Laboratory Report 1 SKO3023 PDF

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LABORATORY REPORTSKO 3023ORGANIC CHEMISTRY 1EXPERIMENT TITLECONFORMATION AND OPTICAL ISOMERSNAME ID / MATRIC NO.LECTURERGROUPDATELABORATORYDEPARTMENT OF CHEMISTRYFACULTY OF SCIENCE AND MATHEMATICSUNIVERSITI PENDIDIKAN SULTAN IDRIS1DAYANG FARIESHAH ASYEERA BINTI ABDUL WAHAB DNOR SAYIDATUL FARIHAH BIN...

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DEPARTMENT OF CHEMISTRY FACULTY OF SCIENCE AND MATHEMATICS UNIVERSITI PENDIDIKAN SULTAN IDRIS

LABORATORY REPORT SKO 3023 ORGANIC CHEMISTRY 1

EXPERIMENT 1

TITLE CONFORMATION AND OPTICAL ISOMERS

NAME

ID / MATRIC NO.

DAYANG FARIESHAH ASYEERA BINTI ABDUL WAHAB

D20191088466

NOR SAYIDATUL FARIHAH BINTI YUSOP

D20191088475

SAIDATUL ZAHIRAH BINTI JOHN YONG

D20191088476

FARAH NADHIRAH BINTI SALLEH

D20191088502

LECTURER GROUP DATE

DR. WAN MOHD NUZUL HAKIMI W SALLEH C 09/03/2020

LABORATORY

……………………………….

NO.

ITEMS

MARKS

1.

Introduction

3

2.

Procedure / Methods

1

3.

Results / Worksheets

5

4.

Discussion

5

5.

Conclusion

2

6.

References

1

7.

Question / Answer (if any)

2

8.

Format

1 TOTAL

20

OBJECTIVE 1. Explain the concept of conformation and optical isomerism INTRODUCTION Stereochemistry is the study of molecules in space and how the atoms in a molecule are arranged in space relative to one another. In this experiment, we focus in two aspects of stereochemistry, conformation and optical isomerism. Conformation: Group bonded by only a sigma (σ) bond can undergo rotation. The temporary molecular shapes that result from rotation of the groups about single bond are called conformations of a molecule. Each possible structure is called a conformer. An analysis of the energy changes associated with a molecule undergoing rotation about single bonds is called conformational analysis. Optical isomerism occurs when the molecule doesn’t have a plane of symmetry in the molecule. All the optical isomers have the same physical properties such as melting points, boiling points, solubility except the rotation of the plane polarized light. APPARATUS Molecular model set PROCEDURE Part A. Conformation 1. A perspective view and Newman projection of ethane for the following conformation were drawn. The more stable conformation was determined and explained. a) Staggered b) Eclipsed 2. The models of following molecules were constructed and the potential energy diagram versus the degrees of rotation (0°-360°) a) Ethane (C1-C2 bond) b) Propane (C1-C2 bond) c) Butane (C2-C3 bond) 3. Chair and boat conformations for cyclohexane were constructed and drawn. The axial hydrogen and equatorial hydrogen were labelled. The more stable conformation was determined and explained. 4. The model of chair conformation and the Newman projection for the following molecules were constructed and drawn. The more stable conformation was determined and explained. a) 1-methylcyclohexane (through C1-C2 and C5-C4) b) 1,2-dimethylcyclohexane (through C1-C2 and C5-C4)

c) 1,3-dimethylcyclohexane (through C1-C6 and C3-C4) d) 1,4-dimethylcyclohexane (through C1-C2 and C5-C4) PART B. Optical isomerism 1. The absolute configuration (R and S) for each of the following molecules were determined using the molecular models. F

a)

CI

COOH

H

b)

CH3

NH2

Br

H

2. The molecular models for the following molecules were constructed and their mirror image were drawn. The object and its mirror image were determined whether identical or a pair of enantiomers. The unsymmetrical (optically active) was also determined. H a)

Br

OCH3 H

CH3

b)

H

OH C

RESULTS: PART A : Conformation 1) Ethane: Explanation :

Newman

Sawhorse

Newman

Sawhorse

Staggered conformation is more stable than Eclipsed conformation. This is due to (Staggered)

the steric hindrance and stabilization of staggered conformation by hyperconjugation.

