Question 1

In the S_N2 reaction,the unstable arrangement of atoms in which both the nucleophile and the leaving group are partially bonded to the same carbon atom is called the ___.

Accepted Answer

The answer of In the S_N2 reaction,the unstable arrangement of...

Question 2

S_N2 reactions of the type,Nu^- + RL $\to$Nu-R + L^-,are favored

Accepted Answer

Reactions of the type described are nucleophilic substitutions (SN1 or SN2). The rate of these reactions can be increased by using a high concentration of the nucleophile, which helps to drive the reaction forward by mass action.

Question 3

S_N1 reactions of the following type: Nu:^- + R-X $\to$ R-Nu + :X^- Are favored

Accepted Answer

The answer of S_N1 reactions of the following type: Nu:^-...

Question 4

As we go down Group 7A of the periodic table,the size of the halogen atom increases; accordingly,the carbon-halogen bond length gets ___ and the bond strength gets ___.

Accepted Answer

The answer of As we go down Group 7A of...

Question 5

In order for colliding species to react,they must ___ and ___.

Accepted Answer

The answer of In order for colliding species to react,they...

Question 6

Racemic mixtures form in S_N1 reactions when leaving group departure results in a loss of chirality followed by subsequent attack of the nucleophile.

Accepted Answer

In S_N1 reactions, racemic mixtures can form when a chiral center is lost during leaving group departure and subsequent attack of the nucleophile. This results in equal amounts of both enantiomers being produced, leading to a racemic mixture.

Question 7

Which of the following statements is (are)true of an S_N2 reaction of (R)-2-bromobutane with hydroxide ion?

Accepted Answer

An S_N2 reaction is a one-step, concerted reaction in which the nucleophile attacks the electrophile and the leaving group departs simultaneously. The rate of an S_N2 reaction is determined by the concentration of both the nucleophile and the electrophile. Doubling the concentration of either the nucleophile or the electrophile will double the rate of the reaction. The stereochemistry of an S_N2 reaction is determined by the orientation of the nucleophile and the electrophile. In an S_N2 reaction of an alkyl halide with a hydroxide ion, the nucleophile attacks the electrophile from the back side, resulting in inversion of configuration. Therefore, the major product of the reaction of (R)-2-bromobutane with hydroxide ion will be (S)-2-butanol.

Question 8

S_N1 reactions of the type,Nu^- + RL $\to$ Nu-R + L^-,are favored

Accepted Answer

Tertiary substrates are more susceptible to nucleophilic substitution reactions than primary or secondary substrates due to the increased stability of the resulting carbocation intermediate. Therefore, reactions of this type are favored when tertiary substrates are used. The concentration of the nucleophile, strength of the base, or solvent polarity may also affect the reaction rate but are less directly related to the substrate structure.

Question 9

What final product is likely to be obtained through the following series of reactions?

Accepted Answer

The answer of What final product is likely to be...

Question 10

Which of the following statements is (are)true of S_N1 reactions of alkyl halides in general?

Accepted Answer

The rate of an S_N1 reaction depends on the concentration of the alkyl halide and S_N1 reactions of alkyl halides are favored by polar solvents.

Question 11

S_N1 reactions of the following type: Nu:^- + R-X $\to$ R-Nu + :X^- Are favored

Accepted Answer

The answer of S_N1 reactions of the following type: Nu:^-...

Question 12

Which of the following statements is (are)true of S_N1 reactions of alkyl halides in general?

Accepted Answer

The answer of Which of the following statements is (are)true...

Question 13

Increasing the temperature of a reaction will speed up the overall rate as this will increase the energy of activation for reaction.

Accepted Answer

Increasing the temperature of a reaction will increase the fraction of reactant molecules with the energy of activation or higher. This will thus, reduce the amount of energy required or overcome the activation energy thereby increasing the rate of reaction. Hence, the statement contradicts the established fact that an increase in temperature decreases the activation energy of a reaction, and thereby speeds up the overall rate of the reaction.

Question 14

Which nucleophilic substitution reaction is not likely to occur?

Accepted Answer

Nucleophilic substitution reactions involving the replacement of a hydroxyl group (-OH) with an iodide ion (I-) are not likely to occur directly because the hydroxyl group is a poor leaving group without prior activation, such as conversion into a better leaving group like a tosylate.

