2-[methyl[(nonafluorobutyl)sulphonyl]amino]ethyl methacrylate

Hydrolysis

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 February 2002 - 11 April 2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.2110 (Hydrolysis as a Function of pH)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

- Name of test material (as cited in study report): 2-(N-methylperfluorobutanesulfonamido)ethyl acrylate (N-MeFBSEA)
- Substance type: single-constituent substance
- Storage condition of test material: Frozen
- Analytical purity: 93.96%
- Lot/batch no.: Lot 40177

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the parent/transformation products: Test bottles with concentration of 4 ppm N-MeFBSEA in buffers of pH 4, 7 and 9 were sampled at 0, and 5 days;
- Sample storage conditions before analysis: 50 °C;

Buffers:

Buffer compositions were not specified in the study report. Experiments were conducted to OPPTS835.2110 at pH 4, 7, and 9.

Details on test conditions:

TEST SYSTEM

- Type, material and volume of test flasks, other equipment used: VOA vials
- Measures to exclude oxygen: Buffers of pH 4, 7, and 9 were sparged with Argon for at least ten minutes prior to transfer into Argon sparged vials.

TEST MEDIUM
- Identity and concentration of co-solvent: no co-solvent

OTHER TEST CONDITIONS
- Adjustment of pH: none
- Dissolved oxygen: purged with Argon
Tetrahydrofuran (THF) will be added post hydrolysis as a dilution solvent

Duration:

5 d

Temp.:

50 °C

Initial conc. measured:

4 mg/L

Number of replicates:

3

Positive controls:

no

Negative controls:

no

Statistical methods:

None

Transformation products:

yes

No.:

#1

Details on hydrolysis and appearance of transformation product(s):

2-(N-methylperfluorobutanesulfonamido) ethyl acrylate (N-MeFBSEA) forms 1,1,2,2,3,3,4,4,4-nonafluoro-N-(2-hydroxyethyl)-N-methylbutane-1-sulfonamide (N-MeFBSE Alcohol) upon hydrolysis. Additional hydrolysis products are expected to be 2-N-methylperfluorobutanesulfonamide (N-MeFBSA), perfluorobutanesulfonate (PFBS) and perfluorobutanesulfonamide (FBSA) (see Illustration). However, the potential hydrolysis products N-MeFBSA and FBSA were observed only at test initiation and were at detection limit at the end of the test. PFBS was not observed at any time point. Therefore, only N-MeFBSE Alcohol is ascribed to hydrolysis.

pH:

7

Temp.:

25 °C

DT50:

0.605 yr

Type:

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

Remarks on result:

other: extrapolation from half-life at 50 °C

pH:

7

Temp.:

50 °C

Hydrolysis rate constant:

0.031 d-1

DT50:

22.078 d

Type:

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

Remarks on result:

other: Remarks: T1/2 = (ln2) /k;

Details on results:

- Formation and decline of each transformation product during test: four possible hydrolysis product were monitored:
*2-(N-methylperfluorobutanesulfonamido) ethyl alcohol (N-MeFBSE Alcohol);
*2-N-methylperfluorobutanesulfonamide (N-MeFBSA);
*perfluorobutanesulfonamide (FBSA);
*perfluorobutanesulfonic acid (PFBS).

Appearance of N-MeFBSE Alcohol as a degradation product was found in all pH buffers, with the hydrolysis most rapid at pH 7 and only slightly slower at pH 9. At pH 4, the appearance of N-MeFBSE Alcohol as a degradation product was much slower. In pH 9 buffer, two additional substances (FBSA and MeFBSA) were found at day 0, however, the concentration decreased to the level of quantitation limits at day 5. No PFBS was found in any buffers.

Typically, hydrolysis is considered to be either acid or base catalyzed and it would appear that the exact opposite of this was observed for N-MeFBSEA. However, this is a two point kinetic analysis where very small changes in observed concentrations resulted in large changes in determined half-lives.