Ethane :

Explanation : Eclipsed conformation is less stable due to the position of

(Eclipsed)

Hydrogen atoms around Carbon that forces them to become closer with each other. This increase the amount of

2)

Ethane

steric strain in the molecule. Potential Energy Diagram

Staggered :

(C1-C2 bond)

Eclipsed :

Propane

Potential Energy Diagram

Staggered :

(C1-C2 bond)

Butane

Eclipsed :

Potential Energy Diagram

Staggered :

(C2-C3 bond)

Eclipsed :

3)

Axial Hydrogen (a)

Equatorial Hydrogen (e)

Equatorial Hydrogen is more stable than Axial Hydrogen because it has less torsional strain.

Cyclo

Hydrogen atoms does not touch between each

hexane

other and this helps in increasing the stability of the conformation. Axial Hydrogen is less stable because it is parallel between each other and this causing unfavourable interactions between the axial atoms on the same side.

4)

1-Methylcyclohexane (through C1-C2 bond and C5-C4 bond)

Axial Conformation (a)

Equatorial Conformation(e)

Equatorial Conformation is more stable because it has less torsional strain. When Methyl is in equatorial position, the distance between it with Hydrogen atoms is much bigger. 1,2-Dimethylcyclohexane (through C1-C2 bond and C5-C4 bond)

(a,e) conformation

(e,a) Conformation

(a,e) and (e,a) Conformation are not stable because when the branch/ the substituents are in the axial position, it tends to have more unfavorable interaction between the axial atoms on the same side. If the substituents are in the equatorial position, they are farther away from each other and thus helps in increasing the conformation stability. 1,3-Dimethylcyclohexane (through C1-C6 bond and C3-C4 bond)

(a,a) Conformation

(e,e) Conformation

(e,e) Conformation is more stable because it has less torsional strain. When Methyl are in the equatorial position, they are farther away with Hydrogen atoms. This helps avoids interaction with Hydrogen atoms and thus increases the stability of conformation. 1,4-Dimethylcyclohexane (through C1-C2 bond and C5-C4 bond)

(a,a) Conformation

(e,e) Conformation

(e,e) Conformation is more stable than (a,a) Conformation because it has less torsional strain. When Methyl are in the equatorial position, they are farther away with Hydrogen atoms. This helps avoids interaction with Hydrogen atoms and thus increases the stability of conformation.

PART B : OPTICAL ISOMERISM B. Optical Isomerism 1) a)

b)

Absolute Configuration : S Configuration

2)

a)

Absolute Configuration : R Configuration

Mirror Image : The object and its mirror image were a pair of enantiomers.

b)

Mirror Image : The object and its mirror image were a pair of enantiomers.This compound is optically active.

RESULTS: PART A : Conformation 1) Ethane: Explanation :

Newman

Sawhorse

Newman

Sawhorse

Staggered conformation is more stable than Eclipsed conformation. This is due to (Staggered)

the steric hindrance and stabilization of staggered conformation by hyperconjugation.

Ethane :

Explanation : Eclipsed conformation is less stable due to the position of

(Eclipsed)

Hydrogen atoms around Carbon that forces them to become closer with each other. This increase the amount of

2)

Ethane

steric strain in the molecule. Potential Energy Diagram

Staggered :

(C1-C2 bond)

Eclipsed :

Propane

Potential Energy Diagram

Staggered :

(C1-C2 bond)

Butane

Eclipsed :

Potential Energy Diagram

Staggered :

(C2-C3 bond)

Eclipsed :

3)

Axial Hydrogen (a)

Equatorial Hydrogen (e)

Equatorial Hydrogen is more stable than Axial Hydrogen because it has less torsional strain.

Cyclo

Hydrogen atoms does not touch between each

hexane

other and this helps in increasing the stability of the conformation. Axial Hydrogen is less stable because it is parallel between each other and this causing unfavourable interactions between the axial atoms on the same side.

