DEP (diethyl phthalate)

✦ Near-odourless synthetic ester used as a primary diluent and carrier in alcoholic perfume bases including EDP, EDT, and cologne
✦ Functions as a fragrance fixative by slowing the evaporation of volatile top and middle notes, extending overall longevity on skin
✦ Fully miscible with ethanol and compatible with virtually all aroma chemicals, natural extracts, and essential oils
✦ Improves smoothness, spreadability, and blendability of fragrance concentrates — reduces harsh or sharp edges in high-intensity synthetics
✦ Widely used in reed diffuser bases, functional fragrances, air care products, and fabric softener formulations
✦ High flash point (161°C) makes it safer to handle and store compared to many volatile solvents
✦ Cosmetic-grade purity at 99%+ — suitable for skin-contact applications in regulated formulations with appropriate usage levels

Diethyl Phthalate is a synthetic diester formed by the reaction of phthalic anhydride with ethanol. It has been used in the fragrance and cosmetic industry for over a century and remains one of the most common carrier solvents in commercial perfumery worldwide. Its long track record in fine fragrance, functional fragrance, and personal care formulation has made it a default component in countless commercial alcohol-based spray perfumes globally.

What distinguishes DEP from other carriers is its exceptional chemical neutrality. Unlike some ester-based solvents, DEP does not contribute meaningfully to the olfactory profile of a finished fragrance, allowing the perfumer's intended composition to express itself without interference. Its moderate viscosity, high solvency power, and excellent miscibility with ethanol allow it to dissolve both polar and non-polar aroma chemicals uniformly, preventing separation or cloudiness in the finished formulation. It also plays a subtle role in moderating the perceived harshness of high-impact synthetic materials when used at appropriate ratios.

Rabibazaar supplies cosmetic-grade Diethyl Phthalate suitable for DIY perfumers, attar blenders, home fragrance crafters, and professional formulators requiring a reliable, high-purity carrier base.

SCENT DESCRIPTION : DEP is functionally odourless in normal working concentrations. At very high concentrations or when smelled neat, it presents an extremely faint, slightly sweet, mildly ester-like background note with no discernible aromatic character. It does not contribute to the olfactory profile of a fragrance and is transparent in the composition. Its value is entirely functional rather than aromatic.

NOTE POSITION : Carrier — no note position applicable

FRAGRANCE FAMILY : Non-contributory carrier — used across all families

FACETS : Odourless · Neutral · Transparent · Faint sweet background · Ester-like at neat concentration only

TENACITY : Not applicable — carrier material

SILLAGE : Not applicable — carrier material

Chemical Name : Diethyl Phthalate
CAS Number : 84-66-2
Synonyms : DEP · Ethyl Phthalate · Diethyl Benzene-1,2-Dicarboxylate · Phthalic Acid Diethyl Ester · 1,2-Benzenedicarboxylic Acid Diethyl Ester
Purity : 99%+ (cosmetic/perfumery grade)
Appearance : Clear, colourless, low-viscosity oily liquid
Odor Threshold : Effectively odourless in use concentrations — faint sweet ester note detectable only neat or at high concentration
Solubility : Fully miscible with ethanol, acetone, and most aroma chemicals — practically insoluble in water
Specific Gravity : 1.118 – 1.122 g/cm³ at 20°C
Flash Point : 161°C (322°F) closed cup
Refractive Index : 1.500 – 1.503 at 20°C
Type : Synthetic

Fine Fragrance ★★★★★
DEP is the classic carrier and diluent of the fine fragrance industry. It is used alongside ethanol to extend the fragrance concentrate in EDP, EDT, and cologne bases, typically comprising 5–20% of the final formulation. It moderates intensity, reduces harshness of high-impact synthetics, and improves overall smoothness and skin feel.

Attar & Oriental Blending ★★★
DEP is occasionally used by attar blenders seeking an odourless carrier that integrates with both ethanol and non-polar materials. It is less traditional than DPG or IPM in this context but useful when an ethanol-miscible carrier is needed for specific synthetic components in complex oriental bases.

Functional Fragrance ★★★★
In fabric softeners, air fresheners, and household fragrance applications, DEP functions as an effective carrier and fixative that improves fragrance diffusion and stability over time. It is widely used in commercial laundry and home care fragrance systems.

