Organic Chemistry (VSAQs)

Chemistry-2 | 11. Organic Chemistry – VSAQs:
Welcome to VSAQs in Chapter 11: Organic Chemistry. This page includes the key FAQs for Very Short Answer Questions. Each answer is provided in simple English and follows the exam format. This approach helps in focusing on essential points and achieving top marks in your final exams.

VSAQ-1 : What are ambident nucleophiles?

Ambident nucleophiles are molecules or ions with two potential donor atoms, such as the cyanide ion (CN^-) and the nitrite ion (NO2^-). These compounds play a significant role in chemistry by providing versatility in chemical reactions due to their ability to donate electron pairs through different atoms.

VSAQ-2 : What are Enantiomers?

Enantiomers are a pair of non-superimposable mirror image molecules. Examples include d-lactic acid and l-lactic acid. They have the same chemical formula but differ in their three-dimensional arrangement, which can lead to distinct biological effects, making them important in fields like pharmacology and biochemistry.

VSAQ-3 : How is aniline prepared?

Aniline is prepared through a chemical reaction involving nitrobenzene, hydrogen gas (H2), and a catalyst, usually palladium (Pd). The reaction can be represented as follows:

C6H5NO2 + 3H2 → Pd C6H5NH2 + 2H2O

VSAQ-4 : How is Grignard reagent prepared?

Grignard reagents are synthesized through a reaction involving alkyl or aryl halides and magnesium (Mg) in anhydrous (dry) ether. The reaction can be summarized as follows:

Rx + Mg →┴ (dry ether) RMgX

VSAQ-5 : Explain Carbylamine reaction with one example.

The Carbylamine reaction, also known as the Isocyanide test, is used to identify primary amines. In this test, a primary amine reacts with chloroform (CHCl3) and alcoholic potassium hydroxide (KOH) to form an isocyanide compound, characterized by its foul odor.

Example:

For instance, when methylamine (CH3NH2) undergoes the Carbylamine reaction, it produces an isocyanide:

CH3NH2 + CHCl3 + KOH → CH3NC (Isocyanide) + 3H2O + KCl

VSAQ-6 : Compare the acidic strength of acedic acid, Chloroacetic acid, benzoic acid and phenol.

Among acetic acid, chloroacetic acid, benzoic acid, and phenol:

  1. Chloroacetic acid is the strongest acid due to the electron-withdrawing effect of chlorine, resulting in a lower pKa value.
  2. Benzoic acid is moderately acidic, with a pKa value between acetic acid and chloroacetic acid.
  3. Acetic acid is a weak acid with a higher pKa than chloroacetic acid and benzoic acid.
  4. Phenol is the weakest acid among them, with the highest pKa value.

VSAQ-7 : Write the reaction showing α-halogenation of carboxylic acid and give its name.

The α-halogenation of carboxylic acids, known as the Hell-Volhard-Zelinsky (HVZ) reaction, involves treating a carboxylic acid (RCOOH) with chlorine or bromine (X2) in the presence of red phosphorus (P) as a catalyst. This reaction results in the formation of α-halo carboxylic acids (RCOX) and hydrogen halide byproducts (HX).