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Environmental fate & pathways

Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Principles of method if other than guideline:
Method: other: see Test condition
GLP compliance:
no
Analytical monitoring:
yes
Transformation products:
yes
No.:
#1
No.:
#2
pH:
4
Temp.:
30 °C
DT50:
ca. 129 d
pH:
7
Temp.:
30 °C
DT50:
ca. 75 h
pH:
9
Temp.:
30 °C
DT50:
ca. 0.5 h


The following reaction mechanism was found for the hydroly-
tic reaction of 1-cyanoallylacetate in water:

              CN                           CN
             /                            /
1.)  H2C=CH-CH     +   H2O  --->  H2C=CH-CH    +   HOAc
                                         
              O-Ac                         OH

     1-cyanoallyl     water       2-hydroxy-     acetic acid
        acetate                   3-butene-
                                  nitrile


              CN
             /             H20
2.)  H2C=CH-CH           <----->  H2C=CH-CHO   +   HCN
             
              OH           

     2-hydroxy-                   2-propenal      hydrogen
     3-butene-                                    cyanide
     nitrile

1st reaction step (reaction of 1-cyanoallyl acetate with
water):
The reaction kinetics for the first reaction step are follo-
wing a pseudo 1st order equation:

               ln [c(t)/c(0)] = k(1) x t

From the test results the following reaction rate constants
k(1) [1/second] were calculated:

                             k(1) [1/s]
pH                      Temperature (°C)
          30                  50                  70
------------------------------------------------------------
1   2.3 x 10 exp(-6)    2.6 x 10 exp(-5)    2.1 x 10 exp(-4)
4   6.2 x 10 exp(-8)    7.0 x 10 exp(-7)    5.6 x 10 exp(-6)
7   2.6 x 10 exp(-6)    2.9 x 10 exp(-5)    2.3 x 10 exp(-4)
9   4.3 x 10 exp(-4)    4.8 x 10 exp(-3)    3.9 x 10 exp(-2)

The minimum reaction rates were determined at pH = 4.

2nd reaction step (decomposition of 2-hydroxy-3-butenenitri-
le in water):
At pH-values > 3 the reaction results in an equilibrium. The
equilibrium is depending on temperature and pH. At pH = 5
and T = 40 °C the equilibrium constant was calculated to
0.00562 (mol/l).

Description of key information

t1/2 30°C pH 4 = 129 d

t1/2 30°C pH 7 = 75 h

t1/2 30°C pH 9 = 0.5 h

Key value for chemical safety assessment

Half-life for hydrolysis:
75 h
at the temperature of:
30 °C

Additional information