Question

Account for the relative rates of solvolysis of these compounds in aqueous acetic acid.

Short answer

Question: Compare the relative rates of solvolysis of an alkyl halide (RX), an ester (RCOOR'), and an amide (RCONR'2) in aqueous acetic acid. Answer: The relative rates of solvolysis in aqueous acetic acid for the three compounds are as follows: ester > alkyl halide > amide.

Step-by-step solution

Identify the compounds

First, we need to know the compounds we are dealing with. Since the exercise does not provide any specific compounds, we'll use three generic compounds as examples – an alkyl halide (RX), an ester (RCOOR'), and an amide (RCONR'2).

Analyze the nature of the solvent

Next, we need to analyze the solvent used – aqueous acetic acid. Acetic acid (CH3COOH) is a weak organic acid, and in an aqueous solution, it forms the acetate ion (CH3COO-) and a hydronium ion (H3O+). The solvent properties, like polarity and nucleophilic strength, will play a crucial role in the solvolysis process.

Reaction mechanisms and their importance

We must consider the reaction mechanisms that each compound may undergo in solvolysis. The alkyl halide can undergo either an SN1 or SN2 reaction, the ester can undergo nucleophilic acyl substitution, and the amide can undergo nucleophilic acyl substitution or amide hydrolysis. Each mechanism's rate depends on the electrophilicity of the carbon atom, the nucleophilicity of the solvent, and the stability of the transition state or intermediate formed.

Determine the reactivity of each compound

Now let's break down the factors that influence reactivity: 1. Alkyl halide (RX): The reactivity depends on the alkyl group's stability, the halide's leaving group ability, and the solvent's nucleophilicity. In this case, the solvent is moderately nucleophilic, and the leaving group and alkyl group could vary. Therefore, the rates of solvolysis may show a wide range of values. 2. Ester (RCOOR'): Esters are more electrophilic as compared to amides and can efficiently undergo nucleophilic acyl substitution reactions. In the presence of water and acetic acid, esters may form stable intermediates leading to faster solvolysis reactions. 3. Amide (RCONR'2): Amides are the least electrophilic among the three compounds, and therefore, they have a reduced reactivity for nucleophilic attacks. Additionally, the amide nitrogen's electron-donating properties make it less susceptible to solvolysis.

Compare the rates of solvolysis

Finally, we can compare the rates of solvolysis of these compounds in aqueous acetic acid. Based on the above analysis, the ester (RCOOR') should react relatively faster as compared to the other two compounds. Although alkyl halides (RX) can exhibit varying rates of solvolysis, esters tend to form more stable intermediates, leading to higher solvolysis rates. Amides (RCONR’2) exhibit the slowest rate of solvolysis due to their reduced electrophilicity. To sum up, the relative rates of solvolysis in aqueous acetic acid for the three compounds are as follows: ester > alkyl halide > amide.