The rate law for the reaction of HO- with tert-butyl bromide to form an elimination

Draw the structure of DDE.

Methoxychlor is an insecticide that was intended to take DDTs place because it is not as soluble in fatty tissues and is more readily biodegradable. It, too, can accumulate in the environment, however, so its use was also bannedin 2002 in the European Union and in 2003 in the United States. Why is methoxychlor less soluble in fatty tissues than DDT?

How will the rate of the reaction between bromomethane and hydroxide ion be affected if the following changes in concentration are made? a. The concentration of the alkyl halide is not changed and the concentration of the nucleophile is tripled. b. The concentration of the alkyl halide is cut in half and the concentration of the nucleophile is not changed. c. The concentration of the alkyl halide is cut in half and the concentration of the nucleophile is doubled.

Does increasing the energy barrier for an SN2 reaction increase or decrease the magnitude of the rate constant for the reaction?

Rank the following alkyl bromides from most reactive to least reactive in an SN2 reaction: 1-bromo-2-methylbutane, 1-bromo-3-methylbutane, 2-bromo-2-methylbutane, and 1-bromopentane.

Draw the products obtained from the SN2 reaction of a. 2-bromobutane and methoxide ion. c. (S)-3-chlorohexane and hydroxide ion. b. (R)-2-bromobutane and methoxide ion. d. 3-iodopentane and hydroxide ion.

Draw the substitution product formed when cis-1-bromo-4-methylcyclohexane and hydroxide ion undergo an SN2 reaction.

Draw the substitution product formed by each of the following SN2 reactions: a. trans-1-iodo-4-ethylcyclohexane and methoxide ion b. cis-1-chloro-3-methylcyclobutane and ethoxide ion

Which alkyl halide is more reactive in an SN2 reaction with a given nucleophile?

Indicate whether each of the following solvents is protic or aprotic: a. chloroform (CHCl3) b. diethyl ether c. acetic acid d. hexane

a. Which is a stronger base: RO- or RS-? b. Which is a better nucleophile in an aqueous solution? c. Which is a better nucleophile in DMSO?

Which is a better nucleophile? Br or Cl in H2O CH3O or CH3OH in H2O CH3O or CH3OH in DMSO Br or Cl in DMSO HO or NH2 in H2O I or Br in H2O I or Br in DMSO

Rank the following species from best nucleophile to poorest nucleophile in an aqueous solution:

Which substitution reaction takes place more rapidly? a. CH3CH2Br + H2O or CH3CH2Br + HO b. CH3CHCH2Br + HO CH3CH2CHBr CH3 or + HO CH3 c. (in ethanol) CH3CH2Cl + CH3O or CH3CH2Cl + CH3S d. CH3CH2Cl + I or CH3CH2Br + I

What is the product of the reaction of bromoethane with each of the following nucleophiles? a. CH3CH2CH2O b. CH3CC- c. (CH3)3N d. CH3CH2SPROBLEM

What product is obtained when ethylamine reacts with excess methyl iodide in a basic solution of potassium carbonate?

a. Explain why the reaction of an alkyl halide with ammonia gives a low yield of primary amine. b. Explain why a much better yield of primary amine is obtained from the reaction of an alkyl halide with azide ion (-N3), followed by catalytic hydrogenation. (Hint: An alkyl azide is not nucleophilic.)

Draw the stereoisomers that are formed from the following SN1 reactions: a. 3-bromo-3-methylpentane and methanol b. 3-chloro-3-methylhexane and methanol

Rank the following alkyl halides from most reactive to least reactive in an SN1 reaction: 2-bromo-2-methylpentane, 2-chloro-2-methylpentane, 3-chloropentane, and 2-iodo-2-methylpentane

Draw the configuration(s) of the substitution product(s) formed from the reaction of the following compounds with the indicated nucleophile:

Which of the following reactions take place more rapidly when the concentration of the nucleophile is increased?

What is the major elimination product obtained from the reaction of each of the following alkyl halides with hydroxide ion?

