In 1 HNMR, Disparlure, C 19 H 38 O, shows a large absorption in the alkane region, 1 to 2 δ and a triplet at 2.8 δ. Treatment of Disparlure first with aqueous acid and then with KMnO4 yielded undecanoic acid and 6-methylheptanoic acid. A structure for disparlure is to be proposed neglecting stereochemistry. Its structure also is to be given with stereochemistry if the actual compound is a chiral molecule with 7R, 8S stereochemistry. Concept introduction: In 1 HNMR, the epoxides absorb in the region 2.5 -3.5 δ and alkanes in the range 1 to 2 δ. Epoxides get protonated in the presence of acids and the nucleophilic attack of water opens the epoxide ring to give a diol . The diol is oxidized by KMnO 4 to carboxylic acids with less number of carbon atoms. To propose: A structure for disparlure neglecting stereochemistry, satisfying the 1 HNMR data and the chemical reactions given. If the actual compound is a chiral molecule with 7R, 8S stereochemistry its structure with stereochemistry also is to be given.

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Chapter 18.SE, Problem 63GP

Interpretation Introduction

Interpretation:

In ¹HNMR, Disparlure, C₁₉H₃₈O, shows a large absorption in the alkane region, 1 to 2 δ and a triplet at 2.8 δ. Treatment of Disparlure first with aqueous acid and then with KMnO4 yielded undecanoic acid and 6-methylheptanoic acid. A structure for disparlure is to be proposed neglecting stereochemistry. Its structure also is to be given with stereochemistry if the actual compound is a chiral molecule with 7R, 8S stereochemistry.

Concept introduction:

In ¹HNMR, the epoxides absorb in the region 2.5 -3.5 δ and alkanes in the range 1 to 2 δ.

Epoxides get protonated in the presence of acids and the nucleophilic attack of water opens the epoxide ring to give a diol. The diol is oxidized by KMnO₄ to carboxylic acids with less number of carbon atoms.

To propose:

A structure for disparlure neglecting stereochemistry, satisfying the ¹HNMR data and the chemical reactions given. If the actual compound is a chiral molecule with 7R, 8S stereochemistry its structure with stereochemistry also is to be given.

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