(2E,4E,6E)-2,7-Dimethyl-2,4,6-octatrienedial
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Product Description
(2E,4E,6E)-2,7-Dimethyl-2,4,6-octatrienedial is a linear, highly conjugated C10 dialdehyde whose all-trans triene backbone is capped by formyl groups and punctuated with strategic methyl branches at C-2 and C-7. The extended π-system—formally three successive α,β-unsaturated aldehyde units—gives the molecule an almost planar geometry reminiscent of retinal, while the methyl substituents tune both steric demand and electron distribution. These structural features make it a prized synthetic linchpin: it can be elongated in either direction through Horner–Wadsworth–Emmons or Julia olefinations, enabling rapid, bidirectional assembly of complex carotenoids such as aurochrome, lycopene, echinenone epoxides, and crocetin esters. Beyond traditional organic synthesis, the dialdehyde serves as a gateway to oxo-carotenoids whose superoxide-scavenging capacity surpasses that of β-carotene by up to 50 %, and it is now being engineered into microbial pathways for on-demand production of high-value ketocarotenoids. Its potent radical-stabilizing character, combined with a rigid, chromophore-rich scaffold, also invites exploration in antioxidant formulations, specialty fragrances, and advanced π-conjugated materials.
Other Information
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Classification: This compound is listed in several regulatory and research classification systems, including the UN GHS, NORMAN Suspect List Exchange, and EPA DSSTox, indicating it is a substance of interest for environmental and toxicological monitoring.
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Patents and Literature: The compound is referenced in multiple patent documents and scientific articles, particularly in the fields of organic synthesis, carotenoid chemistry, and antioxidant research. Links to these are available in the PubChem record.
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Chemical Vendors: The compound is listed as purchasable from various chemical suppliers through the PubChem "Chemical Vendors" section.
Synthesis and Production
(2E,4E,6E)-2,7-Dimethyl-2,4,6-octatrienedial is primarily synthesized as a key intermediate for more complex molecules, particularly carotenoids.
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Primary Method (Horner-Wadsworth-Emmons Olefination):
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This is a one-pot, high-yielding method. It involves the reaction of diethyl (E)-(3-(5,5-dimethyl-1,3-dioxan-2-yl)but-2-en-1-yl)phosphonate with (E)-3-(5,5-dimethyl-1,3-dioxan-2-yl)but-2-enal.
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Conditions: Sodium hydride (NaH) in Tetrahydrofuran (THF) at 0°C to 25°C, followed by deprotection with 1M hydrochloric acid (HCl).
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Yield: Approximately 83%.
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Advantages: High stereoselectivity for the desired E configuration across the double bonds, mild reaction conditions, and scalability to multi-gram quantities.
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Alternative Methods:
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Julia-Kocienski Olefination: Used for chain extension to create longer apocarotenoids (e.g., C20 crocetin dialdehyde).
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Acidic Ionic Liquid-Promoted Synthesis: A method starting from fumaraldehyde bis-dimethylacetal, noted for being simple and having high industrial value.
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Uses and Applications
This dialdehyde serves as a fundamental building block in organic and medicinal chemistry.
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Carotenoid and Vitamin A Synthesis: It acts as a central "linchpin" or core unit in the bidirectional synthesis of important biological molecules like β-carotene, lycopene, retinol (Vitamin A), and crocetin esters.
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Synthesis of Specialized Carotenoids: Used to produce epoxycarotenoids (e.g., aurochrome, auroxanthin) and oxo-carotenoids, which are studied for their biological activities.
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Antioxidant Research: The compound is a precursor to synthetic oxo-carotenoids that demonstrate superior superoxide radical scavenging activity (105-151% better than β-carotene in studies), making them relevant for researching antioxidants.
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Fragrances and Materials: Its conjugated structure makes it a potential intermediate in the synthesis of compounds for use in fragrances and advanced polymeric materials.
Chemical and Physical Properties
Identifiers and Structure
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IUPAC Name: (2E,4E,6E)-2,7-dimethylocta-2,4,6-trienedial
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Molecular Formula: C₁₀H₁₂O₂
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Molecular Weight: 164.20 g/mol
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CAS Number: 5056-17-7
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Other Identifiers:
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InChIKey: AYODHZHFDRRQEZ-XLKYRCCQSA-N
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EC Number: 225-756-0
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DSSTox Substance ID: DTXSID201258250
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Structure: A symmetrical, linear 8-carbon chain with three conjugated trans (E) double bonds, a methyl group on C2 and C7, and an aldehyde group at each terminus (C1 and C8).
Computed Physical and Chemical Properties
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XLogP3: 1.5 (Indicates moderate lipophilicity)
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Hydrogen Bond Donor Count: 0
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Hydrogen Bond Acceptor Count: 2
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Rotatable Bond Count: 4
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Topological Polar Surface Area: 34.1 Ų
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Heavy Atom Count: 12
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Defined Bond Stereocenter Count: 3 (Corresponding to the three E-configured double bonds)
Experimental/Reported Properties
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Appearance: Yellow to dark orange solid or powder.
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Melting Point: 162 - 163.5 °C (reported in methanol).
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Stability: Air-sensitive; prone to oxidation and polymerization due to its conjugated dialdehyde structure.
Spectroscopic Information
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¹H NMR (CDCl₃): δ 1.94 (s, 6H, two CH₃), 6.96–7.10 (m, 4H, four olefinic CH), 9.54 (s, 2H, two CHO).
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13C NMR: Available in databases (PubChem links to SpectraBase).
Safety and Handling
Hazards Identification (GHS Classification)
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Signal Word: Warning
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Hazard Statements:
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H317: May cause an allergic skin reaction.
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H412: Harmful to aquatic life with long-lasting effects.
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Precautionary Statements: P261, P272, P273, P280, P302+P352, P321, P333+P317, P362+P364, P501.
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Pictogram: GHS07 (Exclamation mark)
Handling and Storage
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Handling: Standard organic laboratory precautions are essential. Use personal protective equipment (PPE) including gloves and safety goggles. Handle in a well-ventilated area or fume hood to avoid inhalation of dust.
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Storage: Store in a cool, dry place under an inert atmosphere (e.g., nitrogen or argon) to prevent degradation and polymerization. Keep container tightly closed.
Regulatory Information
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REACH Status: Registered and active in the European Union.