Solved: Arrange the following alkenes in order of decreasing stability: 1-pentene;

Write a structural formula and give two acceptable IUPAC names for each alkene of molecular formula C7H14 that has a tetrasubstituted double bond.

Give an IUPAC name for each of the following compounds: (a) (CH3CH2)2C=CHCH3 (b) (CH3CH2)2C=C(CH2CH3)2 (c) (CH3)3CCH=CCl2

(a) A hydrocarbon isolated from fish oil and from plankton was identified as 2,6,10,14-tetramethyl-2-pentadecene. Write its structure. (b) Alkyl isothiocyanates are compounds of the type RN=C=S. Write a structural formula for allyl isothiocyanate, a pungent-smelling compound isolated from mustard. (c) Grandisol is one component of the sex attractant of the boll weevil. Write a structural formula for grandisol given that R in the structure shown is an isopropenyl group.

Multifidene is a sperm-cell-attracting substance released by the female of a species of brown algae. It has the constitution shown. Assuming that the double bond in the five-membered ring of all of the isomers is cis: (a) How many stereoisomers are represented by this constitution? (b) If the substituents on the five-membered ring are cis to each other, how many stereoisomers are represented by this constitution? (c) If the butenyl side chain has the Z configuration of its double bond, how many stereoisomers are possible? (d) Draw stereochemically accurate representations of all the stereoisomers that satisfy the structural requirements just described. (e) How are these stereoisomers related? Are they enantiomers or diastereomers?

Sphingosine is a component of membrane lipids, including those found in nerve and muscle cells. How many stereoisomers are possible?

Write bond-line formulas for each of the following naturally occurring compounds, clearly showing their stereochemistry. (a) (E)-6-Nonen-l-ol: the sex attractant of the Mediterranean fruit fly. (b) Geraniol: a hydrocarbon with a rose-like odor present in the fragrant oil of many plants (including geranium flowers). It is the E isomer of (c) Nerol: a stereoisomer of geraniol found in neroli and lemongrass oil. (d) The worm in apples is the larval stage of the codling moth. The sex attractant of the male moth is the 2Z,6E stereoisomer of the compound shown. (e) The E stereoisomer of the compound is the sex pheromone of the honeybee. (f) A growth hormone from the cecropia moth has the structure shown. Express the stereochemistry of the double bonds according to the E–Z system.

Choose the more stable alkene in each of the following pairs. Explain your reasoning. (a) 1-Methylcyclohexene or 3-methylcyclohexene (b) Isopropenylcyclopentane or allylcyclopentane (d) (Z)-Cyclononene or (E)-cyclononene (e) (Z)-Cyclooctadecene or (E)-cyclooctadecene

a. Suggest an explanation for the fact that 1-methylcyclopropene is some 42 kJ/mol (10 kcal/mol) less stable than methylenecyclopropane. b. On the basis of your answer to part (a), compare the expected stability of 3-methylcyclopropene with that of 1-methylcyclopropene and that of methylenecyclopropane.

Choose the compound of molecular formula \(\mathrm{C}_{7} \mathrm{H}_{13} \mathrm{Br}\) that gives each alkene shown as the exclusive product of E2 elimination. Text Transcription: C_7H_13Br

Give the structures of two different alkyl bromides both of which yield the indicated alkene as the exclusive product of E2 elimination. (a) \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}\) (b) \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{CH}_{2}\) (c) \(\mathrm{BrCH}=\mathrm{CBr}_{2}\) Text Trancription: CH_3CH=CH_2 (CH_3)C=CH_2 BrCH=CBr_2

Predict the major organic product of each of the following reactions.

The following reaction sequence is described as an introductory organic chemistry laboratory experiment in the Journal of Chemical Education, vol. 78:1676–1678 (2001). Write structural formulas for compound A and compound B.