4)

1-Methylcyclohexane (through C1-C2 bond and C5-C4 bond)

Axial Conformation (a)

Equatorial Conformation(e)

Equatorial Conformation is more stable because it has less torsional strain. When Methyl is in equatorial position, the distance between it with Hydrogen atoms is much bigger. 1,2-Dimethylcyclohexane (through C1-C2 bond and C5-C4 bond)

(a,e) conformation

(e,a) Conformation

(a,e) and (e,a) Conformation are not stable because when the branch/ the substituents are in the axial position, it tends to have more unfavorable interaction between the axial atoms on the same side. If the substituents are in the equatorial position, they are farther away from each other and thus helps in increasing the conformation stability. 1,3-Dimethylcyclohexane (through C1-C6 bond and C3-C4 bond)

(a,a) Conformation

(e,e) Conformation

(e,e) Conformation is more stable because it has less torsional strain. When Methyl are in the equatorial position, they are farther away with Hydrogen atoms. This helps avoids interaction with Hydrogen atoms and thus increases the stability of conformation. 1,4-Dimethylcyclohexane (through C1-C2 bond and C5-C4 bond)

(a,a) Conformation

(e,e) Conformation

(e,e) Conformation is more stable than (a,a) Conformation because it has less torsional strain. When Methyl are in the equatorial position, they are farther away with Hydrogen atoms. This helps avoids interaction with Hydrogen atoms and thus increases the stability of conformation.

PART B : OPTICAL ISOMERISM B. Optical Isomerism 1) a)

b)

Absolute Configuration : S Configuration

2)

a)

Absolute Configuration : R Configuration

Mirror Image : The object and its mirror image were a pair of enantiomers.

b)

Mirror Image : The object and its mirror image were a pair of enantiomers.This compound is optically active.

RESULTS: PART A : Conformation 1) Ethane: Explanation :

Newman

Sawhorse

Newman

Sawhorse

Staggered conformation is more stable than Eclipsed conformation. This is due to (Staggered)

the steric hindrance and stabilization of staggered conformation by hyperconjugation.

Ethane :

Explanation : Eclipsed conformation is less stable due to the position of

(Eclipsed)

Hydrogen atoms around Carbon that forces them to become closer with each other. This increase the amount of

2)

Ethane

steric strain in the molecule. Potential Energy Diagram

Staggered :

(C1-C2 bond)

Eclipsed :

Propane

Potential Energy Diagram

Staggered :

(C1-C2 bond)

Butane

Eclipsed :

Potential Energy Diagram

Staggered :

(C2-C3 bond)

Eclipsed :

3)

Axial Hydrogen (a)

Equatorial Hydrogen (e)

Equatorial Hydrogen is more stable than Axial Hydrogen because it has less torsional strain.

Cyclo

Hydrogen atoms does not touch between each

hexane

other and this helps in increasing the stability of the conformation. Axial Hydrogen is less stable because it is parallel between each other and this causing unfavourable interactions between the axial atoms on the same side.

4)

1-Methylcyclohexane (through C1-C2 bond and C5-C4 bond)

Axial Conformation (a)

Equatorial Conformation(e)

Equatorial Conformation is more stable because it has less torsional strain. When Methyl is in equatorial position, the distance between it with Hydrogen atoms is much bigger. 1,2-Dimethylcyclohexane (through C1-C2 bond and C5-C4 bond)

(a,e) conformation

(e,a) Conformation

(a,e) and (e,a) Conformation are not stable because when the branch/ the substituents are in the axial position, it tends to have more unfavorable interaction between the axial atoms on the same side. If the substituents are in the equatorial position, they are farther away from each other and thus helps in increasing the conformation stability. 1,3-Dimethylcyclohexane (through C1-C6 bond and C3-C4 bond)

(a,a) Conformation

(e,e) Conformation

(e,e) Conformation is more stable because it has less torsional strain. When Methyl are in the equatorial position, they are farther away with Hydrogen atoms. This helps avoids interaction with Hydrogen atoms and thus increases the stability of conformation. 1,4-Dimethylcyclohexane (through C1-C2 bond and C5-C4 bond)

(a,a) Conformation

(e,e) Conformation

(e,e) Conformation is more stable than (a,a) Conformation because it has less torsional strain. When Methyl are in the equatorial position, they are farther away with Hydrogen atoms. This helps avoids interaction with Hydrogen atoms and thus increases the stability of conformation.

PART B : OPTICAL ISOMERISM B. Optical Isomerism 1) a)

b)

Absolute Configuration : S Configuration

2)

a)

Absolute Configuration : R Configuration

Mirror Image : The object and its mirror image were a pair of enantiomers.

b)

Mirror Image : The object and its mirror image were a pair of enantiomers.This compound is optically active.