The hydrolytic degradation of N-MeFBSEA studied was conducted at 50°C over 5 days. Half-lives were extrapolated to 25 °C by multiplying by a factor of 10. This is valid for reactions such as these (ester hydrolysis), which have an Arrhenius Heat of Activation of approximately 18 Kcal/mole.

Table 1: Summary of hydrolysis for C4 Acrylate 

Compound	pH = 4
	Day 0	Day 5	Change	T1/2 (year)¹
FBSA	ND*	ND	UND*	UND
PFBS	ND	ND	UND	UND
MeFBSA	ND	ND	UND	UND
N-MeFBSE Alcohol³	0.0271	0.0520	0.0249	15.14
Compound	pH = 7
	Day 0	Day 5	Change	T1/2 (year)¹
FBSA	ND	ND	UND	UND
PFBS	ND	ND	UND	UND
MeFBSA	ND	ND	UND	UND
N-MeFBSE Alcohol³	0.0172	0.5974	0.5802	0.6049
Compound	pH = 9
	Day 0	Day 5	Change	T1/2 (year)¹
FBSA	0.3669	0.01810²	0.3488	0.03153
PFBS	ND	ND	UND	UND
MeFBSA	0.3044	0.01870²	0.2857	0.03403
N-MeFBSE Alcohol³	0.3284	0.5395	0.2690	1.608

*, ND is Non-Detect, UND is undetermined.

1, Units of the calculated half-life is years at 25°C.

2, Concentrations shown are quantitation limits, half-lives shown represent a "less than" value, see Appendix B for details.

3, Half-life represents rate of formation and is calculated for the degradation of N-MeFBSEA.

Conclusions:

Hydrolysis rates of N-MeFBSEA were calculated by monitoring the appearance of N-MeFBSE Alcohol as a function of pH. N-MeFBSEA was determined to have a hydrolysis half-life of 0.6049 years at pH 7 and 25°C.

Executive summary:

Hydrolysis study for 2-(N-methylperfluorobutanesulfonamido) ethyl acrylate (N-MeFBSEA) was performed according to the US EPA Test Guidelines OPPTS 835.2110 “Hydrolysis as a Function of pH”. 2-(N-methylperfluorobutanesulfonamido) ethyl acrylate (N-MeFBSEA) was suspended in buffers of pH 4,7 and 9 at a nominal concentration of 4 ppm, and was allowed to react for five days at 50°C. After the five-day reaction period, THF was added to the buffer containing vials as a dilution solvent to improve recoveries. Four targeted hydrolysis compounds were analyzed by HPLC/MS. Only N-MeFBSE Alcohol was found as hydrolysis product at pH 7, and was used to calculate the hydrolysis half life. N-MeFBSEA has a hydrolytic half life of 0.6049 years at pH 7 at 25°C determined from the appearance of the degradation product 2-(N-methylperfluorobutanesulfonamido) ethyl alcohol. The measured half-life was longer under both acidic and basic conditions.

 

This is a guideline study conducted under GLP. Therefore, it is considered to be reliable without restriction.

Reference 2

Endpoint:

hydrolysis

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Read across from test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Justification for type of information:

HYPOTHESIS FOR THE ANALOGUE APPROACH
The Target chemical and the Source chemical both contain the nonafluorobutylsulfon-N-methylamidoethoxyl (i.e., C4 sulfonamido alcohol) functionality. The Target chemical contains this structure esterified with methacrylic acid. The Source chemical contains the same group esterified with acrylic acid. The Source chemical and the Target chemical have similar molecular weight. Water solubility differs between the two chemicals by approximately a factor of ten, while octanol-water partition coefficient differs by less than one log unit. Acrylate and methacrylate functionalities are electrophilic and both may participate in Michael addition reactions, although the methacrylate undergoes such reactions much slower owing to both electronic and steric effects. Metabolism is expected to occur through the same pathways: hydrolysis by carboxylesterases and conjugation to gluthathione. Hydrolysis reactions and rates are similar across the acrylate family and enhance the elimination of the chemical upon exposure (McCarthy & Witz, 1997).Enzymatic hydrolysis kinetic constants for methacrylate and acrylate esters are similar. The analogue hypothesis is abiotic hydrolysis data can be read across directly from the acrylate to the methacrylate.

