What effect would you expect the following changes to have

What product would you expect from a nucleophilic substitution reaction of (R)-1-bromo-1-phenylethane with cyanide ion, \(\mathrm {^-C \equiv N}\), as nucleophile? Show the stereochemistry of both reactant and product, assuming that inversion of configuration occurs. Equation Transcription: Text Transcription: ^-C equiv N Na^{+ -}C equiv N

What product would you expect from a nucleophilic substitution reaction of (S)-2-bromohexane with acetate ion, \(\mathrm {CH_3CO_2^-}\)? Assume that inversion of configuration occurs, and show the stereochemistry of both the reactant and product. Equation Transcription: Text Transcription: CH_3CO_2^-

What product would you expect to obtain from \(\mathrm {S_N2}\) reaction of \(\mathrm {OH^-}\) with (R)-2-bromobutane? Show the stereochemistry of both the reactant and product. Equation Transcription: Text Transcription: S_N2 OH^-

Assign configuration to the following substance, and draw the structure of the product that would result from nucleophilic substitution reaction with \(\mathrm {HS^-}\) (reddish brown = Br): Equation Transcription: Text Transcription: HS^-

What product would you expect from SN2 reaction of 1-bromobutane with each of the following? (a) \(\mathrm {NaI}\) (b) \(\mathrm {KOH}\) (c) \(\mathrm {H-C \equiv C-Li}\) (d) \(\mathrm {NH_3}\) Equation Transcription: Text Transcription: H-C equiv C-Li NH_3

Which substance in each of the following pairs is more reactive as a nucleophile? Explain. (a) \(\mathrm {(CH_3)_2N^-}\) or \(\mathrm {(CH_3)_2NH}\) (b) \(\mathrm {(CH_3)_3B}\) or \(\mathrm {(CH_3)_3N}\) (c) \(\mathrm {H_2O}\) or \(\mathrm {H_2S}\) Equation Transcription: Text Transcription: (CH_3)_2N^- (CH_3)_2NH (CH_3)_3B (CH_3)_3N H_2O H_2S

Rank the following compounds in order of their expected reactivity toward \(\mathrm {S_N2}\) reaction: \(\mathrm {CH_3Br,CH_3OTos,(CH_3)_3CCl,(CH_3)_2CHCl}\) Equation Transcription: Text Transcription: S_N2 CH_3Br,CH_3OTos,(CH_3)_3CCl,(CH_3)_2CHCl

Organic solvents like benzene, ether, and chloroform are neither protic nor strongly polar. What effect would you expect these solvents to have on the reactivity of a nucleophile in \(\mathrm {S_N2}\) reactions? Equation Transcription: Text Transcription: S_N2

What product(s) would you expect from reaction of (S)-3-chloro-3-methyl octane with acetic acid? Show the stereochemistry of both reactant and product.

Among the many examples of \(\mathrm {S_N1}\) reactions that occur with incomplete racemization, the optically pure tosylate of 2,2-dimethyl-1-phenyl-1-propanol \(\mathrm {([\alpha]_D=-30.3)}\) gives the corresponding acetate \(\mathrm {([\alpha]_D=+5.3)}\) when heated in acetic acid. If complete inversion had occurred, the optically pure acetate would have had \(\mathrm {[\alpha]_D=+53.6}\). What percentage racemization and what percentage inversion occurred in this reaction? ________________ Equation Transcription: Text Transcription: S_N1 ([alpha]_D=-30.3) ([alpha]_D=+5.3) [alpha]_D=+53.6 C(CH3)3 [alpha]_D=-30.3 [alpha]_D=+5.3 [alpha]_D=+53.6 C(CH_3)_3 CH_3

Assign configuration to the following substrate, and show the stereochemistry and identity of the product you would obtain by \(\mathrm {S_N1}\) reaction with water (reddish brown = Br): Equation Transcription: Text Transcription: S_N1

Rank the following substances in order of their expected \(\mathrm {S_N1}\) reactivity: Equation Transcription: Text Transcription: S_N1 CH_3CH_2Br H_2C=CHCHCH_3 H_2C=CHBr CH_3CHCH_3

3-Bromo-1-butene and 1-bromo-2-butene undergo \(\mathrm {S_N1}\) reaction at nearly the same rate, even though one is a secondary halide and the other is primary. Explain. Equation Transcription: Text Transcription: S_N1

Predict whether each of the following substitution reactions is likely to be \(\mathrm {S_N1}\) or \(\mathrm {S_N2}\): Equation Transcription: Text Transcription: S_N1 S_N2 CH_3CO_2^-Na^+ CH_3CO_2H,H_2O CH_2Br CH_3O^-Na^+ CH_2OCH_3

Review the mechanism of geraniol biosynthesis shown in Figure 11-15, and propose a mechanism for the biosynthesis of limonene from linalyl diphosphate.

