Trimethylcyclopentenyl Methylisopentenol
Synonyms: Ebanol, 3-Methyl-5-(2,2,3-Trimethyl-3-Cyclopentenyl) pent-4-en-2-ol (chemical name), isomer mixture (grade-dependent specification)
INCI / functions: fragrance (perfuming)
Definition
Trimethylcyclopentenyl Methylisopentenol is a synthetic odorant belonging to the terpenoid family (terpenic alcohols), used in perfumery for a woody “sandalwood-like” note and as a building block in fragrance accords. From a compositional standpoint, the ingredient mainly consists of 3-Methyl-5-(2,2,3-Trimethyl-3-Cyclopentenyl) pent-4-en-2-ol (often marketed as an isomer mixture), with possible controlled trace process-related impurities within the supplier’s specification limits. In cosmetics, its function is primarily perfuming; use is driven by compliance requirements (allergen/labeling) and formulation compatibility (solubilization, olfactory stability, packaging).
Cosmetics: fragrance (perfuming); subject to labeling obligations above threshold (see regulatory section).
Industrial use: component for technical perfumery, fragrance accords, and industrial formulations requiring a specific woody note.
Identification data and specifications
| Parameter | Value |
|---|
| Name (INCI) | Trimethylcyclopentenyl Methylisopentenol |
| Reported substance/ingredient (EU annexes) | 3-Methyl-5-(2,2,3-Trimethyl-3-Cyclopentenyl) pent-4-en-2-ol |
| Molecular formula | C₁₄H₂₄O |
| Molar mass | 208.34 g/mol |
| CAS number | 67801-20-1 |
| EC number | 267-140-4 |
Key constituents
| Class | Main components | Technical note |
|---|
| Terpenic alcohols / terpenoids | target substance (often as an isomer mixture) | primary driver of olfactory profile and physical behavior |
| Minor components (grade-dependent) | minor fractions/isomers, impurities within spec | can affect repeatability and olfactory stability |
| Controlled traces | process residues within limits | relevant for QC and SDS/CoA compliance |
Physicochemical properties (formulation-relevant)
| Property | Indicative value |
|---|
| Physical state | liquid |
| Color | colorless to pale yellow (grade-dependent) |
| Water solubility | very low / practically insoluble |
| Solubility | soluble in many organic solvents and fragrance bases |
| Boiling point | ~283 °C (indicative) |
| Flash point | ~108 °C (indicative) |
| Density | ~0.9 (indicative) |
Functional role in formulation
| Function | What it does in the formula | Operational notes |
|---|
| Fragrance | provides a woody, warm, rounded note in fragrance accords | performance depends on the matrix, synergy with other odorants, and long-term stability |
Formulation compatibility
| System / variable | Compatibility | Control notes |
|---|
| Emulsions and fragranced aqueous systems | to be assessed | often requires solubilizers; haze risk if fragrance load is high |
| Surfactant systems (rinse-off) | often compatible | verify clarity, hot/cold olfactive profile, interaction with polymers |
| Transparent polymer gels | sensitive | potential loss of clarity: optimize solubilization and addition order |
| Packaging | caution | run tests with plastics/seals (migration, stress cracking) |
| Olfactory stability | critical | monitor oxidation/note drift with light, air, and temperature |
Use guidelines (indicative)
| Context | Typical range | Technical note |
|---|
| Cosmetics (as a fragrance component) | trace – 0.1% (order of magnitude) | actual level depends on the fragrance concentrate and target profile |
| Technical/industrial perfumery | variable | define per specifications, VOC requirements, and process safety |
Typical applications
Fragranced leave-on products (creams, lotions, deodorants) and rinse-off products (shampoos, shower gels) as part of the fragrance composition.
Modern woody accords and fragrance bases where a warm/persistent effect is desired.
Quality, grades and specifications
| Topic | Detail |
|---|
| Grades | perfumery, technical/industrial (variable specs and purity) |
| Recommended controls | identity and GC profile, purity/isomer ratio, color/odor, water, oxidation stability markers (if specified) |
| Documentation | up-to-date CoA and SDS to align quality, safety, and applicable limits |
Safety, regulation and environment
| Topic | Operational guidance |
|---|
| EU framework (restrictions) | Cosmetic ingredient subject to restriction III/339 as a relevant entry in the annexes of EU Cosmetics Regulation update (EU) 2023/1545 (fragrance allergen update) |
| Reported substance/ingredient | 3-Methyl- 5-(2,2,3-Trimethyl- 3-Cyclopentenyl) pent-4-en-2-ol |
| Labeling obligation (Art. 19(1)(g)) | presence must be indicated in the ingredients list when exceeding the thresholds reported below |
| Practical hazards (SDS, grade-dependent) | possible skin sensitization; possible aquatic environmental hazards; apply risk assessment and spill management |
| Storage | tightly closed containers, cool conditions; minimize light/air exposure to limit olfactive drift; follow SDS |
| Environment | avoid release; manage residues according to classification and local regulations |
| Product type | Labeling threshold |
|---|
| Leave-on | 0.001% |
| Rinse-off | 0.01% |
Formulation troubleshooting
| Issue | Possible cause | Corrective actions |
|---|
| Haze in aqueous systems | insufficient fragrance solubilization | use a suitable solubilizer, pre-dilute in fragrance phase, optimize addition order |
| Note drift over time | thermal stress, light, oxygen, matrix interactions | barrier packaging, compatible antioxidants in the fragrance, controlled storage conditions |
| Packaging interaction | polymer/seal incompatibility | accelerated testing, switch materials (e.g., glass or compatible plastics), reduce fragrance load |
| Label non-compliance | thresholds exceeded without declaration | calculate finished-product concentration, verify fragrance CoA/IFRA info, update labeling artwork |
Conclusion
Trimethylcyclopentenyl Methylisopentenol is a perfuming ingredient used to build modern woody notes, technically manageable but governed by two critical points: (1) EU compliance as a fragrance allergen entry requiring labeling above 0.001% in leave-on and 0.01% in rinse-off products; (2) formulation robustness driven by solubilization, olfactive stability, and packaging compatibility. Proper use requires grade selection, QC alignment (GC/CoA), and consistency with SDS and labeling requirements.
Trimethylcyclopentenyl Methylisopentenol 