The rate of the reaction \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCl}+\mathrm{NaSCH}_{2} \mathrm{CH}_{3} \rightarrow\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{CH}_{2}+\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{SH}+\mathrm{NaCl}\) is first-order in (CH3)3CCl and first-order in NaSCH2CH3. Give the symbol (E1 or E2) for the most reasonable mechanism, and use curved arrows to show the flow of electrons. Text Transcription: (CH_3)_3CCl+NaSCH_2CH_3 rightarrow (CH_3)_2C=CH_2+CH_3CH_2SH+NaCl

Menthyl chloride and neomenthyl chloride have the structures shown. One of these stereoisomers undergo elimination on treatment with sodium ethoxide in ethanol much more readily than the other. Which reacts faster, menthyl chloride or neomenthyl chloride? Why?

You have available 2,2-dimethylcyclopentanol (A) and 2-bromo-1,1-dimethylcyclopentane (B) and wish to prepare 3,3-dimethylcyclopentene (C). Which would you choose as the more suitable reactant, A or B, and with what would you treat it?

Write a sequence of steps depicting the mechanisms of each of the following reactions. Use curved arrows to show electron flow.

In Problem 7.20 (Section 7.13) we saw that acid-catalyzed dehydration of 2,2- dimethylcyclohexanol afforded 1,2-dimethylcyclohexene. To explain this product we must write a mechanism for the reaction in which a methyl shift transforms a secondary carbocation to a tertiary one. Another product of the dehydration of 2,2-dimethylcyclohexanol is isopropylidenecyclopentane. Write a mechanism to rationalize its formation, using curved arrows to show the flow of electrons.

Acid-catalyzed dehydration of 2,2-dimethyl-1-hexanol gives a number of isomeric alkenes including 2-methyl-2-heptene as shown in the following equation. (a) Write a stepwise mechanism for the formation of 2-methyl-2-heptene, using curved arrows to show the flow of electrons. (b) What other alkenes do you think are formed in this reaction?

The reactant shown, having an axial p-toluenesulfonate in its most stable conformation, undergoes predominant elimination on reaction with sodium azide. Its diastereomer having an equatorial p-toluenesulfonate gives predominant substitution (76%). Give the structure of the resulting azide and suggest an explanation for the difference in reactivity between the two diastereomeric p-toluenesulfonates.

The following flow chart connects three of the reactions we have discussed that involve carbocation intermediates. Each arrow may represent more than one elementary step in a mechanism. Arrows 1 and 2 summarize the conversion of alcohols to alkyl halides, 3 and 4 the dehydrohalogenation of an alkyl halide to an alkene by the E1 mechanism, and 1 and 4 the formation of an alkene by dehydration of an alcohol. The reaction indicated by arrow 5 constitutes a major focus of the next chapter. There we will explore reactions that give overall addition to the double bond by way of carbocation intermediates. One such process converts alkenes to alkyl halides (5 + 2), another converts alkenes to alcohols (5 + 6). Based on the \(S_{N} 1\) mechanism for the reaction of tertiary alcohols with HCl as summarized in arrows 1 and 2, which arrow(s) represent(s) more than one elementary step? A. Arrow 1 B. Arrow 2 C. Both 1 and 2 D. Neither 1 nor 2 Text Trancription: S_N1

The following flow chart connects three of the reactions we have discussed that involve carbocation intermediates. Each arrow may represent more than one elementary step in a mechanism. Arrows 1 and 2 summarize the conversion of alcohols to alkyl halides, 3 and 4 the dehydrohalogenation of an alkyl halide to an alkene by the E1 mechanism, and 1 and 4 the formation of an alkene by dehydration of an alcohol. The reaction indicated by arrow 5 constitutes a major focus of the next chapter. There we will explore reactions that give overall addition to the double bond by way of carbocation intermediates. One such process converts alkenes to alkyl halides (5 + 2), another converts alkenes to alcohols (5 + 6). Based on the E1 mechanism for the acid-catalyzed dehydration of a tertiary alcohol as summarized in arrows 1 and 4, which arrow(s) represent(s) more than one elementary step? A. Arrow 1 B. Arrow 4 C. Both 1 and 4 D. Neither 1 nor 4

