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Diss Factsheets

Physical & Chemical properties

Dissociation constant

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Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2004
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
GLP compliance:
yes
Dissociating properties:
yes
No.:
#1
pKa:
ca. 10.67
Temp.:
25 °C

Results
1) 10.67
2) 10.67
3) 10.66
Average: 10.67

Conclusions:
According to CERI (2004), dissociation constant of 1,3-di-o-tolylguanidine is about 10.67.
Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
according to guideline
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
GLP compliance:
no
Other quality assurance:
ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source : MLPC International -- 11011461158
- grad EK DOTG C
- purity by titration = 97.8 %
- oil amount = 1.3 %

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: 2 years
Dissociating properties:
yes
No.:
#1
pKa:
ca. 11.05
Temp.:
20 °C












































































01/08/2012



Tampon10     ml



NaOH 10N ml



DOTG       ml



pH



Abs



volume total



Abs réel



((Absacide-Abs)/(Abs-Absbasique))



log



2



15



0.1



15



10.6



0.245



30.1



0.244



0.272



-0.566



3



15



0.12



15



10.8



0.278



30.11



0.277



0.485



-0.315



4



15



0.13



15



10.9



0.306



30.12



0.305



0.730



-0.137



5



15



0.15



15



11.2



0.364



30.15



0.362



1.626



0.211



6



15



0.2



15



11.9



0.447



30.2



0.444



9.048



0.957


Conclusions:
Dissociation Constant of DOTG is determined to be 11.05.
Executive summary:

pKa = 11.05

Description of key information

According to different methods, pKa of DOTG (1,3-di-o-tolylguanidine) is about 10.5 +/- 1.

Key value for chemical safety assessment

pKa at 20°C:
10.5

Additional information

Three evaluation of pKa of DOTG (1,3 -di-o-tolylguanidine) is made :

Using an estimation with SPARC, the value of 9.9 is found.

With Advanced Chemistry Development software (ACD/labs) V11.02, pKa of 1,3-di-o-tolylguanidine is on the range 10.22-10.42 at 25°C.

According to CERI (2004), dissociation constant of 1,3-di-o-tolylguanidine is measure to be about 10.67.

According to analysis performed at MLPC, pKa of DOTG is 11.5.