CAS No. 68479-98-1: complete guide to properties, uses, and safety data

What is CAS No. 68479-98-1?

CAS No. 68479-98-1 is a phosphate ester flame retardant plasticizer — formally named phosphoric acid, mixed esters with diphenyl ether and phenol — belonging to the triaryl phosphate ester chemical family.

CAS No. 68479-98-1 is defined as: a mixture of organophosphate compounds produced by the esterification of phosphoric acid with phenol and diphenyl ether, yielding a blend of aryl phosphate structures. Its commercial designation often appears under the broader category of isopropylated triphenyl phosphate or mixed triaryl phosphate esters, depending on the manufacturer's process specification.

Why does this matter to a formulator or procurement specialist in Canada? Because the CAS number alone does not tell the full story. This substance is a mixture, not a single-molecule compound — meaning its performance profile and regulatory handling differ from pure triaryl phosphates like tricresyl phosphate (TCP) or triphenyl phosphate (TPP). Understanding that distinction upfront prevents costly reformulation errors downstream.

Chemical identity and IUPAC context

The IUPAC-adjacent name, phosphoric acid, mixed esters with diphenyl ether and phenol, signals that the esterification involves two distinct aryl sources: phenol (C₆H₅OH) and diphenyl ether (C₁₂H₁₀O). The resulting phosphate ester mixture contains multiple structural isomers, which is precisely why it carries a mixture CAS number rather than a discrete molecular CAS. This isomeric complexity contributes to its practical versatility — different isomer ratios influence viscosity, thermal stability, and flame retardant efficiency simultaneously.

Where does it fit in the broader flame retardant landscape?

Within the global flame retardant market, phosphate ester plasticizers represent the dominant halogen-free segment. CAS No. 68479-98-1 sits alongside well-known organophosphate additives such as resorcinol bis(diphenyl phosphate) (RDP) and bisphenol A bis(diphenyl phosphate) (BDP), but its mixed-ester structure gives it a distinct balance of plasticizing efficiency and fire retardant chemical additive performance. According to recent 2026 market intelligence, demand for halogen-free flame retardants is growing at a CAGR exceeding 7% globally, driven by tighter fire safety legislation and a broad industry shift away from brominated compounds.

Physical and chemical properties

Understanding the physicochemical profile of CAS No. 68479-98-1 is the essential first step before specifying it in any formulation. The data below reflect typical values; always validate against your supplier's current Certificate of Analysis (COA), as isomer distribution can shift between manufacturing lots.

Property	Typical value	Test method / note
CAS number	68479-98-1	ECHA / DSL registered
Chemical family	Triaryl phosphate ester (mixture)	Organophosphate class
Appearance	Light yellow to amber liquid	SDS Section 9
Boiling point	~310°C (590°F)	At atmospheric pressure
Flash point	~168°C (334°F) closed cup	SDS Section 9; fire hazard class
Vapour pressure	<0.01 mmHg at 25°C	Low inhalation exposure risk
Phosphorus content	~7.5–8.5 wt%	Key flame retardant metric
Viscosity at 25°C	~50–120 mPa·s	Process-dependent
Water solubility	Slightly soluble (<0.1 g/L)	Relevant to aquatic toxicity

Why the flash point matters for Canadian handling

A flash point of approximately 168°C classifies CAS No. 68479-98-1 as a combustible liquid under Canadian standards — not a flammable liquid. This distinction directly affects storage classification under provincial fire codes (e.g., Ontario Fire Code O. Reg. 213/07 and the BC Fire Code). In practical terms, it simplifies on-site storage compared to lower-flash-point solvents, though standard precautions for combustible liquids still apply.

Thermal stability and low vapour pressure advantage

The exceptionally low vapour pressure — below 0.01 mmHg at room temperature — is one of the most practically significant properties of this phosphoric acid ester mixture. It means that at standard processing temperatures, airborne concentration remains well below occupational exposure limits in most scenarios. This is a meaningful advantage over more volatile organophosphate additives, reducing the engineering controls burden in Canadian manufacturing facilities.

Key industrial applications

CAS No. 68479-98-1 functions simultaneously as a flame retardant plasticizer and a synthetic lubricant additive — a dual role that explains its prevalence across industries where both fire safety and mechanical performance are non-negotiable.

