Syringol

Technical Ingredient Overview

• 🏭 Manufacturer — Commonly produced for flavor/aroma industry

• 🔎 IUPAC Name — 2,6-Dimethoxyphenol

• 🧪 Synonyms — Syringol, 2,6-Dimethoxy-1-hydroxybenzene, Pyrogallol 1,3-dimethyl ether, DMP

• 🧬 Chemical Formula — C₈H₁₀O₃

• 📂 CAS Number — 91-10-1

• 📘 FEMA Number — 3137

• 🇪🇺 EC Number — 202-041-1

• ⚖️ Molecular Weight — 154.16 g/mol

• 🌡️ Melting Point — 50-57°C

• 🌡️ Boiling Point — 261°C

• 📝 Odor Type — Smoky / Phenolic

• 📈 Odor Strength — High

• 👃🏼 Odor Profile — Intense smoky, phenolic, woody, bacon-like with balsamic and powdery nuances

• ⚗️ Uses — Tobacco, leather, incense bases; smoky modifiers in savory-gourmand and whisky-inspired compositions

• 🧴 Appearance — Off-white to dark brown crystalline solid

• 💧 Solubility — Soluble in alcohol, ether, acetone, methanol; slightly soluble in water (20 mg/ml)

What is Syringol?

Syringol is a dimethoxylated phenol, structurally related to guaiacol and eugenol, produced through pyrolytic degradation of lignin or synthesized from veratrole derivatives. It is one of the principal volatile compounds in natural wood smoke, representing a signature aromatic component in smoke aroma profiles. The molecule derives its name from syringin, a glycoside isolated from Syringa vulgaris (common lilac), due to their structural similarity.

Naturally occurring in wood smoke, Syringol is formed specifically through thermal decomposition of the sinapyl alcohol component of lignin during pyrolysis. It is particularly abundant in smoke from hardwood sources, as hardwood lignin contains higher proportions of syringyl units compared to softwood lignin (which yields primarily guaiacol derivatives). This makes Syringol a key reference compound in both flavoring systems and olfactory reconstructions of smoke effects.

Historical Background

Syringol was first identified as a lignin pyrolysis product in the early 20th century during studies of wood combustion chemistry. Its role as a principal aromatic constituent of smoke became established through research into wood smoke composition for food preservation and flavoring applications. The compound gained commercial significance in the mid-20th century with the development of liquid smoke flavorings, where it typically comprises 13-14% of commercial smoke products by mass, alongside guaiacol.

In perfumery, Syringol's adoption has been more recent, primarily within niche and artisanal fragrance circles focused on realistic smoke, leather, and incense reconstructions. Its intense phenolic character and high olfactory impact make it a specialist ingredient rather than a mainstream perfumery material.

Olfactory Profile

Scent Family

Smoky-phenolic with woody-balsamic undertones

Main Descriptors

Top Note: Harsh phenolic smoke, immediately recognizable burnt character

Heart Note: Woody-charred, bacon-like, balsamic with medicinal nuances

Base Note: Sweet-powdery dryout with faint resinous quality

Detailed Character:

Syringol delivers intensely smoky, phenolic notes that evoke charred wood, burnt sugar, bacon, and smoked meats. At low concentrations (1-10 ppm), it exhibits smoky, woody, and cedar characteristics. Higher concentrations reveal musty, earthy, and pungent attributes. The compound is notably less harsh than pure guaiacol, offering a rounder, more balsamic smoke quality.

Differentiation from Guaiacol:

While structurally related, Syringol is considered the primary aroma contributor in smoke (responsible for smoky scent), whereas guaiacol contributes more to smoke taste. Syringol's additional methoxy group provides greater sweetness and less medicinal harshness than guaiacol.

Intensity & Volatility

• Odor Strength: Very high; effective at trace concentrations

• Volatility: Moderate; functions primarily as top-to-heart note modifier

• Tenacity: High persistence with long-lasting phenolic character

• Impact: Immediate recognition of smoke quality

Applications in Fine Fragrance

Functional Roles:

• Smoky booster for tobacco, charcoal, incense, and oud accords

• Balsamic/phenolic depth in leather compositions

• Specialty note in smoky gourmands, whisky, and liquorice profiles

• Realistic charred-wood effects in niche perfumery

• Burning incense reconstructions

Usage Guidelines:

Used sparingly for effects rather than volume. Syringol is a high-impact modifier requiring careful dosage control.

