Draw the alternative chair conformations for the product formed by the addition

Using the BDE values from Appendix 3, calculate the DH0 rxn value and state if the reaction below is exothermic or endothermic. CH25CH21 HCl S CH3CH2Cl

Name and draw a structural formula for the product of each alkene addition reaction.

Arrange these carbocations in order of increasing stability.

Propose a mechanism for addition of HI to 1-methylcyclohexene to give 1-iodo-1- methylcyclohexane. Which step in your mechanism is rate-determining?

Draw a structural formula for the product of each alkene hydration reaction.

Propose a mechanism for the acid-catalyzed hydration of 1-methylcyclohexene to give 1-methylcyclohexanol. Which step in your mechanism is rate-determining?

The acid-catalyzed hydration of 3,3-dimethyl-1-butene gives 2,3-dimethyl-2- butanol as the major product. Propose a mechanism for the formation of this alcohol.

Complete these reactions.

Draw the structure of the chlorohydrin formed by treating 1-methylcyclohexene with Cl2/H2O.

Use a balanced half-reaction to show that each transformation involves a reduction.

Tell which of these transformations are oxidations and which are reductions based on whether there is addition or removal of O or H.

What alkene with the molecular formula C6H12, when treated with ozone and then dimethyl sulfide, gives the following product(s)?

Using the table of average bond dissociation enthalpies at 25C, determine which of the following reactions are energetically favorable at room temperature. Assume that DS 5 0.

Draw structural formulas for the isomeric carbocation intermediates formed on treatment of each alkene with HCl. Label each carbocation 1, 2, or 3 and state which of the iso- meric carbocations forms more readily.

Arrange the alkenes in each set in order of increasing rate of reaction with HI and explain the basis for your ranking. Draw the structural formula of the major product formed in each case.

Predict the organic product(s) of the reaction of 2-butene with each reagent. (a) H2O (H2SO4) (b) Br2 (c) Cl2 (d) Br2 in H2O (e) HI (f) Cl2 in H2O (g) Hg(OAc)2, H2O (h) product (g) 1 NaBH4

Draw a structural formula of an alkene that undergoes acid-catalyzed hydration to give each alcohol as the major product (more than one alkene may give each alcohol as the major product). (a) 3-Hexanol (b) 1-Methylcyclobutanol (c) 2-Methyl-2-butanol (d) 2-Propanol

Reaction of 2-methyl-2-pentene with each reagent is regioselective. Draw a structural formula for the product of each reaction and account for the observed regioselectivity. (a) HI (b) HBr (c) H2O in the presence of H2SO4 (d) Br2 in H2O (e) Hg(OAc)2 in H2O

Draw a structural formula for an alkene with the indicated molecular formula that gives the compound shown as the major product (more than one alkene may give the same compound as the major product).

Account for the fact that addition of HCl to 1-bromopropene gives exclusively 1-bromo-1-chloropropane.

Account for the fact that treating propenoic acid (acrylic acid) with HCl gives only 3-chloropropanoic acid.

Draw a structural formula for the alkene with the molecular formula C5H10 that reacts with Br2 to give each product.

Draw the alternative chair conformations for the product formed by the addition of bromine to 4-tert-butylcyclohexene. The Gibbs free energy differences between equatorial and axial substituents on a cyclohexane ring are 21 kJ (4.9 kcal)/mol for tert-butyl and 2.02.6 kJ (0.480.62 kcal)/mol for bromine. Estimate the relative percentages of the alternative chair conformations you drew in the first part of this problem.

Draw a structural formula for the cycloalkene with the molecular formula C6H10 that reacts with Cl2 to give each compound.

Reaction of this bicycloalkene with bromine in carbon tetrachloride gives a trans dibro- mide. In both (a) and (b), the bromine atoms are trans to each other. However, only one of these products is formed. Which trans dibromide is formed? How do you account for the fact that it is formed to the exclusion of the other trans dibromide?

Terpin, prepared commercially by the acid-catalyzed hydration of limonene, is used medicinally as an expectorant for coughs. (a) Propose a structural formula for terpin and a mechanism for its formation. (b) How many cis, trans isomers are possible for the structural formula you propose?

Propose a mechanism for this reaction and account for its regioselectivity.

When 2-pentene is treated with Cl2 in methanol, three products are formed. Account for the formation of each product (you need not explain their relative percentages).

Treating cyclohexene with HBr in the presence of acetic acid gives bromocyclohexane (85%) and cyclohexyl acetate (15%).

Propose a mechanism for this reaction.

Treating 4-penten-1-ol with bromine in water forms a cyclic bromoether. Account for the formation of this product rather than a bromohydrin as was formed in Problem 6.33.

Provide a mechanism for each reaction.

Treating 1-methyl-1-vinylcyclopentane with HCl gives mainly 1-chloro-1,2-dimethyl- cyclohexane.

Draw a structural formula for the alcohol formed by treating each alkene with borane in tetrahydrofuran (THF) followed by hydrogen peroxide in aqueous sodium hydroxide and specify stereochemistry where appropriate.

Reaction of a-pinene with borane followed by treatment of the resulting trialkylborane with alkaline hydrogen peroxide gives the following alcohol. Of the four possible cis, trans isomers, one is formed in over 85% yield. (a) Draw structural formulas for the four possible cis, trans isomers of the bicyclic alcohol. (b) Which is the structure of the isomer formed in 85% yield? How do you account for its formation? Create a model to help you make this prediction.