SOURCE AND TARGET CHEMICAL:
Source chemical: C4 sulfonamido acrylate (CAS# 67584-55-8)
Target chemical: C4 sulfonamido methacrylate (CAS# 67584-59-2)

See IUCLID Section 13 for an Analog Reporting Format justifying read across for a battery of endpoints.

Reason / purpose for cross-reference:

read-across source

Transformation products:

yes

No.:

#1

pH:

4

Temp.:

25 °C

DT50:

15.14 yr

Type:

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

Remarks on result:

other: extrapolation from half-life at 50 °C

Key result

pH:

7

Temp.:

25 °C

DT50:

0.605 yr

Type:

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

Remarks on result:

other: extrapolation from half-life at 50 °C

pH:

9

Temp.:

25 °C

DT50:

1.608 yr

Type:

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

Remarks on result:

other: extrapolation from half-life at 50 °C

Conclusions:

C4 sulfonamido methacrylate was determined to have hydrolysis half-lives of 0.6049 years at pH 7 and 25°C, 15.14 years at pH 4 and 25 °C, and 1.608 years at pH 9 and 25 °C, by readacross from C4 sulfonamido acrylate.

Executive summary:

C4 sulfonamido methacrylate hydrolysis is assessed by readacross from C4 sulfonamido acrylate. Hydrolysis of the acrylate was assessed at 50 °C for pH values of 4, 7, and 9. Rate constants were extrapolated to 25 °C and used to calculate hydrolysis half-lives. The half-lives were read across directly to C4 sulfonamido methacrylate. As stated in the justification for type of information, biologically mediated hydrolysis of acrylates and methacrylates occurs at roughly the same rate. Abiotic hydrolysis would also occur at roughly the same rate. The electronic and steric effects of the methacrylate substitution may reduce the hydrolysis rate somewhat relative to the already-slow acrylate hydrolysis. However, given the rapidity of primary biodegradation, abiotic hydrolysis is unlikely to contribute significantly to the aquatic fate of C4 sulfonamido methacrylate.

The readacross is based on data from a study done using scientifically valid methods reported in sufficient detail for assessment. The source data are considered reliable without restrictions. Read across of the data is considered reliable with restrictions. The results are considered suitable for Risk Assessment, Classification & Labeling, and PBT Analysis.

Description of key information

C4 sulfonamido methacrylate was determined to have hydrolysis half-lives of 0.6049 years at pH 7 and 25°C, 15.14 years at pH 4 and 25 °C, and 1.608 years at pH 9 and 25 °C, by readacross from C4 sulfonamido acrylate.

Additional information

C4 sulfonamido methacrylate hydrolysis is assessed by readacross from C4 sulfonamido acrylate. The half-lives were read across directly to C4 sulfonamido methacrylate. Biologically mediated hydrolysis of acrylates and methacrylates occurs at roughly the same rate. Abiotic hydrolysis would also occur at roughly the same rate. The electronic and steric effects of the methacrylate substitution may reduce the hydrolysis rate somewhat relative to the already-slow acrylate hydrolysis.  Process water at the manufacturing facility is treated using a combination of technologies.  Reduction of C4 acrylate to <2 ppb (the limit of quantification) in the effluent water during treatment has been shown.  No significant releases of C4 acrylate to aquatic systems are expected.  C4 sulfonamido methacrylate has a somewhat higher log Kow than C4 acrylate, and therefore it is expected to have a somewhat greater extraction efficiency under adsorptive treatment conditions. Releases of C4 sulfonamido methacrylate are expected to be somewhat lower than the already-negligible releases of C4 acrylate. Due to the lack of exposure to aquatic systems, hydrolysis is not expected to be relevant to its fate.