What is the major elimination product obtained from an E2 reaction of each of the following alkyl halides with hydroxide ion?

Which alkyl halide in each pair is more reactive in an E2 reaction with hydroxide ion?

Which alkyl halide in each pair is more reactive in an E2 reaction with hydroxide ion?

Four alkenes are formed from the E1 reaction of 3-bromo-2,3-dimethylpentane and methanol. Draw the structures of the alkenes and rank them according to the amount that would be formed.

If 2-fluoropentane could undergo an E1 reaction, would you expect the major product to be the more stable alkene or the less stable alkene? Explain your answer.

Which of the following compounds would react faster in an a. E1 reaction? b. E2 reaction? c. SN1 reaction? d. SN2 reaction?

Propose a mechanism for the following reaction:

For each of the following reactions, (1) decide whether an E2 or an E1 occurs, and (2) draw the major elimination product:

The rate law for the reaction of HO- with tert-butyl bromide to form an elimination product in 75% ethanol/ 25% water at 30 C is the sum of the rate laws for the E2 and E1 reactions. What percentage of the reaction takes place by an E2 pathway when [HO-] = 5.0 M? (k2 = 7.1 * 10 - 5, and k1 = 1.5 * 10 - 5) rate = rate law for the E2 reaction + rate law for the E1 reation rate = k2 3tert@butyl bromide43HO-4 + k1 3tert@butyl bromide4

What percentage of the reaction described in Problem 31 takes place by the E2 pathway when [HO-] = 0.0025 M?

a. What is the major product obtained when each of the following compounds undergoes an E2 reaction with methoxide ion? Show the configuration of the product. b. Does the product obtained depend on whether you start with the R or S enantiomer of the reactant? 1. CH3CH2CHCHCH3 Br CH3 2. CH3CH2CHCH2CH Cl CH2 3. CH3CH2CHCH2 Cl

What is the major product formed when the following compound undergoes an E1 reaction?

What is the major product formed when the following compounds undergo an E1 reaction? a. CH3CH2CH2CCH3 Cl CH3 b. C CH2CH3 I CH3 c. Cl CH3

Why do cis-1-bromo-2-ethylcyclohexane and trans-1-bromo-2-ethylcyclohexane form different major products when they undergo an E2 reaction?

Which isomer reacts more rapidly in an E2 reaction: cis-1-bromo-4-tert-butylcyclohexane or trans-1- bromo-4-tert-butylcyclohexane? Explain your answer.

Draw the substitution and elimination products for the following reactions, showing the configuration of each product: a. trans-1-chloro-2-methylcyclohexane + CH3O- c. 1-chloro-1-methylcyclohexane + CH3Ob. cis-1-chloro-2-methylcyclohexane + CH3O d. 1-chloro-1-methylcyclohexane + CH3OH

a. Which reacts faster in an SN2 reaction? CH3CH2CH2Br or CH3CH2CHCH3 Br b. Which reacts faster in an E1 reaction? or I CH3 CH3 Br c. Which reacts faster in an SN1 reaction?

You were told in Section 7.11 that is best to use a methyl halide or a primary alkyl halide for the reaction of an acetylide ion with an alkyl halide. Explain why this is so.

How does the ratio of substitution product to elimination product formed from the reaction of propyl bromide with CH3O- in methanol change if the nucleophile is changed to CH3S-?

Explain why only a substitution product and no elimination product is obtained when the following compound reacts with sodium methoxide:

a. Explain why 1-bromo-2,2-dimethylpropane has difficulty undergoing both SN2 and SN1 reactions. b. Can it undergo E2 and E1 reactions?

Assuming that the two compounds shown below have the same stability, which one would you expect to be more reactive in an SN1 reaction?b. Draw the products that each would form when the solvent is ethanol.

What products will be obtained from the E2 reaction of the following alkyl halides?

What products will be obtained from the E1 reaction of the alkyl halides in Problem 45?

Draw the elimination products that are formed when 3-bromo-3-methyl-1-butene reacts with a. CH3O-. b. CH3OH.

