91Ó°ÊÓ

The olefination reaction involving the conversion of a carbonyl compound into an alkene using the triphenylphosphonium ylide is known as the Wittig reaction.

Given data:

Chemical formula =\({{\rm{C}}_7}{{\rm{H}}_{{\rm{14}}}}{\rm{O}}\)

IR absorption at = 1717 \({\rm{c}}{{\rm{m}}^{{\rm{ - 1}}}}\)

\({}^{\rm{1}}{\rm{H}}\)-NMR spectra = 1.02 ppm (9H), 2.13 ppm (3H), 2.33 ppm (2H)

The degree of unsaturation (IHD) \({\rm{ = }}\frac{{\left( {\left( {{\rm{2n + 2}}} \right){\rm{ - x}}} \right)}}{{\rm{2}}}\),

where

n= number of carbon atoms

x= (Number of hydrogen atoms) + (Number of halogen atoms) - (Number of nitrogen atoms)

On substituting the values,

the degree of unsaturation (IHD) \(\begin{aligned}{c} = \frac{{\left( {\left( {{\rm{2}} \times 7{\rm{ + 2}}} \right){\rm{ - 14}}} \right)}}{{\rm{2}}}\\ = 1\end{aligned}\).

The value of IHD indicates the presence of a pi-bond.

The singlet at 1.02 ppm attributes to 9H having a neighboring carbon with no hydrogen atoms.

The singlet at 2.13 ppm attributes to 3H having a neighboring carbon with no hydrogen atoms.

The singlet at 2.33 ppm attributes to 2H having a neighboring carbon with no hydrogen atoms.

The IR stretching at 1717 \({\rm{c}}{{\rm{m}}^{{\rm{ - 1}}}}\) indicates the presence of a ketone group.

The required molecular structure of R is as follows:

Molecular structure of R