Which of the following statement is/are correct ?

Options

A. 3,3-Dimethyl-4-cyanophenol (I) is more acidic than the isomeric 2,6-dimethyl-4-cyanophenol (II) .
B. `(II)` is more acidic than `(I)`
C. `(I)` is more acidic than `(II)` due to no steric inhibition of the two `Me` groups with `(CN)` groups, since `(-CN)` group is linear.
D. Acidic character of `(I)` and `(II)` is determines by `+ I` effect of twp `Me` groups in `(I)` and `+I` and `H.C` effects of two `Me` groups in `(II)`

Answer

To determine which of the statements regarding the acidity of the compounds are correct, we will analyze each statement step by step.

### Step 1: Analyze the first statement
**Statement 1**: 3,3-dimethyl-4-synophenol is more acidic than isomeric 2,6-dimethyl-4-synophenol.

- **Explanation**: The acidity of phenolic compounds is influenced by the substituents on the aromatic ring. The presence of a cyanide group (-CN) at the para position relative to the hydroxyl group (-OH) exerts a -I (inductive) effect, which stabilizes the negative charge on the conjugate base after deprotonation. In 3,3-dimethyl-4-synophenol, the methyl groups are located at the ortho position, allowing for both +I (inductive) and hyperconjugation effects to act, which can reduce acidity. In contrast, in 2,6-dimethyl-4-synophenol, the methyl groups are at the meta position, where only the +I effect is present. Therefore, the first statement is correct.

### Step 2: Analyze the second statement
**Statement 2**: 2 is more acidic than 1.

- **Explanation**: Based on the analysis in Step 1, we found that 3,3-dimethyl-4-synophenol (compound 1) is more acidic than 2,6-dimethyl-4-synophenol (compound 2). Therefore, this statement is incorrect.

### Step 3: Analyze the third statement
**Statement 3**: 1 is more acidic than 2 due to no steric inhibition of the 2-methyl group with the cyanide group since CN-1 group is linear.

- **Explanation**: The lack of steric hindrance between the cyanide group and the methyl groups in compound 1 allows for better stabilization of the conjugate base. This contributes to the increased acidity of compound 1 compared to compound 2. Therefore, this statement is correct.

### Step 4: Analyze the fourth statement
**Statement 4**: The acidic behavior is determined by the position of the methyl group; when it is present at the meta position, only the +I effect is working, while at the ortho position, both +I and hyperconjugation effects are at play.

- **Explanation**: This statement accurately describes the effects of substituents on acidity. The methyl group at the meta position only exerts a +I effect, while at the ortho position, both +I and hyperconjugation contribute to the overall acidity. Therefore, this statement is correct.

### Conclusion
Based on the analysis:
- **Correct Statements**: 1 (first statement), 3 (third statement), and 4 (fourth statement).
- **Incorrect Statement**: 2 (second statement).

### Final Answer
The correct statements are 1, 3, and 4.

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