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Stability in organic solvents and identity of relevant degradation products

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Endpoint:
stability in organic solvents and identity of relevant degradation products
Type of information:
experimental study
Adequacy of study:
key study
Study period:
April 2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well conducted study to support waivers.
Qualifier:
no guideline available
Principles of method if other than guideline:
NMR spectroscopy
 
Spectra are recorded on a Bruker Avance-III 600 NMR spectrometer with a proton resonance frequency of 600MHz, a carbon resonance frequency of 150MHz and a phosphorous resonance frequency of 243MHz.
In time the decrease of the bisisobutyryl peroxide signal and the increase of the signal of the degradation products are measured in a aquous solution.
GLP compliance:
no
Test substance stable:
no
Transformation products:
yes
No.:
#1
No.:
#2
No.:
#3
No.:
#4

A representative spectrum is shown in figure 1 in the attachment.

Several degradation products are detected: Isobutyric acid (isoBAcid), isopropylalcohol (IPA), propene, and acetone. The amounts of these compounds and the rest peroxide (Trigonox 187, abbreviated as Tx-187 in the spectrum) are calculated using acetic acid (peak) as internal standard. The results are listed in table below.

NMR results

Exp

Time

% m/m

No.

sec

min.

Trigonox 187

IsoBAcid

IPA

propene

acetone

1

544

9.1

0.0213

0.0077

0.0036

0.0006

0.0002

2

795

13.3

0.0154

0.0099

0.0041

0.0008

0.0003

3

1016

16.9

0.0116

0.0122

0.0059

0.0011

0.0002

4

1214

20.2

0.0086

0.0131

0.0072

0.0013

0.0002

5

1574

26.2

0.0063

0.0139

0.0071

0.0015

0.0002

6

1831

30.5

0.0039

0.0162

0.0071

0.0015

0.0003

7

2089

34.8

0.0024

0.0149

0.0071

0.0016

0.0003

8

2346

39.1

0.0022

0.0152

0.0085

0.0017

0.0002

9

2604

43.4

0.0015

0.0156

0.0085

0.0016

0.0003

10

2861

47.7

0.0016

0.0172

0.0084

0.0017

0.0002

11

3119

52.0

0.0006

0.0170

0.0081

0.0017

0.0003

12

3376

56.3

0.0005

0.0163

0.0084

0.0017

0.0002

13

3634

60.6

0.0000

0.0164

0.0081

0.0016

0.0003

Conclusions:
The degradation of Bisisobutyryl peroxide in water is measured by 1H-NMR at 27°C. It can be concluded that:

- The start concentration of Bisisobutyryl peroxide in water was approx. 0.05%.
- Bisisobutyryl peroxide decomposes completely in water after 60 minutes at 27°C (room temperature).
- The decomposition products observed are: Isobutyric acid (IBA), Isopropanol, propene and acetone.
- The main decomposition/hydrolysis product found is Isobutyric acid.
- Propene is also likely to be one of the main decomposition products but the exact amount can not be determined due to its high volatile nature.
Executive summary:

This study supports the degradation of Bisisobutyryl peroxide in water, so water solubility and others endpoints which requir solutions in water can be waived.

Endpoint:
stability in organic solvents and identity of relevant degradation products
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2011-2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well conducted and documented study, to investigate the stability of diisobutyryl peroxide in the mixtures used in (eco)tox tests. Certificate of analysis included in the report.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Isothermal Setaram C80 calorimeter and calculations.
GLP compliance:
no
Test substance stable:
no

Results of all experiments are given below.

Sample

Remark

Technique

Temp.

Temp. as

ln k

Batch or

 

 

 

(°C)

1000/T

(k in 1/s)

experiment code

 

 

 

 

 

Tx 187-W26

ex 60% in isododecane + TBHP

aO-stab

0

3,660

-14,84

TCOP M200920007

Tx 187-W26

ex 60% in isododecane + TBHP

aO-stab

-20

3,949

-18,48

TCOP M200920007

Tx 187-W26

ex 48% in isododecane + TBHP

aO-stab

0

3,660

-14,8

TCOP 201120212

Tx 187-W26

ex 48% in isododecane + TBHP

aO-stab

-15

3,873

-17,58

TCOP 201120212

 

 

 

 

 