The following flow chart connects three of the reactions we have discussed that involve carbocation intermediates. Each arrow may represent more than one elementary step in a mechanism. Arrows 1 and 2 summarize the conversion of alcohols to alkyl halides, 3 and 4 the dehydrohalogenation of an alkyl halide to an alkene by the E1 mechanism, and 1 and 4 the formation of an alkene by dehydration of an alcohol. The reaction indicated by arrow 5 constitutes a major focus of the next chapter. There we will explore reactions that give overall addition to the double bond by way of carbocation intermediates. One such process converts alkenes to alkyl halides (5 + 2), another converts alkenes to alcohols (5 + 6). Based on the E1 mechanism for the conversion of a tertiary alkyl chloride to an alkene as summarized in arrows 3 and 4, which arrow(s) represent(s) more than one elementary step? A. Arrow 3 B. Arrow 4 C. Both 3 and 4 D. Neither 3 nor 4

The following flow chart connects three of the reactions we have discussed that involve carbocation intermediates. Each arrow may represent more than one elementary step in a mechanism. Arrows 1 and 2 summarize the conversion of alcohols to alkyl halides, 3 and 4 the dehydrohalogenation of an alkyl halide to an alkene by the E1 mechanism, and 1 and 4 the formation of an alkene by dehydration of an alcohol. The reaction indicated by arrow 5 constitutes a major focus of the next chapter. There we will explore reactions that give overall addition to the double bond by way of carbocation intermediates. One such process converts alkenes to alkyl halides (5 + 2), another converts alkenes to alcohols (5 + 6). Based on the E1 mechanism for the conversion of a tertiary alkyl chloride to an alkene as summarized in arrows 3 and 4, which arrow(s) correspond(s) to exothermic processes? A. Arrow 3 B. Arrow 4 C. Both 3 and 4 D. Neither 3 nor 4

The following flow chart connects three of the reactions we have discussed that involve carbocation intermediates. Each arrow may represent more than one elementary step in a mechanism. Arrows 1 and 2 summarize the conversion of alcohols to alkyl halides, 3 and 4 the dehydrohalogenation of an alkyl halide to an alkene by the E1 mechanism, and 1 and 4 the formation of an alkene by dehydration of an alcohol. The reaction indicated by arrow 5 constitutes a major focus of the next chapter. There we will explore reactions that give overall addition to the double bond by way of carbocation intermediates. One such process converts alkenes to alkyl halides (5 + 2), another converts alkenes to alcohols (5 + 6). What term best describes the relationship between an alkene and a carbocation? A. Isomers B. Resonance contributors C. Alkene is conjugate acid of carbocation D. Alkene is conjugate base of carbocation

The following flow chart connects three of the reactions we have discussed that involve carbocation intermediates. Each arrow may represent more than one elementary step in a mechanism. Arrows 1 and 2 summarize the conversion of alcohols to alkyl halides, 3 and 4 the dehydrohalogenation of an alkyl halide to an alkene by the E1 mechanism, and 1 and 4 the formation of an alkene by dehydration of an alcohol. The reaction indicated by arrow 5 constitutes a major focus of the next chapter. There we will explore reactions that give overall addition to the double bond by way of carbocation intermediates. One such process converts alkenes to alkyl halides (5 + 2), another converts alkenes to alcohols (5 + 6). The overall equation for the addition of HCl to alkenes is: If the transition state for proton transfer from HCl to the alkene (arrow 5) resembles a carbocation and this step is rate-determining, what should be the effect of alkene structure on the rate of the overall reaction? Fastest rate Slowest rate A. H2C=CH2 CH3CH=CHCH3 (CH3)2C=C(CH3)2 B. CH3CH=CHCH3 (CH3)2C=C(CH3)2 H2C=CH2 C. CH3CH=CHCH3 H2C=CH2 (CH3)2C=C(CH3)2 D. (CH3)2C=C(CH3)2 CH3CH=CHCH3 H2C=CH2

