Alpha-Terpineol Introduction
Alpha-Terpineol (CAS 98-55-5), also known as p-menth-1-en-8-ol, is a monocyclic monoterpene tertiary alcohol with the molecular formula C₁₀H₁₈O. It presents as a colorless to slightly yellow viscous liquid (mp 31–35°C, bp 217–218°C / 423–424°F) with a pleasant lilac-like, pine, and citrus odor. Alpha-Terpineol is one of the most commercially important terpene alcohols, listed under FEMA 3045 and recognized as GRAS (Generally Recognized As Safe) for food flavor use. It occurs naturally in over 150 plant species, including pine oil, cajuput oil, eucalyptus oil, tea tree oil, and petitgrain oil.
The compound is produced industrially by acid-catalyzed hydration of α-pinene or limonene, followed by fractional distillation to achieve the desired α-isomer content. UET Chemical supplies Alpha-Terpineol at ≥98.0% purity (GC), manufactured under controlled conditions with consistent odor profile and physical properties. Each shipment includes COA, GC chromatogram, TDS, and SDS. This material serves fragrance houses, flavor manufacturers, pharmaceutical formulators, and industrial solvent users across North America, Europe, and Asia-Pacific.
Chemical Information
| Item | Details |
|---|---|
| CAS No. | 98-55-5 |
| EINECS No. | 202-680-6 |
| MDL No. | MFCD00001557 |
| FEMA No. | 3045 |
| IUPAC Name | 2-(4-Methylcyclohex-3-en-1-yl)propan-2-ol |
| Synonyms | p-Menth-1-en-8-ol; α,α,4-Trimethyl-3-cyclohexene-1-methanol; 2-(4-Methyl-3-cyclohexenyl)-2-propanol; Terpenol; α-Terpineol |
| Molecular Formula | C₁₀H₁₈O |
| Molecular Weight | 154.25 |
| Melting Point | 31–35°C |
| Boiling Point | 217–218°C (423–424°F) at 760 mmHg |
| Density | 0.93 g/mL (25°C) |
| Flash Point | 90°C (194°F), closed cup |
| Refractive Index | n²⁰/D 1.482–1.485 |
| Vapor Pressure | 6.48 Pa (23°C) |
| Water Solubility | 0.71 g/L (25°C) |
| LogP | 2.50 |
| pKa | 15.09 ± 0.29 (predicted) |
| Chemical Class | Monocyclic monoterpene tertiary alcohol |
| Natural Occurrence | Pine oil, cajuput oil, eucalyptus oil, tea tree oil, petitgrain oil, cardamom oil |
| GHS Classification | GHS07 (Irritant) |
Alpha-Terpineol Specifications
| Test Item | Specification |
|---|---|
| Appearance | Colorless to slightly yellow viscous liquid |
| Odor | Characteristic lilac-pine odor |
| Assay (GC) | ≥98.0% |
| Specific Gravity (d²⁰/₄) | 0.9300–0.9450 |
| Refractive Index (n²⁰/D) | 1.482–1.485 |
| Acid Value | ≤1.0 mg KOH/g |
| Color (Gardner) | ≤2 |
| Water Content | ≤0.5% |
📄 Documents available: COA, GC Chromatogram, TDS, SDS, IFRA Compliance Statement (for fragrance grade)
Alpha-Terpineol Applications
| Application | Role | Typical Use Level |
|---|---|---|
| Fragrance Compounding | Lilac, pine, citrus, floral note modifier | 1%–15% in fragrance concentrate |
| Flavor & Food | GRAS flavoring agent (FEMA 3045) | 5–50 mg/kg in finished food |
| Pharmaceutical / Cosmeceutical | Antimicrobial & anti-inflammatory active | 0.1%–2% in topical formulations |
| Industrial Solvent | Solvent for plastics, inks, lacquers, glass decoration | 5%–100% in solvent blends |
| Mineral Flotation | Frothing agent in sulfide ore flotation | 20–100 g/ton ore |
| Agrochemical Intermediate | Precursor for terpene-based pesticides | Per synthetic route |
Key Advantages
GRAS & FEMA-listed — Recognized as safe for food flavor applications (FEMA 3045). Suitable for use in beverages, baked goods, confectionery, and dairy products within regulatory limits. No additional safety dossier required for food use in most jurisdictions.
Versatile odor profile — Combines lilac, pine, citrus, and woody-floral notes in a single molecule. Acts as both a top-note modifier and a fixative, reducing the number of raw materials needed in a fragrance formula.
Low volatility, high substantivity — Vapor pressure of only 6.48 Pa at 23°C ensures long-lasting odor on skin and in products. Outperforms many synthetic alternatives in longevity tests for personal care applications.
Bio-based & renewable — Derived from pinene or limonene (both abundant in turpentine and citrus peel oil). Supports natural/organic product claims and aligns with green chemistry sourcing requirements.
Alpha-Terpineol Storage and Stability
| Item | Guideline |
|---|---|
| Shelf Life | 24 months (unopened, from manufacture date) |
| Temperature | Below 30°C (86°F); avoid freezing (may crystallize below 31°C) |
| Container | Keep tightly sealed; HDPE or glass with PTFE-lined cap |
| Atmosphere | Nitrogen blanket optional for long-term bulk storage |
| Light | Store in a cool, dark place; prolonged UV exposure may cause discoloration |
Stability notes:
- Alpha-Terpineol may crystallize at temperatures below 31°C. This is a physical change only — gently warm to 35–40°C to re-liquefy without affecting quality.
