(E,E,E)-2,7-Dimethyl-2,4,6-octatrien-1,8-dial
[CAS# 5056-17-7]

Identification

• Classification: Organic raw materials >> Aldehyde
• Name: (E,E,E)-2,7-Dimethyl-2,4,6-octatrien-1,8-dial
• Synonyms: (all-E)-2,7-Dimethyl-2,4,6-octatrienedial; 12,12'-Di-apo-carotenedial; all-E-2,7-Dimethylocta-2,4,6-triene-1,8-dial
• Molecular Formula: C₁₀H₁₂O₂
• Molecular Weight: 164.20
• CAS Registry Number: 5056-17-7
• EC Number: 225-756-0
• SMILES: C/C(=C\C=C\C=C(\C=O)/C)/C=O

Properties

• Solubility: Sparingly soluble (13 g/L) (25 ºC), Calc.^*
• Density: 0.973±0.06 g/cm³ (20 ºC 760 Torr), Calc.^*
• Melting point: 162-163.5 ºC (methanol )^**
• Boiling point: 303.3±25.0 ºC 760 mmHg (Calc.)^*, 90-94 ºC (10 Torr)^***
• Flash point: 113.3±20.2 ºC, Calc.^*
• Index of refraction: 1.488 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software V11.02 (©1994-2014 ACD/Labs)

^** Buchta, Emil; Justus Liebigs Annalen der Chemie 1956, V598, P1-24.

^*** Buchta, Emil; Chemische Berichte 1960, V93, P1349-53.

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H317-H412
• Precautionary Statements: P261-P272-P273-P280-P302+P352-P321-P333+P317-P362+P364-P501

Discovory and Applicatios

(E,E,E)-2,7-Dimethyl-2,4,6-octatrien-1,8-dial is a naturally occurring organic compound classified as an apocarotenoid dialdehyde. It belongs to a class of compounds derived from the oxidative cleavage of carotenoids, which are widespread pigments in plants, algae, and some bacteria. This compound has attracted attention primarily because of its role in plant physiology and its occurrence in certain fruit and vegetable volatiles.

The discovery and identification of (E,E,E)-2,7-dimethyl-2,4,6-octatrien-1,8-dial originated in the context of studies on carotenoid degradation products. Carotenoids such as β-carotene and lycopene are known to undergo enzymatic or non-enzymatic cleavage, resulting in a range of smaller molecules called apocarotenoids. These include aldehydes, ketones, and alcohols that often have significant biological and sensory properties. Among these, dialdehydes like (E,E,E)-2,7-dimethyl-2,4,6-octatrien-1,8-dial were isolated and structurally characterized using techniques such as gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) spectroscopy.

The compound's structure consists of an eight-carbon chain with three conjugated double bonds and terminal aldehyde groups. The conjugated system is responsible for its ability to absorb light in the ultraviolet-visible spectrum, a property that plays a role in its reactivity and sensory characteristics. The geometry of the three double bonds in the E (trans) configuration is significant for its stability and biological activity.

One of the primary areas where (E,E,E)-2,7-dimethyl-2,4,6-octatrien-1,8-dial has been studied is in plant signaling and interaction with the environment. Apocarotenoids, including this compound, have been implicated in plant responses to stress, herbivory, and microbial attack. These compounds can serve as semiochemicals, influencing the behavior of herbivores or attracting beneficial insects such as pollinators or predators of herbivores. Furthermore, some apocarotenoids play roles in plant development and hormone regulation.

In the flavor and fragrance industries, (E,E,E)-2,7-dimethyl-2,4,6-octatrien-1,8-dial and structurally related compounds have been studied for their contribution to the aroma profiles of various fruits and vegetables. Although this specific dialdehyde may not be the dominant component in any particular food, its presence as a trace volatile has been noted in several natural sources. The compound has a characteristic odor profile described as fruity, green, or floral, contributing to the overall sensory experience of fresh produce.

In biochemical research, (E,E,E)-2,7-dimethyl-2,4,6-octatrien-1,8-dial has also been used as a reference compound in the study of lipid oxidation and carotenoid breakdown. Its production during the degradation of carotenoids under oxidative conditions helps researchers understand the chemical pathways involved in food spoilage, storage, and processing. This makes it a useful marker for the quality assessment of foods rich in carotenoids, such as tomatoes and peppers.

The synthesis of (E,E,E)-2,7-dimethyl-2,4,6-octatrien-1,8-dial in the laboratory typically involves Wittig or Horner-Wadsworth-Emmons reactions to construct the conjugated triene backbone with controlled stereochemistry. Aldehyde groups are introduced at the termini either during the synthesis or via subsequent oxidation steps. The stereochemical control is essential for producing the E,E,E-isomer, which differs in reactivity and sensory properties from its Z (cis) isomers.

Although the compound is not used directly as a commercial product, its derivatives and related apocarotenoids are studied for potential applications in agriculture, perfumery, and functional foods. Their roles as bioactive compounds open avenues for their use in plant protection or as natural additives.

In conclusion, (E,E,E)-2,7-dimethyl-2,4,6-octatrien-1,8-dial is a well-defined apocarotenoid compound derived from the oxidative cleavage of carotenoids. Its structure, natural occurrence, role in plant signaling, and contribution to aroma profiles have been validated in scientific literature. While not a widely marketed substance on its own, it holds significance in both basic and applied research related to plant biochemistry and food science.

References

2003. Betacarotene. Pharmaceutical Substances.
URL: https://pharmaceutical-substances.thieme.com/ps/search-results?docUri=KD-02-0064

2020. A Method for Extraction and LC-MS-Based Identification of Carotenoid-Derived Dialdehydes in Plants. Methods in molecular biology (Clifton, N.J.).
URL: https://pubmed.ncbi.nlm.nih.gov/31745921

2010. Wittig Reaction. Science of Synthesis.
URL: https://science-of-synthesis.thieme.com/app/text/?id=SD-045-01466