Reaction mass of 2-ethylhexyl diphenyl phosphite and bis(2-ethylhexyl) phenyl phosphite and triphenyl phosphite

Hydrolysis

Administrative data

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

This report represents data generated in accordance with the following Good Laboratory Practice Standards. OECD ENV/MC/CHEM(98)17, Paris, January 26, 1998. All phases of this study were conducted according to the above standards. However, nonstandard protocols were utilized due to the rapid hydrolysis of the test substance.

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report date:

2002

Reference 2

Reference Type:

publication

Title:

“Micellar effects upon acid catalyzed hydrolysis of Triphenyl phosphite.”

Author:

Al-Lohedan, Hamad A.

Year:

1991

Bibliographic source:

Phosphorous, Sulfur, Silicon Relat. Elem: 63 (3-4), 261-71. 1991.

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

yes

Remarks:

Study plan deviated from OECD 111 because TPPi must be sufficiently soluble in test buffers to be detected by the analytical method.

Principles of method if other than guideline:

Method: HPLC
Test type: Hydrolytic stability
The HPLC method used in these studies was based on published reports (Baylocq et al, 1986; Stevenson et al, 1999; Stevenson, 1997; Munteanu et al 1985)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Triphenyl phosphite

EC Number:

202-908-4

EC Name:

Triphenyl phosphite

Cas Number:

101-02-0

Molecular formula:

C18H15O3P

IUPAC Name:

triphenyl phosphite

Radiolabelling:

not specified

Study design

Analytical monitoring:

yes

Positive controls:

no

Negative controls:

no

Results and discussion

Transformation products:

not specified

Identity of transformation products

No.:

#1

Reference

Reference substance name:

Unnamed

IUPAC name:

phenol

Inventory number:

InventoryMultipleMappingImpl [inventoryEntryValue=EC 203-632-7]

CAS number:

108-95-2

Identity:

Phenol

Molecular formula:

C6H6O

Molecular weight:

94.111

SMILES notation:

Oc1ccccc1

InChl:

InChI=1/C6H6O/c7-6-4-2-1-3-5-6/h1-5,7H

Dissipation DT50 of parent compound

Dissipation DT50 of parent compound 1

pH:

7

Temp.:

22 °C

DT50:

0.5 h

Type:

(pseudo-)first order (= half-life)

Dissipation DT50 of parent compound 2

pH:

9

Temp.:

22 °C

DT50:

< 14 h

Type:

(pseudo-)first order (= half-life)

Dissipation DT50 of parent compound 3

pH:

7

Temp.:

25

Hydrolysis rate constant:

0 s-1

DT50:

1.1 h

Type:

(pseudo-)first order (= half-life)

Any other information on results incl. tables

The results of experiments on aqueous/cosolvent TPPi solutions indicated that the half-lives of TPPi in deionized water (initially at pH 6-7) and pH9 buffer were approximately 0.5 hour and less than 14 hours respectively at 22 °C.

Aqueous Solvent	Cosolvent	Temp (°C)	Rate Constant	Half- life (h)^9	Source
Aq. HCl; pH 1.3	(^10)	25	1.8E-4 s^-1	1.1	Al-Lohedanet al., (1991)
Deionized H2O; initial pH 6-7	Methanol (50%)	22	na^11	~ 0.5	BCRI # 252 1518
pH 9 buffer	Acetonitrile (50%)	22	na	< 14	BCRI # 172 1403

⁹ this is the estimated half-life in the absence of cosolvent

¹⁰half-life extrapolated to pure water from results on ethanol/water mixtures

¹¹not available from the data

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The results of experiments on aqueous/cosolvent TPPi solutions indicated that the half-lives of TPPi in deionized water (initially at pH 6-7) and pH 9 buffer were approximately 0.5 h and less than 14 h respectively at 22 °C. Due to these relatively short half-lives, a rapid method is required for the analysis of TPPi in aqueous solutions. However, the low water solubility of TPPi precludes such “direct injection” methods. This was shown by the injection of near saturated TPPi solutions in 1% CH3CH/buffers which showed insufficient HPLC responses. Therefore, an extraction method would be required for the analysis of TPPi in aqueous solutions, which is more time consuming and would likely produce erroneous results due to the relatively rapid hydrolysis of TPPi during the extraction procedure.

It follows that performance of the OECD hydrolysis test was considered not to be technically feasible under normal laboratory conditions. Regarding the hydrolytic pathway of TPPi, literature and experimental evidence indicates that TPPi hydrolyzes essentially completely to phenol and phosphorous acid, with little or no accumulation of the possible di and mono ester hydrolysis products.

Executive summary:

Based on the results of this experiment and previous work, the test substances appears to rapidly hydrolyze in water.

Al-Lohedan et al., (1991) reported a TPPi hydrolysis half-life of 1.1 h in water at pH 1.3 and 25 °C by extrapolation of results on TPPi solutions in ethanol/water. The results of BCRI experiments on aqueous/cosolvent TPPi solutions indicated that the half-lives of TPPi in deionized water (initially at pH 6 - 7) and pH 9 buffer were approximately 0.5 h and less than 14 h respectively, at 22 °C.

Regarding the hydrolytic pathway of TPPi, literature and BCRI experimental evidence indicates that TPPi hydrolyzes essentially completely to phenol and phosphorous acid, with little or no accumulation of the possible di- and mono-ester hydrolysis products.