Assignment Help - homework help

  Compounds with Several Stereogenic Centers Homework Help - K-12 Grade Level, College Level Chemistry

Introduction to Compounds with Several Stereogenic Centers

The Chinese shrub Ma Huang (Ephedra vulgaris) consists of two physiologically active compounds that are pseudoephedrine and ephedrine. Both compounds are stereoisomers of 2-methylamino-1-phenyl-1-propanol and both are optically active, one being levorotatory and the other dextrorotatory. Because the properties of these compounds are considerably distinct, they cannot be enantiomers.

Ephedrine from Ma Huang:               m.p. 35 - 40 º C,   [α]D = -41º,   moderate water solubility [this isomer may be referred to as (-)-ephedrine]

Pseudoephedrine from Ma Huang:   m.p. 119 º C,   [α]D = +52º,       relatively insoluble in water [this isomer may be referred to as (+)-pseudoephedrine]

Each must have an enantiomer because these two compounds are optically active. Even though these missing stereoisomers were not exist in the natural source, they have been prepared synthetically and have the expected similar physical properties and opposite-sign specific rotations with those listed above. The structural formula of 2-methylamino-1-phenylpropanol has two stereogenic carbons (#1 & #2). Each may suppose an R or S configuration; therefore, there are four stereoisomeric combinations possible. These are displayed in the examples, together with the assignments that have been made on the basis of chemical interconversions.

2126_Compounds with Several Stereogenic Centers Homework Help.jpg

Like a general rule, a structure having n chiral centers will have 2n possible combinations of these centers. Depending on the entire symmetry of the molecular structure, some of these combinations may be similar but in the absence of this type of identity, we would suppose to find 2n stereoisomers. Few of these stereoisomers will have enantiomeric relationships but enantiomers come in pairs, and so non-enantiomeric stereoisomers will be common. We consider such type of stereoisomers as diastereomers. In the instance above, either of the ephedrine enantiomers has a diastereomeric relationship with either of the pseudoephedrine enantiomers.

Stereochemical Terminology

1605_Compounds with Several Stereogenic Centers Homework Help 1.jpg

In the development of organic chemistry Concept of the asymmetric carbon has played an essential role. Certainly, it provided the focus for the revolutionary structural theory that is introduced by Joseph A. Le Bel and Jacobus van't Hoff. Though, in recent years the nuance of differentiate among the purely structural definition of an asymmetric carbon and the operational definition of a stereogenic element (for example a chiral center) has become increasingly essential. 

For an instance, consider the tetrasubstituted adamantane molecule displayed in the diagram on the left. Even though four asymmetric carbon atoms (that is blue in color) are exist in this compound, it present in the form of only two stereoisomers (enantiomers) rather than the sixteen expected by the 2n rule. There is, actually, only one stereogenic center, displayed by the red dot at the center of the molecule and the configuration displayed in the diagram is (R). The asymmetric carbon atoms are not stereogenic centers, since any two substituents on any of these bridgehead carbons cannot be exchanged without destroying the constitutional integrity of this rigid, highly bridged molecule.
The configurations of the asymmetric bridgehead carbon units in this structure are (R), (S), (R) and (R) correspondingly, for the Br, Cl, CO2H and CH3 substituents. Its enantiomer would. Certainly, have the opposite configurations.

Email based Compounds with Several Stereogenic Centers Homework Help -Assignment Help

Tutors at the www.tutorsglobe.com are committed to provide the best quality Compounds with Several Stereogenic Centers homework help - assignment help. They use their experience, as they have solved thousands of the Compounds with Several Stereogenic Centers assignments, which may help you to solve your complex Compounds with Several Stereogenic Centers homework. You can find solutions for all the topics come under the Stoichiometry. The dedicated tutors provide eminence work on your Organic Chemistry homework help and devoted to provide K-12 level Chemistry to college level chemistry help before the deadline mentioned by the student. Compounds with Several Stereogenic Centers homework help is available here for the students of school, college and university. TutorsGlobe assure for the best quality compliance to your homework. Compromise with quality is not in our dictionary. If we feel that we are not able to provide the homework help as per the deadline or given instruction by the student, we refund the money of the student without any delay.

Qualified and Experienced Compounds with Several Stereogenic Centers Tutors at www.tutorsglobe.com

Tutors at the www.tutorsglobe.com take pledge to provide full satisfaction and assurance in Compounds with Several Stereogenic Centers homework help. Students are getting Chemistry homework help services across the globe with 100% satisfaction. We value all our service-users. We provide email based Compounds with Several Stereogenic Centers homework help - assignment help. You can join us to ask queries 24x7 with live, experienced and qualified Chemistry tutors specialized in Compounds with Several Stereogenic Centers.
Home | Company Overview | Services | Discover Q&A | Sitemap | Contact Us | T & C | Refund Policy | Copyright Policy | Blog | Q&A | Directory

©TutorsGlobe All rights reserved 2022-2023.