Which compound is more reactive in an SN1 reaction? In each case, you can assume that both alkyl halides have the same stability.

For the pairs of compounds in Problem 48, which is more reactive in an SN2 reaction?

Why is a cumulated diene not formed in the reaction shown above?

Describe how a double bond can be converted to a triple bond. For example, how can 2-butene be converted to 2-butyne?

What product is obtained when the following compound undergoes two successive elimination reactions?

What products are formed from the following reactions?

Amines are good nucleophiles, even though they are neutral. How would the rate of an SN2 reaction between an amine and an alkyl halide be affected if the polarity of the solvent is increased?

How will the rate of each of the following SN2 reactions change if it is carried out in a more polar solvent?

Which reaction in each of the following pairs takes place more rapidly? (EtOH is ethyl alcohol; Et2O is diethyl ether.)

Most of the pKa values given in this text were determined in water. How would the pKa values of carboxylic acids, alcohols, ammonium ions 1RNH32 + , phenol, and an anilinium ion 1C6H5NH32 + change if they were determined in a solvent less polar than water?

Would you expect acetate ion 1CH3CO2 -2 to be a better nucleophile in an SN2 reaction with an alkyl halide carried out in methanol or in dimethyl sulfoxide?

Under which of the following reaction conditions will (R)-1-chloro-1-phenylethane form the most (R)-1-phenyl-1-ethanol: in water or in 1.0 M HO-?

A small amount of another organic product is formed in a Williamson ether synthesis. What is this product when the alkyl halide used in the synthesis of butyl propyl ether is a. propyl bromide? b. butyl bromide?

What is the best way to prepare the following ethers using an alkyl halide and an alkoxide ion? a. CH3CH2CHOCH2CH2CH3 CH3 c. OCH3 b. CH3CH2OCH2CHCH2CH2C

Identify the three products formed when 2-bromo-2-methylpropane is dissolved in a mixture of 80% ethanol and 20% water.

What products (including stereoisomers, if applicable) are formed from the reaction of 3-bromo-3- methylpentane: a. with HO-? b. with H2O?

After a proton is removed from the OH group, which compound in each pair forms a cyclic ether more rapidly?

Draw the products of the following intramolecular reactions:

For each of the following target molecules, design a multistep synthesis to show how it can be prepared from the given starting material:

What product is formed when 1-bromopropane reacts with each of the following nucleophiles? a. HO- c. CH3S- e. CH3Ob. -NH2 d. HS- f. CH3NH2

Which member of each pair is a better nucleophile in methanol? a. H2O or HO- c. H2O or H2S e. I- or Brb. NH3 or H2O d. HO- or HS- f. Cl- or Br-

Which member in each pair in Problem 68 is a better leaving group?

What nucleophiles would form the following compounds as a result of reacting with 1-iodobutane?

Explain how each of the following changes affect the rate of the reaction of 1-bromobutane with ethoxide ion in DMF. a. The concentration of both the alkyl halide and the nucleophile are tripled. b. The solvent is changed to ethanol. c. The alkyl halide is changed to 1-chlorobutane. d. The alkyl halide is changed to 2-bromobutane.

Explain how the following changes affect the rate of the reaction of 2-bromo-2-methylbutane with methanol: a. The alkyl halide is changed to 2-chloro-2-methylbutane. b. The alkyl halide is changed to 2-chloro-3-methylbutane.

Starting with cyclohexene, how can the following compounds be prepared? a. methoxycyclohexane b. cyclohexylmethylamine c. dicyclohexyl ether

Rank the following species in each set from best nucleophile to poorest nucleophile.

The pKa of acetic acid in water is 4.76. What effect will a decrease in the polarity of the solvent have on the pKa? Why?

a. Identify the substitution products that form when 2-bromo-2-methylpropane is dissolved in a mixture of 80% ethanol and 20% water. b. Explain why the same products are obtained when 2-chloro-2-methylpropane is dissolved in a mixture of 80% ethanol and 20% water.