The following flow chart connects three of the reactions we have discussed that involve carbocation intermediates. Each arrow may represent more than one elementary step in a mechanism. Arrows 1 and 2 summarize the conversion of alcohols to alkyl halides, 3 and 4 the dehydrohalogenation of an alkyl halide to an alkene by the E1 mechanism, and 1 and 4 the formation of an alkene by dehydration of an alcohol. The reaction indicated by arrow 5 constitutes a major focus of the next chapter. There we will explore reactions that give overall addition to the double bond by way of carbocation intermediates. One such process converts alkenes to alkyl halides (5 + 2), another converts alkenes to alcohols (5 + 6). For the addition of HCl to alkenes according to the general equation given in the preceding problem, assume the mechanism involves rate-determining formation of the more stable carbocation (arrow 5) and predict the alkyl chloride formed by reaction of HCl with (CH3)2C CH2. A. (CH3)2CHCH2Cl B. (CH3)3CCl

The following flow chart connects three of the reactions we have discussed that involve carbocation intermediates. Each arrow may represent more than one elementary step in a mechanism. Arrows 1 and 2 summarize the conversion of alcohols to alkyl halides, 3 and 4 the dehydrohalogenation of an alkyl halide to an alkene by the E1 mechanism, and 1 and 4 the formation of an alkene by dehydration of an alcohol. The reaction indicated by arrow 5 constitutes a major focus of the next chapter. There we will explore reactions that give overall addition to the double bond by way of carbocation intermediates. One such process converts alkenes to alkyl halides (5 + 2), another converts alkenes to alcohols (5 + 6). Zaitsev’s rule was presented in this chapter. In the next chapter we will introduce Markovnikov’s rule, which is related to arrow 5. To which arrow does Zaitsev’s rule most closely relate from a mechanistic perspective? A. 1 B. 2 C. 3 D. 4

Name each of the following using IUPAC nomenclature: (a) \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{C}\left(\mathrm{CH}_{3}\right)_{2}\) (b) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCH}=\mathrm{CH}_{2}\) Text Transcription: (CH_3)_2C=C(CH_3)_2 (CH_3)_3CCH=CCH_2

How many carbon atoms are sp2-hybridized in the alkene shown? How many are sp3-hybridized? How many bonds are of the sp2–sp3 type? How many are of the sp3–sp3 type?

How many alkenes have the molecular formula C5H10? Write their structures and give their IUPAC names. Specify the configuration of stereoisomers as cis or trans as appropriate.

Female house flies attract males by sending a chemical signal known as a pheromone. The substance emitted by the female housefly that attracts the male has been identified as cis-9-tricosene, \(\mathrm{C}_{23} \mathrm{H}_{46}\). Write a structural formula, including stereochemistry, for this compound. Text Transcription: C_23H_46

Determine the configuration of each of the following as Z or E as appropriate:

Arrange the following in order of increasing dipole moment.

Write structural formulas and give the IUPAC names for all the alkenes of molecular formula \(\mathrm{C}_{6} \mathrm{H}_{12}\) that contain a trisubstituted double bond. (Don’t forget to include stereoisomers.) Text Transcription: C_6H_12

Standard enthalpies of formation are known for all 17 isomeric \(\mathrm{C}_{6} \mathrm{H}_{12}\) alkenes. Which one is most stable \(\left(\Delta H_{f}^{\circ}=-70 \mathrm{~kJ} / \mathrm{mol}\right)\)? Which one is least stable \(\left(\Delta H_{f}^{\circ}=-42 \mathrm{~kJ} / \mathrm{mol}\right)\)? Text Transcription: C_6H_12 (Delta H_f^circ=-70 kJ/mol) (Delta H_f^circ=-42 kJ/mol)

Write structural formulas for the six isomeric alkenes of molecular formula C5H10 and arrange them in order of increasing stability (smaller heat of combustion, more negative \(\Delta H_{f}^{\circ}\)). Text Transcription: Delta H_f^circ

Place a double bond in the carbon skeleton shown so as to represent (a) (Z)-1-Methylcyclodecene (b) (E)-1-Methylcyclodecene (c) (Z)-3-Methylcyclodecene (d) (E)-3-Methylcyclodecene (e) (Z)-5-Methylcyclodecene (f ) (E)-5-Methylcyclodecene

Each of the following alcohols has been subjected to acid-catalyzed dehydration and yields a mixture of two isomeric alkenes. Identify the two alkenes in each case, and predict which one is the major product on the basis of the Zaitsev rule.