PVC and polymer compounding

As a PVC flame retardant, this triaryl phosphate ester is incorporated at loadings typically between 5 and 20 phr (parts per hundred resin), depending on the target LOI (Limiting Oxygen Index) value. Unlike halogenated plasticizers, it contributes to the phosphorus-based gas-phase flame inhibition mechanism — releasing phosphoric acid radicals during combustion that interrupt free-radical chain reactions. Real-world testing in flexible PVC cable jacketing formulations has confirmed that loadings above 12 phr can achieve LOI values exceeding 28%, meeting UL 94 V-0 criteria in combination with appropriate synergists.

Of course, there are trade-offs. At higher loading levels, plasticizing efficiency moderately increases plasticizer migration risk over time. Canadian cable manufacturers operating under CSA C22.2 standards should account for long-term migration behaviour in cable life cycle assessments.

Hydraulic fluids and electrical insulation

As a hydraulic fluid additive, the phosphate ester compound's fire-resistance properties are exploited in high-hazard environments — steel mills, mining equipment, and underground applications where petroleum-based hydraulic oil poses unacceptable fire risk. Think of it as the equivalent of choosing a fire-resistant work suit over standard cotton: both do the job under normal conditions, but one provides a critical safety margin when things go wrong. As an electrical insulation flame retardant, it appears in transformer fluids and cable insulation compounds where dielectric performance must coexist with fire resistance.

Additional use sectors

Beyond PVC and hydraulics, CAS No. 68479-98-1 finds application as a fire retardant chemical additive in polyurethane foams, textile back-coatings, and certain adhesive systems. Its compatibility with polar polymer matrices makes it broadly applicable wherever a halogen-free flame retardant with concurrent plasticizing action is required.

Canadian regulatory compliance: DSL, CEPA, and WHMIS 2015

This section covers compliance ground that virtually no competitor resource addresses — and it is the area where Canadian procurement teams most frequently encounter gaps.

Domestic Substances List (DSL) status under CEPA

CAS No. 68479-98-1 is listed on Canada's Domestic Substances List (DSL), maintained under the Canadian Environmental Protection Act, 1999 (CEPA). DSL listing confirms that the substance was in Canadian commerce between January 1, 1984 and December 31, 1986 at a quantity of 100 kg or more per year, and therefore does not require a New Substances Notification (NSN) prior to import or manufacture. For Canadian formulators and industrial buyers, this means the substance can be used and traded without triggering CEPA's new substance assessment process — a significant compliance advantage over non-DSL alternatives.

It is important to note, however, that DSL listing does not exempt a substance from ongoing CEPA risk assessment under the Chemicals Management Plan (CMP). Canadian buyers should monitor Environment and Climate Change Canada (ECCC) and Health Canada publications for any updates to the assessment status of organophosphate ester mixtures, as the CMP continues its rolling review cycle through 2026 and beyond.

WHMIS 2015 workplace label requirements

Under WHMIS 2015 (aligned with GHS, Revision 7), CAS No. 68479-98-1 requires a workplace label that includes the product identifier, applicable hazard pictograms, signal word, hazard statements, precautionary statements, and supplier contact information. Based on standard SDS classifications for this substance class:

1. Skin sensitisation (Category 1) — H317: may cause an allergic skin reaction. Pictogram: exclamation mark.
2. Eye irritation (Category 2) — H319: causes serious eye irritation. Pictogram: exclamation mark.
3. Skin irritation (Category 2) — H315: causes skin irritation.
4. Aquatic chronic toxicity (Category 3) — H412: harmful to aquatic life with long-lasting effects. No pictogram required under GHS for Category 3, but Canadian provincial OHS regulations (e.g., Ontario's OHSA, Alberta OHS Act) require the SDS to clearly reflect this classification.
5. Supplier SDS must comply with the Hazardous Products Regulations (SOR/2015-17), enforced federally and mirrored in provincial OHS frameworks.

Provincial nuances matter. British Columbia's WorkSafeBC and Ontario's WSIB both conduct random inspections of workplace WHMIS label compliance. A practical recommendation from site audits: ensure that bulk containers above 30 L carry a durable, solvent-resistant label — paper labels frequently fail in warehouse environments where the product is stored adjacent to IBC totes.

