Friday, 15:36 Date 19/08/2022

What are Benzaldehyde and its Properties?

The simplest aromatic aldehyde, which consists of a benzene ring with a formyl (-CHO) substituent, is termed benzaldehyde (C6H5CHO). This organic chemical compound has several industrial applications, including dyes, flavoring agents, perfumes, and the manufacturing of several other organic compounds. Found naturally in glycoside amygdalin, this aromatic aldehyde is known for its distinct, almond oil-like taste and odor.

The molecular formula of this compound is C7H6O, and its IUPAC name is benzenecarbaldehyde. It is also referred to by several other names, including benzenedicarboxaldehyde, phenylmethanol, or benzoic aldehyde. It appears as a clear liquid with a smell like almonds. It is miscible with volatile oils, ether, and alcohol. It is denser than and thus only slightly soluble in water and has a solubility of 3 g/L.

Discovery of Benzaldehyde

Benzaldehyde occurs in a variety of natural items such as almonds or cherries. The isolation of benzaldehyde from bitter almonds goes back to 1803 and is credited to a French pharmacist Martrès. It was later studied by the German chemists Justus von Liebig and Friedrich Wöhler, who first synthesised it successfully in the 1830s. This led to the establishment of the structural theory of organic chemistry.

Structure of Benzaldehyde

The structure of benzaldehyde consists of a benzene ring substituted with an aldehyde unit. This formyl unit has one atom of carbon, hydrogen, and oxygen. The number of benzaldehyde sigma bonds is 14, formed by the head-to-head overlapping of atomic orbitals.

Preparation of Benzaldehyde

This simple aromatic aldehyde can be derived from a variety of natural sources: Almonds, cherries, cinnamon, apricots,…

It can also be manufactured synthetically from toluene which is found in crude oil, for industrial usage. This is done by a series of chemical reactions in which toluene reacts with chlorine. This leads to the formation of benzal chloride, which can be further treated with water to form benzaldehyde.

Benzaldehyde can also be synthesised by the oxidation of benzyl alcohol and carbonylation of benzene. Alkaline hydrolysis of benzal chloride also yields benzaldehyde.

Storage of Benzaldehyde

Benzaldehyde readily undergoes autoxidation to form benzoic acid on exposure to air at room temperature

It should be stored as per the recommended conditions. It should be properly stored in a sealed container away from heat and light. It should be kept away from reactive substances such as acids and reducing agents. It is also recommended to store this compound under nitrogen.

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