Phthalic anhydride

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Principles of method if other than guideline:

Kinetic study of hydrolysis at different pHs at 25°C

GLP compliance:

no

Specific details on test material used for the study:

Phthalic anhydride was sublimated and characterised by IR and 13C NMR before use.
The purity was also checked by comparing the UV-vis adsorption spectrum with a solution containing the fully hydrolysed ester with one at the same concentration prepared with phthalic acid and the corresponding phenol.

Analytical monitoring:

yes

Buffers:

in the pH range 0.63 - 3, HCL was used to regulate the pH
above pH 3, several buffers were used: NaAc/HAc; H2PO4/HPO4

Transformation products:

yes

No.:

#1

pH:

4

Temp.:

25 °C

DT50:

0.7 min

Type:

(pseudo-)first order (= half-life)

pH:

7

Temp.:

25 °C

DT50:

0.3 min

Type:

(pseudo-)first order (= half-life)

pH:

9

Temp.:

25 °C

DT50:

0.02 min

Type:

(pseudo-)first order (= half-life)

Degradation products (CAS No./EC No./EINECS Name): 88-99-3     201-873-2 phthalic acid
RS-Freetext:
Half-life* at 25 degree C at different pH-values in different  buffer-systems:

1/2 (pH-values of 0-6)                   : 70   sec
1/2 (pH-value of 6.8, N-methyl imidazole): 61   sec
1/2 (pH-value of 7.24, phosphate)        : 30.5 sec
1/2 (pH-value of 8.9, CO3/HCO3-)         :  2.4 sec

* calculated from the cited observed rate constants

Executive summary:

The kinetic of the hydrolysis of phthalic anhydride was studied to be 30.5 seconds at pH 7.24 at 25°C (Andres, 2001).

Description of key information

The hydrolysis process of phthalic anhydride was studied to be 30.5 seconds at pH 7.24 at 25°C. The main hydrolsis product is phthalic acid (Andres, 2001).