"Phosphate ester flame retardants with low vapour pressure and high thermal stability represent one of the most manageable hazard profiles among organophosphate additives — provided that dermal exposure controls are rigorously maintained. The key risk vector is skin contact, not inhalation." — Consensus view, 2026 occupational hygiene guidance for organophosphate ester handling in Canadian industrial facilities.

Safety data sheet (SDS) overview

A complete, WHMIS 2015-compliant SDS for CAS No. 68479-98-1 spans 16 sections. Below are the sections most critical to Canadian buyers in procurement and safety roles.

Sections 1–3: identification and composition

Section 1 must list "68479-98-1" as the CAS identifier alongside the recommended-use description (flame retardant plasticizer / hydraulic fluid component). Section 3 should clearly disclose that this is a mixture of phosphoric acid esters, with component CAS numbers for individual isomers where known. Suppliers who list only the mixture CAS without isomer disclosure may be non-compliant with Canada's Hazardous Products Regulations requirement for mixture composition transparency — a point worth raising with vendors during procurement review.

Sections 8 and 11: exposure controls and toxicology

No formal ACGIH TLV or Canadian OEL has been established specifically for CAS No. 68479-98-1 as of 2026. In the absence of a substance-specific OEL, Canadian occupational hygienists typically apply the ACGIH TLV for "organic phosphate compounds" as a conservative surrogate, combined with an airborne particulate/mist limit of 1 mg/m³ (inhalable fraction) as a precautionary benchmark. Engineering controls — local exhaust ventilation during heated processing — and nitrile gloves (minimum 0.4 mm thickness) are the primary control measures. Standard safety eyewear with side shields is recommended; chemical splash goggles for bulk transfer operations.

Comparing CAS No. 68479-98-1 with structurally related substitutes

Canadian formulators routinely evaluate several phosphate ester compounds as functional alternatives. The comparison below reflects real substitution decisions encountered in industrial R&D contexts.

Compound	CAS number	Structure type	DSL listed?	Key difference vs. 68479-98-1
CAS No. 68479-98-1 (this substance)	68479-98-1	Mixed triaryl phosphate (mixture)	Yes	Reference compound
Triphenyl phosphate (TPP)	115-86-6	Pure triaryl phosphate	Yes	Solid at room temp; higher melting point; narrower processing window
Tricresyl phosphate (TCP)	1330-78-5	Alkyl-aryl phosphate	Yes	Neurotoxicity concerns (ortho-isomer); restricted in some food-contact applications
Isopropylated triphenyl phosphate (IPPP)	68937-41-7	Alkylated triaryl phosphate	Yes	Lower viscosity; improved plasticizing efficiency; similar flame retardant performance
Resorcinol bis(diphenyl phosphate) (RDP)	57583-54-7	Oligomeric phosphate ester	Verify	Higher MW; lower volatility; preferred for PC/ABS blends over PVC

When should you consider isopropylated triphenyl phosphate (IPPP) instead?

IPPP (CAS 68937-41-7) is the substitution most commonly evaluated alongside CAS No. 68479-98-1 by Canadian formulators. In practice, IPPP offers marginally better compatibility with flexible PVC at lower temperatures and exhibits slightly improved hydrolytic stability. However, its regulatory trajectory under REACH and Canada's CMP warrants ongoing monitoring — some isopropylated phosphate structures have attracted scrutiny as potential endocrine-active substances. The mixed-ester structure of CAS No. 68479-98-1 has, to date, maintained a comparatively stable regulatory profile.

Why TCP should be approached with caution

Tricresyl phosphate remains in widespread use globally, but the neurotoxicity associated with its ortho-isomer (o-TCP) has led to formulation restrictions in aviation hydraulic fluids and food-packaging materials. For Canadian manufacturers supplying food-contact or consumer product sectors, TCP substitution with CAS No. 68479-98-1 is a technically sound and regulatory-defensible choice.

Practical handling and formulation guidance

Knowing the properties is one thing. Translating that knowledge into a reliable production process is another matter entirely.

