Registration Dossier

Diss Factsheets

Administrative data

Endpoint:
dissociation constant
Type of information:
calculation (if not (Q)SAR)
Remarks:
Migrated phrase: estimated by calculation
Adequacy of study:
key study
Study period:
2009
Reliability:
1 (reliable without restriction)
Cross-reference
Reason / purpose for cross-reference:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009
Report date:
2009

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
Deviations:
yes
Principles of method if other than guideline:
No experimental determination but calculation of pKa.
GLP compliance:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
2-phosphonobutane-1,2,4-tricarboxylic acid
EC Number:
253-733-5
EC Name:
2-phosphonobutane-1,2,4-tricarboxylic acid
Cas Number:
37971-36-1
Molecular formula:
C7H11O9P
IUPAC Name:
2-phosphonobutane-1,2,4-tricarboxylic acid

Results and discussion

Dissociating properties:
yes
Dissociation constantopen allclose all
No.:
#1
pKa:
>= 8.09 - <= 9.09
Temp.:
20 °C
Remarks on result:
other: pKa (HL/H+L)
No.:
#2
pKa:
>= 4.85 - <= 5.04
Temp.:
20 °C
Remarks on result:
other: pKa (H2L/H+HL)
No.:
#3
pKa:
>= 4.34 - <= 4.54
Temp.:
20 °C
Remarks on result:
other: pKa (H3L/H+H2L)
No.:
#4
pKa:
>= 3.78 - <= 4.2
Temp.:
20 °C
Remarks on result:
other: pKa (H4L/H+H3L)
No.:
#5
pKa:
>= 0.66 - <= 1.5
Temp.:
20 °C
Remarks on result:
other: pKa (H5L/H+H4L)

Any other information on results incl. tables

Statistical factors: +/-0.30

Applicant's summary and conclusion

Conclusions:
In total, 2-phosphonobutane-1,2,4-tricarboxylic acid can release 5 protons step by step. Each release is described by one equilibrium constant (pKa). Depending on the value, the acid dissociation constants (pKa values) indicate strong (#5), medium strong (#4, #3, #2) and weak (#1) acids.
The pKa values indicate neither very strong nor very weak acids.
Executive summary:
The calculation of the dissociation constants of 2-phosphonobutane-1,2,4-tricarboxylic acid in water was performed by software ACD ChemSketch ACD/Labs 7.00 Release, Product Version 7.05. Usually the resulting dissociation constants are calculated for 20°C.

2-phosphonobutane-1,2,4-tricarboxylic acid in water can release 5 protons step by step.

Each release is described by one equilibrium reaction or equilibrium constant (pKa):

H5L = H+H4L (pKa = 1.08 ± 0.42)

H4L = H+H3L (pKa = 3.99 ± 0.21)

H3L = H+H2L (pKa = 4.44 ± 0.10)

H2L = H+HL (pKa = 4.99 ± 0.14)

HL = H+L (pKa = 8.59 ± 0.50)

Depending on the pKa value, the acid dissociation constants indicate strong (pKs < 3.8), medium strong (pKs < 7.2) and weak (pKs < 16) acids.

The pKa values indicate neither very strong nor very weak acids.