Chapter 24.SE, Problem 75AP

Interpretation Introduction

Interpretation:

A structure for atropine (C₁₇H₂₃NO₃) is to be proposed from the following observations: i) On basic hydrolysis atropine yields tropic acid C₆H₅CH(CH₂OH)COOH and tropine (C₈H₁₅NO). ii) Tropine is an optically inactive alcohol that yields tropidene on dehydration with H₂SO₄.

Concept introduction:

Esters when hydrolyzed with bases yield alcohols and carboxylic acids. Alcohols when treated with H₂SO₄ give alkenes. Symmetrical compounds are optically inactive.

To predict:

A structure for atropine (C₁₇H₂₃NO₃) from the following observations: i) On basic hydrolysis atropine yields tropic acid C₆H₅CH(CH₂OH)COOH and tropine (C₈H₁₅NO). ii) Tropine is an optically inactive alcohol that yields tropidene on dehydration with H₂SO₄.

Answer:

Structure of atropine is

Explanation:

Atropine gives tropic acid and an alcohol, tropine when hydrolyzed in the presence of bases. Hence it must be an ester. Tropine upon dehydration gives tropidene. Hence structure of tropine (optically inactive) can be obtained by adding water to the structure of tropidene.

The formation of the ester linkage between the OH of atropine and COOH of tropic acid gives atropine. The reactions can be represented as below.

Conclusion:

Structure of atropine is