Birch tar (rectified) (CAS 8001-88-5) — Smoky Base Note Fragrance Ingredient
Birch tar (rectified)
CAS 8001-88-5
What Is Birch tar (rectified)?
Birch tar is a thick, smoky-scented oil traditionally obtained by distilling birch bark. It’s found in leather accords, masculine fragrances, and some niche perfumes. Its intense campfire-like aroma adds depth and rugged character to fragrances. This ingredient matters because it creates an unmistakable ‘burnt wood’ effect that perfumers use to evoke wilderness, tobacco, or vintage leather goods. Modern rectified versions remove harsh phenolic compounds while retaining the desirable smoky core.
Safety Profile
USE WITH AWARENESSWhat Does Birch tar (rectified) Smell Like?
Birch tar opens with an aggressive, medicinal smoke that recalls charred wood and campfire embers. Within minutes, the phenolic edges soften into a complex heart of leathery creosote, faintly sweet birch sap, and tarry depth. The dry-down lasts for days – a warm, animalic base note with hints of smoked meat and antique saddles. Like liquid barbecue in its raw form, rectified versions offer a polished ‘leather jacket’ effect without overwhelming harshness. Pair with vanilla to soften or oakmoss to amplify its vintage character.
Scent Profile
In Famous Fragrances
Fragrance associations may not reflect actual formulations.
This legendary fragrance uses birch tar to recreate the scent of Russian leather – the birch gives the characteristic smoky, tarry backbone that defined historical leather tanning processes.
Andy Tauer employs birch tar as the central ‘campfire’ note, blending it with caraway and jasmine to create a photorealistic Western landscape of leather saddles and wood smoke.
One of the earliest uses of birch tar in perfumery, creating a stark contrast between the smoky leather base and bright citrus-floral top notes in this Austrian classic.
Modern interpretation using rectified birch tar to suggest whiskey-soaked wooden bars and tobacco, softened with vanilla and rum accords for contemporary appeal.
Middle Eastern take on leather fragrances where birch tar provides the ‘black leather jacket’ effect, amplified with saffron and amber for luxurious intensity.
Chemistry, Properties & Perfumer Guide
The Chemistry
Birch tar is produced through destructive distillation of birch bark (Betula spp.), primarily B. pendula and B. pubescens. The crude tar contains hundreds of compounds including guaiacol (15-20%), cresols (10-15%), xylenols, and various phenolic derivatives. Rectification removes most polycyclic aromatic hydrocarbons (PAHs) and reduces phenol content to <1%. Key markers include betulin (a triterpene) and methyl salicylate. The smoky character comes from lignin decomposition products similar to those found in wood smoke and whiskey aging processes.
Chemical Composition
Physical & Chemical Properties
| Appearance | Dark brown viscous liquid |
|---|---|
| Solubility | Soluble in alcohol, insoluble in water |
| Flash Point | >100°C |
Key Constituent Properties
| Constituent | CAS | MW | BP °C | XLogP | Vapor P. |
|---|---|---|---|---|---|
| Guaiacol | 90-05-1 | 124.14 | 205°C | 1.8 | 0.13 mmHg |
| m-Cresol | 108-39-4 | 108.14 | 202°C | 2.0 | 0.11 mmHg |
Perfumer Guide
| Application | Typical % | Range | Notes |
|---|---|---|---|
| Fine Fragrance | 0.1-0.5% | Up to 1% | Exceeding 1% requires careful balancing |
| Leather Accords | 0.5-2% | Up to 3% | Core component of leather bases |
| Tobacco Accords | 0.3-1% | Up to 1.5% | Adds smoked dimension |
| Functional Fragrances | 0.01-0.1% | Up to 0.2% | Trace amounts for masculine character |
Classic Accords
Tip: Pre-dilute to 10% in ethanol before blending to improve miscibility with other materials.
Alternatives & Comparisons
Less phenolic alternative from juniper wood, offering similar smoky-leathery effects with more medicinal top notes. Preferred for modern leather accords requiring IFRA compliance.
Synthetic leather base with sharper, less smoky character. Used when birch tar’s phenolic properties are problematic but leather effect is desired.
Provides smoky-woody facets without phenolic harshness. Works well in combination with birch tar at reduced levels.
Safety, Regulatory & Sustainability
⚠ Regulatory Disclaimer
General reference only. IFRA, REACH, EU Cosmetics Regulation standards update periodically. Consult current IFRA Standards Library before formulating. Not legal or regulatory advice.
IFRA Status
Restricted under IFRA 49 (2019): Maximum 0.01% in leave-on products due to phenol content. Requires allergen labeling for guaiacol and cresols.
EU Allergen Declaration
Must be declared if guaiacol >0.001% or cresols >0.01% in final product. Common allergens present: Guaiacol (CAS 90-05-1), m-Cresol (CAS 108-39-4).
GHS Classification
RIFM Assessment
RIFM assessment complete (2016). Use restricted due to sensitization potential of phenolic compounds. Rectified form preferred for reduced risk profile.
Sustainability
Traditional birch tar production is sustainable when sourced from managed Nordic forests where birch is abundant. Modern rectification reduces environmental impact by removing hazardous PAHs. Synthetic alternatives exist but lack the complexity of natural birch tar. Responsible sourcing programs ensure bark harvesting doesn’t damage trees, as only outer bark is collected.
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References
- Karlberg et al. (1992). Birch tar oil – Composition and allergenicity. Contact Dermatitis. PMID 1395597
- IFRA Standards Library (2023). Restriction of birch tar oil. IFRA 49
- Arctander S. (1960). Perfume and Flavor Materials of Natural Origin.
Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Mar 2026.
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