Reaction mass of 2-methylpentane and Hexanol, branched and linear and diisopropyl ether

Hydrolysis

Administrative data

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Testing was conducted between 23 December 2009 and 03 March 2010.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive, done to a valid guideline and the study was conducted under GLP conditions.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Reaction Products of C3 alcohols and C3 alkenes obtained as by-products from the manufacture of propan-2-ol by hydration of propylene

EC Number:

701-241-0

Molecular formula:

A complex and variable combination of hydrocarbons having carbon numbers predominantly in the C3, C6 & C9 chain length and oxygenated organic molecules, predominantly diisopropyl ether and hexanol (branched and linear). See diagram

IUPAC Name:

Reaction Products of C3 alcohols and C3 alkenes obtained as by-products from the manufacture of propan-2-ol by hydration of propylene

Radiolabelling:

no

Study design

Analytical monitoring:

yes

Details on sampling:

Sample solutions were prepared in stoppered glass flasks at a nominal concentration of 0.500 g/l in the three buffer solutions. A 1% co-solvent of acetonitrile was used to aid solubility.

The test solutions were split into individual vessels for each data point.

The solutions were shielded from light whilst maintained at the test temperature.

Sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5°C for a period of 120 hours.

Buffers:

Buffer Solution (pH 4)
Components: Potassium hydrogen phthalte
Concentration (mMol dm-3): 10

Buffer Solution (pH 7)
Components: Disodium hydrogen orthophosphate (anhydrous), Potassium dihydrogen orthophosphate, Sodium chloride
Concentration (mMol dm-3): 6, 4 and 4 respectively

Buffer Solution (pH 9)
Components: Disodium tetraborate, Sodium chloride
Concentration (mMol dm-3): 2 and 4 respectively

The buffer solutions were filtered through a 0.2 µm membrane filter to ensure they were sterile before commencement of the test. Also these solutions were subjected to ultrasonication and degassing with nitrogen to minimise dissolved oxygen content.

Details on test conditions:

Sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5°C for a period of 120 hours.

Duration of test

Duration of test 1

Duration:

120 h

pH:

4

Initial conc. measured:

0.169 g/L

Duration of test 2

Duration:

120

pH:

7

Initial conc. measured:

0.168 g/L

Duration of test 3

Duration:

120

pH:

9

Initial conc. measured:

0.189 g/L

Number of replicates:

Duplicate aliquots (A and B) of sample solution were diluted by a factor of 5 using methanol at each timepoint.

Positive controls:

no

Negative controls:

no

Results and discussion

Preliminary study:

All pH's: Apparent hydrolysis attributed to a cumulative reduction in the concentration of a number of less significant dissolved components present, the quantification of which was beyond the scope of the method guideline. Less than 10% hydrolysis after 5 days at 50°C, equivalent to a half-life greater than 1 year at 25°C when considering the isopropyl ether content only/specifically.

Test performance:

Equivalent test material concentrations based on the isopropyl ether peak areas only were also determined at each timepoint as this component was identified as the dominant soluble component at lower, more environmentally relevant concentrations.

Transformation products:

not specified

Dissipation DT50 of parent compound

Dissipation DT50 of parent compound 1

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Type:

other:

Remarks on result:

other: Conclusion based on the isopropyl ether content of the test material.

Dissipation DT50 of parent compound 2

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Type:

other:

Remarks on result:

other: Conclusion based on the isopropyl ether content of the test material.

Dissipation DT50 of parent compound 3

pH:

9

Temp.:

25 °C

DT50:

> 1 yr

Type:

other:

Remarks on result:

other: Conclusion based on the isopropyl ether content of the test material.

Details on results:

At pH4, 7 and 9 there was less than 10% hydrolysis after 120 hours at 50°C when monitoring the isopropyl ether content of the test material, equivalent to a half-life greater than 1 year at 25°C.

Any other information on results incl. tables

The mean total peak areas and the mean isopropyl ether peak areas relating to the standard and sample solutions are shown in the following table:

Solution	Mean Total Peak Area	Mean Isopropyl Ether Peak Area
Standard 100 mg/l	1.474 x 10^3	584.320
Standard 105 mg/l	1.537 x 10^3	620.122
pH 4 Matrix Blank	68.193	50.920
Initial Sample A, pH 4	503.524	284.340
Initial Sample B, pH 4	492.150	279.594
Standard 103 mg/l	1.472 x 10^3	596.057
Standard 112 mg/l	1.630 x 10^3	649.095
pH 4 Matrix Blank	84.645	52.027
24 Hour Sample A, pH 4	525.636	289.728
24 Hour Sample B, pH 4	556.744	317.130
Standard 114 mg/l	2.222 x 10^3[1]	675.269
Standard 103 mg/l	1.538 x 10^3	616.006
pH 4 Matrix Blank	98.537	57.451
48 Hour Sample A, pH 4	513.625	286.438
48 Hour Sample B, pH 4	501.418	286.584
Standard 131 mg/l	2.112 x 10^3	865.974
Standard 112 mg/l	1.785 x 10^3	735.324
pH 4 Matrix Blank	90.576	57.865
120 Hour Sample A, pH 4	487.010	302.295
120 Hour Sample B, pH 4	474.933	300.682
Standard 100 mg/l	1.502 x 10^3	600.682
Standard 105 mg/l	1.536 x 10^3	621.155
pH 7 Matrix Blank	89.080	35.596
Initial Sample A, pH 7	491.139	281.784
Initial Sample B, pH 7	500.157	287.075

 

Continued

Solution	Area	Area
Standard 103 mg/l	1.499 x 10^3	598.852
Standard 112 mg/l	1.615 x 10^3	644.665
pH 7 Matrix Blank	113.049	40.548
24 Hour Sample A, pH 7	485.461	267.149
24 Hour Sample B, pH 7	488.150	267.199
Standard 114 mg/l	1.740 x 10^3	681.418
Standard 103 mg/l	1.502 x 10^3	605.732
pH 7 Matrix Blank	117.266	42.351
48 Hour Sample A, pH 7	470.307	259.845
48 Hour Sample B, pH 7	471.027	263.348
Standard 131 mg/l	2.161 x 10^3	902.908
Standard 112 mg/l	1.739 x 10^3	741.967
pH 7 Matrix Blank	112.761	41.781
120 Hour Sample A, pH 7	448.903	308.943
120 Hour Sample B, pH 7	442.877	308.642
Standard 100 mg/l	1.499 x 10^3	593.891
Standard 105 mg/l	1.587 x 10^3	600.655
pH 9 Matrix Blank	106.432	28.662
Initial Sample A, pH 9	564.083	336.907
Initial Sample B, pH 9	571.878	344.326
Standard 103 mg/l	1.535 x 10^3	611.721
Standard 112 mg/l	1.617 x 10^3	648.048
pH 9 Matrix Blank	115.773	32.058
24 Hour Sample A, pH 9	511.531	294.623
24 Hour Sample B, pH 9	537.620	316.402
Standard 114 mg/l	1.688 x 10^3	667.474
Standard 103 mg/l	1.487 x 10^3	600.004
pH 9 Matrix Blank	129.055	34.065
48 Hour Sample A, pH 9	472.903	280.380
48 Hour Sample B, pH 9	474.622	284.704
Standard 131 mg/l	2.134 x 10^3	887.767
Standard 112 mg/l	1.787 x 10^3	753.387
pH 9 Matrix Blank	117.111	35.649
120 Hour Sample A, pH 9	490.241	344.995
120 Hour Sample B, pH 9	515.736	359.867

 

The equivalent test material concentrations based on the total peak areas at the given time points are shown in the following tables:

pH 4 at 50.0 ± 0.5ºC

	Time (Hours)
	Initial (A)	Initial (B)	24 (A)	24 (B)
Concentration (g/l)	0.171	0.167	0.182	0.193
% of mean initial concentration	101	98.9	108	114

pH 4 at 50.0 ± 0.5ºC continued

	Time (Hours)
	48 (A)	48 (B)	120 (A)	120 (B)
Concentration (g/l)	0.172	0.168	0.152	0.148
% of mean initial concentration	101	98.9	89.7	87.5

Result: Apparent hydrolysis attributed to a cumulative reduction in the concentration of a number of less significant dissolved components present, the quantification of which was beyond the scope of the method guideline.

pH 7 at 50.0 ± 0.5ºC

	Time (Hours)
	Initial (A)	Initial (B)	24 (A)	24 (B)
Concentration (g/l)	0.166	0.169	0.168	0.169
% of mean initial concentration	99.1	101	100	101

 pH 7 at 50.0 ± 0.5ºC continued 

	Time (Hours)
	48 (A)	48 (B)	120 (A)	120 (B)
Concentration (g/l)	0.157	0.158	0.140	0.138
% of mean initial concentration	94.2	94.4	83.9	82.8

Result: Apparent hydrolysis attributed to a cumulative reduction in the concentration of a number of less significant dissolved components present, the quantification of which was beyond the scope of the method guideline.

pH 9 at 50.0 ± 0.5ºC

	Time (Hours)
	Initial (A)	Initial (B)	24 (A)	24 (B)
Concentration (g/l)	0.187	0.190	0.174	0.183
% of mean initial concentration	99.3	101	92.5	97.2

  pH 9 at 50.0 ± 0.5ºC continued

	Time (Hours)
	48 (A)	48 (B)	120 (A)	120 (B)
Concentration (g/l)	0.162	0.162	0.152	0.157
% of mean initial concentration	85.7	86.0	80.6	83.2

Result: Apparent hydrolysis attributed to a cumulative reduction in the concentration of a number of less significant dissolved components present, the quantification of which was beyond the scope of the method guideline.

The equivalent test material concentrations based on the isopropyl ether peak areas only at the given time points are shown in the following tables:

pH 4 at 50.0 ± 0.5ºC

	Time (Hours)
	Initial (A)	Initial (B)	24 (A)	24 (B)
Concentration (g/l)	0.242	0.238	0.250	0.274
% of mean initial concentration	101	99.2	104	114

pH 4 at 50.0 ± 0.5ºC continued

	Time (Hours)
	48 (A)	48 (B)	120 (A)	120 (B)
Concentration (g/l)	0.240	0.241	0.229	0.228
% of mean initial concentration	100	100	95.7	95.1

Result:         Less than 10% hydrolysis after 5 days at 50°C, equivalent to a half-life greater than 1 year at 25°C.

pH 7 at 50.0 ± 0.5ºC

	Time (Hours)
	Initial (A)	Initial (B)	24 (A)	24 (B)
Concentration (g/l)	0.236	0.241	0.231	0.231
% of mean initial concentration	99.1	101	96.9	96.9

pH 7 at 50.0 ± 0.5ºC continued

	Time (Hours)
	48 (A)	48 (B)	120 (A)	120 (B)
Concentration (g/l)	0.219	0.222	0.229	0.228
% of mean initial concentration	91.8	93.0	95.9	95.8

Result:         Less than 10% hydrolysis after 5 days at 50°C, equivalent to a half-life greater than 1 year at 25°C.

pH 9 at 50.0 ± 0.5ºC

	Time (Hours)
	Initial (A)	Initial (B)	24 (A)	24 (B)
Concentration (g/l)	0.282	0.288	0.251	0.270
% of mean initial concentration	98.9	101	88.2	94.7

pH 9 at 50.0 ± 0.5ºC continued

	Time (Hours)
	48 (A)	48 (B)	120 (A)	120 (B)
Concentration (g/l)	0.240	0.244	0.256	0.267
% of mean initial concentration	84.1	85.4	89.6	93.5

Result:         Less than 10% hydrolysis after 5 days at 50°C, based on mean concentration, equivalent to a half-life greater than 1 year at 25°C.

[1] Excluded from calculations due to suspected contamination/inconsistent peak profile.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The estimated half-life at 25°C of the test material is shown in the following table:

pH Estimated half-life at 25°C
4 >1 year
7 >1 year
9 >1 year

Assessment of hydrolytic stability was based on the isopropyl ether component of the test material only, as this was determined to be the dominate dissolved component in aqueous solutions originating from lower, more environmentally relevant nominal saturation concentrations of 1.0 g/l and 10 g/l during the water solubility testing. In addition the 2-methylpentane component contained no hydrolysable functional groups. When monitoring the sample solutions as equivalent test material concentration using the total peak area of all dissolved components, slightly greater than 10% apparent hydrolysis was observed after 120 hours incubation at 50°C (percentages remaining of 88.6%, 83.3% and 81.9% for pH 4, pH 7 and pH 9 respectively). However, this was concluded to originate from a cumulative reduction in the concentration of a number of less significant dissolved components present, the quantification of which was beyond the scope of the method guideline.

Executive summary:

Assessment of hydrolytic stability was carried out using Method C7 Abiotic Degradation, Hydrolysis as a Function of pH, Commission Regulation (EC) No 440/2008 of 30 May 2008. The results are as follows:

pH	Estimated half-life at 25°C
4	>1 year
7	>1 year
9	>1 year

--

Assessment of hydrolytic stability was based on the isopropyl ether component of the test material only, as this was determined to be the dominate dissolved component in aqueous solutions originating from lower, more environmentally relevant nominal saturation concentrations of 1.0 g/l and 10 g/l during the water solubility testing. In addition the 2-methylpentane component contained no hydrolysable functional groups. When monitoring the sample solutions as equivalent test material concentration using the total peak area of all dissolved components, slightly greater than 10% apparent hydrolysis was observed after 120 hours incubation at 50°C (percentages remaining of 88.6%, 83.3% and 81.9% for pH 4, pH 7 and pH 9 respectively). However, this was concluded to originate from a cumulative reduction in the concentration of a number of less significant dissolved components present, the quantification of which was beyond the scope of the method guideline.