What product would you expect from reaction of 1-chloro-1-methylcyclohexane with KOH in ethanol? Equation Transcription: Text Transcription: CH_3

Ignoring double-bond stereochemistry, what products would you expect from elimination reactions of the following alkyl halides? Which product will be the major product in each case? Equation Transcription: Text Transcription: CH_3 CH_3CH_2CHCHCH_3 CH_3 CH_3CHCH_2-C-CHCH_3 CH_3 CH_3 CHCH_3

What alkyl halides might the following alkenes have been made from? Equation Transcription: Text Transcription: CH_3 CH_3 CH_3CHCH_2CH_2CHCH=CH_2 CH_3 CH_3

What stereochemistry do you expect for the alkene obtained by E2 elimination of (1S,2S)-1,2-dibromo-1,2-diphenylethane?

What stereochemistry do you expect for the alkene obtained by E2 elimination of (1R,2R)-1,2-dibromo-1,2-diphenylethane? Draw a Newman projection of the reacting conformation.

What stereochemistry do you expect for the trisubstituted alkene obtained by E2 elimination of the following alkyl halide on treatment with KOH? (Reddish brown = Br.)

Which isomer would you expect to undergo E2 elimination faster, trans-1-bromo4-tert-butylcyclohexane or cis-1-bromo-4-tert-butylcyclohexane? Draw each molecule in its more stable chair conformation, and explain your answer.

Tell whether each of the following reactions is likely to be \(\mathrm {S_N1,S_N2}\), E1, E1cB, or E2, and predict the product of each: Equation Transcription: Text Transcription: S_N1,S_N2 Na^+ -OCH_3 CH_3OH HCO_2H H_2O

Tell whether each of the following reactions is likely to be \(\mathrm {S_N1,S_N2}\), E1, E1cB, or E2: Equation Transcription: Text Transcription: S_N1,S_N2 CH_3CH_2CH_2CH_2Br NaN_3 CH_3CH_2CH_2CH_2N=N=N CH_3CH_2CHCH_2CH_3 CH_3CH_2CH=CHCH_3 CH_3 CH_3CO_2H OCCH_3 CH_3

Write the product you would expect from reaction of each of the following alkyl halides with (1) \(\mathrm {Na^{+\ -}SCH_3}\) and (2) \(\mathrm {Na^{+\ -}OH}\) (green = Cl): Equation Transcription: Text Transcription: Na^{+-}SCH_3 Na^{+-}OH

From what alkyl bromide was the following alkyl acetate made by \(\mathrm {S_N2}\) reaction? Write the reaction, showing all stereochemistry. Equation Transcription: Text Transcription: S_N2

Assign R or S configuration to the following molecule, write the product you would expect from \(\mathrm {S_N2}\) reaction with NaCN, and assign R or S configuration to the product (green = Cl): Equation Transcription: Text Transcription: S_N2

Draw the structure and assign Z or E stereochemistry to the product you expect from E2 reaction of the following molecule with NaOH (green = Cl):

Predict the product(s) and show the mechanism for each reaction below. What do the mechanisms have in common? Why? ________________ Equation Transcription: Text Transcription: CH_3CH_2CH_2OTos+NaBr CH_3CCLi CH_3SNa

Show the mechanism for each reaction below. What do the mechanisms have in common? Why? Equation Transcription: Text Transcription: H_O CH_3CO_2Na CH_3CO_2H CO_2CH_3 CH_3OH OCH_3

Predict the product(s) for each elimination reaction below. In each case show the mechanism. What do the mechanisms have in common? Why? Equation Transcription: Text Transcription: H_2SO_4 CH_3CO_2Na CH_3CO_2H CH_3 CH_3 H_2SO_4

