Chapter 5.9, Problem 28CC

(a)

Interpretation Introduction

Interpretation:

Check whether the given allene is chiral or achiral.

Concept Introduction:

Allenes are compounds with two or more double bonds side-by side. Such bonds are called cumulated double bonds.

Chiral centre: A chiral centre is defined as the tetrahedral carbon atom in an organic molecule that is connected to four non-identical groups/substituents. It is sometimes known as a stereo genic centre.

An achiral carbon is a carbon having two or more identical groups around it.

Chirality: The geometric property of molecules where the structure of the molecule and its mirror image are not superimposable is known as chirality. Chiral molecules are optically active and they can rotate the plane polarized light.

Allenes shows axial chirality. Axial chirality is a stereoisomerism resulting from the non-planar arrangement of four groups in pairs about a chiral axis.

Example:

Here cumulated $\pi$ bonds of an allene lie in perpendicular planes and so unsymmetrically substituted allenes are chiral.

(b)

Interpretation Introduction

Interpretation:

Check whether the given allene is chiral or achiral.

Concept Introduction:

Allenes are compounds with two or more double bonds side-by side. Such bonds are called cumulated double bonds.

Chiral centre: A chiral centre is defined as the tetrahedral carbon atom in an organic molecule that is connected to four non-identical groups/substituents. It is sometimes known as a stereo genic centre.

An achiral carbon is a carbon having two or more identical groups around it.

Chirality: The geometric property of molecules where the structure of the molecule and its mirror image are not superimposable is known as chirality. Chiral molecules are optically active and they can rotate the plane polarized light.

Allenes shows axial chirality. Axial chirality is a stereoisomerism resulting from the non-planar arrangement of four groups in pairs about a chiral axis.

Example:

Here cumulated $\pi$ bonds of an allene lie in perpendicular planes and so unsymmetrically substituted allenes are chiral.

(c)

Interpretation Introduction

Interpretation:

Check whether the given allene is chiral or achiral.

Concept Introduction:

Allenes are compounds with two or more double bonds side-by side. Such bonds are called cumulated double bonds.

Chiral centre: A chiral centre is defined as the tetrahedral carbon atom in an organic molecule that is connected to four non-identical groups/substituents. It is sometimes known as a stereo genic centre.

An achiral carbon is a carbon having two or more identical groups around it.

Chirality: The geometric property of molecules where the structure of the molecule and its mirror image are not superimposable is known as chirality. Chiral molecules are optically active and they can rotate the plane polarized light.

Allenes shows axial chirality. Axial chirality is a stereoisomerism resulting from the non-planar arrangement of four groups in pairs about a chiral axis.

Example:

Here cumulated $\pi$ bonds of an allene lie in perpendicular planes and so unsymmetrically substituted allenes are chiral.

(d)

Interpretation Introduction

Interpretation:

Check whether the given allene is chiral or achiral.

Concept Introduction:

Allenes are compounds with two or more double bonds side-by side. Such bonds are called cumulated double bonds.

Chiral centre: A chiral centre is defined as the tetrahedral carbon atom in an organic molecule that is connected to four non-identical groups/substituents. It is sometimes known as a stereo genic centre.

An achiral carbon is a carbon having two or more identical groups around it.

Chirality: The geometric property of molecules where the structure of the molecule and its mirror image are not superimposable is known as chirality. Chiral molecules are optically active and they can rotate the plane polarized light.

Allenes shows axial chirality. Axial chirality is a stereoisomerism resulting from the non-planar arrangemen6t of four groups in pairs about a chiral axis.

Example:

Here cumulated $\pi$ bonds of an allene lie in perpendicular planes and so unsymmetrically substituted allenes are chiral.