Question 15

Draw the potential energy diagram that represents an exothermic reaction between a tertiary alkyl halide and methanol.Briefly explain your rationale.

Accepted Answer

The answer of Draw the potential energy diagram that represents...

Question 16

When 5-bromo-1-pentanol is treated with sodium hydride in diethyl ether,the product is analyzed to be C₅H₁₀O.Propose a likely structure for this product,suggesting a reasonable mechanistic pathway for its formation.

Accepted Answer

The answer of When 5-bromo-1-pentanol is treated with sodium hydride...

Question 17

In a highly exergonic S_N2 reaction we can assume the transition state is similar to the products formed in the reaction.

Accepted Answer

In an exergonic reaction, the transition state is not necessarily similar to the products; it represents the highest energy state between reactants and products, and its structure can be quite different from both.

Question 18

A nucleophile in an S_N2 reaction must approach from the ___ of the carbon atom attached to the leaving group since the electrons in the nucleophile's HOMO begins to overlap with the ___ of the carbon atom attached to the leaving group.

Accepted Answer

The answer of A nucleophile in an S_N2 reaction must...

Question 19

Which nucleophilic substitution reaction would be likely to occur (although probably not in excellent yield,due to competing elimination)?

Accepted Answer

In choice A, the leaving group is a fluoride ion which is known to be a weak base and, therefore, a good leaving group. Additionally, the nucleophile in this reaction is an alcohol which is also known to be a good nucleophile. However, the fact that this reaction involves a primary alkyl halide means that there will likely be significant competition with elimination reactions. Choice B involves a secondary alkyl halide which also makes elimination competition likely, but the leaving group, chloride, is generally a weaker leaving group than fluoride. Choice C involves a nucleophilic attack on a sulfonium ion which is not a typical substrate for substitution reactions. Therefore, choice A is the best option for a likely nucleophilic substitution reaction.

Question 20

An endergonic S_N2 reaction will have a have a higher energy of activation ($\Delta$G^‡)than an exergonic S_N2 reaction.

Accepted Answer

This statement is true because an endergonic reaction requires energy to be put into the system in order for the reaction to occur. The higher energy of activation reflects the amount of energy required for the reaction to proceed. On the other hand, an exergonic reaction releases energy and therefore has a lower energy of activation.

Quiz 6: Nucleophilic Reactions

In the S_N2 reaction,the unstable arrangement of atoms in which both the nucleophile and the leaving group are partially bonded to the same carbon atom is called the ___.

S_N2 reactions of the type,Nu^- + RL $\to$ Nu-R + L^-,are favored

S_N1 reactions of the following type: Nu:^- + R-X $\to$ R-Nu + :X^- Are favored

As we go down Group 7A of the periodic table,the size of the halogen atom increases; accordingly,the carbon-halogen bond length gets _ and the bond strength gets _.

In order for colliding species to react,they must _ and _.

Racemic mixtures form in S_N1 reactions when leaving group departure results in a loss of chirality followed by subsequent attack of the nucleophile.

Which of the following statements is (are) true of an S_N2 reaction of (R) -2-bromobutane with hydroxide ion?

S_N1 reactions of the type,Nu^- + RL $\to$ Nu-R + L^-,are favored

What final product is likely to be obtained through the following series of reactions?

Which of the following statements is (are) true of S_N1 reactions of alkyl halides in general?

S_N1 reactions of the following type: Nu:^- + R-X $\to$ R-Nu + :X^- Are favored

Which of the following statements is (are) true of S_N1 reactions of alkyl halides in general?

Increasing the temperature of a reaction will speed up the overall rate as this will increase the energy of activation for reaction.

Which nucleophilic substitution reaction is not likely to occur?

Draw the potential energy diagram that represents an exothermic reaction between a tertiary alkyl halide and methanol.Briefly explain your rationale.

When 5-bromo-1-pentanol is treated with sodium hydride in diethyl ether,the product is analyzed to be C₅H₁₀O.Propose a likely structure for this product,suggesting a reasonable mechanistic pathway for its formation.

In a highly exergonic S_N2 reaction we can assume the transition state is similar to the products formed in the reaction.

A nucleophile in an S_N2 reaction must approach from the _ of the carbon atom attached to the leaving group since the electrons in the nucleophile's HOMO begins to overlap with the _ of the carbon atom attached to the leaving group.