- Avoid contact with strong acids (may catalyze dehydration to limonene/terpinolene) and strong oxidizers.
- Flash point is 90°C (194°F) — store away from ignition sources. Classify as combustible liquid per GHS.
- Prolonged exposure to air and light may cause gradual yellowing. Use amber containers or opaque drums for extended storage.
- Odor stability is excellent under recommended conditions. Off-odors (turpentine-like) indicate oxidation or contamination — verify by GC before use.
Alpha-Terpineol Usage Guide
Step 1 – Verify upon receipt: Check appearance (colorless to slightly yellow liquid), odor (characteristic lilac-pine), and GC assay (≥98%) against the COA. Confirm refractive index (1.482–1.485) and specific gravity (0.930–0.945).
Step 2 – Handling precautions: Work in a well-ventilated area. Wear nitrile gloves and safety glasses. Flash point 90°C (194°F) — keep away from open flames and hot surfaces. Avoid prolonged skin contact (may cause mild irritation in sensitive individuals).
Step 3 – Formulation use:
- Fragrance: Add during the blending stage at room temperature. Compatible with most perfume bases (alcoholic, oil-based, emulsion). Typical use: 1–15% of fragrance concentrate.
- Flavor: Dilute in ethanol or propylene glycol before incorporation. Follow FEMA/IOFI usage level guidelines for the target food category.
- Industrial solvent: Use neat or in blends with other terpenes/alcohols. Effective for dissolving resins, waxes, and nitrocellulose.
Step 4 – Waste disposal: Collect waste in labeled containers. Biodegradable; incineration or approved chemical waste disposal per local regulations. Do not discharge to waterways.
Compatibility
| ✅ Compatible | ⚠️ Caution | ❌ Incompatible |
|---|---|---|
| Ethanol, DPG, IPM, most essential oils, fixed oils, waxes, resins, nitrocellulose | Prolonged heat >80°C (may dehydrate), strong mineral acids (catalyzes elimination) | Concentrated H₂SO₄, HCl (dehydration to terpinolene/limonene), strong oxidizers (KMnO₄, CrO₃) |
Why Source Alpha-Terpineol from UET Chemical
| Advantage | Details |
|---|---|
| Consistent Odor Profile | Every batch evaluated by trained perfumers; lilac-pine character verified and documented |
| Full Analytical Package | COA includes GC assay, specific gravity, refractive index, acid value, color, water content |
| GMP-Aligned Production | Manufactured in ISO 22716 / GMP-certified facility with dedicated terpene processing line |
| Batch Consistency | GC assay variation < ±0.5% between batches; RI variation < ±0.001 |
| Flexible MOQ | 1 kg sample bottle; 25 kg or 200 kg drum for bulk; custom volumes on request |
| Regulatory Support | REACH registered; FEMA 3045 documentation; IFRA compliance statement available |
| Fast Response | Inquiry answered within 12 hours; sample ships in 1–3 days |
Alpha-Terpineol FAQ
Q1: What is the difference between CAS 98-55-5 and CAS 8000-41-7?
CAS 98-55-5 refers specifically to α-Terpineol (the alpha isomer, ≥98% α-content). CAS 8000-41-7 refers to Terpineol (mixed isomers) — a blend of α-, β-, γ-, and δ-terpineol, typically containing 50–70% α-terpineol. For fragrance applications requiring a defined odor profile, CAS 98-55-5 is preferred. For industrial solvent or flotation use, the mixed-isomer product (8000-41-7) may be more cost-effective.
Q2: Why does my Alpha-Terpineol solidify in winter?
Alpha-Terpineol has a melting point of 31–35°C. In cold climates or unheated warehouses, it will crystallize into a white solid mass. This is a reversible physical change — gently warm the container to 35–40°C (do not exceed 50°C) to re-liquefy. Quality and odor are unaffected.
Q3: Is Alpha-Terpineol safe for use in food and cosmetics?
Yes. It is listed as FEMA 3045 and recognized as GRAS (Generally Recognized As Safe) by the U.S. FDA for food flavor use. In cosmetics, it is permitted under EU Cosmetics Regulation (EC) No 1223/2009. It is listed as a fragrance allergen under Annex III, meaning it must be declared on the label when present above 0.001% (leave-on) or 0.01% (rinse-off).
Q4: What analytical method is used for purity testing?
We use capillary GC (e.g., DB-WAX or equivalent polar column, FID detection) to quantify α-terpineol content and identify impurities (terpinolene, limonene, γ-terpineol, etc.). A full GC chromatogram with peak integration is included with every COA.
Q5: What is the lead time for bulk orders?
- In-stock (25 kg drum): Ships in 5–7 business days after payment.
- 200 kg drum or custom specs: 10–15 business days production.
- Sea freight: 25–35 days (North America), 20–30 days (Europe), 7–15 days (SE Asia).
Q6: Is Alpha-Terpineol classified as a dangerous good for shipping?
With a flash point of 90°C (194°F), Alpha-Terpineol is not classified as a dangerous good under IATA/IMDG (flash point >60°C). It ships as non-regulated general cargo by air and sea. However, it is classified as a combustible liquid under GHS and should be stored and handled accordingly. No UN number or DG declaration is required for transport.
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