ch. 5 - Prob. 5.15PCh. 5 - Prob. 5.16PCh. 5 - Prob. 5.17PCh. 5 - For each molecule that shows cis, trans isomerism,...Ch. 5 - -Ocimene, a triene found in the fragrance of...Ch. 5 - Prob. 5.20PCh. 5 - Prob. 5.21PCh. 5 - Prob. 5.22PCh. 5 - Prob. 5.23PCh. 5 - Prob. 5.24PCh. 5 - Measure the CH3,CH3 distance in the...Ch. 5 - Prob. 5.26PCh. 5 - Measure the CCC and CCH bond angles in the...Ch. 5 - Prob. 5.28PCh. 5 - Prob. 5.29PCh. 5 - Prob. 5.30PCh. 5 - Prob. 5.31PCh. 5 - Prob. 5.32PCh. 5 - Prob. 5.33PCh. 5 - Pyrethrin II and pyrethrosin are two natural...Ch. 5 - Prob. 5.35PCh. 5 - Prob. 5.36PCh. 5 - Bromine adds to cis- and trans-2-butene to give...
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