Chemistry - STEREO ISOMERISM Question with Solution | TestHub
How many of the compounds (i)-(ix) shown can exhibit geometrical isomerism?
Answer:
Solution:
Entry (i) has different groups at both alkene ends and permits E/Z. Entries (iii),(iv) have two methyl groups on saturated ring carbons and permit cis/trans. Entry (v) is an unsymmetrical oxime; (vi), HN=NH, permits cis/trans. Entry (ii) has one saturated-ring methyl and one vinylic methyl, with no trans alternative for its small-ring double bond. Entry (vii) has identical methyls externally, and (ix) is linear. Enlarged source inspection shows (viii) has only one saturated-ring methyl; its other two methyls are vinylic. A stable carbon-only cis/trans pair does not follow. Counting labile nitrogen configurations as distinct could be the source convention, but ordinary amine inversion prevents stable isolation without further restriction. Thus five entries clearly qualify: (i),(iii),(iv),(v),(vi). Printed 6 is retained with this unresolved sixth-entry convention, rather than inventing a second saturated-ring substituent.