Draw the substitution products for each of the following reactions; if the products can exist as stereoisomers, show what stereoisomers are obtained: a. (R)-2-bromopentane + CH3Ob. (R)-3-bromo-3-methylheptane + CH3OH c. benzyl chloride + CH3CH2OH d. allyl chloride + CH3OH e. 1-bromo-2-butene + CH3Of. 1-bromo-2-butene + CH3OH

Draw the products obtained from the solvolysis of each of the following compounds in ethanol:

Would you expect methoxide ion to be a better nucleophile if it is dissolved in CH3OH or if it is dissolved in DMSO? Why?

Which reaction in each of the following pairs takes place more rapidly? (EtOH is ethyl alcohol; Et2O is diethyl ether.)

Alkylbenzyldimethyl ammonium chloride is a leave-on skin antiseptic used to treat such things as cuts and cold sores. It is also the antiseptic in many hand sanitizers. It is actually a mixture of compounds that differ in the number of carbons (any even number between 8 and 18) in the alkyl group. Show three different sets of reagents (each set composed of an alkyl chloride and an amine) that can be used to synthesize the alkylbenzyldimethyl ammonium chloride shown here.

Fill in the squares in the following chemical equations:

Draw the major product obtained when each of the following alkyl halides undergoes an E2 reaction: Cl CH3CHCH2CH3 Br a. CH3CHCH2CH3 b. d. f. c. Cl e. CH3CHCH2CH2CH3

Draw the major product obtained when an alkyl halide in Problem 83 undergoes an E1 reaction.

a. Indicate how each of the following factors affects an E1 reaction: 1. the strength of the base 2. the concentration of the base 3. the solvent b. Indicate how each of the same factors affects an E2 reaction.

Which species in each pair is more stable?

A chemist wanted to synthesize the anesthetic 2-ethoxy-2-methylpropane. He used ethoxide ion and 2-chloro-2-methylpropane for his synthesis and ended up with no ether. What was the product of his synthesis? What reagents should he have used?

Which reactant in each of the following pairs undergoes an elimination reaction more rapidly? Explain your choice.

For each of the following reactions, draw the major elimination product; if the product can exist as stereoisomers, indicate which stereoisomer is obtained in greater yield. a. (R)-2-bromohexane + high concentration of CH3Ob. (R)-3-bromo-3-methylhexane + CH3OH c. trans-1-chloro-2-methylcyclohexane + high concentration of CH3Od. trans-1-chloro-3-methylcyclohexane + high concentration of CH3Oe. 3-bromo-3-methylpentane + high concentration of CH3CH2Of. 3-bromo-3-methylpentane + CH3CH2OH

a. Which reacts faster in an E2 reaction: 3-bromocyclohexene or bromocyclohexane? b. Which reacts faster in an E1 reaction?

When the following reactions are carried out under the same conditions, the rate constant for the first reaction (kH) is found to be 7 times greater than the rate constant for the second reaction (kD). What does that tell you about the mechanism of the reaction? (Hint: a CD bond is 1.2 kcal/mol stronger than a CH bond.)

Starting with an alkyl halide, how could the following compounds be prepared? a. 2-methoxybutane b. 1-methoxybutane c. butylmethylamine

Indicate which species in each pair gives a higher substitution-product-to-elimination-product ratio when it reacts with isopropyl bromide: a. ethoxide ion or tert-butoxide ion b. -OCN or -SCN c. Cl- or Br- d. CH3S- or CH3O-

Rank the following from most reactive to least reactive in an E2 reaction:

Rank the following from most reactive to least reactive in an SN1 reaction.

For each of the following alkyl halides, indicate the stereoisomer that would be obtained in greatest yield in an E2 reaction. a. 3-bromo-2,2,3-trimethylpentane b. 4-bromo-2,2,3,3-tetramethylpentane c. 3-bromo-2,3-dimethylpentane d. 3-bromo-3,4-dimethylhexane

Which of following ethers cannot be made by a Williamson ether synthesis?

