Di-(2-ethylhexyl)phosphoric acid (DEHPA or HDEHP)

CHEMICAL SUBSTANCE IDENTIFICATION

Chemical name                 

Di-(2-ethylhexyl)phosphoric acid  (DEHPA or HDEHP) [2]

Synonyms                           

• Bis(2-ethylhexyl) hydrogen phosphate, DEHPA, Bis(2-ethylhexyl) Hydrogen Phosphate (for Rare Metals Extraction) [1]
• Di(2-ethylhexyl)phosphate [2]
• Di-2-ethylhexyl hydrogen phosphate  [2]
• Di(2-ethylhexyl)orthophosphoric acid  [2]

IUPAC name

bis[(2-ethylhexyl)oxy]phosphinic acid [1]

CAS No

298-07-7

REACH registration number

EC No

Molecular formula              

C16H35O4P

Substance group/chemical family

Organic, Mono constituent substance

Appearance

Physical state

Odour

Form

Colour

Liquid (100%) at 20°C and 1013 hPa  [1]

Odourless

Viscous (100%)  [1]

USES AND HANDLING ISSUES

Relevant identified uses

extractant in  manufacture of basic metals, including alloys, production of PUR foam,  polymer preparations and compounds

Handling considerations

Precautions for safe handling:
Put on appropriate personal protective equipment. Eating, drinking and smoking should be prohibited in areas where this material is handled, stored and processed. Workers should wash hands and face before eating, drinking and smoking. Do not get in eyes or on skin or clothing. Do not breathe vapor or mist. Do not ingest. If during normal use the material presents a respiratory hazard, use only with adequate ventilation or wear appropriate respirator. Keep in the original container or an approved alternative made from a compatible material, kept tightly closed when not in use. Empty containers retain product residue and can be hazardous.
Conditions for safe storage, including any incompatibilities:
Store in accordance with local regulations. Store in original container protected from direct sunlight in a dry, cool and well-ventilated area, away from incompatible materials and food and drink. Keep container tightly closed and sealed until ready for use. Containers that have been opened must be carefully resealed and kept upright to prevent leakage. Do not store in unlabeled containers. Use appropriate containment to avoid environmental contamination. [1]

PHYSICO-CHEMICAL PROPERTIES

Molecular weight                                  

322.42 g/mol [2]

Bulk density/Specific gravity

 0.976 g/cm³ @ 20 °C [1]

pH

 Strongly acidic [2]

Particle size

EC

Melting point

-50 °C   at 101 325 Pa [1]

Boiling point

240 °C   at 101 325 Pa [1]

Flash point

181 °C @ 101.3 kPa [1]

Flammability

Non flammable (100%)  [1]

Vapour density

Vapour pressure

0 Pa @ 25 °C [1]

Solubility in water

182 mg/L @ 20 °C   [1] 

Solubility in organic solvents

Soluble in benzene, hexane, and 4-methyl-2-pentanone [2]

Solubility in inorganic solvents

Hydrolysis

Ionicity in water

Surface tension

52.24 mN/m @ 164 mg/L and 20 °C  [1]

Dispersion properties

Explosiveness

Non-explosive (100%) [1]

Other properties

 Self-ingnition (Autoflammability) 255 °C @ 101.1 kPa [1]

Non- oxidising (100%) [1]

Dynamic viscosity at 20 °C: 40.99 mPa.s  [1]

Stability and reactivity

Chemical stability

The product is stable. [1]

Reactivity hazards

No specific test data related to reactivity available for this product or its ingredients. [1]

Corrosivity

Mildly corrosive to most metals [2]

Polimerization

Incompatibility with various substances

 No specific data.

Special remarks on reactivity

Avoid hydrogen formation: Keep away from alkaline solutions and non-noble metals (e.g. iron, zinc, aluminum) [1]

Physical, chemical and biological coefficient

Koc

251 @ 20 °C [1]

Kow

 2.88 @ 25 °C (log Kow) [1]

pKa

1.47 @ 25 °C [1]

log Kp

Henry-constant

0.004 Pa m³/mol @ 25 °C  [1]

ENVIRONMENTAL FATE AND BEHAVIOUR

Artificial pollution sources

Bis(2-ethylhexyl) phosphate's production and use as a metal extraction agent, a textile lubricant and antistatic agent, an extreme pressure additive, an intermediate for wetting agents and detergent, and a feedstock for chemical synthesis may result in its release to the environment through various waste streams. [2]

General terrestrial fate

If released to soil, bis(2-ethylhexyl) phosphate is expected to have no mobility based upon an estimated Koc of 1.7X10+4. Volatilization from moist soil surfaces is not expected to be an important fate process based upon an estimated Henry's Law constant of 4.1X10-8 atm-cu m/mole. The pKa of bis(2-ethylhexyl) phosphate has been estimated as 1.47, indicating that this compound will primarily exist in anion form in the environment and anions generally do not adsorb more strongly to organic carbon than their neutral counterparts. The sorption of organophosphorus compounds in soil depends on both organic matter and clay content of soil and the sorption increases as the pH of soil decreases. In a study on the sorption of bis(2-ethylhexyl) phosphate on kaolinite and amectite, the acidic phosphoric group reacted rapidly and almost irreversibly with the surface cations of the clay mineral structure. Bis(2-ethylhexyl) phosphate is not expected to volatilize from dry soil surfaces based upon its vapor pressure. [2]

