2-Methoxynaphthalene (12-11-7) Physical and Chemical Properties
2-Methoxynaphthalene
A methoxy-substituted naphthalene aromatic used as a fragrance/flavor intermediate and specialty chemical building block for formulation and R&D.
| CAS Number | 12-11-7 |
| Family | Naphthalenes |
| Typical Form | Powder or crystalline solid |
| Common Grades | EP, JP |
2-Methoxynaphthalene is an alkyl aryl ether belonging to the naphthalene family; its molecular formula is \(\ce{C11H10O}\). Structurally, it is a naphthalene core bearing a methoxy substituent at the 2-position (the 2‑naphthyl methyl ether motif). The substituent introduces a single oxygen lone‑pair donor (hydrogen‑bond acceptor count = 1) and slightly increases the local electron density of the adjacent aromatic ring system through resonance donation. The compound is neutral (formal charge = 0) and relatively nonpolar overall, with a small topological polar surface area and low hydrogen‑bonding capacity combined with an extended aromatic surface.
As an aromatic methyl ether, 2‑methoxynaphthalene displays class-typical behavior: modest chemical inertness toward mild nucleophiles and bases, susceptibility to electrophilic aromatic substitution at activated positions of the naphthalene ring, and potential for O‑demethylation under strong oxidative or metabolic conditions. Physicochemically it is lipophilic (high log P) and poorly soluble in water but readily miscible with nonpolar media and many organic solvents; this disposition underlies its use in fragrance and flavor applications as well as its occurrence as a lipophilic intermediate in organic synthesis. The compound forms white crystalline solids under ambient conditions and has a characteristic sweet, orange‑blossom/acetonic aroma profile used in odor and flavor applications.
Common commercial grades reported for this substance include: EP, JP.
Basic Physical Properties
Density
No experimentally established value for this property is available in the current data context.
Melting Point
Melting point: \(72\ \mathrm{^\circ C}\).
The substance crystallizes as white shiny crystals and, depending on sample handling, is described experimentally as pellets, large crystals, dry powder, or other solid forms. Crystalline behavior is consistent with the single methoxy substitution on the polyaromatic core.
Boiling Point
Boiling point: \(274.00\ \mathrm{^\circ C}\) @ \(760.00\ \mathrm{mmHg}\).
The relatively high boiling point reflects the large aromatic surface area and relatively low volatility compared with monoaromatic methyl ethers of smaller ring size.
Vapor Pressure
Vapor pressure: \(0.00823\ \mathrm{mmHg}\).
The low vapor pressure at ambient conditions is consistent with a nonvolatile, high‑molecular‑weight aromatic ether.
Flash Point
No experimentally established value for this property is available in the current data context.
Chemical Properties
Solubility and Phase Behavior
Reported solubility: insoluble in water, miscible in oils; soluble (in ethanol).
The compound's low aqueous solubility derives from its extended hydrophobic aromatic framework and small polar headgroup (a single methoxy oxygen). It dissolves readily in organic solvents and oils, reflecting its use in fragrance formulations and flavoring matrices. Partitioning behavior is consistent with high lipophilicity and low aqueous mobility.
Reactivity and Stability
2‑Methoxynaphthalene is chemically typical of aromatic methyl ethers: stable under normal handling and storage at ambient temperature, generally resistant to mild hydrolysis, but susceptible to O‑demethylation under strong oxidative conditions or in metabolic systems. The methoxy substituent is an electron‑donating group by resonance, increasing the reactivity of some ring positions toward electrophilic substitution compared with unsubstituted naphthalene. The compound may cause irritation on prolonged inhalation or skin contact; aquatic toxicity has been noted in hazard classification summaries.
Handle as a stable organic aromatic ether but avoid strong oxidants and conditions that promote demethylation or ring oxidation.
Thermodynamic Data
Standard Enthalpies and Heat Capacity
No experimentally established value for this property is available in the current data context.
Molecular Parameters
Molecular Weight and Formula
Molecular formula: \(\ce{C11H10O}\)
Molecular weight: \(158.20\ \mathrm{g\ mol^{-1}}\)
Exact mass (monoisotopic): \(158.073164938\ \mathrm{Da}\)
The molecular weight and exact mass reflect the substituted naphthalene skeleton plus a single methoxy substituent.
LogP and Polarity
Computed and experimental partitioning descriptors: \(XLogP = 3.5\); \(\log P = 3.47\).
Topological polar surface area (TPSA): \(9.2\).
