Quiz - Delocalized Systems | Delocalized π Systems

1

Which of the following molecules has a conjugated π system?

1-vinylcyclohex-1-ene

cyclohexa-1,4-diene

penta-1,4-diene

3-methoxyprop-1-ene

Conjugated π system: system of connected p orbitals with delocalized electrons

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Conjugated Dienes Overlap of Adjacent p Orbitals
2

What dienophile should be used to synthesize the trans-4,5-dimethylcyclohex-1-ene?

(E)-but-2-ene

(Z)-but-2-ene

2-methyl-prop-1-ene

1,3-butandiene

3

What is the best synthetic condition to perform a radical halogenation of an allylic group?

Br2 in acid condition

Br2 in basic condition

NBS, CCl4, hν

Br2, ROOR

4

What is the best condition to favor the kinetic product?

Low temperature + short time

Low temperature + long time

High temperature + short time

High temperature + long time

Kinetic control:
Irreversible conditions: low temperature + short time. The major product is the product from the fastest reaction

Thermodynamic control:
Reversible conditions: high temperature + long time. The major product is the most stable product

Kinetic versus Thermodynamic Control
5

What is the thermodynamic product for the hydrobromination of 1,3-butandiene?

1-bromobut-2-ene

3-bromobut-1-ene

1,4-dibromobut-2-ene

3,4-dibromobut-1-ene

6

Which statement is true concerning the Diels-Alder reactions?

It is a [4+2] cycloaddition

It is accelerated when the diene is electron-rich

It is stereospecific: the endo product is favored

All of the above