Tx 187-W40

ex 70% in 1-decene, no TBHP

DSC scan

29,8

3,300

-9,643

Ch111201A / Nuk11158

Tx 187-W40

ex 70% in 1-decene, no TBHP

DSC scan

63,5

2,970

-5,35

Ch111201A / Nuk11158

Tx 187-W40

ex 70% in 1-decene, no TBHP

Iso Setaram

24,57

3,358

-10,4

Ch111201A / Nuk11157

Tx 187-W40

ex 70% in 1-decene, no TBHP

aO-stab

0

3,660

-14,13

OVP11040-A

Tx 187-W40

ex 70% in 1-decene + TBHP

aO-stab

0

3,660

-14,37

OVP11040-B

Tx 187-W40

ex 70% in 1-decene, no TBHP

aO-stab

-25

4,029

-19,01

OVP11040-A

Tx 187-W40

ex 70% in 1-decene +TBHP

aO-stab

-25

4,029

-19,13

OVP11040-B

Tx 187-W40

ex 70% in isododecane + TBHP

DSC scan

29,8

3,300

-9,62

Ch 090324 / Nuk09084

Tx 187-W40

ex 70% in isododecane + TBHP

DSC scan

63,5

2,970

-5,23

Ch 090324 / Nuk09084

Tx 187-W40

ex 70% in isododecane + TBHP

Iso Setaram

24,57

3,358

-10,39

Ch 090324

Tx 187-W40

ex 70% in isododecane + TBHP

DSC iso

40

3,193

-8,26

Nuk09082

Tx 187-W40

ex 70% in isododecane + TBHP

aO-stab

0

3,660

-14,34

TCOP 201120212

Tx 187-W40

ex 70% in isododecane + TBHP

aO-stab

-15

3,873

-17,17

TCOP 201120212

Tx 187-WS40

ex 70% in Spirdane D 60 + TBHP

aO-stab

0

3,660

-14,49

BET 0909

Tx 187-WS40

ex 70% in Spirdane D 60 + TBHP

aO-stab

-25

4,029

-19,55

Lug 2093-034

Tx 187-W40

ex 70% in 1-decene, no TBHP

aO-stab

0

3,660

-14,13

OVP11040-A

Tx 187-W40

ex 70% in 1-decene + TBHP

aO-stab

0

3,660

-14,37

OVP11040-B

Tx 187-W40

ex 70% in 1-decene, no TBHP

aO-stab

-25

4,029

-19,01

OVP11040-A

Tx 187-W40

ex 70% in 1-decene +TBHP

aO-stab

-25

4,029

-19,13

OVP11040-B

 

 

 

 

 

Tx 187-C48

Tx 187-C48 + TBHP

aO-stab

-20

3,949

-18,78

TCOP M200920007

Tx 187-C31

Tx 187-C31 no TBHP added

aO-stab

-15

3,873

-17

RCD 901-607

Tx 187-C31

Tx 187-C31 no TBHP added

aO-stab

-20

3,949

-19,56

RCD 901-607

Tx 187-C75

TBHP added

aO-stab

-20

3,949

-18,46

OVP02037

Tx 187 55% in n-nonane

in n-nonane, + TBHP

NMR

0

3,660

-15,39

OVP03016C

Tx 187-C30

no TBHP

NMR

25

3,354

-12,01

1101447007

 

 

 

 

 

13.1% in isododecane

sample ex Tx 187-C70

TAM

25

3,354

-11,12

Nuk11181

1.73% in isododecane

sample ex Tx 187-C70

TAM

25

3,354

-12,53

Nuk11127

1.57% in chlorobenzene

sample ex Tx 187-C70

TAM

25

3,354

-10,54

Data ex Product Catalog

15.8% in corn oil

sample ex Tx 187-C70

Iso Setaram

24,5

3,359

-10,84

Nuk11083

1.73% in corn oil

sample ex Tx 187-C70

TAM

25

3,354

-11,12

Nuk11128

1.69% in ethanol 99.9%

sample ex Tx 187-C70

TAM

25

3,354

-9,78

Nuk11124

1.74% in PEG 200

sample ex Tx 187-C70

TAM

25

3,354

-8,74

Nuk11123

1.72% in DMSO

sample ex Tx 187-C70

TAM

25

3,354

-8,47

Nuk11125

1.78% in 1,2-propanediol

sample ex Tx 187-C70

TAM

25

3,354

-8,17

Nuk11126

 

 

 

 

 

Tx 187 dissolved in water

conc peroxide at t= 0 is around 0.05 wt%

NMR

27

3,331

-6,64

ECG-MAS A20120902

0.012% in water + 1% CMC

sample ex Tx 187-C70

TAM

25

3,354

-7,09

Nuk11130

DSC

Results of the DSC scan are given in the chart 3 in the attachment: Arrhenius plot of the Trigonox 187 decomposition.

