Write the structure of compound A, used in this synthesis of the perfume ingredient

Using the (E)(Z) designation [and in parts (e) and (f) the (R)(S) designation as well] Practice Problem 7.1 give IUPAC names for each of the following: Cl CH2CH2CH3 Br H (a) C C CH3 H3C CH2CH(CH3)2 H (c) C C CH3 CH3 H3C H H (e) CH2CH3 I Cl Br (b) C C CH2CH3 Cl CH3 I (d) C C Br Cl H H (f) H3C

Rank the following cycloalkenes in order of increasing stability.

Heats of hydrogenation of three alkenes are as follows: Practice Problem 7.3 2-methyl-1-butene (-119 kJ mol-1 ) 3-methyl-1-butene (-127 kJ mol-1 ) 2-methyl-2-butene (-113 kJ mol-1 ) (a) Write the structure of each alkene and classify it as to whether its doubly bonded atoms are monosubstituted, disubstituted, trisubstituted, or tetrasubstituted. (b) Write the structure of the product formed when each alkene is hydrogenated. (c) Can heats of hydrogenation be used to relate the relative stabilities of these three alkenes? (d) If so, what is the predicted order of stability? If not, why not? (e) What other alkene isomers are possible for these alkenes? Write their structures. (f) What are the relative stabilities among just these isomers?

Predict the more stable alkene of each pair: (a) 2-methyl-2-pentene or 2,3-dimethyl2-butene; (b) cis-3-hexene or trans-3-hexene; (c) 1-hexene or cis-3-hexene; (d) trans-2- hexene or 2-methyl-2-pentene.

How many stereoisomers are possible for 4-methyl-2-hexene, and how many fractions would you obtain if you distilled the mixture?

Predict the major product formed when 2-bromobutane is subjected to dehydrobromination using sodium ethoxide in ethanol at 55 8C.

List the alkenes that would be formed when each of the following alkyl halides is subjected to dehydrohalogenation with potassium ethoxide in ethanol and use Zaitsevs rule to predict the major product of each reaction: (a) 2-bromo-3-methylbutane and (b) 2-bromo-2,3-dimethylbutane.

Examine Solved Problem 7.3. Your task is to prepare A in the highest possible yield by Practice Problem 7.8 dehydrobromination. Which base would you use?

Consider a simple molecule such as ethyl bromide and show with Newman projection for- Practice Problem 7.9 mulas how the anti coplanar transition state would be favored over the syn coplanar one.

(a) When cis-1-bromo-2-methylcyclohexane undergoes an E2 reaction, two products Practice Problem 7.11 (cycloalkenes) are formed. What are these two cycloalkenes, and which would you expect to be the major product? Write conformational structures showing how each is formed. (b) When trans-1-bromo-2-methylcyclohexane reacts in an E2 reaction, only one cycloalkene is formed. What is this product? Write conformational structures showing why it is the only product.

Dehydration of 2-propanol occurs in 14M H2SO4 at 100 8C. (a) Using curved arrows, write all steps in a mechanism for the dehydration. (b) Explain the essential role performed in alcohol dehydrations by the acid catalyst. [Hint: Consider what would have to happen if no acid were present.]

Rank the following alcohols in order of increasing ease of acid-catalyzed dehydration. (a) OH (b) OH (c) OH

Acid-catalyzed dehydration of neopentyl alcohol, (CH3)3CCH2OH, yields 2-methyl-2- Practice Problem 7.14 butene as the major product. Outline a mechanism showing all steps in its formation.

Acid-catalyzed dehydration of either 2-methyl-1-butanol or 3-methyl-1-butanol gives Practice Problem 7.15 2-methyl-2-butene as the major product. Write plausible mechanisms that explain these results.

When the compound called isoborneol is heated with 9 M sulfuric acid, the product of the Practice Problem 7.16 reaction is the compound called camphene and not bornylene, as one might expect. Using models to assist you, write a step-by-step mechanism showing how camphene is formed.

Predict the products of the following acidbase reactions. If the equilibrium would not result in the formation of appreciable amounts of products, you should so indicate. In each case label the stronger acid, the stronger base, the weaker acid, and the weaker base: (a) CH3CHCH2 + NaNH2 9: (b) CH3Ci CH + NaNH2 9: (c) CH3CH2CH3 + NaNH2 9: (d) CH3Ci CC- + CH3CH2OH 9: (e) CH3Ci CC- + NH4Cl 9:

Show how you might synthesize ethynylbenzene from methyl phenyl ketone.

Outline all steps in a synthesis of propyne from each of the following: (a) CH3COCH3 (b) CH3CH2CHBr2 (c) CH3CHBrCH2Br (d) CH3CHCH2

Write the structure of compound A, used in this synthesis of the perfume ingredient Practice Problem 7.21 (Z )-jasmone. (Z )-Jasmone O H2, Pd/CaCO3 (Lindlars catalyst)

How would you convert 2-nonyne into (E)-2-nonene?

Referring to the retrosynthetic analysis for 2-methylhexane in this section, write reac- Practice Problem 7.23 tions for those synthesis routes that are feasible.

