Chapter 10, Problem 10.35UKC

Answer the following questions about the alkane drawn below.

1. a. Give the IUPAC name.
2. b. Draw one constitutional isomer.
3. c. Predict the solubility in water.
4. d. Predict the solubility in an organic solvent.
5. e. Write a balanced equation for complete combustion.

Interpretation Introduction

Interpretation:

The IUPAC name of given compound has to be identified.

Concept Introduction:

IUPAC Nomenclature of alkane compounds.

IUPAC nomenclature is a system of writing a name for organic compounds.  The full form of IUPAC name is International Union of Pure and Applied chemistry.

There are certain rules followed for writing IUPAC name:

• The longest continuous carbon chain present in compound can be given as parent name.  Then add the prefix and suffix name to the parent name.  The suffix group represents the functional group present in a molecule.  The prefix name explains about the identity, location, and number of substituents present in compound.
• The functional groups or alkyl groups have to be determined.  The numbering of carbon starts from left side and ends at right side. 
• The suffix group –ane represents alkane molecule.  The prefix group represents the number of carbon atom present in the longest carbon chain.  Then the substituent group attached to the longest chain can be numbered in alphabetical order.  The prefix name can be given, depends on the number of substituent present in molecule.

Explanation of Solution

In this compound the longest chain has seven carbon atoms.  The parent name of given compound is heptane.  Then number the substituents in alphabetical order.  The ethyl group ${\text{(CH}}_{\text{2}}{\text{CH}}_{\text{3}}\text{)}$ is present at third carbon.  The two methyl groups ${\text{(CH}}_{\text{3}}\text{)}$ are present at fourth carbon position in chain.  Then add the prefix name di- to indicate two methyl substituents ${\text{(CH}}_{\text{3}}\text{)}$ present in the compound.  Hence the given compound can be named as 3-ethyl-4,4-dimethylheptane.

The IUPAC name of compound is given below,

Interpretation Introduction

Interpretation

The one constitutional isomer for the given compound has to be drawn.

Concept Introduction:

Isomers:

Isomers contain two or more compounds in which the molecular formula of compounds is same but the atoms are arranged in different order. The arrangement of atoms will be in different manner.

Constitutional isomer:

The compounds have the same molecular formula but atoms are arranged in different connectivity is known as constitutional isomer.

Explanation of Solution

The isomer 3-ethyl-4,5-dimethylheptane has seven carbon atoms present in the longest chain. The two substituents methyl groups ${{\text{(CH}}_{\text{3}}\text{)}}_{\text{2}}$ are attached to chain at different positions.  The methyl groups ${\text{(CH}}_{\text{3}}\text{)}$ are attached to fourth and fifth carbon in chain.  The ethyl group is attached to third position in chain.  The constitutional isomers have same molecular formula but the atoms are arranged in different positions.  The same molecular formula is given as ${\text{C}}_{\text{11}}{\text{H}}_{\text{24}}$.  The compounds have same molecular formula but the position of substituents methyl group ${\text{(CH}}_{\text{3}}\text{)}$ is different.  The possible position of substituent methyl groups ${{\text{(CH}}_{\text{3}}\text{)}}_{\text{2}}$ group in fourth and fifth carbon.  Hence the isomer can be named as 3-ethyl-4,5-dimethylheptane.

The constitutional isomers of $\text{3-}$ ethyl-$\text{4,5-}$ dimethylheptane is given below,

Interpretation Introduction

Interpretation:

The solubility of given compound in water has to be predicted.

Concept Introduction:

Solubility:

The solubility is defined as the solid or liquid or gaseous substance which dissolves in suitable solvent.  The solubility also depends upon polar or nonpolar molecule.  The nonpolar molecule has no separate positive and negative charge.  Polar molecules have separate positive and negative charges.

Explanation of Solution

The 3-ethyl-4,4-dimethylheptane is insoluble in water.  The water molecule is said to be polar molecules.  It has both positive and negative charge.  The given compound is a nonpolar alkane.  The nonpolar alkanes cannot soluble in water molecule.  Hence the given compound 3-ethyl-4,4-dimethylheptane is insoluble in water.

Interpretation Introduction

Interpretation:

The solubility of given compound in organic compound has to be predicted.

Concept Introduction:

Refer part: c.

Explanation of Solution

The given compound is soluble in organic solvent. The reason for the solubility of the given compound, it belongs to nonpolar molecule.  Nonpolar molecules cannot soluble in polar molecule.  The nonpolar molecule has no separate charges.  Hence given molecule

3-ethyl-4,4-dimethylheptane is soluble in organic solvent.

Interpretation Introduction

Interpretation:

The balanced equation for complete combustion of given compound 3-ethyl-4, 4-dimethylheptane has to be written.

Concept Introduction:

Combustion reaction:

The hydrocarbon compound reacts with oxygen to form carbon dioxide and water as product is known as hydrocarbon combustion reaction.  It is an exothermic reaction.  The hydrocarbon compounds are generally organic compounds contain carbon and hydrogen element.  The compounds such as alkanes, alkenes, alkynes and aromatic compounds.

The general equation is given as,

  ${\text{C}}_{\text{x}}{\text{H}}_{\text{y}}{\text{+N(O}}_{\text{2}}\text{)}\leftrightarrow {\text{x(CO}}_{\text{2}}\text{)+}\frac{\text{y}}{\text{2}}{\text{(H}}_{\text{2}}\text{O)}$

Where,

• x represents the number of carbon atoms present in the hydrocarbon
• y represents the number of carbon atoms present in the hydrocarbon
• N represents the number of oxygen atoms requires in the hydrocarbon combustion reaction

Chemical equation:

In chemical equation, the substance reacts (reactant) to give products.  The number of atoms present in reactant side should be equal to the number of atom present in the product side.

Explanation of Solution

The compound 3-ethyl-4, 4-dimethylheptane ${\text{(C}}_{11}{\text{H}}_{24}\text{)}$ undergoes combustion in presence of flame and oxygen molecule and the product formed will be carbon di oxide and water, heat energy.

The chemical reaction for complete combustion of ethane is given below,

  ${\text{C}}_{\text{11}}{\text{H}}_{\text{24}}\text{+}\text{17}{\text{O}}_{\text{2}}\to {\text{CO}}_{\text{2}}\text{+}{\text{H}}_{\text{2}}\text{O}\text{+Energy}$

In reactant side the molecules of ${\text{(C}}_{11}{\text{H}}_{24}\text{)}$, in which eleven carbon atoms and twenty four hydrogen and thirty four atoms oxygen atoms is present.  In product side there are eleven carbon and twenty two hydrogen atom present at carbon dioxide.  The twenty four hydrogen atoms and twelve oxygen atoms are present in water molecule.  In this reaction the molecule ${\text{(C}}_{11}{\text{H}}_{24}\text{)}$ reacts with sufficient oxygen to forms carbon dioxide ${\text{(CO}}_2\text{)}$ and water as product.

The balanced equation for complete combustion reaction of 3-ethyl-4,4-dimethylheptane is given below,

  ${\text{C}}_{\text{11}}{\text{H}}_{\text{24}}\text{+}\text{17}{\text{O}}_{\text{2}}\to {\text{11CO}}_{\text{2}}\text{+}\text{12}{\text{H}}_{\text{2}}\text{O}\text{+Energy}$