Registration Dossier

Administrative data

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
March 2004
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2004

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
Test item: (N-Cyclohexyl-diazeniumdioxy)-potassium
IUPAC name: Cyclohexylhydroxydiazene 1-oxide, potassium salt
Chemical name: Cyclohexylhydroxydiazene 1-oxide, potassium salt; synonyma: (N-Cyclohexyl-diazeniumdioxy)-potassium, K-HDO, K-NCH, Xyligen K powder, Xyligen K
Molecular formula: C6 H11 K N2 O2
Molecular mass: 182.27
Specific details on test material used for the study:
Test material: K-HDO monohydrate (includes 1 molecule of water of crystallisation)
Lot/Batch number: E7350/1
Specification: Solid
Purity: 100 %; corresponds to 91.1 % when 1 molecule of water of crystallisation is disregarded.
Radiolabelling:
no

Study design

Analytical monitoring:
yes
Details on sampling:
Sampling intervals: at 0,1,2,3,4,7 days
At the end of each testing interval the samples were thermostated at 20°C. Then the aliquots for the analysis were taken out and the samples were replaced at once in the thermostated ovens (at testing temperature).
Buffers:
Citrate buffer (pH=4),
Phosphate buffer (pH=7)
Borate buffer (pH=9)
All buffers prepared according to the OECD guideline 111.
Details on test conditions:
The determination of the hydrolysis has been carried out according to OECD guideline 111, US-EPA OPPTS 835.2110 and EU-guideline 79/831/EWG.
As solvent bi-distilled water was used. The citrate buffer (pH=4), the phosphate buffer (pH=7) and the borate buffer (pH=9) were prepared according to the OECD guideline 111. All buffer materials were from analytical grade and purchased from Merck.
The glassware and the bi-distilled water were sterilised by heating. All test samples were stored in darkness and were free from oxygen by bubbling nitrogen for five minutes before preparation of each solution.
Duration of test
Remarks:
see table below
Number of replicates:
One hydrolysis test; repeating determination of each sample at every analysis day

Results and discussion

Preliminary study:
See table below
Test performance:
See below
Transformation products:
yes
Identity of transformation products
No.:
#1
Reference
Reference substance name:
Unnamed
Inventory number:
InventoryMultipleMappingImpl [inventoryEntryValue=EC 202-874-0]
IUPAC name:
cyclohexanone oxime
Identity:
Cyclohexanone, oxime
CAS number:
100-64-1
Molecular formula:
C6H11NO
Molecular weight:
113.158
SMILES notation:
ON=C1CCCCC1
InChl:
InChI=1/C6H11NO/c8-7-6-4-2-1-3-5-6/h8H,1-5H2
Details on hydrolysis and appearance of transformation product(s):
The degradation of K-HDO leads to the formation of cyclohexanone oxime, which was checked with HPLC in combination with a diode-array detector. The retention time and the UV-VIS spectra are in good agreement with the pure standards of KHDO and cyclohexanone oxim.
Total recovery of test substance (in %)
Remarks on result:
other: see remark
Remarks:
Results are presented in the table below
Dissipation DT50 of parent compound
Remarks on result:
other: see remark
Remarks:
Results are presented in the table below
Details on results:
see below

Any other information on results incl. tables

Results of preliminary test:

A preliminary test was performed on the substance at 50° C at each of pH 4.0, 7.0 and 9.0. The samples were stored for five days in a sample conditioning bath. If less than 10 per cent of the reaction is observed, the chemical is considered to be stable.

 

Hydrolysis of K-HDO at pH 4, 7 and 9 and 50 °C

PH value
(buffer / measured pH)

T/°C

Conc. of test substance / mg/100ml

Stability check

4
(monopotassium citrate/ 4.14)

50

Day 0: 99.2

Day 5: 9.2

Hydrolytically not stable

7
(monopotassium phosphate/ 7.02)

50

Day 0: 83.39

Day 5: 81.38

Sufficient hydrolytically stable

9
(boric acid/ 9.07)

50

Day 0: 94.03

Day 5: 93.03

Sufficient hydrolytically stable

Hydrolysis of K-HDO at pH 4 and 30, 42 and 50 °C

Temperature t/°C

Temperature control of measurement day

Retention time

Conc. of test substance C /mg/100 ml

Velocity constant K /d-1

a)

Half-life value

t0.5/d

b)

30 °C

30

0

100.28

 

 

 

31

1

55.13

0.598

1.16

 

31

2

17.75

0.866

0.80

 

31

3

12.22

0.702

0.988

 

31

4

10.88

0.555

1.248

 

31

7

11.85

0.305

2.271

 

 

 

 

Mean

1.293

 

 

 

 

 

 

42 °C

42

0

99.71

 

 

 

42

1

36.10

1.016

0.682

 

41.5

2

10.93

1.106

0.627

 

41.5

3

8.94

0.804

0.862

 

41.3

4

10.36

0.566

1.224

 

41.5

7

11.04

0.314

2.204

 

 

 

 

Mean

1.12

 

 

 

 

 

 

50 °C

50

0

99.71

 

 

 

50

1

16.18

1.819

0.381

 

50

2

9.08

1.198

0.578

 

50

3

10.02

0.766

0.905

 

50

4

10.29

0.568

1.220

 

50

7

8.44

0.353

1.963

 

 

 

 

Mean

1.01

a) k = (2.303/t)log(C0/Ct): C0=start concentration of test substance; Ct= concentration of the test substance at time t.

b) t0.5= 0.693/k

 

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Conclusions:
K-HDO ist hydrolytically stable at pH 7 and pH 9 and 50 °C. At pH 4 and 30, 42 and 50 °C hydrolysis has been observed. The degradation product cyclohexanone oxime has been determined via HPLC.
Executive summary:

The determination of the hydrolysis of K-HDO has been carried out according to OECD guideline 111, US-EPA OPPTS 835.2110 and EU-guideline 79/831/EWG. As solvent bi-distilled water was used. The citrate buffer (pH=4), the phosphate buffer (pH=7) and the borate buffer (pH=9) were prepared according to the OECD guideline 111.

The determination of the hydrolysis of K-HDO has been carried out according to OECD guideline 111, US-EPA OPPTS 835.2110 and EU-guideline 79/831/EWG. As solvent bi-distilled water was used. The citrate buffer (pH=4), the phosphate buffer (pH=7) and the borate buffer (pH=9) were prepared according to the OECD guideline 111.

A preliminary test on K-HDO was performed at 50° C each at pH 4.0, 7.0 and 9.0. The samples were stored for five days in a sample conditioning bath. At pH 7 and pH 9 at 50 °C less than 10 per cent are hydrolysed in 5 days and the substance was therefore considered to be hydrolytically stable. In the main test the hydrolysis of K-HDO was determined at pH 4 and 30, 42 and 50 °C.

The reaction order of the hydrolysis reaction didn’t follow a first order reaction. Therefore the half life time is calculated by the velocity constants of each measurement and the average of five measurement is given for 30, 42 and 50 °C.

From the velocity constants at 30 and 42 °C the following values can be calculated for the factor A and the activation energy B of the Arrhenius equation k= Ae-B/RT:

A = 249.47 d-1, B = 15170.7 J/mol.

Therefore, a velocity constant of k (25°C) = 0.5485 d-1, and a half-live time t0.5(25 °C) = 1.26 d can be calculated.