(a) Devise retrosynthetic schemes for all conceivable alkynide anion alkylation syntheses of the Practice Problem 7.24 insect pheromones undecane and 2-methylheptadecane (see The Chemistry of ... Pheromones box in Chapter 4). (b) Write reactions for two feasible syntheses of each pheromone.

Each of the following names is incorrect. Give the correct name and explain your reasoning. (a) trans-3-Pentene (b) 1,1-Dimethylethene (c) 2-Methylcyclohexene (d) 4-Methylcyclobutene (e) (Z)-3-Chloro-2-butene (f) 5,6-Dichlorocyclohexene

Write a structural formula for each of the following: (a) 3-Methylcyclobutene (b) 1-Methylcyclopentene (c) 2,3-Dimethyl-2-pentene (d) (Z)-3-Hexene (e) (E)-2-Pentene (f) 3,3,3-Tribromopropene (g) (Z,4R)-4-Methyl-2-hexene (h) (E,4S )-4-Chloro-2-pentene (i) (Z)-1-Cyclopropyl-1-pentene (j) 5-Cyclobutyl-1-pentene (k) (R)-4-Chloro-2-pentyne (l) (E)-4-Methylhex-4-en-1-yne

Write three-dimensional formulas for and give names using (R)(S ) and (E)(Z) designations for the isomers of: (a) 4-Bromo-2-hexene (b) 3-Chloro-1,4-hexadiene (c) 2,4-Dichloro-2-pentene (d) 2-Bromo-4-chlorohex-2-en-5-yne

Give the IUPAC names for each of the following

Without consulting tables, arrange the following compounds in order of decreasing acidity: Pentane 1-Pentene 1-Pentyne 1-Pentanol

Outline a synthesis of cyclopentene from each of the following: (a) Bromocyclopentane (b) Cyclopentanol

Starting with ethyne, outline syntheses of each of the following. You may use any other needed reagents, and you need not show the synthesis of compounds prepared in earlier parts of this problem. (a) Propyne (b) 1-Butyne (c) 2-Butyne (d) cis-2-Butene (e) trans-2-Butene (f) 1-Pentyne (g) 2-Hexyne (h) (Z)-2-Hexene (i) (E)-2-Hexene (j) 3-Hexyne

Starting with 1-methylcyclohexene and using any other needed reagents, outline a synthesis of the following deuterium-labeled compound:

Outline a synthesis of phenylethyne from each of the following

Write a three-dimensional representation for the transition state structure leading to formation of 2-methyl-2-butene from reaction of 2-bromo-2-methylbutane with sodium ethoxide.

When trans-2-methylcyclohexanol (see the following reaction) is subjected to acid-catalyzed dehydration, the major product is 1-methylcyclohexene: HA heat OH CH3 CH3 However, when trans-1-bromo-2-methylcyclohexane is subjected to dehydrohalogenation, the major product is 3-methylcyclohexene: CH3 Br CH3 EtONa EtOH, heat Account for the different products of these two reactions.

Write structural formulas for all the products that would be obtained when each of the following alkyl halides is heated with sodium ethoxide in ethanol. When more than one product results, you should indicate which would be the major product and which would be the minor product(s). You may neglect cistrans isomerism of the products when answering this question.

Write structural formulas for all the products that would be obtained when each of the following alkyl halides is heated with potassium tert-butoxide in tert-butyl alcohol. When more than one product results, you should indicate which would be the major product and which would be the minor product(s). You may neglect cistrans isomerism of the products when answering this question.

Starting with an appropriate alkyl halide and base, outline syntheses that would yield each of the following alkenes as the major (or only) product:

Give the products that would be formed when each of the following alcohols is subjected to acid-catalyzed dehydration. If more than one product would be formed, designate the alkene that would be the major product. (Neglect cistrans isomerism.) (a) OH (b) OH (c) OH (d) OH (e) OH

1-Bromobicyclo[2.2.1]heptane does not undergo elimination (below) when heated with a base. Explain this failure to react. (Construction of molecular models may help.) Br

When the deuterium-labeled compound shown at right is subjected to dehydrohalogenation using sodium ethoxide in ethanol, the only alkene product is 3-methylcyclohexene. (The product contains no deuterium.) Provide an explanation for this result.

Provide a mechanistic explanation for each of the following reactions: (a) OH (major product) acid (cat.) (b) OH (major product) acid (cat.) (c) I (major product) AgNO3 EtOH (d) Ph Ph Br H H Ph Ph (Z only) EtONa EtOH,

What is the index of hydrogen deficiency (IHD) (degree of unsaturation) for each of the following compounds? C6H8Br4

Caryophyllene, a compound found in oil of cloves, has the molecular formula C15H24 and has no triple bonds. Reaction of caryophyllene with an excess of hydrogen in the presence of a platinum catalyst produces a compound with the formula C15H28. How many (a) double bonds and (b) rings does a molecule of caryophyllene have?

Squalene, an important intermediate in the biosynthesis of steroids, has the molecular formula C30H50 and has no triple bonds. (a) What is the index of hydrogen deficiency of squalene? (b) Squalene undergoes catalytic hydrogenation to yield a compound with the molecular formula C30H62. How many double bonds does a molecule of squalene have? (c) How many rings?