General aquatic fate

If released into water, bis(2-ethylhexyl) phosphate is expected to adsorb to suspended solids and sediment based upon the estimated Koc. Bis(2-ethylhexyl) phosphate, present at 100 mg/L, reached 0-17% of its theoretical BOD in 4 weeks using an activated sludge inoculum at 30 mg/L and the Japanese MITI test and therefore this compound is not expected to biodegrade rapidly in the environment. Volatilization from water surfaces is not expected to be an important fate process based upon this compound's estimated Henry's Law constant. Measured BCF values of 1-2.4 and 2.7-6.0 suggest bioconcentration in aquatic organisms is low. Hydrolysis is expected to be an important environmental fate process since this compound contains functional groups (esters) that hydrolyze under environmental conditions. The hydrolysis half-life of the analog dimethyl phosphoric acid in neutral solution at 100 °C was found to be 2.4 days. Increasing the carbon chain substituent on phosphoric acid (as in the case of bis(2-ethylhexyl) phosphate) may not increase the rate of hydrolysis. [2]

General atmospheric fate

If released to air, an estimated vapor pressure of 4.7X10-8 mm Hg at 25 °C indicates bis(2-ethylhexyl) phosphate will exist solely in the particulate phase in the atmosphere. Particulate-phase bis(2-ethylhexyl) phosphate will be removed from the atmosphere by wet or dry deposition. Bis(2-ethylhexyl) phosphate does not contain chromophores that absorb at wavelengths >290 nm and therefore is not expected to be susceptible to direct photolysis by sunlight. [2]

General persistence and degradability

Abiotic degradation and metabolites

Biodegradation and metabolites

Readily biodegradable (100%) [1]

To test for its biodegradability potential, bis(2-ethylhexyl) hydrogen phosphate was incubated for 28 days in continuously stirred 250 ml closed flask in the dark with an inoculum originally collected from a local, predominantly municipal wastewater treatment plant. The applied method was the OECD Guideline 301 F. In this assay, biodegradation was estimated by biological oxygen demand (BOD) over time. BOD was measured daily by a manometer. The incubation temperature was 20 +/-1°C. The concentration of innoculum was 30 mg /L and the one of the substance was 100 mg/L. Degradation was calculated by substracting the amount BOD in the negative (innoculum only) control from that in the substance or positive control at any given time point and divided by the chemical oxygen demand (COD) or thereotical oxygen demand (ThOD). The 28-day degradation was 75% forbis(2-ethylhexyl) hydrogen phosphate and 82% for the positive control (with reference substance).

A second test on ready biodegradability was conducted according to the national Japanese standard method comparable to the OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)). After 14 days, the substance showed 0-17% degradation realting to BOD, and 0% degradation relating to the test substance concentration.

As recommended in Guidance R.7b (ECHA, 2012), in cases of conflicting test results, differences in stringency and the origin of the inoculum in order to check whether or not differences in the adaptation of the inoculum may be the reason are considered. The reported data are carefully checked and no differences in test design were found in both tests. The positive result in the well documented study for ready biodegradability is considered as indicative of rapid and ultimate degradation and the positive test result supersede the negative test result.[3]

Bioconcentration

BCF aquatic/sediment: 6 (dimensionless) [1] Therefore, bioconcentration in aquatic organisms is low. [2]

Volatilization

Volatilization from water surfaces is not expected to be an important fate process based upon this compound's estimated Henry's Law constant. Bis(2-ethylhexyl) phosphate is not expected to volatilize from dry soil surfaces based upon its vapor pressure. [2]

Photolysis

Bis(2-ethylhexyl) phosphate does not contain chromophores that absorb at wavelengths >290 nm and therefore is not expected to be susceptible to direct photolysis by sunlight. [2]

Hydrolysis

Hydrolysis is expected to be an important environmental fate process since this compound contains functional groups (esters) that hydrolyze under environmental conditions. The hydrolysis half-life of the analog dimethyl phosphoric acid in neutral solution at 100 °C was found to be 2.4 days. Increasing the carbon chain substituent on phosphoric acid (as in the case of bis(2-ethylhexyl) phosphate) may not increase the rate of hydrolysis. [2]

Soil adsorption and mobility

 It is expected to have no mobility based upon an estimated Koc of 1.7X10⁺⁴ .  This compound will primarily exist in anion form in the environment and anions generally do not adsorb more strongly to organic carbon than their neutral counterparts. The sorption of organophosphorus compounds in soil depends on both organic matter and clay content of soil and the sorption increases as the pH of soil decreases. [2]

ENVIRONMENTAL CONCENTRATIONS

Measured data

ECOTOXICOLOGICAL INFORMATION

General adverse effects on ecosystem

Acute toxicity (LC50, EC50)

Aquatic systems

LC50: 30 mg/L (Freshwater fish) (4 days) [1]