Typical Concentrations:

• Fine Fragrance: 0.001-0.1% (trace to moderate impact)

• Specialty/Niche: Up to 0.5% for extreme smoke effects

• Functional Products: Variable based on desired intensity

Synergistic Combinations:

• Guaiacol, Creosol, Methylguaiacol: Authentic smoke complexity

• Isobutyl Quinoline, Birch Tar: Enhanced leather-smoke effects

• Cade Oil, Labdanum, Peru Balsam: Balsamic-resinous depth

• Patchouli, Vetiver: Earthy-smoky foundations

• Whisky Lactone, Vanillin, Coffee Absolutes: Gourmand-smoke applications

Industrial & Technical Uses

Flavor Applications (FEMA 3137):

• Smoke flavorings for seafood, meat, and poultry

• Spice blends and savory seasonings

• Whisky, rum, and aged spirit aromatization

• Smoked tea and coffee profiles

• BBQ and grilled food flavoring systems

Beverage Industry:

Key compound in smoke-tainted wine research; used to recreate aged barrel and smoky spirit characteristics.

Perfumery Applications:

Employed in leather, tobacco, incense, and aromatic woody compositions for charred-phenolic realism. Particularly valued in niche perfumery for authentic smoke reconstructions.

Note: Syringol is frequently combined with other pyrolysis-derived phenolics (creosol, methylguaiacol, 4-methylsyringol) to recreate multi-dimensional burnt, aged, or smoked effects with greater authenticity than single-component approaches.

Regulatory & Safety Overview

IFRA Status: Not restricted in perfumery applications under IFRA 51st Amendment

EU Allergens: Not listed among the 26 declarable fragrance allergens under EC Regulation 1223/2009

FEMA GRAS: ✅ FEMA 3137; approved for use in flavor applications

ECHA (REACH): Registered; not classified as hazardous under CLP at standard concentrations

Toxicology:

• Low acute toxicity at perfumery and flavoring concentrations

• Potential sensitizer at high concentrations; monitor dosage in leave-on applications

• Readily biodegradable; not classified as PBT (Persistent, Bioaccumulative, Toxic) or vPvB (very Persistent, very Bioaccumulative)

• Generally recognized as safe at regulated concentrations

Safety Recommendation: ✅ Safe in regulated perfumery and flavor use. Exercise restraint due to high olfactory impact and persistence.

Chemical & Technical Properties

Structural Characteristics:

• Symmetrical dimethylated derivative of pyrogallol

• Two methoxy groups (-OCH₃) in flanking (2,6) positions

• Phenolic hydroxyl group (-OH) at position 1

• Related to guaiacol (monomethoxyphenol) and eugenol

Physical Properties:

• Density: ~1.1 g/cm³ (predicted)

• Refractive Index: n₂₀/D 1.52 (predicted)

• pKa: 9.97

• Solubility: Higher in organic solvents than water; typical for phenolic compounds

Stability:

• Stable under normal storage conditions

• May darken due to air oxidation of impurities (typical samples appear brown)

• Degradation occurs in strongly acidic or basic environments

• Thermal stability maintained until pyrolysis temperatures (>400°C)

Biosynthetic Origin:

Formed during lignin pyrolysis specifically from syringyl units (sinapyl alcohol-derived lignin components). High syringol content indicates hardwood source, as softwood lignins lack syringyl components.

References

• American Chemical Society. (2022, March 23). Molecule of the Week: Syringol. Retrieved from https://www.acs.org/molecule-of-the-week/archive/s/syringol.html

• Arctander, S. (1969). Perfume and Flavor Chemicals (Aroma Chemicals). Self-published, Montclair, NJ.

• Baltes, W., Wittkowski, R., & Söchtig, I. (1981). Composition of liquid smoke preparations for smoking food. Deutsche Lebensmittel-Rundschau, 77, 365-370.

• European Commission. (2024). CosIng – Cosmetic Ingredient Database. Retrieved from https://ec.europa.eu/growth/tools-databases/cosing/

• FEMA (Flavor and Extract Manufacturers Association). (2024). FEMA GRAS Database – FEMA No. 3137. Retrieved from https://www.femaflavor.org

• Guillén, M. D., & Manzanos, M. J. (1996). Study of the volatile composition of an aqueous oak smoke preparation. Food Chemistry, 55(3), 283-297.

• Guillén, M. D., Manzanos, M. J., & Zabala, L. (1995). Study of a commercial liquid smoke flavouring by means of gas chromatography/mass spectrometry and Fourier transform infrared spectroscopy. Journal of Agricultural and Food Chemistry, 43(2), 463-468.

• Kostyra, E., & Barylko-Pikielna, N. (2006). Volatiles composition and flavour profile identity of smoke flavourings. Food Quality and Preference, 17(1-2), 85-95.

• Maga, J. A. (1987). The flavor chemistry of wood smoke. Food Reviews International, 3(1-2), 139-183.

• Wang, H., & Chambers, E., IV. (2018). Sensory characteristics of various concentrations of phenolic compounds potentially associated with smoked aroma in foods. Molecules, 23(4), 780. https://doi.org/10.3390/molecules23040780