Chapter 11, Problem 83P

Answer the following questions about aldosterone, a compound that helps to control the absorption of Na⁺and Cl^- ions in the kidneys and, as a result, affects water retention.

1. Identify the functional groups.
2. Draw in all lone pairs on O atoms.
3. How many C’s does aldosterone contain?
4. How many H’s are present at each C labeled with an asterisk (*)?
5. Give the shape around each atom labeled in gray.
6. Label all polar bonds.

Interpretation Introduction

(a)

Interpretation:

The functional group in aldosterone should be midentified.

Concept Introduction:

Functional groups are the atoms or group of atoms that gives chemical properties to an organic compound and also chemical reactivity centre. Examples of functional groups are aldehyde, ketone, alcohol, double bond.

Answer to Problem 83P

In aldosterone, functional groups present are alcohol, aldehyde, ketone and alkene.

Explanation of Solution

Functional groups are the atoms or group of atoms that gives chemical properties to an organic compound and also chemical reactivity centre. Structures of different functional groups are as follows:

R represents any alkyl chain.

In functional group ketone carbonyl carbon is bonded to two alkyl groups, in aldehyde carbonyl carbon is attached to one alkyl group and one hydrogen atom, in alcohol functional group an −OH is bonded to an alkyl group.

The compound aldosterone consists of two alcohol frunctional group, two ketone functional groups and one aldehyde functional group and one alkene. So, four types of functional group, that is, alcohol, aldehyde, ketone and alkene.

Interpretation Introduction

(b)

Interpretation:

All the lone pairs on oxygen atom of aldosterone should be drawn.

Concept Introduction:

Oxygen atom has six valence electrons. The electrons which are used in bond formation are called bonding electrons. The electrons that remain on an atom after bond formation are called lone pair electrons.

Answer to Problem 83P

The structure of aldosterone having all lone pairs on oxygen atom is,

Explanation of Solution

The structure of aldosterone is as follows:

In the compound, three double bonded oxygen atoms present. Oxygen has six valence electrons. Two electrons in all double bonded oxygen atoms are used for formation of double bond. Remaining four electrons present as two lone pair. Also the compound contains three single bonded oxygen atoms. One electron is used for making O-H bond and one electron is used for making O-C bond. Remaining four electrons present as two lone pairs on each single bonded oxygen atom. Hence, the structure having all lone pairs on oxygen atom is,

Interpretation Introduction

(c)

Interpretation:

The number of carbon atoms in the structure of aldosterone should be determined.

Concept Introduction:

In skeletal structure the terminals represent methyl $-{\text{CH}}_{\text{3}}$ groups, joining of two bonds in represented by methylene groups $-{\text{CH}}_2$ groups if no substituent present, if one substituent present then the group will be $-\text{CH}$.

Answer to Problem 83P

Twenty one carbon atoms present in the aldosterone.

Explanation of Solution

The structure of aldosterone is given as follows:

In skeletal structure the terminals represent methyl $-{\text{CH}}_{\text{3}}$ groups, joining of two bonds in represented by methylene groups $-{\text{CH}}_2$ groups if no substituent present, if one substituent present then the group will be $-\text{CH}$ . So, the complete structure of aldosterone is as follows:

Hence, twenty one carbon atoms present in the compound.

Interpretation Introduction

(d)

Interpretation:

The number of hydrogen atoms present in the * carbon atoms in aldosterone should be determined.

Concept Introduction:

In skeletal structure the terminals represent methyl $-{\text{CH}}_{\text{3}}$ groups, joining of two bonds in represented by methylene groups $-{\text{CH}}_2$ groups if no substituent present, if one substituent present then the group will be $-\text{CH}$.

Answer to Problem 83P

The * carbon atoms have total five hydrogen atoms.

Explanation of Solution

In skeletal structure the terminals represent methyl $-{\text{CH}}_{\text{3}}$ groups, joining of two bonds in represented by methylene groups $-{\text{CH}}_2$ groups if no substituent present, if one substituent present then the group will be $-\text{CH}$ . So, the complete structure of aldosterone is as follows:

Hence, the * carbon atoms have total five hydrogen atoms.

Interpretation Introduction

(e)

Interpretation:

The shape around each indicated carbon atom in aldosterone should be determined.

Concept Introduction:

The following table should be used while determining the shape around an atom.

Number of groups	Number of atoms	Number of lone pairs	Shape	Bond angle
2	2	0	Linear	$180°\text{C}$
3	3	0	Trigonal planar	$120°\text{C}$
4	4	0	Tetrahedral	$109.5°\text{C}$
4	3	1	Trigonal pyramidal	$109.5°\text{C}$
4	2	2	Bent	$109.5°\text{C}$

Answer to Problem 83P

• Shape around carbon (1) is tetrahedral, shape around carbon (2) is tetrahedral, shape around oxygen (3) is bent, shape around carbon (4) is trigonal planar and shape around carbon (5) is tetrahedral.

Explanation of Solution

The complete structure of aldosterone is as follows:

• Carbon (1) has four groups ( two hydrogen and two carbon) surrounding it. So, shape around carbon (1) is tetrahedral.
• Carbon (2) has four groups (three hydrogen and one carbon) surrounding it. So, shape around carbon (2) is tetrahedral.
• Oxygen (3) has two groups (one carbon and one hydrogen) and two lone pairs surrounding it. So, shape around oxygen (3) is bent.
• Carbon (4) has three groups (two carbon and one oxygen) surrounding it. So, shape around carbon (4) is trigonal planar.
• Carbon (5) has four groups (three carbon and one hydrogen) surrounding it. So, shape around carbon (5) is tetrahedral.

Interpretation Introduction

(f)

Interpretation:

All the polar bonds in aldosterone should be labeled.

Concept Introduction:

The unequal sharing of valence electrons in a bond is called polar bond. Polar bond result when the bond formed between two atoms in which one atom is more electronegative than the other one. One example of polar bond is $\text{H}-\text{Cl}$.

Structure of HCl is as follows:

In $\text{H}-\text{Cl}$ , Chlorine is more electronegative than hydrogen.

Answer to Problem 83P

The structure of aldosterone with all polar bonds is as follows:

Explanation of Solution

In organic compound, most of the polar bonds formed between carbon and heteroatoms like oxygen, nitrogen, sulphur etc. To identify the polar bonds in the compound aldosterone, find the bonds between carbon and oxygen or oxygen and hydrogen because oxygen is more electronegative than carbon and oxygen is more electronegative than carbon. In aldostrone, five polar bonds are formed between carbon and oxygen (oxygen is more electronegative than carbon) and two polar bonds present between oxygen and hydrogen (oxygen is more electronegative than hydrogen). Thus, the polar bonds are: