3-Methyltetrahydrofuran
[CAS 13423-15-9]

Identification

• Classification: Flavors and spices >> Synthetic spice >> Lactone and oxygen-containing heterocyclic compound >> Furan and pyran
• Name: 3-Methyltetrahydrofuran
• Molecular Formula: C₅H₁₀O
• Molecular Weight: 86.13
• CAS Registry Number: 13423-15-9
• EC Number: 236-537-4
• SMILES: CC1CCOC1

Properties

• Density: 0.9±0.1 g/cm³ Calc.^*
• Boiling point: 83.8±8.0 °C 760 mmHg (Calc.)^*, 86.5 °C (Expl.)
• Flash point: -6.7 °C (Calc.)^*
• Index of refraction: 1.411 (Calc.)^*

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

Safety Data

• Hazard Symbols: GHS02;GHS05;GHS07 DangerGHS02
• Risk Statements: H225-H314-H318-H336
• Safety Statements: P210-P233-P240-P241-P242-P243-P260-P261-P264-P264+P265-P271-P280-P301+P330+P331-P302+P361+P354-P303+P361+P353-P304+P340-P305+P354+P338-P316-P317-P319-P321-P363-P370+P378-P403+P233-P403+P235-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Flammable liquids	Flam. Liq.	2	H225
Skin corrosion	Skin Corr.	1C	H314
Serious eye damage	Eye Dam.	1	H318
Specific target organ toxicity - single exposure	STOT SE	3	H336
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315

Discovery and Applications

3-Methyltetrahydrofuran is a saturated oxygen-containing heterocyclic compound belonging to the class of substituted tetrahydrofurans. It consists of a five-membered cyclic ether ring with a methyl substituent attached to the carbon at the 3-position. The compound is an aliphatic ether characterized by a stable C–O–C linkage, moderate polarity, and a flexible ring structure.

The parent structure, tetrahydrofuran (THF), is a five-membered heterocycle containing four carbon atoms and one oxygen atom. The oxygen atom is part of the ring and is connected to two carbon atoms through single bonds. Unlike aromatic heterocycles, tetrahydrofuran is fully saturated and contains no π-electron system. The ring atoms are predominantly sp³-hybridized, allowing conformational flexibility.

In 3-methyltetrahydrofuran, a methyl group is attached to the third carbon atom of the ring. The methyl substituent replaces one hydrogen atom on the ring carbon and introduces additional hydrophobic character while slightly increasing steric effects within the cyclic structure. The carbon bearing the methyl group remains sp³-hybridized and adopts tetrahedral geometry.

The oxygen atom in the ether ring possesses two lone pairs of electrons and functions as a hydrogen bond acceptor. Because the molecule contains no hydroxyl, amino, or other proton-donating functional groups, it cannot act as a hydrogen bond donor. The ether oxygen is the primary source of molecular polarity.

The five-membered ring is not planar. Similar to other saturated cyclic ethers, 3-methyltetrahydrofuran adopts puckered conformations that reduce torsional strain. The ring can undergo rapid interconversion between different conformational states, allowing flexibility while maintaining the stability of the cyclic ether structure.

The methyl substituent affects the conformational preferences of the ring by introducing steric interactions with neighboring hydrogen atoms. Depending on the orientation of the methyl group, different conformers may have slightly different energies. The overall molecule remains conformationally mobile because of the absence of rigid aromatic or multiple-bond systems.

From an electronic perspective, the molecule contains localized C–O single bonds rather than an extended conjugated system. The electronegative oxygen atom withdraws electron density from adjacent carbon atoms through inductive effects, creating a polarized ether linkage. However, the saturated carbon framework prevents significant electron delocalization.

Physicochemically, 3-methyltetrahydrofuran has moderate polarity due to the ether oxygen but is less hydrophilic than compounds containing hydroxyl groups. The methyl group increases the hydrophobic portion of the molecule compared with unsubstituted tetrahydrofuran. The compound is therefore compatible with many organic solvents and exhibits limited hydrogen-bonding interactions.

Chemically, the ether oxygen is relatively stable under neutral conditions. The main reactions characteristic of 3-methyltetrahydrofuran involve the oxygen atom, including protonation under strongly acidic conditions and possible ring-opening reactions in the presence of strong nucleophiles or reactive electrophilic species. The saturated carbon framework is generally resistant to ordinary chemical transformations.

The carbon atoms adjacent to the oxygen atom are slightly activated because of the inductive electron-withdrawing effect of the ether oxygen. Under strong oxidative conditions, oxidation of the carbon atoms adjacent to oxygen may occur, potentially leading to oxygenated derivatives.

The compound can also undergo combustion typical of saturated ethers, producing carbon dioxide and water under complete oxidation conditions. Because it lacks unsaturation, it does not readily participate in addition reactions associated with alkenes or aromatic substitution reactions.

Overall, 3-methyltetrahydrofuran is a saturated cyclic ether composed of a five-membered oxygen-containing ring with a methyl substituent. Its ether oxygen provides moderate polarity and hydrogen-bond acceptor ability, while the saturated ring and methyl group contribute flexibility and hydrophobic character. The molecule’s chemical behavior is dominated by the stability and reactivity of the cyclic ether functionality.

References

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DOI: 10.1007/s13201-025-02608-w

2025. Comparative Analysis of Biotechnological and Catalytic Approaches to Synthesizing Organic Acids. Catalysis in Industry.
DOI: 10.1134/s2070050424700429

2024. Effect of bacterial diversity on the quality of fermented apple juice during natural fermentation of Hanfu apples. Food Science and Biotechnology.
DOI: 10.1007/s10068-024-01593-1