Sodium 4-vinylbenzenesulphonate

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2001

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

The stability of test substance was investigated with 5% aqoueous solution at 25 C and 40 C at pH4, 7 and 11.

GLP compliance:

no

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the parent/transformation products:See results
- Sampling method: Not known
- Sampling intervals/times for pH measurements: see result section
- Sampling intervals/times for sterility check:not known
- Sample storage conditions before analysis:room temperature
- Other observation, if any (e.g.: precipitation, color change etc.):

Buffers:

- pH:4
- Type and final molarity of buffer:Phthalate buffer
- pH:7
- Type and final molarity of buffer:Phosphate buffer
- pH:11
- Type and final molarity of buffer:Phosphate buffer
- pH:
- Type and final molarity of buffer:
- Composition of buffer:

Details on test conditions:

5 % aqueous solutions of test substance were stored at specified pH (4,7,11) and temperature (24C and 40C)
Samplings of the solution were took place on the specified date.

Duration:

10 d

pH:

4

Temp.:

40

Initial conc. measured:

>= 96 - <= 98 other: %

Duration:

20 d

pH:

7

Temp.:

40

Initial conc. measured:

> 98 - <= 99 other: %

Duration:

20 d

pH:

11

Temp.:

60

Initial conc. measured:

>= 96 - <= 98 other: %

Number of replicates:

3

Positive controls:

not specified

Negative controls:

not specified

Preliminary study:

Stability of 5% aqueous solutions of sodium p-styrenesulfonate was investigated at pH4, 7 and 11 at 40 C.
Recovery ratio of test substace after 20 days were above 90%.

Transformation products:

yes

No.:

#1

No.:

#1

No.:

#1

No.:

#1

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

Sodium p-styrenesulfonate has no functional group to be hydrolyzed. This substance is stable in neutral to basic conditions, but slowly polymerizes in acidic conditions.

% Recovery:

97

St. dev.:

1

pH:

4

Temp.:

40 °C

Duration:

10 d

% Recovery:

96

St. dev.:

2

pH:

4

Temp.:

40 °C

Duration:

20 d

% Recovery:

98.7

St. dev.:

0.6

pH:

7

Temp.:

40 °C

Duration:

20 d

% Recovery:

97

St. dev.:

1

pH:

11

Temp.:

60 °C

Duration:

20 d

Key result

pH:

4

Temp.:

40 °C

Hydrolysis rate constant:

0.001 d-1

DT50:

499 d

St. dev.:

0

Type:

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

Remarks on result:

other: log(1/C)=0.000592t-1.995, r2=0.956

Key result

pH:

7

Temp.:

40 °C

Hydrolysis rate constant:

0 d-1

DT50:

3 976 d

St. dev.:

0

Type:

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

Remarks on result:

other: log(1/C)=0.0000756t-2.000, r2=0.533

Key result

pH:

11

Temp.:

60 °C

Hydrolysis rate constant:

0 d-1

DT50:

724 d

St. dev.:

0

Type:

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

Remarks on result:

other: log(1/C)=0.000424t-2.006, r2=0.860

Details on results:

Recovery ratios of sodium p-styrenesulfonate in pH4, 7 and 11 at 40 C or 60 C were larger than 90%.
In the long term test, this substance deteriorated due to slow polymerization of this substance, especially in an acidic condition.

Stability of Spinomar NaSS at various pH

Unit: %

pH		pH=4		pH=7		pH=11
Temp.^oC		24^oC	40^oC	24^oC	40^oC	24^oC	60^oC
Storage dates	0	100,100,100	100,100,100	100,100,100	100,100,100	100,100,100	100,100
	10	100,100,99	97,96,98
	20	97,98,97	98,94,96	100,99,99	99,98,99	99,100,99	97,98
	31	97,96,96	95,94,93
	48	96,96,96	95,92,91	99,99,99	99,98,99	99,98,99	96,96
	68	96,95,97	88,89,90	99,99,99	99,99,99	99,99,99	93,95
	93	95,92,93	90,86,86	99,98,99	99,99	99,97,99	92,93
	122	92,92,90	86,82,91	99,98,99	97,98,97	98,100,98	89,91
	151	91,90,89	85,78,78	98,98,98	98,97,97	99,97,98	89,88
	184	90,88,86	83,77,75	98,98,97	98,99,97	98,98,97	89,87
	227	89,86,85	78,71,69	99,99,99	97,97,95	98,100,100	86,84
	263	86,85,82	75,68,66	98,98,98	97,97,94	98,99,98	83,81
	303	86,83,82	70,64,61	99,99,98	97,97,93	98,98,99	74,80
	346	83,82,79	65,60,60	99,98,98	96,96,89	99,98,98	62,69
	388	81,81,77	62,58,54	98,99,96	96,95,86	98,98,98

 

 

 

Sodium p-styrenesulfonate was stable under from neutral to basic conditions at 40oC.

But the substance was slowly polymerized at lower pH (pH=4) even at room temperature.

 

Conclusion

Sodium p-styrenesulfonate was stable under neutral to basic conditions even at 40^oC.

But the substance slowly polymerizes at lower pH (pH=4).

Validity criteria fulfilled:

not applicable

Conclusions:

Sodium p-styrenesulfonate is considered hyrolytically stable.

Executive summary:

According to OECD guideline for the testing of chemicals 111 (hydrolysis as a function of pH), the preliminary test is performed at 50 +/- 0.5 °C and pH 4.0, 7.0 and 9.0. If less than 10 percent of hydrolysis is observed after 5 day, the test substance is considered hydrolytically stable and, normally, no additional test is required. For this substance, less than 10 percent of deterioration was observed after 20 days at 40 °C or 60 °C and pH 4.0, 7.0 and 11.0. Judging from this test, this substance (sodium p-styrenesulfonate) is considered hydrolytically stable.

Description of key information

According to OECD guideline for the testing of chemicals 111 (hydrolysis as a function of pH), the preliminary test is performed at 50 +/- 0.5 °C and pH 4.0, 7.0 and 9.0. If less than 10 percent of hydrolysis is observed after 5 day, the test substance is considered hydrolytically stable and, normally, no additional test is required. For this substance, less than 10 percent of deterioration was observed after 20 days at 40 °C or 60 °C and pH 4.0, 7.0 and 11.0. Judging from this test, this substance (sodium p-styrenesulfonate) is considered hydrolytically stable.

Key value for chemical safety assessment

Half-life for hydrolysis:

3 976 d

at the temperature of:

40 °C