RESULTS: PART A : Conformation 1) Ethane: Explanation :

Newman

Sawhorse

Newman

Sawhorse

Staggered conformation is more stable than Eclipsed conformation. This is due to (Staggered)

the steric hindrance and stabilization of staggered conformation by hyperconjugation.

Ethane :

Explanation : Eclipsed conformation is less stable due to the position of

(Eclipsed)

Hydrogen atoms around Carbon that forces them to become closer with each other. This increase the amount of

2)

Ethane

steric strain in the molecule. Potential Energy Diagram

Staggered :

(C1-C2 bond)

Eclipsed :

Propane

Potential Energy Diagram

Staggered :

(C1-C2 bond)

Butane

Eclipsed :

Potential Energy Diagram

Staggered :

(C2-C3 bond)

Eclipsed :

3)

Axial Hydrogen (a)

Equatorial Hydrogen (e)

Equatorial Hydrogen is more stable than Axial Hydrogen because it has less torsional strain.

Cyclo

Hydrogen atoms does not touch between each

hexane

other and this helps in increasing the stability of the conformation. Axial Hydrogen is less stable because it is parallel between each other and this causing unfavourable interactions between the axial atoms on the same side.

4)

1-Methylcyclohexane (through C1-C2 bond and C5-C4 bond)

Axial Conformation (a)

Equatorial Conformation(e)

Equatorial Conformation is more stable because it has less torsional strain. When Methyl is in equatorial position, the distance between it with Hydrogen atoms is much bigger. 1,2-Dimethylcyclohexane (through C1-C2 bond and C5-C4 bond)

(a,e) conformation

(e,a) Conformation

(a,e) and (e,a) Conformation are not stable because when the branch/ the substituents are in the axial position, it tends to have more unfavorable interaction between the axial atoms on the same side. If the substituents are in the equatorial position, they are farther away from each other and thus helps in increasing the conformation stability. 1,3-Dimethylcyclohexane (through C1-C6 bond and C3-C4 bond)

(a,a) Conformation

(e,e) Conformation

(e,e) Conformation is more stable because it has less torsional strain. When Methyl are in the equatorial position, they are farther away with Hydrogen atoms. This helps avoids interaction with Hydrogen atoms and thus increases the stability of conformation. 1,4-Dimethylcyclohexane (through C1-C2 bond and C5-C4 bond)

(a,a) Conformation

(e,e) Conformation

(e,e) Conformation is more stable than (a,a) Conformation because it has less torsional strain. When Methyl are in the equatorial position, they are farther away with Hydrogen atoms. This helps avoids interaction with Hydrogen atoms and thus increases the stability of conformation.

PART B : OPTICAL ISOMERISM B. Optical Isomerism 1) a)

b)

Absolute Configuration : S Configuration

2)

a)

Absolute Configuration : R Configuration

Mirror Image : The object and its mirror image were a pair of enantiomers.

b)

Mirror Image : The object and its mirror image were a pair of enantiomers.This compound is optically active.

DISCUSSION Newman projections consists of two conformation which are eclipsed and staggered. An eclipsed conformation occurs when the bonds from the front carbon align with the bond from the back carbon. The dihedral angle which is the angle between the bond is 0˚. A staggered conformation results when the bond from the front carbon and the bonds from the back carbon have a dihedral angle of 60˚. Between staggered and eclipsed conformation, staggered conformation is more stable. In eclipse conformation of ethane, the perfectly lined up hydrogen atoms is energetically unfavourable as the negatively charged electrons in the bond strongly repel each other. Meanwhile, in the staggered conformation which have the dihedral angle of 60˚ where the hydrogen atom at the first carbon atom are at maximum separation from the hydrogen atom at the second carbon. Thus, staggered energy has less torsional strain, which is more stable (lower in energy). Besides staggered and eclipsed conformation, structure also exists in chair and boat conformation. Cyclohexane do exist in both of these conformation in which chair conformation is the most stable due no torsional strain. Next is boat conformation which it has less torsional strain which is associated with four eclipsed carbon atoms in the structure.

QUESTION 1. When the compound does not has a plane of symmetry, is it optically active? Explain.

When the compound does not has a plane of symmetry, it is optically active. A compound with plane of symmetry has an internal symmetry plane that divides them in half. These two halves reflect each other by the internal mirror. The compound that does not has a plane of symmetry have non-superimposable mirror images. Each non-superimposable m...