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Physical & Chemical properties

Dissociation constant

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Reference
Endpoint:
dissociation constant
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The (Q)SAR used to generate the value for dissociation constant met the requirements of the OECD principles for validity and falls within the applicability domain of allylamine. The value is therefore considered suitable for use in chemical safety assessment.
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
Guideline:
other: EPA/600/R-03/030 (2003) PREDICTION OF CHEMICAL REACTIVITY PARAMETERS AND PHYSICAL PROPERTIES OF ORGANIC COMPOUNDS FROM MOLECULAR STRUCTURE USING SPARC
Guideline:
other: EPA/600/R-03/033 (2003) VERIFICATION AND VALIDATION OF THE SPARC MODEL
GLP compliance:
no
Dissociating properties:
yes
No.:
#1
pKa:
9.7
Temp.:
20 °C

Model Output

Two individual species variants were identified by the software and presented in the accompanying graph.

QMRF/QPRF Reports are available in the attached full study report.

Table 1. SPARC Output - Species Fraction with Changing pH

 pH  Species 1  Species 2
 -0.2  1.25e-10  1
 -1.05e-15  1.99e-10  1
 0.2  3.15e-10  1
 0.4  4.99e-10  1
 0.6  7.91e-10  1
 0.8  1.25e-09  1
 1  1.99e-09  1
 1.2  3.15e-09  1
 1.4  4.99e-09  1
 1.6  7.91e-09  1
 1.8  1.25e-08  1
 2  1.99e-08  1
 2.2  3.15e-08  1
 2.4  4.99e-08  1
 2.6  7.91e-08  1
 2.8  1.25e-07  1
 3  1.99e-07  1
 3.2  3.15e-07  1
 3.4  4.99e-07  1
 3.6  7.91e-07  1
 3.8  1.25e-06  1
 4  1.99e-06  1
 4.2  3.15e-06  1
 4.4  4.99e-06  1
 4.6  7.91e-06  1
 4.8  1.25e-05  1
 5 1.99e-05   1
 5.2  3.15e-05  1
 5.4  4.99e-05  1
 5.6  7.91e-05  1
 5.8  1.25e-04  1
 6  1.99e-04  1
 6.2  3.15e-04  1
 6.4  4.99e-04  1
 6.6  7.90e-04  1
 6.8  0.001251623  1
 7  0.001982238  1
 7.2  0.003137998  1
 7.4  0.00496428  1
 7.6  0.007845074 0.99 
 7.8  0.01  0.99
 8  0.02  0.98
 8.2  0.03  0.97
 8.4  0.05  0.95
 8.6  0.07  0.93
 8.8  0.11  0.89
 9  0.17  0.83
 9.2  0.24  0.76
 9.4  0.33  0.67
 9.6  0.44  0.56
 9.8  0.56  0.44
 10  0.67  0.33
 10.2  0.76  0.24
 10.4  0.83  0.17
 10.6 0.89   0.11
 10.8  0.93  0.07
 11  0.95  0.05
 11.2  0.97  0.03
 11.4  0.98  0.02
 11.6  0.99  0.01
 11.8  0.99  0.007916453
 12  0.99  0.00500958
 12.2  1  0.003166686
 12.4  1  0.002000381
 12.6  1  0.001263088
 12.8  1  7.97e-04
 13  1  5.03e-04
 13.2  1  3.18e-04
 13.4  1  2.00e-04
 13.6  1  1.26e-04
 13.8  1  7.98e-05
 14  1  5.03e-05
Conclusions:
The macro pKa is the pH at which 50% of total 2-propen-1-amine is in the non-ionised form (Species 1), which is 9.70 for allylamine.

Description of key information

A single key study is used to determine the dissociation constant of allylamine:

pKa at 20 °C = 9.7 (SPARC), Carson (2012).

Key value for chemical safety assessment

pKa at 20°C:
9.7

Additional information

The macro pKa is the pH at which 50% of total 2-propen-1-amine is in the non-ionised form (Species 1), which is 9.70 for allylamine.