Write structural formulas for the major organic product(s) formed by reaction of 1-meth- ylcyclohexene with each oxidizing agent. (a) OsO4/H2O2 (b) O3 followed by (CH3)2S

Consider the following reaction. (a) Draw a structural formula for the compound with the molecular formula C8H12. (b) Do you predict the product to be the cis isomer, the trans isomer, or a mixture of cis and trans isomers? Explain. (c) Draw a suitable stereorepresentation for the more stable chair conformation of the dicarbaldehyde formed in this oxidation.

Predict the major organic product(s) of the following reactions and show stereochemistry where appropriate.

The heat of hydrogenation of cis-2,2,5,5-tetramethyl-3-hexene is 2154 kJ (236.7 kcal)/ mol, while that of the trans isomer is only 2113 kJ (226.9 kcal)/mol. (a) Why is the heat of hydrogenation of the cis isomer so much larger (more negative) than that of the trans isomer? (b) If a catalyst could be found that allowed equilibration of the cis and trans isomers at room temperature (such catalysts do exist), what would be the ratio of trans to cis isomers?

Show how to convert ethylene to these compounds. (a) Ethane (b) Ethanol (c) Bromoethane (d) 2-Chloroethanol (e) 1,2-Dibromoethane (f) 1,2-Ethanediol (g) Chloroethane

Show how to convert cyclopentene into these compounds. (a) trans-1,2-Dibromocyclopentane (b) cis-1,2-Cyclopentanediol (c) Cyclopentanol (d) Iodocyclopentane (e) Cyclopentane (f) Pentanedial

State the number and kind of stereoisomers formed when (R)-3-methyl-1-pentene is treated with these reagents. Assume that the starting alkene is enantiomerically pure and optically active. Will each product be optically active or inactive? (a) Hg(OAc)2, H2O followed by NaBH4 (b) H2/Pt (c) BH3 followed by H2O2 in NaOH (d) Br2 in CCl4

Describe the stereochemistry of the bromohydrin formed in each reaction (each reaction is stereospecific). (a) cis-3-Hexene 1 Br2/H2O (b) trans-3-Hexene 1 Br2/H2O

In each of these reactions, the organic starting material is achiral. The structural formula of the product is given. For each reaction, determine the following. (1) How many stereoisomers are possible for the product? (2) Which of the possible stereoisomers is/are formed in the reaction shown? (3) Will the product be optically active or optically inactive?

The 2-propenyl cation appears to be a primary carbocation, and yet it is considerably more stable than a 1 carbocation such as the 1-propyl cation. CH2"CH9CH2 1 CH39CH29CH2 1 2-Propenyl cation 1-Propyl cation

In this chapter, we studied the mechanism of the acid-catalyzed hydration of an alkene. The reverse of this reaction is the acid-catalyzed dehydration of an alcohol. Propose a mechanism for the acid-catalyzed dehydration of 2-propanol to propene.

As we have seen in this chapter, carbon-carbon double bonds are electron-rich regions that are attacked by electrophiles (e.g., HBr); they are not attacked by nucleophiles (e.g., diethylamine). However, when the carbon-carbon double bond has a carbonyl group adjacent to it, the double bond reacts readily with nucleophiles by nucleophilic addition (Section 19.8). Account for the fact that nucleophiles add to a carbon-carbon double bond adjacent to a carbonyl group and account for the regiochemistry of the reaction.

Following is an example of a type of reaction known as a Diels-Alder reaction (Chapter 20). The Diels-Alder reaction between a diene and an alkene is quite remarkable in that it is one of the few ways that chemists have to form two new carbon-carbon bonds in a single reaction. Given what you know about the relative strengths of carbon-carbon sigma and pi bonds, would you predict the Diels-Alder reaction to be exothermic or endothermic? Explain your reasoning.

We now introduce the concept of an organic chemistry roadmap. An organic chemistry roadmap is a graphical representation of the different reactions that can be used to inter- convert functional groups in molecules. Comparing the organic chemistry roadmap to a real roadmap, the functional groups are analogous to cities and the reactions are the roads between them. The power of the organic chemistry roadmap is that it helps students visu- alize how to interconvert key functional groups for use in multistep syntheses problems. It also will be a useful place for you to keep track of the reactions we encounter in future To make your own roadmap, take a blank full sheet of paper and write the following func- tional groups in the orientations shown. Fill the entire sheet of paper and leave plenty of room between functional groups. Most students finRefer to the Key Reactions section at the end of this chapter. Draw arrows between functional groups to account for each reaction. Write the reagents required to bring about each reaction next to the arrow. Next, record any regiochemistry or stereochemistry considerations relevant to the reaction, such as Markovnikov regiochemistry or anti addition stereochemistry. You should also record any key aspects of the mechanism, such as formation of a carbocation intermediate, as a helpful reminder. On the above organic chemistry roadmap template, the information for the first reaction, hydrohalogenation of an alkene, has been added to help you get started. For this initial roadmap, do not write an arrow for reaction 10, enantioselective reduction, because it is of a highly specific nature and a roadmap is intended to organize reactions that are of more general use. Note that the roadmap template applies to Chapters 611, so you will not use all of the functional groups listed until you are finished with Chapter 11. Appendix 11 contains a series of roadmaps for different sections of the book, but you should use those for reference only after you have completed your own.d it helpful to use a poster-sized sheet of paper filled out in landscape orientation.