Question

Column - I (Reaction) (A) \(\mathrm{R}-\mathrm{OH} \stackrel{\mathrm{SOCl}_{2}}{\longrightarrow} \mathrm{R}-\mathrm{Cl}\) (B) \(R-\mathrm{Br} \frac{\text { Nal }}{\text { Acetone }}\) R-I (C) \(R-I \rightarrow \mathrm{AgF}{\longrightarrow} \mathrm{R}-\mathrm{F}\) (D) \(\mathrm{EtOH} \frac{\mathrm{H}_{2} \mathrm{SO}_{4}}{140^{\circ} \mathrm{C}}\) EtOEt Column - II (Name of reaction) (P) Swarts reaction (Q) Williamson ether synthesis (R) Darzen process (S) Finkelstein reaction (T) Williamson continuous ether synthesis

Short answer

The matched pairs for each reaction are: - (A) with (R): Darzen process - (B) with (S): Finkelstein reaction - (C) with (P): Swarts reaction - (D) with (Q): Williamson ether synthesis

Step-by-step solution

Identify reaction A

In reaction A, \(\mathrm{R}-\mathrm{OH}\) reacts with \(\mathrm{SOCl}_{2}\) to form \(\mathrm{R}-\mathrm{Cl}\). This is a reaction where an alcohol (R-OH) is being converted into alkyl chloride (R-Cl) using thionyl chloride (SOCl₂) as a reagent.

Match reaction A with its name

The reaction in step 1 corresponds to the Darzen process. So, (A) matches with (R).

Identify reaction B

In reaction B, \(R-\mathrm{Br}\) reacts with NaI in the presence of acetone to form R-I. This is a reaction where an alkyl bromide (R-Br) is being replaced by an iodide (R-I) using sodium iodide (NaI) as a reagent.

Match reaction B with its name

The reaction in step 3 corresponds to the Finkelstein reaction. So, (B) matches with (S).

Identify reaction C

In reaction C, \(R-I\) reacts with \(\mathrm{AgF}\) to form \(\mathrm{R}-\mathrm{F}\). This is a reaction where an alkyl iodide (R-I) is being replaced by a fluoride (R-F) using silver fluoride (AgF) as a reagent.

Match reaction C with its name

The reaction in step 5 corresponds to the Swarts reaction. So, (C) matches with (P).

Identify reaction D

In reaction D, \(\mathrm{EtOH}\frac{\mathrm{H}_{2} \mathrm{SO}_{4}}{140^{\circ} \mathrm{C}}\) forms EtOEt. This reaction involves conversion of ethanol into diethyl ether in the presence of an acid catalyst, sulfuric acid (H₂SO₄), at 140 °C.

Match reaction D with its name

The reaction in step 7 corresponds to the Williamson ether synthesis. So, (D) matches with (Q). Finally, we get the matched pairs: - (A) with (R): Darzen process - (B) with (S): Finkelstein reaction - (C) with (P): Swarts reaction - (D) with (Q): Williamson ether synthesis

Key concepts

Darzen Process

The Darzen process, also known as the Darzens glycidic ester condensation, is an organic reaction involving the transformation of an aldehyde or ketone into a glycidic ester through the reaction with an alpha haloester in the presence of a strong base. This reaction is crucial in the synthesis of epoxides, which are three-membered cyclic ethers offering significant synthetic utility. The reaction proceeds through a carbanion intermediate that attacks the carbonyl carbon of the aldehyde or ketone, followed by an intramolecular nucleophilic substitution to form the epoxide ring.

Students should note the importance of this process for constructing complex molecules, as it installs an epoxide which can further undergo a plethora of reactions such as ring opening with nucleophiles or rearrangements, thereby aiding in molecular diversity and complexity in organic synthesis.

Finkelstein Reaction

In organic chemistry, the Finkelstein reaction serves as a classic example of a halogen exchange reaction. This reaction typically involves the conversion of an alkyl chloride or bromide to an alkyl iodide by treatment with sodium iodide. The reaction is typically conducted in acetone, a polar aprotic solvent, which promotes the reactants' solubility and assists in the swift exchange of the halide ions.

The Finkelstein reaction is driven by the precipitation of the less soluble sodium chloride or sodium bromide out of the reaction mixture, making this reaction an excellent example of what chemists refer to as the 'driving force' of a reaction. Such transformations are useful, particularly because alkyl iodides are more reactive in further nucleophilic substitution reactions, enabling the synthesis of a wider array of compounds.

Swarts Reaction

The Swarts reaction is named after the Belgian chemist Frédéric Swarts and is employed for the fluorination of aliphatic and aromatic halides, typically chlorides or bromides, to form the corresponding fluorides. This conversion is accomplished through the use of metal fluoride reagents such as silver fluoride (AgF), antimony trifluoride (SbF3), or mercuric fluoride (Hg2F2).

Fluorinated organic compounds have many applications, from pharmaceuticals to agrochemicals, due to the unique reactivity and properties imparted by the carbon-fluorine bond, such as increased stability and lipophilicity. Understanding the Swarts reaction is essential for students as it highlights a practical approach to introducing fluorine, a critical element in medicinal chemistry, into organic molecules.

Williamson Ether Synthesis

The Williamson ether synthesis is a fundamental reaction for the formation of ethers, involving the reaction of an alkoxide ion with a primary alkyl halide via an S_N2 mechanism. Typically, the alkoxide ion is generated by treating an alcohol with a strong base like sodium hydride or sodium metal. The alkoxide then acts as a nucleophile that displaces the halide ion from the alkyl halide, resulting in the formation of an ether product.

Ethers are a critical class of compounds with applications ranging from solvents to complex organic molecule construction. The Williamson synthesis is one of the most versatile methods to synthesize ethers and is particularly valuable due to its simplicity and the broad range of possible substrates. Students should grasp the importance of reaction conditions, such as the use of a primary alkyl halide to avoid side reactions like elimination, thereby ensuring a successful ether synthesis.