Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 5: Q.70 (page 212)

A sulfonium ion (R3S+) is a stereogenic center if three different alkyl groups are bonded to sulfur because sulfur is surrounded by four different groups, including its lone pair. In assigning an R or S designation to sulfur, the lone pair is always assigned the lowest priority (4). SAM, S-adenosylmethionine, is a biologically active sulfonium ion that we will learn about in Section 7.16. Locate all the stereogenic centers in SAM, and assign an R,S designation to each center.

Short Answer

Expert verified

These are atoms that have different substituents in a compound such that interchanging the positions of two groups gives two stereoisomers.

Step by step solution

01

Stereogenic centres

These are atoms that have different substituents in a compound such that interchanging the positions of two groups gives two stereoisomers.

02

R and S nomenclatures.

The priorities are assigned according to the rules of R and S, and the stereogenic centers are named R if the groups ordered from highest priority 1 to the lowest priority are aligned clockwise and vice-versa.

03

Drawing the structures of the given compounds

The given compound SAM has 6 stereogenic centers. All the stereogenic centers are marked with a (*) and designated as R and S hereunder.

Stereogenic centers marked as R and S

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

a. Locate all the tetrahedral stereogenic centers in discodermolide, a tumor inhibitor isolated from the Caribbean marine sponge Discodermiadissoluta.

b. Certain carbon–carbon double bonds can also be stereogenic centers. With reference to the definition in Section 5.3, explain how this can occur, and then locate the three additional stereogenic centers in discodermolide.

c. Considering all stereogenic centers, what is the maximum number of stereoisomers possible for discodermolide?

Which group in each pair is assigned the higher priority in R,S nomenclature?

  1. -CD3,-CH3
  2. localid="1648446360910" -CH(CH3)2,-CH2OH
  3. localid="1648447310055" -CH2Cl,-CH2CH2CH2Br
  4. -CH2NH2,-NHCH3

Amygdalin, a compound isolated from the pits of apricots, peaches, and wild cherries, has been used as an unsanctioned anticancer drug both within and outside of the United States. One hydrolysis product formed from amygdalin is mandelic acid, used in treating common skin problems caused by photo-aging and acne.

a. How many stereogenic centres are present in amygdalin? What is the maximum number of stereoisomers possible?

b. Draw both enantiomers of mandelic acid and label each stereogenic centre as R or S.

c. Pure (R)-mandelic acid has a specific rotation of –154. If a sample contains 60% of the R isomer and 40% of its enantiomer, what is [α]of this solution?

d. Calculate the ee of a solution of mandelic acid having [α] = +50. What is the percentage of each enantiomer present?

Consider the ball-and-stick models of A-D. How is each pair of compounds related: (a) A and B; (b) A and C; (c) A and D; (d) C and D? Choose from identical molecules, enantiomers, or diastereomers.

Locate the stereogenic centers in each molecule. Compounds may have one or more stereogenic centers.

a.

b.

c.

d.

e.

f.
See all solutions

Recommended explanations on Chemistry Textbooks

Nuclear Chemistry

Read Explanation

Inorganic Chemistry

Read Explanation

Chemistry Branches

Read Explanation

Physical Chemistry

Read Explanation

Chemical Reactions

Read Explanation

The Earths Atmosphere

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free