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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Administrative data

Endpoint:
dissociation constant
Type of information:
calculation (if not (Q)SAR)
Remarks:
estimation by calculation
Adequacy of study:
key study
Study period:
2020
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2020
Report date:
2020

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
other: other: Software: ACD/I-Lab Web service (pKa Algorithm Version: v5.0.0.184
Principles of method if other than guideline:
pKa is calculated from structural parameters. The algorithm is derived from a correlation of a large number of chemical structures with experimental pKa values.

Test material

Constituent 1
Chemical structure
Reference substance name:
(benzothiazol-2-ylthio)acetic acid
EC Number:
228-565-0
EC Name:
(benzothiazol-2-ylthio)acetic acid
Cas Number:
6295-57-4
Molecular formula:
C9H7NO2S2
IUPAC Name:
2-(1,3-benzothiazol-2-ylsulfanyl)acetic acid
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder

Results and discussion

Dissociating properties:
yes
Dissociation constantopen allclose all
No.:
#1
pKa:
ca. 3.7
Temp.:
25 °C
No.:
#2
pKa:
ca. 1.8
Temp.:
25 °C
Remarks on result:
other: 2 (strongest base) = 1.8 ± 0.8

Applicant's summary and conclusion

Conclusions:
Result:
The pKa values of (Benzothiazol-2-ylthio)acetic acid at 25 °C are:
pKai (strongest acid): 3.7 ± 0.4
pKa2 (strongest base): 1.8 ± 0.8
Executive summary:

ACD/pKa-algorithm calculates acid-base ionization constants (pKa values) for 25 °C and zero ionic

strength in aqueous solutions. Each calculation is provided with its 95% confidence limits. The

accuracy of calculations is usually better than ±0.2 pKa units.

The structure was entered as SMILES code c12c(cccc1)N=C(SCC(=O)O)S2.

The calculation gave two pKa values for strongest acid and strongest base.

pKa1 (strongest acid) = 3.7 ± 0.4 and pKa2 (strongest base) = 1.8 ± 0.8 at 25 °C and zero ionic

strength.