Predict the product(s) for each elimination reaction below. In each case show the mechanism. What do the mechanisms have in common? Why? Equation Transcription: Text Transcription: CH_3ONa CH_3 CH_3OH (CH_3)_3COK CH_3ONa CH_3OH

Predict the product(s) for each elimination reaction below. In each case show the mechanism. What do the mechanisms have in common? Why? Equation Transcription: Text Transcription: CH_3ONa CH_3OH CH_3 H_2O CH_3ONa CH_3OH

Predict the product of each reaction below and indicate if the mechanism is likely to be \(\mathrm {S_N1,S_N2}\), E1, E2, or E1cB. Equation Transcription: Text Transcription: S_N1,S_N2 H_2O CH_3CH_2I CH_3OH CH_3CH_2ONa CH_3CH_2OH

We saw in Section 8-7 that bromohydrins are converted into epoxides when treated with base. Propose a mechanism, using curved arrows to show the electron flow. Equation Transcription: Text Transcription: C-C CH_3 CH_3 C-C CH_3 CH_3

The following tertiary alkyl bromide does not undergo a nucleophilic substitution reaction by either \(\mathrm {S_N1}\) or \(\mathrm {S_N2}\) mechanisms. Explain. Equation Transcription: Text Transcription: SN_1 SN_2

Metabolism of S-adenosylhomocysteine (Section 11-6) involves the following sequence. Propose a mechanism for the second step. Equation Transcription: Text Transcription: NH_3 CO_2^- NAD^+ NADH,H^+ NH_3 CO_2^- NH_3 CO_2^- H_2C

Reaction of iodoethane with \(\mathrm {CN^-}\) yields a small amount of isonitrile, \(\mathrm {CH_3CH_2N \equiv C}\), along with the nitrile \(\mathrm {CH_3CH_2C \equiv N}\) as the major product. Write electron-dot structures for both products, assign formal charges as necessary, and propose mechanisms to account for their formation. Equation Transcription: Text Transcription: CN^- CH_3CH_2N equiv C CH_3CH_2C equiv N

One step in the urea cycle for ridding the body of ammonia is the conversion of argininosuccinate to the amino acid arginine plus fumarate. Propose a mechanism for the reaction, and show the structure of arginine. Equation Transcription: Text Transcription: ^-O_2C NH_3 NH_2 CO_2^- CO_2^- ^-O_2C CO_2^-

Methyl esters \(\mathrm{(RCO_2CH_3)}\) undergo a cleavage reaction to yield carboxylate ions plus iodomethane on heating with LiI in dimethylformamide: The following evidence has been obtained: (1) The reaction occurs much faster in DMF than in ethanol. (2) The corresponding ethyl ester \(\mathrm{(RCO_2CH_2CH_3)}\) cleaves approximately 10 times more slowly than the methyl ester. Propose a mechanism for the reaction. What other kinds of experimental evidence could you gather to support your hypothesis? ________________ Equation Transcription: Text Transcription: (RCO_2CH_3) (RCO_2CH_2CH_3) OCH_3 O^- Li^+ CH3_I

\(\mathrm{S_N2}\) reactions take place with inversion of configuration, and \(\mathrm{S_N1}\) reactions take place with racemization. The following substitution reaction, however, occurs with complete retention of configuration. Propose a mechanism. Equation Transcription: Text Transcription: S_N2 S_N1 H_3C NaOH, H_2O H_3O^+ H_3C

Propose a mechanism for the following reaction, an important step in the laboratory synthesis of proteins: Equation Transcription: Text Transcription: H_3C H_3C CH_3 CH_3CO_2H H_3C H_3C C=CH_2

Draw all isomers of \(\mathrm{C_4H_9Br}\), name them, and arrange them in order of decreasing reactivity in the \(\mathrm{S_N2}\) reaction. Equation Transcription: Text Transcription: C_4H_9Br S_N2

The following Walden cycle has been carried out. Explain the results, and indicate where Walden inversion occurs. ________________ Equation Transcription: Text Transcription: CH_3CHCH_2 CH_3CHCH_2 CH_3CH_2OH OCH_2CH_3 CH_3CHCH_2 [alpha]_D=+33.0 [alpha]_D=+31.1 [alpha]_D=-19.9 O^- K^+ CH_3CHCH_2 CH_3CH_2Br OCH_2CH_3 CH_3CHCH_2 [alpha]_D=+23.5

