The ascending order of acidity of –OH group in the following compounds is:
Choose the correct answer from the options given below :
Choose the correct answer from the options given below :
\( (A) < (D) < (C) < (B) < (E)\)
\( (C) < (A) < (D) < (B) < (E)\)
\( (C) < (D) < (B) < (A) < (E)\)
\( (A) < (C) < (D) < (B) < (E)\)
The Correct Option is D
Approach Solution - 1
To determine the acidity order of the –OH group in the given compounds, we need to understand the effect of substituents on the phenol ring.
- Phenol Acidity: Phenols are acidic because they can donate a hydrogen ion (proton) from the hydroxyl group, resulting in a phenoxide ion. The stability of the phenoxide ion determines the acidity of phenols.
- Effect of Substituents:
- Electron-withdrawing groups (EWG) like \(-\text{NO}_2\) increase acidity by stabilizing the negative charge on the phenoxide ion through resonance or induction.
- Electron-donating groups (EDG) like \(-\text{OCH}_3\) decrease acidity by destabilizing the phenoxide ion.
- Analysis of Each Compound:
- (A) Bu – OH: A simple butanol with no resonance stabilizing effects, therefore, least acidic.
- (B) \(p-\text{NO}_2\text{-C}_6\text{H}_4\text{-OH}\): Contains a strong electron-withdrawing \(-\text{NO}_2\) group, significantly increasing acidity.
- (C) \(p-\text{OCH}_3\text{-C}_6\text{H}_4\text{-OH}\): Contains an electron-donating \(-\text{OCH}_3\) group, decreasing acidity.
- (D) Phenol: Standard reference for acidic strength in phenols.
- (E) \(2,4-\text{NO}_2\text{-C}_6\text{H}_3\text{-OH}\): The presence of two \(-\text{NO}_2\) groups greatly enhances the acidity due to strong electron-withdrawing effects.
- Conclusion: Based on the effects explained above, the correct order of acidity is:
\((A) < (C) < (D) < (B) < (E)\)
Approach Solution -2
The acidity of phenols increases with the presence of electron-withdrawing groups (like -NO2) and decreases with electron-donating groups (like -CH3).
- (A): Contains a butyl group (electron-donating), making it the least acidic.
- (C): Contains a methoxy group (CH3O-) (electron-donating), slightly more acidic than (A).
- (D): Simple phenol (C6H5OH), with no additional electron-withdrawing or donating groups, has moderate acidity.
- (B): Contains an -OH group with a chlorine substituent (electron-withdrawing) on the aromatic ring, making it more acidic than (D).
- (E): Contains an -OH group with a nitro substituent (NO2) which is strongly electron-withdrawing, making it the most acidic.
Thus, the correct order of acidity is $(A) < (C) < (D) < (B) < (E)$.
Top JEE Main Chemistry Questions
What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)- At equilibrium the concentrations of and in a sealed vessel at . What will be for the reaction
- Find out the major products from the following reactions
Cobalt chloride when dissolved in water forms pink colored complex $X$ which has octahedral geometry. This solution on treating with cone $HCl$ forms deep blue complex, $\underline{Y}$ which has a $\underline{Z}$ geometry $X, Y$ and $Z$, respectively, are
- The correct order of atomic radii is:
Top JEE Main Aldehydes, Ketones and Carboxylic Acids Questions
- What is the correct IUPAC name of the given compound?
- m–chlorobenzaldehyde on treatment with 50\(\%\) KOH solution yields
- The molecular formula of second homologue in the homologous series of monocarboxylic acid is
- Sugar which does not give reddish brown precipitate with Fehling‟s reagent is:
- Which reagent on reacting with phenol gives salicylaldehyde?
Top JEE Main Questions
- In a hydrogen like atom, when an electron jumps from the $M$ - shell to the $L$ - shell, the wavelength of emitted radiation is $\lambda$. If an electron jumps from $N$-shell to the $L$-shell, the wavelength of emitted radiation will be :
- Two masses $m$ and $\frac{m}{2}$ are connected at the two ends of a massless rigid rod of length $l$. The rod is suspended by a thin wire of torsional constant $k$ at the centre of mass of the rod-mass system(see figure). Because of torsional constant $k$, the restoring torque is $\tau =k\theta$ for angular displacement $\theta$. If the rod is rota ted by $\theta_0$ and released, the tension in it when it passes through its mean position will be:
What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)- The value of is
- The number of terms of an is even. The sum of the odd terms is and of the even terms is . The last term exceeds the first by . Then the number of terms in the series is ______.
Concepts Used:
Aldehydes, Ketones and Carboxylic Acids - Chemical Reactions
Chemical Reactions of Aldehydes and Ketones:
- Cross aldol condensation
Read Also: Aldehydes, Ketones, and Carboxylic Acids
Read More: Chemistry Named Reactions