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Dissociation constant

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Reference
Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: 1a titration method -- GLP
Qualifier:
according to guideline
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
GLP compliance:
yes (incl. QA statement)
Dissociating properties:
yes
No.:
#1
pKa:
ca. 11.603
Temp.:
20.8 °C
No.:
#2
pKa:
ca. 11.95
Temp.:
20.8 °C
Conclusions:
Two pKa values were determinated on DPTU :
pKa1 = 11.603 at 20.8 +/- 0.4 °C
pKa2 = 11.950 at 20.8 +/- 0.4 °C
Executive summary:

The Dissociation Constants in Water (Spectrophotometric Method) of the test item N,N’-Diphenyl thiourea (DPTU) was studied according to the OECD guideline 112. Measurements were performed at a temperature of 20.8 +/- 0.4 °C.

Two pKa values were determinated :

pKa1 = 11.603 at 20.8 +/- 0.4 °C

pKa2 = 11.950 at 20.8 +/- 0.4 °C

Description of key information

Two pKa values were determinated on DPTU :
pKa1 = 11.603 at 20.8 +/- 0.4 °C
pKa2 = 11.950 at 20.8 +/- 0.4 °C

Key value for chemical safety assessment

pKa at 20°C:
11.77

Additional information

The Dissociation Constants in Water (Spectrophotometric Method) of the test item N,N’-Diphenyl thiourea (DPTU) was studied according to the OECD guideline 112. Measurements were performed at a temperature of 20.8 +/- 0.4 °C.

Two pKa values were determinated :

pKa1 = 11.603 at 20.8 +/- 0.4 °C

pKa2 = 11.950 at 20.8 +/- 0.4 °C