Which compound in each of the following pairs will react faster in an \(\mathrm{S_N2}\) reaction with \(\mathrm{OH^-}\)? (a) \(\mathrm{CH_3Br}\) or \(\mathrm{CH_3I}\) (b) \(\mathrm{CH_3CH_2I}\) in ethanol or in dimethyl sulfoxide (c) \(\mathrm{(CH_3)_3CCl}\) or \(\mathrm{(CH_3)_3CCl}\) (d) \(\mathrm{H_2C=CHBr}\) or \(\mathrm{H_2C=CHCH_2Br}\) Equation Transcription: Text Transcription: SN_2 OH^- CH_3Br CH_3I CH_3CH_2I (CH_3)_3CCl CH_3Cl H_2C=CHBr H_2C=CHCH_2Br

Which reactant in each of the following pairs is more nucleophilic? Explain. (a) \(\mathrm{^-NH_2}\) or \(\mathrm{NH_3}\) (b) \(\mathrm{H_2O}\) or \(\mathrm{CH_3CO_2^-}\) (c) \(\mathrm{BF_3}\) or \(\mathrm{F^-}\) (d) \(\mathrm{(CH_{3})_3P}\) or \(\mathrm{(CH_{3})_3N}\) (e) \(\mathrm{I^-}\) or \(\mathrm{Cl^-}\) (f) \(\mathrm{^-C \equiv N}\) or \(\mathrm{^-OCH_3 }\) Equation Transcription: Text Transcription: ^-NH_2 NH_3 H_2O CH_3CO_2^- BF_3 F^- (CH_3)_3P (CH_3)_3N I^- Cl^- ^-C equiv N ^-OCH_3

What effect would you expect the following changes to have on the rate of the \(\mathrm{S_N2}\) reaction of 1-iodo-2-methylbutane with cyanide ion? (a) The \(\mathrm{CN^-}\) concentration is halved, and the 1-iodo-2-methylbutane concentration is doubled. (b) Both the \(\mathrm{CN^-}\) and the 1-iodo-2-methylbutane concentrations are tripled. Equation Transcription: Text Transcription: S_N2 CN^- CN^-

What effect would you expect the following changes to have on the rate of the reaction of ethanol with 2-iodo-2-methylbutane? (a) The concentration of the halide is tripled. (b) The concentration of the ethanol is halved by adding diethyl ether as an inert solvent.

How might you prepare each of the following molecules using a nucleophilic substitution reaction at some step? Equation Transcription: Text Transcription: CH_3 CH_3CCCHCH_3 CH_3 CH_3-O-CCH_3 CH_3 CH_3CH_2CH_2CH_2CN CH_3CH_2CH_2NH_2

Which reaction in each of the following pairs would you expect to be faster? (a) The \(\mathrm{S_N2}\) displacement by \(\mathrm{I^-}\) on \(\mathrm{CH_3Cl}\) or on \(\mathrm{CH_3OTos}\) (b) The \(\mathrm{S_N2}\) displacement by \(\mathrm{CH_3CO_2^-}\) on bromoethane or on bromocyclohexane (c) The \(\mathrm{S_N2}\) displacement on 2-bromopropane by \(\mathrm {CH_3CH_2O^-}\) or by \(\mathrm{CN^-}\) (d) The \(\mathrm{S_N2}\) displacement by \(\mathrm{HC \equiv C^-}\) on bromomethane in benzene or in acetonitrile Equation Transcription: Text Transcription: S_N2 I^- CH_3Cl CH_3OTos S_N2 CH_3CO_2^- S_N2 CH_3CH_2O^- CN^- S_N2 HC equiv C^-

Predict the product and give the stereochemistry resulting from reaction of each of the following nucleophiles with (R)-2-bromooctane: (a) \(\mathrm{^-CN}\) (b) \(\mathrm{CH_3CO_2^-}\) (c) \(\mathrm{CH_3S^-}\) Equation Transcription: Text Transcription: ^-CN CH_3CO_2^- CH_3S^-

