Benzaldehyde
[CAS# 100-52-7]

Identification

• Classification: Organic raw materials >> Aldehyde
• Name: Benzaldehyde
• Synonyms: Benzoic aldehyde; Phenylmethanal
• Molecular Formula: C₇H₆O
• Molecular Weight: 106.12
• CAS Registry Number: 100-52-7
• EC Number: 202-860-4
• FEMA: 2127
• SMILES: C1=CC=C(C=C1)C=O

Properties

• Density: 1.044 g/mL (20 °C) (Expl.)
• Melting point: -26 °C (Expl.)
• Boiling point: 179 °C (Expl.)
• Refractive index: 1.545 (Expl.)
• Flash point: 64 °C (Expl.)
• Water solubility: <0.01 g/100 mL (19.5 °C) (Expl.)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H319-H332-H336
• Safety Statements: P261-P264-P264+P265-P270-P271-P280-P301+P317-P304+P340-P305+P351+P338-P317-P319-P330-P337+P317-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302
Acute toxicity	Acute Tox.	4	H332
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H336
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin sensitization	Skin Sens.	1	H317
Skin irritation	Skin Irrit.	2	H315
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Reproductive toxicity	Repr.	1B	H360D
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Acute toxicity	Acute Tox.	3	H331
Acute toxicity	Acute Tox.	4	H312
Specific target organ toxicity - repeated exposure	STOT RE	2	H373
Reproductive toxicity	Repr.	1B	H360

• Transport Information: UN 1989

Discovery and Applications

Benzaldehyde is a simple aromatic aldehyde with the molecular formula C₆H₅CHO. It is one of the most important and widely used aromatic compounds in both organic synthesis and industrial applications. Benzaldehyde was first isolated in the early 19th century from bitter almonds, a natural source of the compound, and its distinctive almond-like odor has made it an important ingredient in flavoring and fragrance industries. Its discovery and the development of its applications have contributed to a variety of fields, including pharmaceuticals, cosmetics, and materials science.

The first recorded synthesis of benzaldehyde is attributed to the German chemist, August Wilhelm von Hofmann, in 1855. Hofmann synthesized the compound by oxidizing toluene, a methylated benzene derivative, using chromic acid. This marked a significant advancement in the ability to produce benzaldehyde synthetically, as prior to this, it was primarily obtained through the distillation of bitter almonds, where it occurs as part of the cyanogenic glycoside amygdalin. Over time, other methods of synthesizing benzaldehyde were developed, such as the oxidation of toluene or the reaction of benzyl chloride with sodium hydroxide.

Benzaldehyde is characterized by its aromatic odor, which is often associated with almonds, cherries, or certain flowers, making it highly useful in the production of flavors and fragrances. It is a key ingredient in almond-flavored products and is also used in the fragrance industry to impart a sweet, nutty scent. Beyond its use in flavorings and perfumes, benzaldehyde plays a significant role as a building block in the synthesis of various chemicals. It is a precursor in the production of other compounds like cinnamic acid, benzoin, and certain pharmaceuticals. Additionally, benzaldehyde serves as a starting material in the preparation of plastics, dyes, and resins.

In the pharmaceutical industry, benzaldehyde is used as an intermediate in the synthesis of a range of active pharmaceutical ingredients (APIs), including those used in the treatment of cardiovascular diseases, antimicrobial agents, and anti-inflammatory drugs. Its utility in medicinal chemistry arises from its ability to undergo various chemical reactions, such as condensation, reduction, and substitution, which allow the production of a wide array of biologically active compounds.

Another important application of benzaldehyde is in the synthesis of benzoin, a compound with antiseptic properties, which is further used to prepare benzoin derivatives. It also serves as a key reactant in the production of plastics, where its reactivity enables the formation of polymers and resins. Furthermore, benzaldehyde is employed in the synthesis of various specialty chemicals, including rubber accelerators and dyes.

Benzaldehyde has a relatively low toxicity, but exposure to high concentrations can cause irritation to the eyes, skin, and respiratory system. As with many chemicals, proper handling and safety protocols are necessary to minimize risks during its production and use.

In conclusion, benzaldehyde is a versatile and widely used compound in industries ranging from food and cosmetics to pharmaceuticals and material science. Its distinct odor, chemical reactivity, and role as a precursor to a variety of other chemicals make it a valuable substance in both industrial and laboratory settings. As research continues into its applications, new uses for benzaldehyde may emerge, further cementing its importance in modern chemistry.

References

2014. Inhibitory Effects of Benzaldehyde Derivatives from the Marine Fungus Eurotium sp. SF-5989 on Inflammatory Mediators via the Induction of Heme Oxygenase-1 in Lipopolysaccharide-Stimulated RAW264.7 Macrophages. International Journal of Molecular Sciences, 15(12).
DOI: 10.3390/ijms151223749

2018. Molecular cloning and characterization of vanillin dehydrogenase from Streptomyces sp. NL15-2K. BMC Microbiology, 18(1).
DOI: 10.1186/s12866-018-1309-2

2019. Predominant Mechanisms in the Treatment of Wastewater Due to Interaction of Benzaldehyde and Iron Slag Byproduct. International Journal of Environmental Research and Public Health, 17(1).
DOI: 10.3390/ijerph17010226