LC50: >56 mg/L (Danio rerio) (96 h)

LC50: 34 mg/L (Oncorhynchus mykiss) (48 h) [2]

LC50: 30 mg/L (Oncorhynchus mykiss) (96 h) [2]

EC50 / LC50: 60.7 mg/L (freshwater invertebrates) (48 h) [1]

LC50: 46.8 mg/L (Daphnia magna) (72 h) [2]

LC50:  >42 mg/L (Daphnia magna) (24 h) [2]

LC50:  >42 mg/L (Daphnia magna) (48 h) [2]

LC50:  27.2 mg/L (Daphnia magna) (96 h) [2]

EC50:  100 mg/L (freshwater algae) (72 h) [1]

EC50: 890 mg/L (microorganisms) (3h) [1]

Terrestrial systems

Chronic toxicity (NOEC, LOEC)

Aquatic systems

EC10 / LC10 or NOEC: 20.6 mg/L(freshwater fish) (48 days) [1]

EC10 or NOEC: 50 mg/L (freshwater algae) (72 h) [1]

EC10 or NOEC: 196 mg/L (microorganisms) (3h) [1]

Terrestrial systems

HUMAN HEALTH EFFECTS and PROTECTION

Routes of human exposures

inhalation, dermal, oral, eye exposure

General effects

Endocrine disruption

Mutagenicity

Carcinogenicity

Reprotoxicity

No adverse effect observed NOAEL 150 mg/kg bw/day (subacute, rat) (effect on fertility) (oral route) [1]

No adverse effect observed NOAEL 1 000 mg/kg bw/day (subacute, rat) (Effect on developmental toxicity) (oral route) [1]

Teratogenicity

Skin, eye and respiratory irritations

Adverse effect observed (corrosive to skin, irritative to eyes) [1]

Metabolism:

absorption, distribution & excretion

Low bioaccumulation potential [1]

Exposure limits

Inhalation: Long term: DNEL: 3.52 mg/m³ (workers, systemic effects)

Inhalation: Long term: (DNEL) 870 µg/m³ (general population, systemic effects)

Inhalation: Short term: DNEL: 3.52 mg/m³ (workers, systemic effects)

Inhalation: Short term: DNEL: 870 µg/m³ (general population, systemic effects)

Inhalation: Long term: DNEL: 1 mg/m³ (workers, local effects)

Inhalation: Acute/short term: DNEL: 1 mg/m³ (workers, local effects)

Dermal: Long term: 500 µg/kg bw/day  (workers, systemic effects)

Dermal: Long term: 250  µg/kg bw/day  (general population, systemic effects)

Dermal: Acute/short term: 500  µg/kg bw/day  (workers, systemic effects)

Dermal: Acute/short term: 250 µg/kg bw/day  (general population, systemic effects)

Oral: Long term: 250  µg/kg bw/day  (general population, systemic effects)

Oral: Acute/short term: 250 µg/kg bw/day  (general population, systemic effects)

Eye: Medium hazard (no threshold derived)  [1]

Drinking water MAC

Other information

Animal toxicity data

Acute toxicity (LD50)

LD50: 1 400 mg/kg bw (rat, oral)  [1]

LD50: 2 000 mg/kg bw (rabbit, dermal) [1]

Chronic toxicity (NOEL, LOEL)

NOAEL: 150 mg/kg bw/day (subacute, rat) (Oral route – repeated dose toxicity) [1]

ENVIRONMENTAL STANDARDS AND REGULATIONS

Danger! According to the classification provided by companies to ECHA in REACH registrations this substance causes severe skin burns and eye damage, is harmful if swallowed and causes serious eye damage.

According to REACH registrations

H318: Causes serious eye damage. H302: Harmful if swallowed. H314: Causes severe skin burns and eye damage

Additionally, the classification provided by companies to ECHA in CLP notifications identifies that this substance is harmful in contact with skin and causes skin irritation.

According to CLP notifications

H318: Causes serious eye damage. H302: Harmful if swallowed. H3012: Harmful in contact with skin. H314: Causes severe skin burns and eye damage. H315: Causes skin irritation. H412: Harmful to aquatic life with long-lasting effects.

EINECS regulation

Listed on EINECS (European INventory of Existing Commercial chemical Substances) List

OSHA regulations etc.

OTHER INFORMATION, SPECIAL REMARKS

Classification and proposed labelling with regard to toxicological data

CREATED, LAST UPDATE

Created

2019. 11. 25

Last update

2019. 11. 26

REFERENCES

[1] ECHA, Bis(2-ethylhexyl) hydrogen phosphate, https://echa.europa.eu/hu/brief-profile/-/briefprofile/100.005.507  Accessed 2019.11.25

[2] PUBChem  https://pubchem.ncbi.nlm.nih.gov/compound/Bis_2-ethylhexyl_-hydrogen-phosphate  Accessed 2019.11.26

[3] ECHA, Bis(2-ethylhexyl) hydrogen phosphate, https://echa.europa.eu/hu/registration-dossier/-/registered-dossier/5599/5/3/2 Accessed 2020.05.10