Interpretation: Among the given two molecules, the major product that is formed by
Concept Introduction:
Addition reaction of dienes:
The diene with a four carbon system is
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Chapter 20 Solutions
Organic Chemistry
- 1,3-pentadiene reacts with HBr. When the double bond at the 3-position reacts, the hydrogen attaches to the 4-carbon, thus forming an allylic carbocation with delocalized electrons. This carbocation has another resonance structure. Because there are equal amounts of diene and hydrogen bromide, in which molecule only one of the double bonds reacts. Which of the following correctly describes this new resonance structure? a) It has a double bond between carbons 3 and 4 b) It has a positive charge on carbon 2 c) It has a positive charge on carbon 4 d) It has a double bond between carbons 2 and 3arrow_forwardNAME and DRAW the STRUCTURE of ALL the alkenes which could undergo catalytic hydrogenation at 900°C to form methylcyclopentane. Circle the alkene with the HIGHEST stability and X the alkene with the HIGHEST heat of hydrogenation. Give reasons for your choice.arrow_forwardWhich reaction would you expect to be faster, addition of HBr to cyclohexene or to 1-methylcyclohexane? Explain.arrow_forward
- Select the correct isomer of 2-bromo-4-isopropyl-1-methylcyclohexane that, when subjected to ethoxide followed by hydrogenation, would yield a single isomer of 4-isopropyl-1- methylcyclohexane.arrow_forward(dehydrobromination) A chemist carried out an elimination reaction of 1,1-dimethyl-2- bromocyclopentane. The chemist expected the reaction to yield alkene Z as product. However, alkene Z DID NOT form. Instead, three alkenes were produced: one alkene was the major product, the other two alkenes was the minor products. What was the major alkene product that formed? Br Select one: A. I B. II C. IV D. III alcohol HEAT || Z = + (HBr) IVarrow_forwardDraw the mechanism of the hydroboration reaction for 1-octene. Why are carbocation rearrangements not observed in this reaction?arrow_forward
- Which of these alkyl chlorides undergoes dehydrohalogenation in the presence of a strong base to give pent-2-ene (shown below) as the only alkene product? O l-chloro-2-methylbutane O 2-chloropentane O 3-chloropentane O 1-chloropentane O l-chloro-3-methylbutanearrow_forwardDraw the alkene that would react with the reagent given to account for the product formed. OH H₂SO4 CH3CH2CCH2CH3 ? + H₂O CH2CH3 . You do not have to consider stereochemistry. • You do not have to explicitly draw H atoms. • In cases where there is more than one answer, just draw one.arrow_forwardAddition of HBr to 3,3-dimethyl-1-butene gives a mixture of two isomeric alkyl bromide products. Please daw structures for the two products, and give a mechanistic explanation for their formation.arrow_forward
- Reaction of 2-methyl-2-butene (above) with HBr might, in principle, lead to a mixture of two alkyl bromide addition products. Draw these two alkyl bromides.arrow_forwardIllustrate the Addition of X2 to an Alkene—Halogenation ?arrow_forwardМЕСНANISMS 1,2-epoxy-1-methylcyclopentane undergoes both acid-catalyzed and base-catalyzed opening of the epoxide ring to form two different products. > Using ethanol as the solvent and an appropriate acid, show the steps in the acid catalyzed mechanism, writing structures for all products of the steps. Circle the major product(s). > Using ethanol as the solvent and an appropriate base, show the steps in the base- catalyzed mechanism, writing structures for all products of the steps. Circle the major product(s). 1,2-epoxy-1-methylcyclopentane CH3arrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning