Carboxylic Acids

Step 1: Understanding the reaction of a carboxylate with sodalime.
The reaction of a sodium salt of a carboxylic acid with sodalime (NaOH + CaO) is a decarboxylation reaction. In this reaction, a carboxyl group (-COOH) is removed from the molecule as carbon dioxide, typically leading to the formation of an alkane or an aromatic hydrocarbon with one less carbon atom in the main chain or ring for each carboxyl group removed. Calcium oxide (CaO) helps to keep the mixture dry and acts as a flux.
Step 2: Identifying Sodium Phthalate and its structure.
Sodium phthalate is the disodium salt of phthalic acid. Phthalic acid is an aromatic dicarboxylic acid with two carboxyl groups attached to adjacent carbon atoms on a benzene ring.
The structure of sodium phthalate is a benzene ring with two -COONa groups attached to adjacent carbons.
Step 3: Predicting the product of decarboxylation.
When sodium phthalate undergoes decarboxylation with sodalime, both -COONa groups are removed as Na₂CO₃. Since there are two carboxyl groups, two molecules of CO₂ (in the form of Na₂CO₃) are removed, leaving behind the benzene ring.
The reaction can be represented as:
C₆H₄(COONa)₂ + 2(NaOH + CaO) → C₆H₆ + 2Na₂CO₃
Sodium Phthalate → Benzene + Sodium Carbonate
Step 4: Evaluate the options.

• Option (1): Benzene: This is the correct product, as the two carboxylate groups are removed from the benzene ring, leaving benzene.
• Option (2): Toluene: Toluene has a methyl group attached to a benzene ring (C₆H₅CH₃). Decarboxylation of sodium phthalate does not introduce a methyl group.
• Option (3): Phthalic acid: Phthalic acid is the starting material (or its precursor) and not the product of decarboxylation.
• Option (4): Phenol: Phenol has a hydroxyl group attached to a benzene ring (C₆H₅OH). Decarboxylation does not introduce a hydroxyl group.

Step 5: Conclusion.
The reaction of sodium phthalate with sodalime results in the formation of benzene.

The -COOH group, known as the carboxylic acid group, consists of a carbon atom double bonded to an oxygen atom and single bonded to a hydroxyl group (-OH).
Now, let's evaluate the compounds:
Aspirin (acetylsalicylic acid) contains a carboxylic acid group attached to a benzene ring along with an ester group. Therefore, it has a -COOH group.
Ethanol (CH CH OH) has only a hydroxyl group (-OH), not a -COOH.
Acetone (CH COCH ) is a ketone, having a carbonyl group (C=O) but no -COOH.
Formaldehyde (HCHO) is an aldehyde with a -CHO group, not -COOH.
Hence, among the given options, only Aspirin contains the carboxylic acid (-COOH) group.

Fruits and vegetables contain various organic acids that contribute to their taste and nutritional characteristics. Let’s examine each of the acids listed in the options:

• Acetic acid – Commonly found in vinegar, produced during fermentation. It is not naturally abundant in tomatoes.
• Citric acid – Present in citrus fruits like oranges and lemons. Tomatoes do contain small amounts of citric acid, but it is not their defining acid.
• Tartaric acid – Found in grapes and tamarind. Tomatoes do not contain significant amounts of this acid.
• Oxalic acid – This acid occurs naturally in many plants including tomatoes, spinach, and beets. It is a dicarboxylic acid (HOOC–COOH) and can bind with minerals such as calcium to form oxalates.

Among the options given, oxalic acid is the correct answer because tomatoes are widely known to be a natural source of oxalic acid.