(R)-2-Bromooctane undergoes racemization to give \((\pm)\)-2-bromooctane when treated with NaBr in dimethyl sulfoxide. Explain. Equation Transcription: Text Transcription: (+-)

Propose structures for compounds that it the following descriptions: (a) An alkyl halide that gives a mixture of three alkenes on E2 reaction (b) An organohalide that will not undergo nucleophilic substitution (c) An alkyl halide that gives the non-Zaitsev product on E2 reaction (d) An alcohol that reacts rapidly with HCl at \(\mathrm{0^\circ C}\) Equation Transcription: Text Transcription: 0^oC

What products would you expect from the reaction of 1-bromopropane with each of the following? (a) \(\mathrm{NaNH_2}\) (b) \(\mathrm{KOC(CH_3)_3}\) (c) \(\mathrm{NaI}\) (d) \(\mathrm{NaCN}\) (e) \(\mathrm{NaC \equiv CH}\) (f) \(\mathrm{Mg}\), then \(\mathrm{H_2O}\) Equation Transcription: Text Transcription: NaNH_2 KOC(CH_3)_3 NaC equiv CH H_2O

1-Chloro-1,2-diphenylethane can undergo E2 elimination to give either cis- or trans-1,2-diphenylethylene (stilbene). Draw Newman projections of the reactive conformations leading to both possible products, and suggest a reason why the trans alkene is the major product. Equation Transcription: Text Transcription: CHCH_2 ^-OCH_3 CH=CH

Predict the major alkene product of the following E1 reaction: Equation Transcription: Text Transcription: H_3C CH_3 CH_3CHCBr CH_2CH_3

There are eight diastereomers of 1,2,3,4,5,6-hexachlorocyclohexane. Draw each in its more stable chair conformation. One isomer loses HCl in an E2 reaction nearly 1000 times more slowly than the others. Which isomer reacts so slowly, and why?

The reactions shown below are unlikely to occur as written. Tell what is wrong with each, and predict the actual product. Equation Transcription: Text Transcription: CH_3CHCH_2CH_3 K^+ ^-OC(CH_3)_3 (CH_3)_3COH OC(CH_3)_3 CH_3CHCH_2CH_3 Na^+ ^-OH CH_3 SOCl_2 CH_3

Arrange the carbocations below, in order of increasing stability.

Order each of the following sets of compounds with respect to \(\mathrm{S_N1}\) reactivity: ________________ Equation Transcription: Text Transcription: S_N1 CH_3 H_3C-C-Cl CH_3 H_3C CH_3 NH_2 CH_3CH2CHCH_3 (CH_3)_3CCl (CH_3)_3CBr (CH_3)_3COH CH_2Br CHCH_3

Order each of the following sets of compounds with respect to \(\mathrm{S_N2}\) reactivity: ________________ Equation Transcription: Text Transcription: S_N2 CH_3 H_3C-C-Cl CH_3 CH_3CH_2CH_2Cl CH_3CH_2CHCH_3 CH_3 CH_3CHCHCH_3 CH_3 CH_3CHCH_2Br CH_3 CH_3CCH_2Br CH_3 CH_3CH_2CH_2OCH_3 CH_3CH_2CH_2OTos CH_3CH_2CH_2Br

Predict the major product(s) of each reaction below. Identify those reactions where you would expect the product mixture to rotate plane polarized light. Equation Transcription: Text Transcription: CH_3 CH_3 CH_3 CH_3 CH_3 CH_3O-Na^+ CH_3OH CH_3 CH_3 CH_3OH

Reaction of the following S tosylate with cyanide ion yields a nitrile product that also has S stereochemistry. Explain. Equation Transcription: Text Transcription: H_3C CH_2OCH_3

Ethers can often be prepared by \(\mathrm{S_N2}\) reaction of alkoxide ions, \(\mathrm{RO^-}\), with alkyl halides. Suppose you wanted to prepare cyclohexyl methyl ether. Which of the two possible routes shown below would you choose? Explain. Equation Transcription: Text Transcription: S_N2 RO^- O^- CH_3I OCH_3 CH_3O^-

Show the stereochemistry of the epoxide (see Problem 11-31) you would obtain by formation of a bromohydrin from trans-2-butene, followed by treatment with base.