Compounds I and J both have the molecular formula C7H14. Compounds I and J are both optically active and both rotate planepolarized light in the same direction. On catalytic hydrogenation I and J yield the same compound K (C7H16). Compound K is optically active. Propose possible structures for I, J, and K. (+)I (C7H14) K (C7H16) (Optically active) (+)J (C7H14) H2, Pt H2, Pt

Compounds L and M have the molecular formula C7H14. Compounds L and M are optically inactive, are nonresolvable, and are diastereomers of each other. Catalytic hydrogenation of either L or M yields N. Compound N is optically inactive but can be resolved into separate enantiomers. Propose possible structures for L, M, and N. L (C7H14) (Optically inactive) N (Optically inactive, M (C7H14) resolvable) (Optically inactive) (L and M are diastereomers) H2, Pt H2, Pt

Consider the interconversion of cis-2-butene and trans-2-butene. (a) What is the value of DH8 for the reaction cis-2-butene : trans-2-butene (see Section 7.3A)? (b) Assume DH8 DG8. What minimum value of DG would you expect for this reaction (see Section 1.13A)? (c) Sketch a free-energy diagram for the reaction and label DG8 and DG

(a) Partial dehydrohalogenation of either (1R,2R)-1,2-dibromo-1,2-diphenylethane or (1S,2S)-1,2-dibromo-1,2-diphenylethane enantiomers (or a racemate of the two) produces (Z)-1-bromo-1,2-diphenylethene as the product, whereas (b) partial dehydrohalogenation of (1R,2S)-1,2-dibromo-1,2-diphenylethane (the meso compound) gives only (E)-1-bromo-1,2-diphenylethene. (c) Treating (1R,2S)-1,2-dibromo-1,2-diphenylethane with sodium iodide in acetone produces only (E)-1,2-diphenylethene. Explain these results

(a) Using reactions studied in this chapter, show steps by which this alkyne could be converted to the seven-membered ring homolog of the product obtained in Problem 7.44(b). (b) Could the homologous products obtained in these two cases be relied upon to show infrared absorption in the 16201680-cm-1 region?

Predict the structures of compounds A, B, and C: A is an unbranched C6 alkyne that is also a primary alcohol. B is obtained from A by use of hydrogen and nickel boride catalyst or dissolving metal reduction. C is formed from B on treatment with aqueous acid at room temperature. Compound C has no infrared absorption in either the 16201680-cm-1 or the 35903650-cm-1 region. It has an index of hydrogen deficiency of 1 and has one chirality center but forms as the racemate

What is the index of hydrogen deficiency for (a) C7H10O2 and (b) C5H4N4?

Write the structure(s) of the major product(s) obtained when 2-chloro-2,3-dimethylbutane (either enantiomer) reacts with (a) sodium ethoxide (EtONa) in ethanol (EtOH) at 80 8C or (in a separate reaction) with (b) potassium tert-butoxide (t-BuOK) in tert-butyl alcohol (t-BuOH) at 80 8C. If more than one product is formed, indicate which one would be expected to be the major product. (c) Provide a detailed mechanism for formation of the major product from each reaction, including a drawing of the transition state structures.

Explain using mechanistic arguments involving Newman projections or other three-dimensional formulas why the reaction of 2-bromo-1,2-diphenylpropane (either enantiomer) with sodium ethoxide (EtONa) in ethanol (EtOH) at 80 8C produces mainly (E)-1,2-diphenylpropene [little of the (Z) diastereomer is formed].

(a) Write the structure of the product(s) formed when 1-methylcyclohexanol reacts with 85% (coned) H3PO4 at 150 8C. (b) Write a detailed mechanism for the reaction.

Consider the reaction of 1-cyclobutylethanol (1-hydroxyethylcyclobutane) with concentrated H2SO4 at 120 8C. Write structures of all reasonable organic products. Assuming that methylcyclopentene is one product, write a mechanism that accounts for its formation. Write mechanisms that account for formation of all other products as well.

Consider the following compound: (a) Develop all reasonable retrosynthetic analyses for this compound (any diastereomer) that, at some point, involve carboncarbon bond formation by alkylation of an alkynide ion. (b) Write reactions, including reagents and conditions, for syntheses of this compound that correspond to the retrosynthetic analyses you developed above. (c) Infrared spectroscopy could be used to show the presence of certain impurities in your final product that would result from leftover intermediates in your syntheses. Which of your synthetic intermediates would show IR absorptions that are distinct from those in the final product, and in what regions of the IR spectrum would the absorptions occur? (d) Draw a three-dimensional structure for either the cis or trans form of the target molecule. Use dashed and solid wedges where appropriate in the alkyl side chain and use a chair conformational structure for the ring. (Hint: Draw the structure so that the carbon chain of the most complicated substituent on the cyclohexane ring and the ring carbon where it is attached are all in the plane of the paper. In general, for three-dimensional structures choose an orientation that allows as many carbon atoms as possible to be in the plane of the paper.)