Pericyclic Reactions and Photochemistry - Organic Chemistry - Chemistry Previous Year Questions

1

2008 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2008

Match the entries a-d with their corresponding structures p-s.

A

s; b-r; c-q; d-p

B

p; b-s; c-q; d-r

C

q; b-p; c-s; d-r

D

s; b-r; c-p; d-q

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2

2008 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2008

The reaction between X and Y to give Z proceeds via

A

4π-conrotatory opening of X followed by endo Diels-Alder cycloaddition

B

4π-disrotatory opening of X followed by endo Diels-Alder cycloaddition

C

4π-conrotatory opening of X followed by exo Diels-Alder cycloaddition

D

4π-disrotatory opening of X followed by exo Diels-Alder cycloaddition

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3

2008 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2008

The products Y and Z are formed, respectively, from X via

A

hv, conrotatory opening and Δ, disrotatory opening

B

hv, disrotatory opening and Δ, conrotatory opening

C

Δ, conrotatory opening and hv, disrotatory opening

D

Δ, disrotatory opening and hv, conrotatory opening

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4

2008 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2008

For butyrophenone (PhCOCH₂CH₂CH₃), photoirradiation leads to the following set of products.

A

B

C

D

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5

2009 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2009

In the reaction sequence
[Reaction Scheme: Cyclooctatetraene + maleic anhydride → [X] → (Δ) [Y]]
X and Y, respectively, are

A

[Structure: bicyclic adduct with maleic anhydride] and [Structure: fused bicyclic adduct]

B

[Structure: cyclooctatetraene] and [Structure: fused bicyclic adduct]

C

[Structure: fused bicyclic adduct] and [Structure: fused bicyclic adduct with different stereochemistry]

D

[Structure: cyclooctatetraene] and [Structure: fused bicyclic adduct with different stereochemistry]

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6

2009 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2009

In the reaction sequence (cyclopentadiene + nitrostyrene) → [X] (Δ) → [Y] (conc. H2SO4), the major products X and Y, respectively, are

A

endo-5-nitro-6-phenylbicyclo[2.2.1]hept-2-ene and endo-5-phenyl-6-nitrosobicyclo[2.2.1]hept-2-ene

B

endo-5-nitro-6-phenylbicyclo[2.2.1]hept-2-ene and endo-5-phenyl-6-nitrosobicyclo[2.2.1]hept-2-ene

C

endo-5-nitro-6-phenylbicyclo[2.2.1]hept-2-ene and endo-5-phenyl-6-nitrosobicyclo[2.2.1]hept-2-ene

D

endo-5-nitro-6-phenylbicyclo[2.2.1]hept-2-ene and endo-5-phenyl-6-nitrosobicyclo[2.2.1]hept-2-ene

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7

2011 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2011

The diene which undergoes Diels-Alder reaction with maleic anhydride is

A

A

B

B

C

C

D

D

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8

2011 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2011

In the following reaction, the major product [X] is

A

\(\text{Structure: cyclopentanone with CH2CHO at alpha position}\)

B

\(\text{Structure: 2-methylcyclopentanone with CHO at alpha position}\)

C

\(\text{Structure: 2-methylcyclopentene with CHO at vinylic carbon}\)

D

\(\text{Structure: 3-methylcyclopentene with CHO at vinylic carbon}\)

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9

2013 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2013

The pericyclic reaction given below is an example of

A

[1,3]-sigmatropic shift

B

[1,5]-sigmatropic shift

C

[3,5]-sigmatropic shift

D

[3,3]-sigmatropic shift

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10

2013 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2013

The major product formed in the reaction given below is

A

B

C

D

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11

2014 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2014

Formation of the product in the following photochemical reaction involves

A

di-π-methane rearrangement

B

Paterno-Buchi reaction

C

[2,3]-sigmatropic rearrangement

D

Norrish type I reaction

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12

2014 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2014

The correct order of stability for the following conformations of cyclohexane is

A

I > II > III

B

I > III > II

C

II > I > III

D

III > I > II

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13

2014 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2014

Formation of the ketone II from the diazoketone I involves

A

generation of carbene and a [2,3]-sigmatropic rearrangement

B

generation of carbene and an electrocyclic ring closing reaction

C

generation of ketene and a [2+2] cycloaddition

D

generation of ketene and a [3,3]-sigmatropic rearrangement

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14

2014 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2014

The major products X and Y formed in the following reaction sequence are

A

X = ; Y =

B

X = ; Y =

C

X = ; Y =

D

X = ; Y =

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15

2019 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2019

The major product formed in the following reaction is

A

B

C

D

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16

2023 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2023

The major product formed in the given reaction is

\n

\n

R = CO₂Me

A

B

C

D

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17

2023 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2023

On irradiation using UV light (>300 nm), compounds X and Y, predominantly, undergo

A

X: Norrish type I reaction and Y: Norrish type II reaction

B

X: Norrish type II reaction and Y: Norrish type I reaction

C

Both X and Y: Norrish type I reaction

D

Both X and Y: Norrish type II reaction

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18

2025 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2025

Choose the correct option(s) with regard to mechanism of the following transformation.

A

It proceeds through divinyl cyclopropane rearrangement

B

It involves a diradical intermediate

C

It proceeds through di-π-methane rearrangement

D

It proceeds through [2+2+2] cycloaddition reaction

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19

2007 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2007

The direction of rotation of the following thermal electrocyclic ring closures respectively is

A

disrotatory, disrotatory, disrotatory

B

conrotatory, conrotatory, conrotatory

C

disrotatory, disrotatory, conrotatory

D

disrotatory, conrotatory, disrotatory

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20

2015 · Chemistry · Organic Chemistry · Pericyclic Reactions and Photochemistry

Chemistry (CY) 2015

Amongst the following, the compound that DOES NOT act as a diene in Diels-Alder reaction is

A

Structure A

B

Structure B

C

Structure C

D

Structure D

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