alpha-Methylcinnamylaldehyde
[CAS# 15174-47-7]

Identification

• Classification: Organic raw materials >> Aldehyde
• Name: alpha-Methylcinnamylaldehyde
• Synonyms: 2-Methyl-3-phenyl-trans-prop-2-enal
• Molecular Formula: C₁₀H₁₀O
• Molecular Weight: 146.18
• CAS Registry Number: 15174-47-7
• EC Number: 701-219-0
• SMILES: C/C(=C\C1=CC=CC=C1)/C=O

Properties

• Density: 1.0±0.1 g/cm³ Calc.^*, 1.037 g/mL (Expl.)
• Boiling point: 254.6±9.0 ºC 760 mmHg (Calc.)^*, 279.2 - 280.5 ºC (Expl.)
• Flash point: 79.4 ºC (Calc.)^*, 79 ºC (Expl.)
• Index of refraction: 1.563 (Calc.)^*, 1.605 (Expl.)

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H317
• Precautionary Statements: P261-P272-P280-P302+P352-P321-P333+P317-P362+P364-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin sensitization	Skin Sens.	1	H317
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411

Discovory and Applicatios

α-Methylcinnamylaldehyde is an aromatic aldehyde belonging to the class of substituted cinnamyl derivatives. Structurally, it consists of a benzene ring attached to a propenal chain bearing a methyl substituent at the α-position, which gives the compound both unique reactivity and a characteristic odor profile. It is a pale yellow liquid with a strong, sweet, and spicy scent, which has led to its long-standing use in the fragrance industry.

The compound was first identified during systematic investigations of cinnamic acid derivatives and related aldehydes in the early 20th century, as researchers studied the relationship between structural modifications of aromatic aldehydes and their olfactory properties. Its introduction into perfumery soon followed, where its warm, balsamic, and cinnamon-like note made it a valuable additive in the formulation of complex fragrances.

In practical applications, α-methylcinnamylaldehyde is mainly used in perfumes, soaps, and household products. Its ability to impart sweet and spicy undertones allows it to act as a blending material, often combined with floral, woody, and oriental fragrance components. It is also used in flavor compositions in food products, although its application in this area is more limited and subject to safety regulation, as aldehydes can be reactive and require controlled dosage.

From a chemical standpoint, the aldehyde functional group at the terminal position of the α-methylcinnamyl chain provides reactivity suitable for condensation, oxidation, and reduction reactions. This makes the compound a useful intermediate in synthetic organic chemistry. It can undergo reactions such as aldol condensation, Schiff base formation with amines, or reduction to the corresponding alcohol, α-methylcinnamyl alcohol. These transformations have been exploited in laboratory studies aimed at synthesizing related fragrance compounds and in developing building blocks for fine chemicals.

Industrial synthesis of α-methylcinnamylaldehyde generally follows condensation pathways, such as the Claisen–Schmidt condensation of acetophenone derivatives with aldehydes, followed by further modification to introduce the methyl group at the α-position. Advances in catalytic methods, including heterogeneous catalysis, have provided more efficient and selective routes, reducing byproducts and improving yield.

Toxicological studies have shown that α-methylcinnamylaldehyde is safe for controlled use in fragrances and consumer products, though as with many aldehydes, it may cause sensitization or irritation in susceptible individuals at high concentrations. This has led regulatory authorities such as the International Fragrance Association (IFRA) to set guidelines on maximum allowable concentrations in different product categories to ensure consumer safety.

Research on α-methylcinnamylaldehyde continues in the context of both fragrance chemistry and organic synthesis. Its structural similarity to naturally occurring cinnamaldehyde has prompted comparative studies into its odorant activity and structure–odor relationships. Furthermore, its reactivity as an aldehyde provides opportunities for developing derivatives with tailored properties, whether in perfumery or in the synthesis of specialty organic materials.

Through its history of discovery, characterization, and practical use, α-methylcinnamylaldehyde illustrates the dual importance of aromatic aldehydes as both industrially significant fragrance compounds and versatile intermediates in organic chemistry.

References

2019. Redox-Neutral Conversion of a,�-Unsaturated Aldehydes into Saturated Acids. Science of Synthesis.
URL: SD-232-00192

2023. Inhibitory Mechanism of Cinnamon Essential Oil and Its Active Components Against Fungi. Cinnamon: A Medicinal Plant and A Functional Food Systems.
DOI: 10.1007/978-3-031-33505-1_9

2025. Enantioselective �-alkenylation of a,�-unsaturated aldehydes via chiral biphosphine ligand modified dirhodium(II) catalysis. Science China Chemistry.
DOI: 10.1007/s11426-024-2468-0