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Physical & Chemical properties

Dissociation constant

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Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2006
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
Ullmann's Encyclopedia of Industrial Chemistry
Qualifier:
no guideline available
Principles of method if other than guideline:
No guideline mentioned, handbook data
GLP compliance:
not specified
Remarks:
handbook data
Dissociating properties:
yes
No.:
#1
pKa:
14.8
Remarks on result:
other: Temperature not mentioned.
No.:
#2
pKa:
14.4
Remarks on result:
other: pKb-value! Temperature not mentioned.
Conclusions:
The pka of dicyandiamide is 14.8, the pKb is 14.4.
Executive summary:

The information is taken from a handbook (Ullmann's Encyclopedia of Industrial Chemistry).

The pka of dicyandiamide is 14.8, the pKb is 14.4.

Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Study period:
March 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
GLP compliance:
no
Dissociating properties:
yes
No.:
#1
pKa:
2.42
Temp.:
20 °C
No.:
#2
pKa:
2.61
Temp.:
20 °C
No.:
#3
pKa:
2.74
Temp.:
20 °C
No.:
#4
pKa:
2.81
Temp.:
20 °C
No.:
#5
pKa:
2.91
Temp.:
20 °C
No.:
#6
Temp.:
20 °C
Remarks on result:
other: Value was not included in the calculation due to the low measured conductivity and the appropriately resulting measuring inaccuracy.
No.:
#7
Temp.:
20 °C
Remarks on result:
other: Value was not included in the calculation due to the low measured conductivity and the appropriately resulting measuring inaccuracy.
No.:
#8
Temp.:
20 °C
Remarks on result:
other: Value was not included in the calculation due to the low measured conductivity and the appropriately resulting measuring inaccuracy.

The graphs for molar conductivity and the limit of conductivity are shown in the attached background material.

The limit of conductivity is determined to be 0.42 -1cm² mol-1

Conclusions:
The dissociation constant (KD) was determined to be 0.00218 mol dm-3. The pKD-value is 2.66.
Executive summary:

The study was conducted according OECD Guideline 112 using the conductometric method. The dissociation constant (KD) was determined to be 0.00218 mol dm-3. The pKD-value is 2.66.

Description of key information

An OECD 112 study is available using the conductometric method.

Supporting information is provided in Ullmann's Encyclopedia of Industrial Chemistry.

Key value for chemical safety assessment

pKa at 20°C:
2.66

Additional information

According to an OECD 112 guideline study the pKa of DCD is 2.66 at 20°C. According to Ullmann's Encyclopedia the pKa is 14.8, the pKb is 14.4. The handbook data do not indicate temperature information. Therefore the result of the guideline study is used.