Galaxolide (HHCB) CAS 1222-05-5

Introduction to Galaxolide

Galaxolide is a colorless to pale-yellow viscous liquid belonging to the polycyclic musk family. A hexamethyl-substituted cyclopenta-benzopyran structure provides a heavy, sweet, powdery odour profile with extremely low volatility. Formulators rely on it as a base-note fixative in fine fragrances, laundry care, and personal-care wash-off products.

Compared with Tonalide (AHTN), HHCB delivers roughly 15–25% higher substantivity on cotton after a 7-day dry-down (headspace GC, 25 °C) and a sweeter, more powdery dry-down profile. Against macrocyclic musks (e.g., Ambrettolide), HHCB costs 80–90% less while maintaining comparable diffusion in wash-off systems. One practical caution: pure HHCB is highly lipophilic (log P ~5.9) and poorly soluble in high-ethanol or high-water systems without co-solvents; pre-dissolve it in dipropylene glycol (DPG) or isopropyl myristate (IPM) to prevent crystallisation in clear aqueous formulas.

Key Features of Galaxolide

• Zero nitro, non-discolouring. Lacking aromatic nitro groups, HHCB does not undergo photo-reduction under UV light. White fabrics and clear cosmetics remain colourless, avoiding the yellow/red shifts typical of legacy nitro-musks.
• Exceptional base-note substantivity. Extremely low vapour pressure (~0.001 mmHg at 25 °C) and high lipophilicity allow the molecule to bind tightly to keratin and cellulose, extending fragrance longevity on skin and textiles for days.
• High chemical stability. The saturated polycyclic backbone resists hydrolysis and oxidation. HHCB remains fully intact in highly alkaline liquid laundry detergents (pH 10–11) and survives active bleach or protease enzymes without odour degradation.
• Excellent blending synergy. Acts as a universal blender that smooths harsh aldehydic top notes and boosts floral or woody heart notes without masking their primary character.

Galaxolide Chemical & Physical Properties

Applications of Galaxolide

Fine fragrances (EDP/EDT): Used at 5–20% of the fragrance concentrate. The low volatility anchors highly volatile citrus and floral top notes, providing a smooth, clean, musky dry-down that lasts 8–12 hours on skin blotter tests.

Fabric softeners and dryer sheets: Dosed at 0.5–2.0% in the final emulsion. The high lipophilicity drives strong adsorption onto cotton and polyester fibres during the rinse cycle, releasing a persistent bloom during tumble drying and ironing.

Liquid laundry detergents: Added at 0.1–0.5%. The polycyclic structure withstands anionic surfactants (LAS/AES) and high alkalinity. It deposits onto fabrics during the wash phase, leaving a residual scent that survives line-drying.

Body wash and shampoo: Formulated at 0.2–1.0%. Despite being a wash-off product, the high log P (~5.9) ensures sufficient deposition onto skin and hair keratin, providing a lingering clean-musk feel post-shower.

Storage & Safety Precautions for Galaxolide

Storage conditions. Store in tightly sealed HDPE or steel drums at 10–30 °C, away from direct sunlight. Pure HHCB is a supercooled liquid at room temperature but may crystallise if exposed to temperatures below 10 °C for extended periods. If crystallisation occurs, gently warm the drum to 30–40 °C in a water bath and stir to re-melt. Do not use open flames or high-heat steam, which can cause localised thermal degradation.

Safety and PPE. Not classified as hazardous under GHS. HHCB is a known mild skin sensitiser in rare cases; follow IFRA (International Fragrance Association) concentration limits for leave-on and wash-off categories. Wear standard nitrile gloves and safety glasses during drum transfers to prevent sticky residue. Spills are non-toxic but highly slippery; clean with warm water and detergent.

Transport classification. Non-DG. Not regulated under IMDG, IATA, or ADR. Ship as standard general cargo.

Practitioner note: When formulating clear aqueous products (e.g., micellar water or clear body wash), pure HHCB will crash out and cause cloudiness due to its low water solubility. Always use a 50% solution in IPM, or pre-blend the pure musk with PEG-40 hydrogenated castor oil at a 1:3 ratio before adding it to the water phase.

Galaxolide FAQ

Q: How does Galaxolide (CAS 1222-05-5) compare to Tonalide (AHTN) in laundry care?

A: HHCB has a sweeter, more powdery profile, while AHTN is woodier. On cotton fabrics, HHCB shows roughly 15–25% higher substantivity after a 7-day dry-down. However, AHTN performs slightly better in highly alkaline powder detergents. For liquid detergents and fabric softeners, HHCB is the industry standard due to its superior bloom during the drying cycle.

Q: My clear body wash turned cloudy after adding pure Galaxolide. How do I fix it?

A: Pure HHCB is highly lipophilic (log P ~5.9) and insoluble in water. It crashed out of the micellar structure. To fix it, pre-dissolve the HHCB in dipropylene glycol (DPG) or use a 50% Galaxolide-IPM solution. Alternatively, increase your solubiliser (e.g., PEG-40 hydrogenated castor oil) by 1–2% to encapsulate the musk molecules and restore clarity.

Q: Are there regulatory restrictions on using HHCB in eco-labelled products?

A: Yes. While safe for human use under current IFRA and EU cosmetics regulations, HHCB has a high bioaccumulation potential. Eco-labels like Nordic Swan and Blue Angel strictly limit or ban polycyclic musks. If formulating for these certifications, substitute HHCB with macrocyclic musks like Ambrettolide or ethylene brassylate.