Which nucleophilic substitution reaction would be likely to occur (although probably not in excellent yield,due to competing elimination) ?

An endergonic S_N2 reaction will have a have a higher energy of activation ( $\Delta$ G^‡)than an exergonic S_N2 reaction.

Quiz 6: Nucleophilic Reactions

In the SN2 reaction,the unstable arrangement of atoms in which both the nucleophile and the leaving group are partially bonded to the same carbon atom is called the ___.

SN2 reactions of the type,Nu- + RL →\to→ Nu-R + L-, are favored

SN1 reactions of the following type: Nu:- + R-X →\to→ R-Nu + :X- Are favored

As we go down Group 7A of the periodic table,the size of the halogen atom increases; accordingly,the carbon-halogen bond length gets ___ and the bond strength gets ___.

In order for colliding species to react,they must ___ and ___.

Racemic mixtures form in SN1 reactions when leaving group departure results in a loss of chirality followed by subsequent attack of the nucleophile.

Which of the following statements is (are) true of an SN2 reaction of (R) -2-bromobutane with hydroxide ion?

SN1 reactions of the type,Nu- + RL →\to→ Nu-R + L-,are favored

What final product is likely to be obtained through the following series of reactions?

Which of the following statements is (are) true of SN1 reactions of alkyl halides in general?

SN1 reactions of the following type: Nu:- + R-X →\to→ R-Nu + :X- Are favored

Which of the following statements is (are) true of SN1 reactions of alkyl halides in general?

Increasing the temperature of a reaction will speed up the overall rate as this will increase the energy of activation for reaction.

Which nucleophilic substitution reaction is not likely to occur?

Draw the potential energy diagram that represents an exothermic reaction between a tertiary alkyl halide and methanol.Briefly explain your rationale.

When 5-bromo-1-pentanol is treated with sodium hydride in diethyl ether,the product is analyzed to be C5H10O.Propose a likely structure for this product,suggesting a reasonable mechanistic pathway for its formation.

In a highly exergonic SN2 reaction we can assume the transition state is similar to the products formed in the reaction.

A nucleophile in an SN2 reaction must approach from the ___ of the carbon atom attached to the leaving group since the electrons in the nucleophile's HOMO begins to overlap with the ___ of the carbon atom attached to the leaving group.

Which nucleophilic substitution reaction would be likely to occur (although probably not in excellent yield,due to competing elimination) ?

An endergonic SN2 reaction will have a have a higher energy of activation ( Δ\DeltaΔ G‡)than an exergonic SN2 reaction.

In the S_N2 reaction,the unstable arrangement of atoms in which both the nucleophile and the leaving group are partially bonded to the same carbon atom is called the ___.

S_N2 reactions of the type,Nu^- + RL $\to$ Nu-R + L^-,are favored

S_N1 reactions of the following type: Nu:^- + R-X $\to$ R-Nu + :X^- Are favored

As we go down Group 7A of the periodic table,the size of the halogen atom increases; accordingly,the carbon-halogen bond length gets _ and the bond strength gets _.

In order for colliding species to react,they must _ and _.

Racemic mixtures form in S_N1 reactions when leaving group departure results in a loss of chirality followed by subsequent attack of the nucleophile.

Which of the following statements is (are) true of an S_N2 reaction of (R) -2-bromobutane with hydroxide ion?

S_N1 reactions of the type,Nu^- + RL $\to$ Nu-R + L^-,are favored

Which of the following statements is (are) true of S_N1 reactions of alkyl halides in general?

S_N1 reactions of the following type: Nu:^- + R-X $\to$ R-Nu + :X^- Are favored

Which of the following statements is (are) true of S_N1 reactions of alkyl halides in general?

When 5-bromo-1-pentanol is treated with sodium hydride in diethyl ether,the product is analyzed to be C₅H₁₀O.Propose a likely structure for this product,suggesting a reasonable mechanistic pathway for its formation.

In a highly exergonic S_N2 reaction we can assume the transition state is similar to the products formed in the reaction.

A nucleophile in an S_N2 reaction must approach from the _ of the carbon atom attached to the leaving group since the electrons in the nucleophile's HOMO begins to overlap with the _ of the carbon atom attached to the leaving group.

An endergonic S_N2 reaction will have a have a higher energy of activation ( $\Delta$ G^‡)than an exergonic S_N2 reaction.