This are the blue dots in the 1000/T range of 2.9 to 3.3.

Results of a40% emulsion, prepared from a 70% sample in isododecane, are added also. This is a sample with batch code Ch 090324. This sample contained 0.4% TBHP as a stabilizing agent. The rate of decomposition of the sample in isododecane is just a bit higher. The difference is most likely not significant.

TAM and Setaram C80 investigations

The result of a TAM investigation is given in the chart 4 in the attachment .

Results of all the TAM investigations are given in the table below.

 

Solvent

 

Concentration

(w/w %)

 

Half life time at 25°C

(h)

 

Factor of increased rate of reaction related to 1.74% in isododecane

 

Isododecane

Isododecane

Chlorobenzene

Corn oil

Corn oil

Ethanol 99.9%

PEG 200

DMSO

1,2-propanediol

Water + 1% CMC

 

   1.73

13.1

   1.57

   15.8

   1.73

   1.69

   1.74

   1.72

   1.78

     0.012

 

53

13

  7.3  

  9.8

13

   3.4

   1.2

    0.92

    0.68

     0.23

 

 1

   4.2

   7.3

   5.4

   4.2

 16

 44

 58

 78

230

Remark: a concentration of 1.74% w/w corresponds with 0.1 Mole / kg.

Results of the TAM investigations are given as green - triangles in the chart in the attachment 3 at 1000/T is around 3.36. The green – triangle data points are the results of investigations in organic solvents.

Test results in alkanes

 

Test results of the rate of decomposition in isododecane or n-nonane are given as red stars  in the Arrhenius plot. These results were obtained by iodometric titrations after storage over longer periods of time as low temperature.

 

Influence of isobutyricacid and isobutanal on the stability of the peroxide

 

The influence of minor amounts of isobutanal and isobutyric acid are investigated in the Setaram C80. These compositions simulate the composition of the peroxide as prepared in an alternative chemical process.

See plot 5 in the attachment.

Conclusion: Isobutanal gives a stronger de-stabilizing of the peroxide compared to isobutyric acid.

Results of investigations in water

 

See plot 3 in the attachment: Arrhenius plot of the Trigonox 187 decomposition.

The red - square dot at the same 1000/T above the green – triangles is the result of the TAM investigation in water at 25ºC. The red – square dot left of this point is the result of NMR investigations at 27ºC, see

Degradation study of Bisisobutylyl peroxide in water at room temperature, Doc code: ECG-MAS A20120902, J. ter Weele and S Datta, November 12, 2012 and NMR data. See: 3437-84-1, Stability in water, Weele, 2012, RS

Conclusions:
Bisisobutyryl peroxide as such is a quite unstable substance.
Stability of bisisobutyryl peroxide is increased by dilution in non polar solvents.
Stability of bisisobutyryl peroxide is decreased by dilution in polar solvents.
Executive summary:

The stability of bisisobutyryl peroxide CAS#: 3437-84-1in different organic solvents and in water is measured at various temperatures by four different techniques.

The experiments in this report were carried out to investigate

  • rate of decomposition during storage of the peroxide
  • kinetics of a runaway reaction
  • stability of the tests substance in different solvents as applied in REACH tests
  • stability of the peroxide after addition of different components as applied in an alternative chemical route.

The test substance as such is a quite unstable substance.

Stability of the test substance is increased by dilution in non polar solvents.

Stability of the test substance is decreased by dilution in polar solvents.

Endpoint:
stability in organic solvents and identity of relevant degradation products
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well conducted and documented study, to investigate the stability of diisobutyryl peroxide in the mixtures used in (eco)tox tests.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Isothermal Setaram C80 calorimeter and calculations.
GLP compliance:
no
Test substance stable:
ambiguous

Overview of tested samples and results 

Concentration of

diisobutyryl peroxide

(% w/w)

Mass ratio

isododecane / corn oil

% corn oil

in diluent

Heat production at 24.5°C (W/kg)

 

13.1

14.8

15.8

 

 

100 / 0

41 / 59

8 / 92

 

0

59

92

 

2.5

3.3

4.2

  

Heat production as a function of time is given in the chart in the attachment.

