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Sigmatropic - Chemistry Organic Free MCQ Test with solutions


MCQ Practice Test & Solutions: Test: Sigmatropic (30 Questions)

You can prepare effectively for Chemistry Organic Chemistry with this dedicated MCQ Practice Test (available with solutions) on the important topic of "Test: Sigmatropic". These 30 questions have been designed by the experts with the latest curriculum of Chemistry 2026, to help you master the concept.

Test Highlights:

  • - Format: Multiple Choice Questions (MCQ)
  • - Duration: 90 minutes
  • - Number of Questions: 30

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Test: Sigmatropic - Question 1

The product obtained in the following reaction is (are): 

Test: Sigmatropic - Question 2

Thermal rearrangement of the following compound would give:

Test: Sigmatropic - Question 3

The major product formed in the thermal reaction given below, is:

Test: Sigmatropic - Question 4

In the sigmatropic rearrangement shown below, which of the following choices explains the difference in products for thermal and photochemical conditions?

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Detailed Solution: Question 4

Answer: B.

Orbital-symmetry (molecular orbital phase) considerations determine which sigmatropic shifts are allowed under thermal or photochemical conditions.

For the [1,3]-hydrogen shift the relevant π framework is a 4π-electron system. In the electronic ground state the highest occupied combination involved in the shift has terminal lobes of opposite phase (commonly labelled ψ2), so a suprafacial transfer of H is thermally forbidden.

Upon photoexcitation an electron is promoted and the excited-state orbital set contains an orbital with terminal lobes of the same phase (commonly ψ3). This makes the [1,3]-suprafacial shift allowed photochemically, so the photochemical product forms under irradiation.

By contrast, the pathway that operates under thermal conditions corresponds to a [1,5]-type shift (a 6π-electron pathway) which is thermally allowed suprafacially; therefore the thermal product is the [1,5]-rearranged isomer while the [1,3] product appears only under photochemical conditions.

Test: Sigmatropic - Question 5

In the reaction the major products X and Y are:

Test: Sigmatropic - Question 6

In the reaction, the major product (X) is:

Test: Sigmatropic - Question 7

The pericyclic reaction given below is an example of:

Detailed Solution: Question 7

A sigmatropic reaction involves the migration of a sigma (σ) bond with a simultaneous rearrangement of pi (π) electrons in a cyclic transition state.

  • In this reaction, the hydroxyl (OH) group migrates from one position to another.
  • To classify the shift, number the atoms involved in the cyclic system starting from the migrating group.
  • Here, 3 atoms are on one side and 3 on the other side of the migration path.

Thus, this is a [3,3]-sigmatropic shift, and the correct answer is d) [3,3]-sigmatropic shift.

Test: Sigmatropic - Question 8

Claisen rearrangement is an example of:

Test: Sigmatropic - Question 9

The product of the following reaction is: 

Detailed Solution: Question 9

Answer: (b)

Heating this molecule (a divinylcyclobutane fused system, i.e., bicyclo[4.2.0]octa-2,4-diene) triggers the classic divinylcyclobutane → cyclooctadiene thermal rearrangement. The cyclobutane ring opens (4π conrotatory ring opening), followed by bond reorganization to give an eight-membered ring with two non-conjugated double bonds, i.e., 1,5-cyclooctadiene — which matches option b.

Test: Sigmatropic - Question 10

In sigmatropic thermal expansion of 1, 1-dicyclopropyl ethene, the final product:

Test: Sigmatropic - Question 11

Give the structure of the product in the following reaction:

Test: Sigmatropic - Question 12

This sigmatropic reaction is example of:

Test: Sigmatropic - Question 13

The following transformation proceeds by the sequence indicated. Give the structure of product: 

Detailed Solution: Question 13

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Hence C is the correct answer.

Test: Sigmatropic - Question 14

Allyl aryl ether on heating at 200°C give the major product:

Test: Sigmatropic - Question 15

Which of adducts (a)-(d) is the main product of the following Diels-Alder reaction?

Test: Sigmatropic - Question 16

Consider the following statements:

(I) Clasisen rearrangement is a [3, 3] sigmatropic rearrangement.
(II) Cope rearrangement proceeds via is chair like transition state.
(III) In the photochemical [2 + 2] cycloaddition of ethylene overlapping of HOMO of one molecule with LUMO of the other molecular takes place.

Select the correct statements.

Test: Sigmatropic - Question 17

The product is:

Test: Sigmatropic - Question 18

The major product of the following reaction is:

Test: Sigmatropic - Question 19

The major product of the following reaction is:

Test: Sigmatropic - Question 20

In which of the following reaction, which sigmatropic reaction will take place:

Test: Sigmatropic - Question 21

The reaction given below is an example of:

Test: Sigmatropic - Question 22

Among the following dienes, the one that undergoes a degenerate Cope rearrangement is:

Test: Sigmatropic - Question 23

Pericyclic reaction involved in one of the steps of the following reaction sequence is:

Test: Sigmatropic - Question 24

The product formed and the process involved in the following reaction is:

Test: Sigmatropic - Question 25

The two step conversion of 7-dehydrocholesterol to vitamin D3 proceeds through:

Test: Sigmatropic - Question 26

The major product formed in the following reaction is:

Test: Sigmatropic - Question 27

With respect to the following biogenetic conversion of chorismic acid (A) to 4-ydroxyphenylpyruvic acid (C), the correct statement is:

Test: Sigmatropic - Question 28

Formation of the ketone (II) fro m the diazoketone (I) involves:

Test: Sigmatropic - Question 29

The reaction is given below is an example of:

Test: Sigmatropic - Question 30

The major product is:

Detailed Solution: Question 30

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