A mixture of benzaldehyde and formaldehyde on heating with aqueous \(\mathrm{NaOH}\) solution gives (a) Benzyl alcohol and sodium formate (b) Sodium benzoate and methyl alcohol (c) Sodium benzoate and sodium formate (d) Benzyl alcohol and methyl alcohol

Benzaldehyde is an aromatic aldehyde with a chemical formula of C₇H₆O and a distinctive almond-like scent. It's a transparent liquid at room temperature and is widely used in the synthesis of various chemicals. In educational chemistry, especially when studying organic reactions, benzaldehyde captures attention due to its lack of alpha-hydrogen atoms.

Alpha-hydrogens are the hydrogens attached to the carbon atom adjacent to the carbonyl group in aldehydes and ketones. The absence of these hydrogens in benzaldehyde means it doesn't undergo typical reactions such as aldol condensation, which requires alpha-hydrogens. However, this characteristic makes benzaldehyde a prime candidate for the Cannizzaro reaction, where it's transformed into two products: benzyl alcohol and a carboxylic acid salt, sodium benzoate.

Formaldehyde, with the simplest form of the aldehyde group, is a pungent gas represented by the formula CH₂O. This aldehyde is fundamental in organic chemistry, with its reactivity central in numerous synthesis processes. As a building block in chemistry, it readily participates in polymerization and other reaction mechanisms.

In the context of the Cannizzaro reaction, formaldehyde is unique because, like benzaldehyde, it has no alpha-hydrogen atoms. This characteristic allows it to undergo disproportionation reactions under basic conditions. Formaldehyde is oxidized to formic acid, which then combines with sodium hydroxide present in the reaction mixture to form sodium formate, another key product of the Cannizzaro reaction.

Sodium formate (HCOONa) is the sodium salt of formic acid and is often encountered in organic chemistry exercises related to oxidation-reduction reactions. It's a white crystalline powder and is used industrially in various applications like fabric dyeing and printing.

During the Cannizzaro reaction, when formaldehyde is oxidized, formic acid is generated and subsequently reacts with the base present – sodium hydroxide, to form sodium formate. It's crucial to understand that sodium formate is the final product in the oxidation pathway of a Cannizzaro reaction involving formaldehyde, showcasing the transfer of electrons from formaldehyde to a molecule of another aldehyde, such as benzaldehyde.

Benzyl alcohol is a mild, aromatic alcohol with the formula C₆H₅CH₂OH, and it's an important product in both industrial and pharmaceutical applications. In the context of organic chemistry, benzyl alcohol often arises from the reduction of benzaldehyde.

In the Cannizzaro reaction, benzyl alcohol is produced as the reduced counterpart to the oxidized aldehyde. Understanding how this reduction occurs highlights an essential principle in redox chemistry—the relocation of electrons between molecules. The direct transfer of a hydride ion from one aldehyde molecule to another is what leads to the formation of benzyl alcohol, with the concurrent formation of the carboxylic salt being a pivotal aspect of the Cannizzaro reaction.