 

Calculations and discussion

 

The total heat of decomposition of diisobutyryl peroxide pure is around 1500 J/g. This value is applied for the calculation of the data in the second column of table below.

 

Total heat of decomposition(J/g) = [ concentration (%)/ 100(%)] x 1500 (J/g)

      

Total heat of decomposition of each sample is applied to calculate the rate of decomposition as given in the third column of table below.

 

Rate of reaction (k in 1/s) = Heat production (W/kg) / Total heat of reaction ( J/kg)     

 

 

The degree of decomposition after 1 hr at 24.5°C is calculated from the relation:  

 

ln c/ c0  = -k x t

 

In which:

c          concentration at time t, in this case in the range of 0 to 1

c0         concentration at t0, c0is set to 1

k           rate of reaction at 24.5°C (1/s)

t           time (in this case 3600 s)

 

Results of calculations.

 

Concentration of

diisobutyryl peroxide

(% w/w)

Total heat of decomposition (J/kg)

Rate of reaction

(k at 24.5°C in 1/s)

% decomposed peroxide

during 1 hr at 24.5°C

13.1

14.8

15.8

188000

212400

226700

 1.33*10-5

1.55*10-5

1.85*10-5

4.7

5.4

6.5

   

The rate of reaction is increased with around 40% by comparing a formulation in only isododecane as solvent with the rate of reaction of a solution in a mixture of isododecane / corn oil with a ratio of 8 / 92.

The rate of decomposition at 20°C based on the measured data at 24.5°C can be derived by applying Arrhenius law, see attachment

Calculation is now carried out for the 13.1% solution in isododecane:

 

                      1.33*10-5= k0* e-120000/(8.3142*297.7),               k0= 1.51*10-161/s.

 

The value of k at 20°C is now calculated: 6.3*10-61/s.

 

So, the rate of reaction at 24.5°C is 1.33*10-5(1/s) and the rate of reaction at 20°C is 6.3*10-6(1/s). This is a decrease of a factor 2.1 per 4.5°C.

So, the rate of reaction at 20°C and the amount of decomposed peroxide after 1 hour at 20°C, is around 50% of the values at 24.5°C as given in the last two columns of the table above.

 

 

Conclusions:
Stability of diisobutyryl peroxide is slightly reduced by the addition of corn oil. A 40% increase in rate of decomposition was obtained by changing
the solvent from pure isododecane to a mixture of 9 parts isododecane and 92 parts corn oil.
Executive summary:

Corn oil will be applied as a carrier (or diluent) of diisobutyryl in tox tests. The influence of corn oil on the stability of diisobutyryl peroxide was investigated and the results are given in this robust summary.

Diisobutyryl peroxide is prepared in isododecane and the most common formulation of diisobutyryl peroxide is an emulsion in water.

Description of key information

Bisisobutyryl peroxide as such is a quite unstable substance.

Stability of bisisobutyryl peroxide  is increased by dilution in non polar solvents.

Stability of bisisobutyryl peroxide  is decreased by dilution in polar solvents.

Bisisobutyryl peroxide decomposes completely in water after 60 minutes at 27°C.

Stability of diisobutyryl peroxide is slightly reduced by the addition of corn oil. A 40% increase in rate of decomposition was obtained by changing

the solvent from pure isododecane to a mixture of 9 parts isododecane and 92 parts corn oil.

Additional information

The degradation of Bisisobutyryl peroxide in water is measured by 1H-NMR at 27°C. It can be concluded that:

- The start concentration of Bisisobutyryl peroxide in water was approx. 0.05%.

- Bisisobutyryl peroxide decomposes completely in water after 60 minutes at 27°C (room temperature).

- The decomposition products observed are: Isobutyric acid (IBA), Isopropanol, propene and acetone.

- The main decomposition/hydrolysis product found is Isobutyric acid.

- Propene is also likely to be one of the main decomposition products but the exact amount cannot be determined due to its high volatile nature.

The study in corn oil was conducted because corn oil was applied as a carrier (or diluent) of diisobutyryl peroxide in tox tests.