Hydrogen bond donor count: \(0\).
Hydrogen bond acceptor count: \(1\).
Rotatable bond count: \(1\).
These values indicate a lipophilic molecule with minimal polar surface area and limited hydrogen‑bonding potential, consistent with strong partitioning into organic phases and low aqueous solubility.
Structural Features
SMILES: COC1=CC2=CC=CC=C2C=C1
InChI: InChI=1S/C11H10O/c1-12-11-7-6-9-4-2-3-5-10(9)8-11/h2-8H,1H3
InChIKey: LUZDYPLAQQGJEA-UHFFFAOYSA-N
The methoxy group at the 2‑position is conjugated with the naphthalene π system; resonance donation raises electron density at proximal positions and modulates spectral and reactivity properties relative to unsubstituted naphthalene. Spectroscopic datasets available experimentally include 1H and 13C NMR, FT‑IR/ATR, Raman, and GC‑MS fragmentation patterns (major m/z = 158).
Crystal structure data (experimental): Hermann–Mauguin space group symbol: P 1 21/c 1; Hall space group symbol: -P 2ybc; space group number: 14. Unit cell parameters: \(a = 17.1040\ \mathrm{\AA}\), \(b = 6.0120\ \mathrm{\AA}\), \(c = 8.1100\ \mathrm{\AA}\); \(\alpha = 90.00^\circ\), \(\beta = 95.460^\circ\), \(\gamma = 90.00^\circ\); \(Z = 4\), \(Z' = 1\). Residual factor: 0.046.
Identifiers and Synonyms
Registry Numbers and Codes
CAS number: 12-11-7
European Community (EC) number: 202-213-6
UNII: VX2T1Z50C4
FEMA number: 4704
ChEBI: CHEBI:177835
ChEMBL: CHEMBL195857
DSSTox Substance ID: DTXSID7044392
Other structural identifiers: InChI and InChIKey and SMILES are given above in the Structural Features subsection.
Synonyms and Structural Names
Common synonyms and depositor-supplied names include: 2-methoxynaphthalene; Methyl 2-naphthyl ether; 2-Naphthol methyl ether; beta-Naphthyl methyl ether; Nerolin; beta-Methoxynaphthalene. Additional historical and vendor synonyms are associated with material listings and impurity standards.
Industrial and Commercial Applications
Representative Uses and Industry Sectors
2‑Methoxynaphthalene is used as a fragrance ingredient and flavoring agent; it is listed among flavouring/odorant classes and appears in fragrance and odorant formulations. It has application as a flavoring adjuvant in food industry uses and is included in product types where aromatic, sweet, or orange‑blossom notes are required. Industrial sectors reporting use include flavor and fragrance manufacturing, food and beverage processing (as a flavoring agent or adjuvant), and general chemical manufacturing where polyaromatic intermediates are handled.
Role in Synthesis or Formulations
In formulations, the compound functions as a lipophilic odorant with good solubility in oils and organic solvents. In synthetic chemistry, substituted methoxynaphthalenes can serve as intermediates or reference standards; the methoxy substituent can be selectively transformed (e.g., demethylation, directed functionalization of the naphthalene ring) in multi‑step syntheses. No niche brand names or proprietary formulations are described here.
Safety and Handling Overview
Acute and Occupational Toxicity
No detailed, standardized acute toxicology numeric values (e.g., LD50) are provided in the current data context. Reported hazard summaries note potential for irritation on contact and inhalation; aggregated hazard classifications include aquatic chronic hazard descriptors with associated precautionary recommendations. When used as a flavoring at typical levels, authoritative evaluations have indicated no safety concern at current levels of intake for that use classification.
Occupational precautions appropriate for low‑to‑moderate volatility aromatic ethers are recommended: minimize vapor and dust exposure, use engineering controls (local exhaust ventilation) and appropriate personal protective equipment (gloves and eye protection), and avoid skin contact and inhalation of concentrates.
Storage and Handling Considerations
Store in a cool, well‑ventilated area away from strong oxidizers and ignition sources; keep containers tightly closed and protected from prolonged exposure to heat and light. Given the compound's lipophilicity and potential aquatic hazard, prevent release to drains and surface waters. For detailed hazard, transport and regulatory information, users should refer to the product‑specific Safety Data Sheet (SDS) and local legislation.
For formulation and quality control, select commercial grade consistent with the intended use (e.g., flavoring grade vs. technical grade). Common commercial grades reported for this substance include: EP, JP.
