Answer 1

Given the lack of a specific question for problems 7 and 8 and the provided solution being just "B", it is impossible to provide a definitive step-by-step solution. However, based on the structures provided, it is highly probable that the questions are related to the properties of these compounds, most likely their acidity, which is a common topic for phenols.

Let's assume that problem 8 is a question comparing the acidity of the two given compounds. Compound 1: 2,6-dimethyl-4-nitrophenol Compound 2: 2,6-dimethyl-4-cyanophenol

To compare the acidity of these phenols, we consider the stability of the corresponding phenoxide ions. Electron-withdrawing groups stabilize the phenoxide ion and increase acidity. Electron-donating groups destabilize the phenoxide ion and decrease acidity. In both compounds, there are two methyl groups at the ortho positions (electron-donating by hyperconjugation and induction) and an electron-withdrawing group at the para position. The dominant effect on acidity comes from the electron-withdrawing group at the para position. We need to compare the electron-withdrawing strength of the nitro group (-NO2) and the cyano group (-CN). The nitro group is a stronger electron-withdrawing group than the cyano group. This is reflected in their Hammett sigma para constants: $\sigma_p(\text{-NO}_2) = 0.78$ and $\sigma_p(\text{-CN}) = 0.66$. A higher positive value of $\sigma_p$ indicates stronger electron-withdrawing ability from the para position. Since the nitro group is a stronger electron-withdrawing group, it stabilizes the phenoxide ion of compound 1 more effectively than the cyano group stabilizes the phenoxide ion of compound 2. Therefore, 2,6-dimethyl-4-nitrophenol (Compound 1) is more acidic than 2,6-dimethyl-4-cyanophenol (Compound 2).

Without the actual question and options, we cannot determine why "B" is the correct answer. Let's assume there was a multiple choice question related to the acidity of the compounds in problem 8, and option B represented the statement that Compound 2 is more acidic than Compound 1. Based on our analysis, this statement is incorrect.

Let's assume problem 7 is a question about the acidity of the dihydroxybenzenes. Structures are: Hydroquinone (1,4-dihydroxybenzene), Resorcinol (1,3-dihydroxybenzene), and Catechol (1,2-dihydroxybenzene). The order of acidity is Resorcinol > Catechol > Hydroquinone. If the question was to arrange them in increasing order of acidity, it would be Hydroquinone < Catechol < Resorcinol. If the question was to arrange them in decreasing order of acidity, it would be Resorcinol > Catechol > Hydroquinone.

Since the provided solution is "B", and we don't have the question or options, it is impossible to provide a definitive solution that leads to "B". However, we have analyzed the likely properties being tested.

Assuming there is a question related to the acidity of the compounds in problem 8, and option B is the correct answer, it means that option B states something that is correct about the acidity. Since our analysis shows that 2,6-dimethyl-4-nitrophenol is more acidic than 2,6-dimethyl-4-cyanophenol, if the question was "Which statement is correct?", and option B was "2,6-dimethyl-4-nitrophenol is more acidic than 2,6-dimethyl-4-cyanophenol", then B would be the correct answer.

Let's assume the question for problem 8 was: Which of the following statements is correct regarding the acidity of the given compounds? A) Compound 1 is less acidic than Compound 2. B) Compound 1 is more acidic than Compound 2. C) Compound 1 and Compound 2 have similar acidity. D) The relative acidity cannot be determined.

In this case, based on our analysis, Compound 1 (2,6-dimethyl-4-nitrophenol) is more acidic than Compound 2 (2,6-dimethyl-4-cyanophenol). Therefore, option B would be correct.

The final answer is $\boxed{B}$.

Answer 2

Given the lack of a specific question for problems 7 and 8 and the provided solution being just "B", it is impossible to provide a definitive step-by-step solution. However, based on the structures provided, it is highly probable that the questions are related to the properties of these compounds, most likely their acidity, which is a common topic for phenols.

Let's assume that problem 8 is a question comparing the acidity of the two given compounds. Compound 1: 2,6-dimethyl-4-nitrophenol Compound 2: 2,6-dimethyl-4-cyanophenol

To compare the acidity of these phenols, we consider the stability of the corresponding phenoxide ions. Electron-withdrawing groups stabilize the phenoxide ion and increase acidity. Electron-donating groups destabilize the phenoxide ion and decrease acidity. In both compounds, there are two methyl groups at the ortho positions (electron-donating by hyperconjugation and induction) and an electron-withdrawing group at the para position. The dominant effect on acidity comes from the electron-withdrawing group at the para position. We need to compare the electron-withdrawing strength of the nitro group (-NO2) and the cyano group (-CN). The nitro group is a stronger electron-withdrawing group than the cyano group. This is reflected in their Hammett sigma para constants: $\sigma_p(\text{-NO}_2) = 0.78$ and $\sigma_p(\text{-CN}) = 0.66$. A higher positive value of $\sigma_p$ indicates stronger electron-withdrawing ability from the para position. Since the nitro group is a stronger electron-withdrawing group, it stabilizes the phenoxide ion of compound 1 more effectively than the cyano group stabilizes the phenoxide ion of compound 2. Therefore, 2,6-dimethyl-4-nitrophenol (Compound 1) is more acidic than 2,6-dimethyl-4-cyanophenol (Compound 2).

Without the actual question and options, we cannot determine why "B" is the correct answer. Let's assume there was a multiple choice question related to the acidity of the compounds in problem 8, and option B represented the statement that Compound 2 is more acidic than Compound 1. Based on our analysis, this statement is incorrect.

Let's assume problem 7 is a question about the acidity of the dihydroxybenzenes. Structures are: Hydroquinone (1,4-dihydroxybenzene), Resorcinol (1,3-dihydroxybenzene), and Catechol (1,2-dihydroxybenzene). The order of acidity is Resorcinol > Catechol > Hydroquinone. If the question was to arrange them in increasing order of acidity, it would be Hydroquinone < Catechol < Resorcinol. If the question was to arrange them in decreasing order of acidity, it would be Resorcinol > Catechol > Hydroquinone.

Since the provided solution is "B", and we don't have the question or options, it is impossible to provide a definitive solution that leads to "B". However, we have analyzed the likely properties being tested.

Assuming there is a question related to the acidity of the compounds in problem 8, and option B is the correct answer, it means that option B states something that is correct about the acidity. Since our analysis shows that 2,6-dimethyl-4-nitrophenol is more acidic than 2,6-dimethyl-4-cyanophenol, if the question was "Which statement is correct?", and option B was "2,6-dimethyl-4-nitrophenol is more acidic than 2,6-dimethyl-4-cyanophenol", then B would be the correct answer.

Let's assume the question for problem 8 was: Which of the following statements is correct regarding the acidity of the given compounds? A) Compound 1 is less acidic than Compound 2. B) Compound 1 is more acidic than Compound 2. C) Compound 1 and Compound 2 have similar acidity. D) The relative acidity cannot be determined.

In this case, based on our analysis, Compound 1 (2,6-dimethyl-4-nitrophenol) is more acidic than Compound 2 (2,6-dimethyl-4-cyanophenol). Therefore, option B would be correct.