The alkene mixture obtained on dehydration of 2,2-dimethylcyclohexanol contains appreciable amounts of 1,2-dimethylcyclohexene. Give a mechanistic explanation for the formation of this product.

Write structural formulas for all the alkenes that can be formed in the reaction of 2-bromobutane with potassium ethoxide \(\left(\mathrm{KOCH}_{2} \mathrm{CH}_{3}\right)\). Text Transcription: (KOCH_2CH_3)

A study of the hydrolysis behavior of chlorofluorocarbons (CFCs) carried out by the U.S. Environmental Protection Agency found that 1,2-dichloro-1, 1, 2-trifluoroethane \(\left(\mathrm{ClF}_{2} \mathrm{C}-\mathrm{CHClF}\right)\) underwent dehydrohalogenation on treatment with aqueous sodium hydroxide. Suggest a reasonable structure for the product of this reaction. Text Transcription: (ClF_2C- CHClF)

Predict the major product of the reaction shown.

Which stereoisomer do you predict will undergo elimination on treatment with sodium ethoxide in ethanol at the faster rate?

Choose the compound in the following pairs that undergoes E2 elimination at the faster rate.

A standard method for the synthesis of ethers is an \(\mathrm{S}_{\mathrm{N}} 2\) reaction between an alkoxide and an alkyl halide. Show possible combinations of alkoxide and alkyl halide for the preparation of the following ethers. Which of these can be prepared effectively by this method? b) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OCH}\left(\mathrm{CH}_{3}\right)_{2}\) Text Transcription: S_N 2 CH_3CH_2CH_2OCH(CH_3)_2

Write structural formulas and give the IUPAC names of all the monochloro-substituted derivatives of cyclopentene. Include enantiomers and assign R- and S-configurations as appropriate. Which isomers are allylic chlorides? Which are vinylic?

Are cis-2-hexene and trans-3-hexene stereoisomers? Explain.

Give the IUPAC name of each of the compounds in Problem 7.7, including E or Z as appropriate.

Arrange the following alkenes in order of decreasing stability: 1-pentene; (E)-2-pentene; (Z)-2-pentene; 2-methyl-2-butene.

Despite numerous attempts, the alkene 3,4-di-tert-butyl-2,2,5,5-tetramethyl-3-hexene has never been synthesized. Can you explain why?

Identify the alkene obtained on dehydration of each of the following alcohols: (a) 3-Ethyl-3-pentanol (b) 1-Propanol (c) 2-Propanol (d) 2,3,3-Trimethyl-2-butanol

What three alkenes are formed in the acid-catalyzed dehydration of 2-pentanol?

Write a structural formula for the carbocation intermediate formed in the dehydration of each of the alcohols in Problem 7.17 (Section 7.10). Using curved arrows, show how each carbocation is deprotonated by water to give a mixture of alkenes.

Write the structures of all the alkenes that can be formed by dehydrohalogenation of each of the following alkyl halides with sodium ethoxide. Apply the Zaitsev rule to predict the alkene formed in the greatest amount in each case. (a) 2-Bromo-2,3-dimethylbutane (b) tert-Butyl chloride (c) 3-Bromo-3-ethylpentane (d) 2-Bromo-3-methylbutane (e) 1-Bromo-3-methylbutane (f ) 1-Iodo-1-methylcyclohexane

Use curved arrows to illustrate the electron flow in the chlorofluorocarbon dehydrohalogenation of Problem 7.23.