When 2-bromo-2,3-dimethylbutane reacts with a strong base, two alkenes (2,3-dimethyl-1-butene and 2,3-dimethyl-2-butene) are formed. a. Which of the bases (A, B, C, or D) would form the highest percentage of the 1-alkene? b. Which would give the highest percentage of the 2-alkene?

What are the products of the following reactions?

a. Draw the structures of the products obtained from the reaction of each enantiomer of cis-1-chloro-2-isopropylcyclopentane with sodium methoxide in methanol. b. Are all the products optically active? c. How would the products differ if the starting material were the trans isomer? Are these products optically active? d. Will the cis enantiomers or the trans enantiomers form substitution products more rapidly? e. Will the cis enantiomers or the trans enantiomers form elimination products more rapidly?

When the following compound undergoes solvolysis in ethanol, three products are obtained. Propose a mechanism to account for the formation of these products.

cis-1-Bromo-4-tert-butylcyclohexane and trans-1-bromo-4-tert-butylcyclohexane both react with sodium ethoxide in ethanol to form 4-tert-butylcyclohexene. Explain why the cis isomer reacts much more rapidly than the trans isomer.

Draw the substitution and elimination products.

tert-Butyl chloride undergoes solvolysis in both acetic acid and formic acid. Solvolysis occurs 5000 times faster in one of these two solvents than in the other. In which solvent is solvolysis faster? Explain your answer. (Hint: Formic acid is more polar than acetic acid.)

What substitution products are obtained when each of the following compounds is added to a solution of sodium acetate in acetic acid? a. 2-chloro-2-methyl-3-hexene

Show how each of the following compounds can be synthesized from the given starting materials: a. CH3CH2CH2Br CH3CH2CH2CH2CH3 b. CH3CH2CH2Br CH3CH2CH2CCH3 c. CH3CH2CH2Br CH3CH2CH2CH2CH d. CH3CH2CH2Br CH3CH2CH2CH CH2 O O O a. CH3CH2CH2Br CH3CH2CH2CH2CH3 b. CH3CH2CH2Br CH3CH2CH2CCH3 c. CH3CH2CH2Br CH3CH2CH2CH2CH d. CH3CH2CH2Br CH3CH2CH2CH CH2

In which solventethanol or diethyl etherwould the equilibrium for the following SN2 reaction lie farther to the right? CH3 CH3SCH3 + CH3Br CH3SCH3 + Br

d. CH3CH2CH2Br CH3CH2CH2CH CH2 O O O a. CH3CH2CH2Br CH3CH2CH2CH2CH3 b. CH3CH2CH2Br CH3CH2CH2CCH3 c. CH3CH2CH2Br CH3CH2CH2CH2CH d. CH3CH2CH2Br CH3CH2CH2CH CH2 O O O 107. In which solventethanol or diethyl etherwould the equilibrium for the following SN2 reaction lie farther to the right? CH3 CH3SCH3 + CH3Br CH3SCH3 + Br + 108. The rate of the reaction of methyl iodide with quinuclidine was measured in nitrobenzene, and then the rate of the reaction of methyl iodide with triethylamine was measured in the same solvent. The concentration of the reagents was the same in both experiments. a. Which reaction had the larger rate constant? b. The same experiment was done using isopropyl iodide instead of methyl iodide. Which reaction had the larger rate constant? c. Which alkyl halide has the larger kquinuclidine/ktriethylamine ratio?

Two bromoethers are obtained from the reaction of the following alkyl dihalide with methanol. Draw the structures of the ethers.

Draw the substitution products for each of the following SN2 reactions. If the products can exist as stereoisomers, show which stereoisomers are formed: a. (3S,4S)@3@bromo@4@methylhexane + CH3O- c. (3R,4R)@3@bromo@4@methylhexane + CH3Ob. (3S,4R)@3@bromo@4@methylhexane + CH3O- d. (3R,4S)@3@bromo@4@methylhexane + CH3O-

Draw the elimination products for each of the following E2 reactions; if the products can exist as stereoisomers, indicate which stereoisomers are obtained. a. (2S,3S)@2@chloro@3@methylpentane + high concentration of CH3Ob. (2S,3R)@2@chloro@3@methylpentane + high concentration of CH3Oc. (2R,3S)@2@chloro@3@methylpentane + high concentration of CH3Od. (2R,3R)@2@chloro@3@methylpentane + high concentration of CH3Oe. 3@chloro@3@ethyl@2,2@dimethylpentane + high concentration of CH3CH2O-

Draw the major elimination product that would be obtained from each of the following reactants with a strong base and with a weak base:

Which of the following hexachlorocyclohexanes is the least reactive in an E2 reaction?