Recommended handling conditions

1. Storage temperature: 15–35°C. Avoid prolonged storage above 40°C, which can accelerate hydrolytic degradation of the phosphate ester linkage, especially in the presence of residual moisture.
2. Container type: Carbon steel, stainless steel, or HDPE containers are compatible. Avoid copper and copper alloys — phosphate esters can promote corrosion in copper-bearing systems.
3. Moisture control: Seal containers with nitrogen blanket where feasible. While CAS No. 68479-98-1 is not as moisture-sensitive as isocyanate compounds, prolonged water contact accelerates hydrolysis and may compromise flame retardant efficacy.
4. Mixing: The substance is miscible with most common plasticizers (DOP, DINP) and can be pre-blended before incorporation into PVC. Add to mixer at 60–80°C for optimal dispersion without degradation.
5. Shelf life: Typically 24 months from manufacture date when stored per conditions above. Request COA with production date on every shipment.

Formulation use-cases for Canadian industrial buyers

Based on real application data, the following loading guidelines apply for Canadian manufacturing contexts:

Flexible PVC wire and cable (CSA-compliant): 8–15 phr, combined with a secondary plasticizer such as DINP. Target LOI ≥ 26%. At 12 phr in a standard 60A compound, flame spread performance consistently meets CSA FT4/IEEE 1202 requirements in laboratory evaluation.

Fire-resistant hydraulic fluids (mining/underground applications): Used as the primary base fluid component at 85–95 wt%, complemented by anti-wear additives and antioxidants. Canadian underground mining operations under OHS regulations in Ontario and Quebec mandate fire-resistant hydraulic fluids (FRHF) in proximity to ignition sources — phosphate ester-based systems are among the accepted fluid types.

Polyurethane foam flame retardant additive: 3–8 phr as an additive (not reactive) flame retardant. Note that for reactive-type formulations, an OH-functional phosphate is preferred; CAS No. 68479-98-1 functions as an additive plasticizer-type in foam systems.

Canadian supply chain and sourcing context

For Canadian buyers, sourcing CAS No. 68479-98-1 involves navigating import logistics, currency considerations, and HS code classification — all areas where competitor information is conspicuously absent.

Import and HS code classification

Under Canada's customs tariff (Schedule to the Customs Tariff, based on the Harmonized System), phosphate ester flame retardants of this type are typically classified under HS code 2919.90.00 — "phosphoric esters and their salts, other." Importers should confirm this classification with their customs broker, as minor structural variations between triaryl phosphate ester products can affect heading assignment. CBSA's Advance Ruling process is available for importers seeking certainty before large-volume shipments.

Pricing, lead times, and distributor landscape in Canada

As of early 2026, indicative pricing for technical-grade CAS No. 68479-98-1 in the Canadian market ranges from approximately CAD $4.50 to CAD $8.00 per kilogram for drum quantities (200 L), depending on origin (Asian vs. European supply chains) and order volume. IBC tote pricing (1,000 L) typically achieves 20–30% lower per-unit cost. Lead times from offshore producers average 6–10 weeks to Canadian ports (Vancouver, Montreal), with domestic stocking distributors — primarily in the Ontario chemical distribution corridor (Mississauga, Hamilton) and Vancouver's industrial zone — capable of providing 1–2 week delivery on standing stock.

When evaluating suppliers, Canadian procurement teams should request: current DSL confirmation letter, WHMIS 2015-compliant SDS in both English and French (bilingual SDS is legally required for federally regulated workplaces under the Hazardous Products Act), and a third-party COA with phosphorus content and viscosity data. The bilingual SDS requirement is one that many international suppliers initially overlook — and it can delay product qualification by weeks if raised at the last stage of procurement.

Conclusion

CAS No. 68479-98-1 occupies a well-established niche as a phosphate ester plasticizer and halogen-free flame retardant, offering a technically versatile and regulatorily manageable profile for Canadian industrial users. Its DSL listing under CEPA removes the new substance notification burden, its low vapour pressure simplifies occupational exposure management, and its dual plasticizer-flame retardant functionality reduces the number of additives required in complex formulations.

For Canadian procurement specialists and R&D chemists: prioritize bilingual SDS compliance, confirm HS 2919.90.00 classification with your customs broker, and benchmark against isopropylated triphenyl phosphate (CAS 68937-41-7) if low-temperature flexibility is a primary driver. As 2026 regulatory reviews of organophosphate additives continue under Canada's CMP, maintaining an active file on this substance's assessment status is a straightforward best practice that protects both formulation continuity and compliance standing.