a)
Interpretation:
Whether the electrocyclic reaction shown takes place in conrotatory or disrotatory manner is to be stated. The conditions, thermal or photochemical, under which the reaction can be carried out also is to be stated.
Concept introduction:
In elecrocyclic reactions involving even number of electron pairs, a thermal reaction occurs in conrotatory manner and a photochemical reaction occurs in disrotatory manner.
In elecrocyclic reactions involving odd number of electron pairs, a thermal reaction occurs in disrotatory manner and a photochemical reaction occurs in conrotatory manner.
b)
Interpretation:
Whether the electrocyclic reaction shown takes place in conrotatory or disrotatory manner is to be stated. The conditions, thermal or photochemical, under which the reaction can be carried out also is to be stated.
Concept introduction:
In elecrocyclic reactions involving even number of electron pairs, a thermal reaction occurs in conrotatory manner and a photochemical reaction occurs in disrotatory manner.
In elecrocyclic reactions involving odd number of electron pairs, a thermal reaction occurs in disrotatory manner and a photochemical reaction occurs in conrotatory manner.
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Chapter 30 Solutions
Organic Chemistry
- By using FMO principles, complete and predict the regioselectivity of the following pericyclic reaction:arrow_forwardWrite the mechanism of this pericyclic reactionarrow_forward(a) Give a mechanism for this reaction, showing how the two products arise as aconsequence of the resonance-stabilized intermediate.(b) The bromination of cyclohexene using NBS gives only one major product, as shown onthe previous page. Explain why there is no second product from an allylic shift.arrow_forward
- What are several products for the following reaction with mechanisms included?arrow_forwardComplete the following reactions, clearly indicating regio-and stereochemistry where applicable. In cases, where ortho-and para-products are formed, draw both.arrow_forwardProvide reasonable mechanisms for the following reaction.arrow_forward
- Indane can undergo free-radical chlorination at any of the alkyl positions onthe aliphatic ring. Once the products have been separated, what instrumental technique would be most helpful for determining the structures of all the dichlorinated products?arrow_forwardIndane can undergo free-radical chlorination at any of the alkyl positions onthe aliphatic ring.Once the products have been separated, what instrumental technique would be most helpful for determining the structures of all the dichlorinated products?arrow_forwardStrong support for the mechanism of the nucleophilic aromatic substitutionreaction that proceeds through a benzyne intermediate comes from the reaction shown here, in which bromobenzene is treated with KNH2 in the presence of cyclopentadiene. A product that is isolated has the formula C11H10. Draw the structure of that product and explain how it validates the production of a benzyne intermediate.arrow_forward
- On photolysis, A undergoes primarily Norrish II chemistry, but B undergoes primarily Norrish I chemistry. Rationalize the difference and draw the major products expected from each reaction. (note the stereochemistry in the ring structure).arrow_forwardClassify the following sigmatropic rearrangement and determine whether it takes place readily under thermal or photochemical reaction conditions.arrow_forwardShow detailed reaction mechanisms for the following reaction. Include all relevant resonance structures and the structure of the expected organic and inorganic products.arrow_forward