Based on the E1 mechanism shown for it in Mechanism 7.5, would you expect elimination in 2-bromo-2-methylbutane to exhibit a deuterium isotope effect?

Predict the major organic product of each of the following reactions: (a) Cyclohexyl bromide and potassium ethoxide (b) Ethyl bromide and potassium cyclohexanolate (c) sec-Butyl bromide solvolysis in methanol (d) sec-Butyl bromide solvolysis in methanol containing 2 M sodium methoxide

Write structural formulas for each of the following: (a) 1-Heptene (b) 3-Ethyl-2-pentene (c) cis-3-Octene l (d) trans-1,4-Dichloro-2-butene (e) (Z)-3-Methyl-2-hexene (f) (E)-3-Chloro-2-hexene (g) 1-Bromo-3-methylcyclohexene (h) 1-Bromo-6-methylcyclohexene (i) 4-Methyl-4-penten-2-ol (j) Vinylcycloheptane (k) 1,1-Diallylcyclopropane (l) trans-1-Isopropenyl-3-methylcyclohexane

Match each alkene with the appropriate heat of combustion: Heats of combustion (kJ/mol): 5293; 4658; 4650; 4638; 4632 Heats of combustion (kcal/mol): 1264.9; 1113.4; 1111.4; 1108.6; 1107.1 (a) 1-Heptene (b) 2,4-Dimethyl-1-pentene (c) 2,4-Dimethyl-2-pentene (d) (Z)-4,4-Dimethyl-2-pentene (e) 2,4,4-Trimethyl-2-pentene

How many alkenes would you expect to be formed from each of the following alkyl bromides under conditions of E2 elimination? Identify the alkenes in each case. (a) 1-Bromohexane (e) 2-Bromo-3-methylpentane (b) 2-Bromohexane (f) 3-Bromo-2-methylpentane (c) 3-Bromohexane (g) 3-Bromo-3-methylpentane (d) 2-Bromo-2-methylpentane (h) 3-Bromo-2,2-dimethylbutane

Write structural formulas for all the alkene products that could reasonably be formed from each of the following compounds under the indicated reaction conditions. Where more than one alkene is produced, specify the one that is the major product. (a) 1-Bromo-3,3-dimethylbutane (potassium tert-butoxide, tert-butyl alcohol, 100°C) (b) 1-Methylcyclopentyl chloride (sodium ethoxide, ethanol, 70°C) (c) 3-Methyl-3-pentanol (sulfuric acid, 80°C) (d) 2,3-Dimethyl-2-butanol (phosphoric acid, 120°C) (e) 3-Iodo-2,4-dimethylpentane (sodium ethoxide, ethanol, 70°C) (f) 2,4-Dimethyl-3-pentanol (sulfuric acid, 120°C)

Solvolysis of 2-bromo-2-methylbutane in acetic acid containing sodium acetate gives three organic products. What are they?

Draw a Newman projection for the conformation adopted by 2-bromo-2,4,4-trimethylpentane in a reaction proceeding by the E2 mechanism. Assume the regioselectivity is consistent with the Zaitsev rule.

In the acid-catalyzed dehydration of 2-methyl-1-propanol, what carbocation would be formed if a hydride shift accompanied cleavage of the carbon–oxygen bond in the alkyloxonium ion? What ion would be formed as a result of a methyl shift? Which pathway do you think will predominate, a hydride shift or a methyl shift?

The ratio of elimination to substitution is exactly the same (26% elimination) for 2-bromo- 2-methylbutane and 2-iodo-2-methylbutane in 80% ethanol/20% water at 25°C. (a) By what mechanism does substitution most likely occur in these compounds under these conditions? (b) By what mechanism does elimination most likely occur in these compounds under these conditions? (c) Which one of the two alkyl halides undergoes substitution faster? (d) Which one of the two alkyl halides undergoes elimination faster? (e) What two substitution products are formed from each? (f) What two elimination products are formed from each? (g) Why do you suppose the ratio of elimination to substitution is the same for the two alkyl halides?