In light of your answer to Problem 11-31, what product might you expect from treatment of 4-bromo-1-butanol with base? Equation Transcription: Text Transcription: BrCH_2CH_2CH_2CH_2OH

In addition to not undergoing substitution reactions, the alkyl bromide shown in Problem 11-32 also fails to undergo an elimination reaction when treated with base. Explain.

The tosylate of (2R,3S)-3-phenyl-2-butanol undergoes E2 elimination on treatment with sodium ethoxide to yield (Z)-2-phenyl-2-butene. Explain, using Newman projections. Equation Transcription: Text Transcription: CH_3CHCHCH_3 Na^+ -OCH_2CH_3 CH_3C=CHCH_3

In light of your answer to Problem 11-64, which alkene, E or Z, would you expect from an E2 reaction on the tosylate of (2R,3R)-3-phenyl-2-butanol? Which alkene would result from E2 reaction on the (2S,3R) and (2S,3S) tosylates? Explain.

How can you explain the fact that trans-1-bromo-2-methylcyclohexane yields the non-Zaitsev elimination product 3-methylcyclohexene on treatment with base? Equation Transcription: Text Transcription: CH_3 CH_3

Predict the product(s) of the following reaction, indicating stereochemistry where necessary: Equation Transcription: Text Transcription: H_3C CH_3 H_2O

Alkynes can be made by dehydrohalogenation of vinylic halides in a reaction that is essentially an E2 process. In studying the stereochemistry of this elimination, it was found that (Z)-2-chloro-2-butenedioic acid reacts 50 times as fast as the corresponding E isomer. What conclusion can you draw about the stereochemistry of eliminations in vinylic halides? How does this result compare with eliminations of alkyl halides? ________________ Equation Transcription: Text Transcription: HO_2C-C=C-CO_2H Na^+ ^-NH_2 H_3O^+ HO_2C-C equiv C-CO_2H

Based on your answer to Problem 11-68, predict the product(s) and show the mechanism for each reaction below. Equation Transcription: Text Transcription: CH_3CH_2 C=C Na^+ ^-NH_2 H_3O^+ CH_3 C=C N_a^+ ^-NH_2 H_3O^+ C=C Na^+ ^-NH_2 H_3O^+

(S)-2-Butanol slowly racemizes on standing in dilute sulfuric acid. Explain. Equation Transcription: Text Transcription: CH_3CH_2CHCH_3

Reaction of HBr with (R)-3-methyl-3-hexanol leads to racemic 3-bromo3-methylhexane. Explain. Equation Transcription: Text Transcription: CH_3CH_2CH_2CCH_2CH_3 CH_3

Treatment of 1-bromo-2-deuterio-2-phenylethane with strong base leads to a mixture of deuterated and nondeuterated phenylethylenes in an approximately 7:1 ratio. Explain. Equation Transcription: Text Transcription: (CH_3)_3CO^-

Propose a structure for an alkyl halide that gives only (E)-3-methyl2-phenyl-2-pentene on E2 elimination. Make sure you indicate the stereochemistry.

Although anti periplanar geometry is preferred for E2 reactions, it isn’t absolutely necessary. The deuterated bromo compound shown here reacts with strong base to yield an undeuterated alkene. Clearly, a syn elimination has occurred. Make a molecular model of the reactant, and explain the result.

In light of your answer to Problem 11-74, explain why one of the following isomers undergoes E2 reaction approximately 100 times as fast as the other. Which isomer is more reactive, and why? ________________ Equation Transcription: Text Transcription: RO^- RO^-

The reaction of 1-chlorooctane with \(\mathrm {CH_3CO_2^-}\) to give octyl acetate is greatly accelerated by adding a small quantity of iodide ion. Explain. Equation Transcription: Text Transcription: CH_3CO_2^-

Compound X is optically inactive and has the formula \(\mathrm {C_{16}H_{16}Br_2}\). On treatment with strong base, X gives hydrocarbon Y, \(\mathrm {C_{16}H_{14}}\). Compound Y absorbs 2 equivalents of hydrogen when reduced over a palladium catalyst and reacts with ozone to give two fragments. One fragment, Z, is an aldehyde with formula \(\mathrm {C_7H_6O}\). The other fragment is glyoxal, \(\mathrm {(CHO)_2}\). Write the reactions involved, and suggest structures for X, Y, and Z. What is the stereochemistry of X? Equation Transcription: Text Transcription: C_{16}H_{16}Br_2 C_{16}H_{14} C_7H_6O (CHO)_2

