3-chlorophthalic anhydride

Hydrolysis

Administrative data

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2004

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

GLP compliance:

no

Remarks:

This work was conducted in the “spirit” of GLP according to OECD GLP principles.

Test material

Test material information

Constituent 1

Reference substance name:

3-chlorophthalic anhydride

EC Number:

204-179-8

EC Name:

3-chlorophthalic anhydride

Cas Number:

117-21-5

Molecular formula:

C8H3ClO3

IUPAC Name:

4-chloro-1,3-dihydro-2-benzofuran-1,3-dione

Study design

Analytical monitoring:

yes

Details on sampling:

Multiple pH measurements of the 3-CLPA solution were taken over a 50 minute period

Estimation method (if used):

Calculation with computer software developed by ACD.

Results and discussion

Preliminary study:

In a preliminary experiment, the Test Substance 3-chlorophthalic anhydride (3CPA) was mixed with water/acetonitrile (80/20, v/v) at ambient temperature (23 ± 2 °C). The pH of this solution decreased from 5.1 to 2.9 within 5 min, and was fairly stable at 2.5 after 50 min of stirring.

Transformation products:

yes

Identity of transformation products

No.:

#1

Reference

Reference substance name:

Unnamed

Inventory number:

InventoryMultipleMappingImpl [inventoryEntryValue=EC 248-527-7]

CAS number:

27563-65-1

Molecular formula:

C8H5ClO4

Dissipation DT50 of parent compound

Key result

Temp.:

23 °C

DT50:

ca. 1 min

Type:

not specified

Details on results:

When 3-CLPA was added to the stirred water/acetonitrile solution (80/20, v/v), the finer particles dissolved within minutes, whereas the larger particles required ~ 40 min to dissolve. The pH vs time profile showed that the solution immediately became more acidic, approaching a final pH of 2.5 which was in fair agreement with the calculated pH of 2.1. The half-life of this 3-CLPA “decay curve” was estimated graphically at 1 minute. This decay curve was similar to that observed for the 3-CLPA analog, 4-CLPA. In the case of 4-CLPA, it was shown in a separate study that its pH decay curve was due to the hydrolysis of 4-CLPA. Given that the structural difference between 3-CLPA and 4-CLPA is the position of the chlorine on the aromatic ring, and that these chlorine substituents are removed from the site of hydrolysis, it follows that the 3-CLPA decay curve was due to 3-CLPA hydrolysis and that the hydrolysis half-life of 3-CLPA in water/CH3CN (80/20, v/v) was ~ 1 minute at ambient temperature (23 +/- 2 °C).

This half-life was less than the OECD Guideline 111 half-life criterion of 24 hours at 25 °C which required 1) that 3-CLPA be designated as hydrolytically unstable, and 2) that no further testing be performed.

Any other information on results incl. tables

Observed pHs of 3-CLPA solution in water/acetonitrile

Time (min)	pH	Time (min)	pH
0.0	5.09	13.0	2.70
1.0	3.59	17.0	2.65
2.0	3.29	21.0	2.61
3.0	3.12	27.0	2.59
4.0	3.01	31.0	2.52
5.0	2.92	37.0	2.50
7.0	2.83	46.0	2.48
9.0	2.78	50.0	2.47

Applicant's summary and conclusion

Conclusions:

Based on this analysis, it is concluded that due to the half-life of 3-CLPA being less than the OECD Guideline 111 half-life criterion of 24 h at 25 °C that 1) 3-CLPA be designated as hydrolytically unstable, and 2) that no further testing be performed.

Executive summary:

In a preliminary experiment, the Test Substance 3-chlorophthalic anhydride (3CPA) was mixed with water/acetonitrile (80/20, v/v) at ambient temperature (23 ± 2 °C). The pH of this solution decreased from 5.1 to 2.9 within 5 min, and was fairly stable at 2.5 after 50 min of stirring. Based on the reported (Reimer, 2004) rapid hydrolysis of the 4-chloro analog of 3CPA (4CPA), it was concluded that the observed pH drop of the 3CPA solution was due to 3CPA hydrolysis, with an estimated half-life of 1 min at 23 ± 2 °C, as determined from the pH vs time plot. This half-life was less than the OECD Guideline 111 (OECD, 2002) half-life criterion of 24 h at 25 °C which required 1) that 3CPA be designated as hydrolytically unstable, and 2) that no further testing be performed.