Explain why the rate of the reaction of 1-bromo-2-butene with ethanol is increased if silver nitrate is added to the reaction mixture.

Draw the products of each of the following SN2/E2 reactions. If the products can exist as stereoisomers, show which stereoisomers are formed. a. (3S,4S)@3@bromo@4@methylhexane + CH3O- c. (3S,4R)@3@bromo@4@methylhexane + CH3Ob. (3R,4R)@3@bromo@4@methylhexane + CH3O- d. (3R,4S)@3@bromo@4@methylhexane + CH3O-

Two elimination products are obtained from the following E2 reaction: CH3O CH3CH2CHDCH2Br a. What are the elimination products? b. Which is formed in greater yield? (Hint: See Problem 91.)

Draw the structures of the products obtained from the following reaction:

How could you prepare the following compounds from the given starting materials? a. CH3CH2CH2CH2Br CH3CH2CCH2CH2CH3 O b. CH2CH3 BrCH2CH2CH2CH2Br

cis-4-Bromocyclohexanol and trans-4-bromocyclohexanol form the same elimination product but a different substitution product when they react with HO-.a. Why do they form the same elimination product? b. Explain, by showing the mechanisms, why different substitution products are obtained. c. How many stereoisomers does each of the elimination and substitution reactions form?

a. Draw the product of each of the following reactions: CH3CH2C CH CH3CH2CH2OH 1. NaNH2 2. CH3CH2Br 1. NaH 2. CH3Br 1. 2. b. Give two sets of reactants (each set including an alkyl halide and a nucleophile) that could be used to synthesize the following alkyne: CH3CH2C CCH2CH2CH2CH3 c. Give two sets of reactants (each set including an alkyl halide and a nucleophile) that could be used to synthesize the following ether: CH3

Propose a mechanism for the following reaction:

Explain why tetrahydrofuran can solvate a positively charged species better than diethyl ether can.

The reaction of an alkyl chloride with potassium iodide is generally carried out in acetone to maximize the amount of alkyl iodide that is formed. Why does the solvent increase the yield of alkyl iodide? (Hint: Potassium iodide is soluble in acetone, but potassium chloride is not.)

a. Propose a mechanism for the following reaction. b. Explain why two products are formed. c. Explain why methanol substitutes for only one of the bromines.

What products are formed when the following stereoisomer of 2-chloro-1,3-dimethylcyclohexane reacts with methoxide ion?

Predict the product for the following reaction and write a mechanism to explain how it is formed.

For each of the following compounds, draw the product that forms in an E2 reaction and indicate its configuration: a. (1S,2S)-1-bromo-1,2-diphenylpropane b. (1S,2R)-1-bromo-1,2-diphenylpropane

Chlordane, like DDT, is an alkyl halide that was used as an insecticide for crops such as corn and citrus and for lawns. In 1983, it was banned for all uses except against termites, and in 1988, it was banned for use against termites as well. Chlordane can be synthesized from two reactants in one step. One of the reactants is hexachlorocyclopentadiene. What is the other reactant? (Hint: See Section 8.14.)

When equivalent amounts of methyl bromide and sodium iodide are dissolved in methanol, the concentration of iodide ion quickly decreases and then slowly returns to its original concentration. Account for this observation.

Explain why the following alkyl halide does not undergo a substitution reaction, regardless of the base that is used.

The reaction of chloromethane with hydroxide ion at 30 C has a G value of -21.7 kcal/mol. What is the equilibrium constant for the reaction?