Organic Chemistry As a Second Language, 3e: First Semester Topics

Published by John Wiley & Sons
ISBN 10: 111801040X
ISBN 13: 978-1-11801-040-2

Chapter 7 - Configurations - 7.7 Drawing Fischer Projections - Problems - Page 162: 7.76


The stereocenters of this compound is R. The enantiomer will have: (Et) on the top. (H) on the right. (Me) on the bottom. (Br) on the left.

Work Step by Step

1. Draw wedges in the horizontal lines, and dashes on the vertical lines. 2. Now we have to choose one wedge and one dash to switch to "normal" bonds. - I will choose the Hydrogen and the Ethyl. 3. Determine the configuration of this stereocenter: - We will have to use the switch method. - Switch the Hydrogen with the group on the wedge (Methyl) - Now, determine the numbers that each group will get. - Bromo (1), Ethyl (2), Methyl (3). - The numbers are increasing on the counterclockwise direction. - Which means that this compound is "S". - But, this compound is not the original one: we have switched two groups. - Therefore, the configuration of the original compound is the opposite: "R". 4. To draw the enantiomer, redraw the molecule and just switch the left groups with the right groups.
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