Chapter 19, Problem 28PE

(a)

Interpretation Introduction

Interpretation:

Structural formula of 1,2-diphenylethene has to be drawn.

Concept introduction:

IUPAC Nomenclature:

IUAC gives rules for the naming of chemical compounds. These rules are,

For unsaturated hydrocarbons, longest chain is the parent chain of the compound and remaining groups and atoms are consider as substituent.

In the nomenclature, Find the parent chin first then number the carbon atoms in the parent chain by giving lest number to the unsaturated double/triple bonded carbon followed by designate the substituent in its position in parent chain.

If more than one same substituent were occurs, add a prefix (di-, tri-, tetra-, ect..) in front of parent chain name.

If compound contains double bond means, name end with suffix of ene or if compound contains triple bond means name end with suffix of yne.

Finally the systematic name was written as, the substituent position number with prefix (di-, tri-, tetra-, ect..) of number of substituents followed by name of the substituent then write the parent chain name (which contains large number of carbon atoms in the chain) with suffix of suffix ene/yne.

The parent chain names based on the carbon atoms are,

$\begin{array}{l}\text{Alkenes}\\ {\text{CH}}_2{\text{=CH}}_2\text{Ethene}\\ {\text{CH}}_2{\text{=CH-CH}}_3\text{Propene}\\ {\text{CH}}_2{\text{=CH-CH}}_{\text{2}}{\text{-CH}}_3\text{Butene}\\ {\text{CH}}_2{\text{=CH-CH}}_{\text{2}}{\text{-CH}}_{\text{2}}\text{-}{\text{CH}}_3\text{Pentene, etc}\mathrm{..}.\end{array}$          $\begin{array}{l}\text{Alkyne}\\ \text{CH}\equiv \text{CH }\text{Ethyne}\\ \text{CH}\equiv {\text{C-CH}}_3\text{Propyne}\\ \text{CH}\equiv {\text{C-CH}}_{\text{2}}{\text{-CH}}_3\text{Butyne}\\ \text{CH}\equiv {\text{C-CH}}_{\text{2}}{\text{-CH}}_{\text{2}}\text{-}{\text{CH}}_3\text{Pentyne, ect}\mathrm{...}\end{array}$

The substituent names based on the carbon atoms are,

$\begin{array}{l}{\text{CH}}_{\text{3}}\text{-}\text{methyl}\\ {\text{CH}}_{\text{3}}{\text{-CH}}_{\text{2}}\text{- }\text{ethyl}\\ {\text{CH}}_{\text{3}}{\text{-CH}}_{\text{2}}{\text{-CH}}_{\text{2}}\text{-}\text{propyl}\end{array}$

Explanation of Solution

The structural formula of 1,2-diphenylethene is,

From the given name parent compound is ethene, its structure is,

Two phenyl groups are present at 1 and 2 positions so substitute phenyl groups at 2 and 5 positions to get the complete structural formula of 1,2-diphenylethene.

Hence, the complete structural formula of 1,2-diphenylethene is,

(b)

Interpretation Introduction

Interpretation:

Structural formula of 3-pentene-1-yne has to be drawn.

Concept introduction:

Refer part (a).

Explanation of Solution

The structural formula of 3-pentene-1-yne is,

From the given name parent compound is Pentane, its structure is,

From the given name, double bond at third position and triple bond at first position. Therefore draw the double bond at third position and triple bond at first position of the pentane.

Hence, the complete structural formula of 3-pentene-1-yne is,

(c)

Interpretation Introduction

Interpretation:

Structural formula of 3-phenyl-1-butyne has to be drawn.

Concept introduction:

Refer part (a).

Explanation of Solution

The structural formula of 3-phenyl-1-butyne is,

From the given name parent compound is 1-butyne, its structure is,

Phenyl group is present at third carbon so substitute phenyl group at 3 carbon atom to get structural formula of 3-phenyl-1-butyne.

Hence, the complete structural formula of 3-phenyl-1-butyne is,