Cresyl Diphenyl Phosphate, known in the chemical industry as CDP or by its chemical formula C19H15O4P, belongs to the family of organophosphates. Its structure is built from a phosphate group bound to one cresyl ring and two phenyl groups. Product forms include a clear or faintly yellowish liquid at room temperature, but certain formulations also yield solid flakes, crystalline forms, or pearl-like granules. This compound draws attention for its chemistry and its uses as an additive in flame-retardant systems, plasticizers, and lubricants.
Examining CDP, one of the first things a technician or chemist notes is its density, usually measured at about 1.2 g/cm3 at 20°C, making it heavier than water. It resists dissolving in water, but dissolves easily in most organic solvents. The boiling point reaches above 200°C, offering stability under standard manufacturing conditions. Its appearance ranges from clear liquid to faintly amber hues, sometimes forming a syrupy layer when exposed to cold. For storage and shipping, CDP maintains stability if protected from excessive heat, moisture, or direct sunlight. It does not crystallize easily unless temperature drops substantially below room temperature. Melting point varies—several sources note melting at points above room temperature for some solid variants but this typically matters less in liquid bulk use scenarios.
Cresyl Diphenyl Phosphate comes with a backbone built from a central phosphate group. The phosphate is fully esterified by the cresyl and phenyl groups, giving the molecule unique steric properties. This structure limits reactivity in neutral conditions but can hydrolyze in the presence of acids or bases. In the chemical space, this arrangement helps CDP act as an excellent flame retardant and plasticizer due to aromatic ring stability and phosphorus content. From experience in lab settings, identification with IR, NMR, and GC-MS provides strong confirmation due to distinctive spectral features. The molecular weight of around 340 g/mol marks it as a heavier organic phosphate.
Industries purchase CDP in various forms depending on application: thick liquid, powder, crystalline flakes, or dense pearls. Bulk product usually ships in drums either as a viscous liquid or as a solidified mass, depending on handling and shipping environments. The material feels slick, slightly oily, and leaves a gentle, lingering smell reminiscent of other phosphate esters. In testing, I have witnessed CDP retain its homogeneity even after cycling through moderate temperature changes, meaning producers rarely deal with phase separation or stratification issues. Typical purity levels in industrial supply run above 98%, and reputable suppliers list HS Code 2919900090 or similar under customs classifications.
The Harmonized System (HS) Code for CDP usually appears as 2919900090, which covers various organic phosphates. Exporters and importers depend on this code for international trade. Regulations in North America, Europe, and Asia watch the transport and handling of such organophosphates closely. Each region's safety datasheets detail correct handling, disposal, and emergency measures. European REACH regulations, for example, may call for updated registration and tracking through a specialized database, reflecting long-term health and safety concerns. Meanwhile, in a U.S. context, the Environmental Protection Agency’s TSCA Inventory categorizes CDP within organophosphates, meaning that storage, labeling, and documentation protocols apply at all major distribution sites.
Concerns around CDP stem from its chemistry as an organophosphate. In personal experience dealing with this class of raw materials, proper protective equipment counts for everything. Skin contact may cause mild irritation in some cases, and extended respiratory exposure could pose risks, especially in heated or aerosolized product scenarios. CDP does not carry the acute toxicity profile of some other organophosphates, but improper disposal or long-term environmental release remains a major worry for sustainability. This is why industrial users take extra care with secondary containment, regular staff training, and routine air monitoring. Waste management follows hazardous chemical requirements in many regions. For workers, Material Safety Data Sheets (MSDS) stress prompt washing if the product touches skin, avoidance of inhalation, and never eating or drinking near the product. In hazardous settings, spill kits and neutralizing agents should be readily available.
The chemical formula for Cresyl Diphenyl Phosphate (C19H15O4P) points to a structure noted for poor water solubility—less than 1 g/L at room temperature. Handling the compound in plant environments often means transferring viscous liquid between reactors using peristaltic pumps and resistant hoses, as some organic plastics swell or degrade upon extended contact. For those preparing dilutions, organic solvents such as toluene or acetone typically allow fast mixing. Facilities working with powders or flakes rely on dust containment, as the fine material may linger in the air and settle slowly. In my own lab time, precise weighing and slow addition to a reaction minimize clumping and spills, especially when dealing with solid grades.
As a raw material, CDP operates behind the scenes in flame-retardant and softening applications for plastics. Its chemistry bestows a degree of flame resistance in polymers like PVC, making it a staple in the production of cables, insulation, or flooring. Industrial lubricants and hydraulic fluids also use CDP for its thermal stability and anti-wear properties; users select it for environments needing both fire suppression and smooth operation under pressure. Producers of specialty coatings add CDP for both flexibility and safety. Because it persists under moderate heat, installations in automotive and aerospace often specify this chemical for wire, tubing, or seat fabrics. Chemical producers recommend careful blending due to its high purity and concentration, often suggesting pilot batch testing to head off issues at scale.
CDP’s hazards underline the need for hands-on safety management. I have seen production floors where the right gloves and goggles make a world of difference. As with any organophosphate, accidental ingestion, prolonged skin exposure, or vapor inhalation can harm human health. Environmental releases—spills, leaks, or runoff—call for immediate containment because phosphate esters can impact aquatic ecosystems over time. Workers who respect the rules—using fume hoods, practicing regular hygiene, and staying aware of symptoms—cut through much of the risk. Users rely on neutralizing agents, regular training, and a strong safety culture, knowing all it takes is a single moment of distraction for an incident to unfold.
Improving the reputation and environmental footprint of chemicals like CDP falls to both industry and regulators. Engineers and technicians gain trust by recording incident data and adopting safer alternatives where possible, while producers who provide full ingredient disclosure support customer confidence. Recyclers work to recover valuable phosphorus from waste streams, making the material lifecycle gentler on the planet. As new regulations push for even lower exposure limits and cleaner waste, the industry adapts. It takes individual responsibility as much as corporate policy; everyone who handles, ships, or disposes of CDP shapes its impact in the real world.