Home Fragrance ★★★★
DEP performs well in reed diffusers and spray air fresheners where it acts as a carrier base, helping to regulate the release rate of volatile fragrance components. Its low odour and good solvency make it a useful component of diffuser bases, typically blended with IPM or DPG.

Cosmetics & Personal Care ★★★
DEP is used in cosmetic formulations at regulated levels. Regulatory scrutiny on phthalates has led some markets and brands to reduce DEP in leave-on products. Suitable for rinse-off formulations at appropriate levels. Formulators in EU-regulated markets should verify current compliance status for specific product categories before use.

RECOMMENDED USAGE RATES

Application : Typical Usage Rate
EDP (Eau de Parfum) : 5 – 15% of total formulation
EDT (Eau de Toilette) : 5 – 20% of total formulation
Body Lotion / Cream : 0.5 – 3% (verify regulatory compliance for leave-on)
Shampoo / Body Wash : 0.5 – 2% (rinse-off — lower risk profile)
Reed Diffuser : 10 – 30% of base
Fabric Softener : 2 – 8%
Candle : Not recommended — see warning below

IFRA 51ST AMENDMENT STATUS

DEP (Diethyl Phthalate) is not listed as a restricted fragrance material in the IFRA 51st Amendment. IFRA restrictions apply to fragrance-active materials with sensitisation or phototoxicity risk. DEP is a carrier solvent and is not governed by IFRA limits.

⚠️ REGULATORY NOTICE — EU COSMETICS REGULATION
DEP is currently permitted in cosmetics in the EU, unlike DEHP and DBP which are banned. However, phthalates as a class are under ongoing regulatory review in the EU and several national markets. Formulators supplying EU-registered products should verify the current compliance status with their regulatory consultant before incorporating DEP into leave-on cosmetic products.

⚠️ CANDLE USE
DEP is not recommended for candle applications. Combustion of phthalate-containing materials raises concerns about the release of degradation products. Most professional candle makers prefer phthalate-free alternatives such as DPG or IPM as carrier bases.

⚠️ LIP PRODUCTS
DEP is not recommended for lip products such as lipstick or lip balm due to potential ingestion risk associated with phthalate compounds.

METHOD 1 — FRAGRANCE DILUTION IN ALCOHOL BASE
The most common application. Add DEP to a fragrance concentrate at 5–20% alongside perfumers alcohol (96% ethanol). DEP softens and rounds the fragrance, moderates the initial high-intensity burst of volatile synthetics, and improves adhesion to skin. Blend DEP with the fragrance concentrate first before adding ethanol for uniform mixing.

METHOD 2 — REED DIFFUSER BASE FORMULATION
Combine DEP with DPG or IPM at a ratio of 1:1 to 1:2 as a diffuser carrier base, then blend with fragrance at 20–30% of total volume. DEP contributes solvency and helps keep high-concentration fragrance blends clear and stable in the diffuser vessel. It also moderates the rate of wicking and diffusion.

METHOD 3 — AROMA CHEMICAL CARRIER FOR DILUTION
When working with very high-impact or viscous aroma chemicals — such as Iso E Super, Ambroxan, or musks — DEP can be used as a pre-dilution carrier to bring concentrated materials to a working percentage before incorporation into a fragrance formula. Pre-dilute at 10–50% in DEP, mix thoroughly, then formulate as normal.

BEST PAIRINGS

DEP functions as a carrier and is technically compatible with all aroma chemicals and fragrance materials. The following represent especially effective functional pairings:

DPG (Dipropylene Glycol) → Complementary carrier — blend DEP and DPG for hybrid alcohol-miscible and oil-miscible carrier bases in diffusers and functional fragrances
IPM (Isopropyl Myristate) → Skin-feel enhancer — combine with DEP in body spray bases to add emollient glide and reduce the drying effect of alcohol
Ethanol (Perfumer's Alcohol) → Primary base partner — DEP and ethanol together form the classic two-component carrier system for alcoholic spray perfumes
Hedione → DEP effectively smooths and rounds the diffusive, semi-volatile character of Hedione in floral and fresh bases
Habanolide / Galaxolide → DEP improves the dispersion of musk materials in alcoholic bases and supports longevity

AVOID

DEP should not be used in water-based systems without solubilisers as it is practically insoluble in water and will cause phase separation and cloudiness.