When a primary alcohol is treated with p-toluenesulfonyl chloride at room temperature in the presence of an organic base such as pyridine, a tosylate is formed. When the same reaction is carried out at higher temperature, an alkyl chloride is often formed. Explain. Equation Transcription: Text Transcription: CH_2OH 60^oC CH_2Cl

The amino acid methionine is formed by a methylation reaction of homocysteine with N-methyltetrahydrofolate. The stereochemistry of the reaction has been probed by carrying out the transformation using a donor with a “chiral methyl group” that contains protium (H), deuterium (D), and tritium (T) isotopes of hydrogen. Does the methylation reaction occur with inversion or retention of configuration? Equation Transcription: Text Transcription: H_3N CO_2 H_3N CO_2^- H_2N

Amines are converted into alkenes by a two-step process called Hofmann elimination. \(\mathrm {S_N2}\) reaction of the amine with an excess of \(\mathrm {CH_3I}\) in the first step yields an intermediate that undergoes E2 reaction when treated with silver oxide as base. Pentylamine, for example, yields 1-pentene. Propose a structure for the intermediate, and explain why it readily undergoes elimination. Equation Transcription: Text Transcription: S_N2 CH_3I CH_3CH_2CH_2CH_2CH_2NH_2 CH_3I Ag_2O,H_2O CH_3CH_2CH_2CH=CH_2

The antipsychotic drug flupentixol is prepared by the following scheme: (a) What alkyl chloride B reacts with amine A to form C? (b) Compound C is treated with \(\mathrm {SOCl_2}\), and the product is allowed to react with magnesium metal to give a Grignard reagent D. What is the structure of D? (c) We’ll see in Section 19-7 that Grignard reagents add to ketones, such as E, to give tertiary alcohols, such as F. Because of the newly formed chirality center, compound F exists as a pair of enantiomers. Draw both, and assign R,S configuration. (d) Two stereoisomers of flupentixol are subsequently formed from F, but only one is shown. Draw the other isomer, and identify the type of stereoisomerism. Equation Transcription: Text Transcription: OCH_2Ph OCH_2Ph SOCl_2 CF_3 CF_3 SOCl_2

What is the likely mechanism of the reaction in Step 1 of the mechlorethamine example shown? (a) \(\mathrm{S_N1}\) (b) \(\mathrm{S_N2}\) (c) \(\mathrm{E1}\) (d) \(\mathrm{S_{N}Ar}\) Equation Transcription: Text Transcription: S_N1 S_N2 E1 S_NAr

What is the likely mechanism of the reaction in Step 2 of the mechlorethamine example shown? (a) \(\mathrm{S_N1}\) (b) \(\mathrm{S_N2}\) (c) \(\mathrm{E1}\) (d) \(\mathrm{S_{N}Ar}\) Equation Transcription: Text Transcription: S_N1 S_N2 E1 S_NAr

In the nucleobase, guanine, a six-membered pyrimidine ring is fused to five-membered imidazole ring, which has two types of nitrogen: a pyridinetype nitrogen (N7) and a pyrrole-type nitrogen (N9). Which best describes the difference in the nucleophilicity of the pyridine-type N7 over the pyrrole-type N9? (a) The pyridine-type N7 has a lone pair in an \(sp^2\) hybrid orbital. (b) The pyrrole-type N9 has a lone pair in an \(sp3\) hybrid orbital. (c) The pyridine-type N7 has a lone pair in a p orbital in resonance in its ring. (d) The pyrrole-type N9 has a lone pair in an \(sp^2\) hybrid orbital. Equation Transcription: Text Transcription: NH_2 sp^2 sp^3 sp^2

The biological activity of chemical mustards depends on the relative nucleophilicity of the attacking atom, either nitrogen or sulfur. Which order of decreasing nucleophilicity is correct? (a) melphalan > sulfur mustard > mechlorethamine (b) sulfur mustard > melphalan > mechlorethamine (c) sulfur mustard > mechlorethamine > melphalan (d) mechlorethamine > sulfur mustard > melphalan