Working with DEP has taught me that great perfumery is as much about what the customer does not smell as what they do. DEP is invisible — odourlessly present throughout the formulation, doing the structural work that holds everything together. When I am developing an EDP and a particular synthetic is reading too sharp or too linear on the dry-down, adjusting the DEP ratio in the base before adding ethanol often resolves the issue more elegantly than reformulating the accord itself. It acts as a buffer, slightly moderating volatility without adding its own character. In commercial fragrance, this transparency is exactly what makes it indispensable — the consumer never knows it is there.

ADVANCED TIP
When evaluating a new fragrance concentrate on a blotter, always test it in your intended carrier base — not neat. A concentrate that reads beautifully at 100% may behave very differently when diluted in a DEP-ethanol base at 20%. Specifically, DEP can suppress the top-note brightness of some volatile citrus and ozonic materials in the opening. If you notice this effect, reduce DEP in the base to 5–8% and compensate with additional ethanol. Alternatively, hold 2–3% of your ethanol out of the initial blend and add it after final concentration adjustment — this keeps the top-note clarity while retaining DEP's fixative contribution in the body and base of the fragrance.

Physical State : Clear, colourless oily liquid at room temperature
Skin Safety : Generally low irritation potential at typical use levels — avoid prolonged undiluted skin contact. Wash with soap and water after handling.
Eye Contact : Irritant — avoid contact with eyes. Flush thoroughly with water for 15 minutes if contact occurs and seek medical advice.
Ingestion : Do not ingest. Not for internal use. Keep out of reach of children.
Ventilation : Use in well-ventilated areas when working with large quantities. No special respiratory protection needed for small-scale use.
Storage : Store in a cool, dry, well-ventilated location away from heat sources and direct sunlight. Keep container tightly sealed.
Shelf Life : 3 – 5 years when stored correctly in sealed, unopened containers
Container : Store in original HDPE or glass containers. Avoid PVC or low-quality plastic containers as DEP may cause plasticisation or leaching.
Flammability : Combustible liquid — flash point 161°C. Not classified as flammable under standard conditions. Keep away from open flame and high heat sources.

Q: What is DEP used for in perfumery?
A: DEP is used as a carrier, diluent, and fixative in alcoholic perfume bases. It softens the fragrance, extends longevity, and improves blendability of aroma chemicals in EDP, EDT, and cologne formulations.

Q: Is DEP the same as DPG?
A: No. DEP (Diethyl Phthalate) is a phthalate ester that is miscible with ethanol and primarily used in alcohol-based perfumes. DPG (Dipropylene Glycol) is a glycol carrier used in oil-based perfumes, attars, and diffusers. They are chemically different and not interchangeable in all applications.

Q: Is DEP safe to use in cosmetics?
A: DEP is currently permitted in cosmetics in most markets including the EU and US. However, phthalates are under regulatory review in some regions. Formulators should verify current compliance for their specific product category and market before use, particularly for leave-on skin products.

Q: Does DEP affect the smell of my fragrance?
A: No. DEP is effectively odourless at normal working concentrations and does not contribute to or alter the olfactory character of a fragrance. It may moderately reduce the perceived sharpness of some high-impact synthetics, which most perfumers consider a benefit rather than a drawback.

Q: How does DEP compare to IPM as a perfumery carrier?
A: DEP and IPM serve different roles. DEP is ethanol-miscible, making it ideal for alcoholic spray perfumes. IPM (Isopropyl Myristate) is an oil-based emollient carrier better suited for anhydrous bases, roll-ons, and skin-feel formulations. Many formulators combine both in hybrid bases to achieve solvency across both alcohol and oil phases.

Professional formulation workflow

DEP (diethyl phthalate) should be evaluated in a controlled small batch before production. Confirm the supplied grade, active concentration and recommended application range from the current supplier documentation. Weigh accurately instead of measuring by drops, record every adjustment, and compare the modified trial against an unchanged control.

Compatibility and quality checks

Test the ingredient in the actual alcohol, oil, surfactant, emulsion or wax base intended for sale. Observe clarity, separation, color, odor and performance immediately after mixing and again after a suitable resting period. A material that looks stable in a concentrate can behave differently in the finished formulation.

Scale-up and safety

Convert percentages into exact batch weights and verify the final consumer-product concentration before scaling. Follow the latest applicable IFRA, cosmetic, chemical and supplier safety documentation for the intended category. Use appropriate protective equipment, ventilation and clearly labeled containers, and retain a sample from every approved batch for quality comparison.