Isobutyl acrylate

Hydrolysis

Administrative data

Endpoint:

hydrolysis

Type of information:

calculation (if not (Q)SAR)

Remarks:

Migrated phrase: estimated by calculation

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Scientifically accepted calculation method; substance within applicability domain of the model

Data source

Reference

Reference 1

Reference Type:

other: EPIWin calculation

Title:

Unnamed

Year:

2021

Reference 2

Reference Type:

other: Estimation software

Title:

Estimation Programs Interface Suite for Microsoft Windows, v4.10

Author:

US-EPA

Year:

2012

Bibliographic source:

United States Environmental Protection Agency, Washington, DC, USA

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Calculation of aqueous hydrolysis rate constant. Software used: SRC HYDROWIN v2.00

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Isobutyl acrylate

EC Number:

203-417-8

EC Name:

Isobutyl acrylate

Cas Number:

106-63-8

Molecular formula:

C7H12O2

IUPAC Name:

isobutyl acrylate

Study design

Estimation method (if used):

HYDROWIN v2.00 (chemical class: ESTER)

Results and discussion

Transformation products:

not measured

Dissipation DT50 of parent compound

Dissipation DT50 of parent compound 1

pH:

7

Temp.:

25 °C

DT50:

16.512 yr

Type:

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

Remarks on result:

other: Kb half-life; The substance is within the applicability domain of the model.

Dissipation DT50 of parent compound 2

pH:

8

Temp.:

25 °C

DT50:

1.651 yr

Type:

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

Remarks on result:

other: Kb half-life; The substance is within the applicability domain of the model.

Other kinetic parameters:

SMILES : O=C(OCC(C)C)C=C
CHEM : 2-Propenoic acid, 2-methylpropyl ester
MOL FOR: C7 H12 O2
MOL WT : 128.17
--------------------------- HYDROWIN v2.00 Results ---------------------------


ESTER: R1-C(=O)-O-R2 R1: -CH=CH2
000106-63-8 R2: iso-Butyl-
Kb hydrolysis at atom # 2: 1.330E-002 L/mol-sec

Total Kb for pH > 8 at 25 deg C : 1.330E-002 L/mol-sec
Kb Half-Life at pH 8: 1.651 years
Kb Half-Life at pH 7: 16.512 years

Applicant's summary and conclusion

Executive summary:

QPRF: HYDROWIN v2.00

 

1.	Substance	See “Test material identity”
2.	General information
2.1	Date of QPRF	24 Oct. 2013
2.2	QPRF author and contact details	BASF SE, Dept. for Product Safety, Ludwigshafen, Germany
3.	Prediction
3.1	Endpoint (OECD Principle 1)	Endpoint	Aqueous hydrolysis rate
		Dependent variable	Hydrolytic half-life
3.2	Algorithm (OECD Principle 2)	Model or submodel name	WSKOWWIN
		Model version	v. 2.00
		Reference to QMRF	Estimation of Aqueous Hydrolysis Rate Constants using HYDROWIN v2.00 (EPI Suite v4.11) (QMRF)
		Predicted value (model result)	See “Results and discussion”
		Input for prediction	Chemical structure via CAS number or SMILES
		Descriptor values	- SMILES: structure of the compound as SMILES notation Fragment values: - Taft constant (sigma*) - Steric factor (Es) - Hammett constants (sigma-meta and sigma-para)
3.3	Applicability domain (OECD principle 3)	Domains:
		1) Chemical class	An equation for the estimation of the aqueous hydrolytic rate constant is available for the chemical class of the substance.
		2) Fragments (On-Line HYDROWIN User’s Guide, Appendix E)	All fragments were identified.
3.4	The uncertainty of the prediction (OECD principle 4)	According to REACH Guidance Document R.7a, (Nov. 2012), hydrolysis kinetics are usually determined experimentally. The guidance document also lists HYDROWIN as a means to estimate the hydrolytic half-life. The estimation is limited to only a few chemical classes. The model marks uncertainties of the estimate due to substitute values for missing fragments. As yet, the QSAR equations in HYDROWIN have not been rigorously tested with an external validation dataset. Currently, the number of chemicals with evaluated hydrolysis rates is relatively small in number, and the available data have been used to train the QSAR regressions. The training data set for esters has an acceptable size (n = 124). Equations for the other chemical classes were developed on very small databases (n = 7 to 20); therefore the reliability of estimations for members of other chemical classes than esters is low.
3.5	The chemical mechanisms according to the model underpinning the predicted result (OECD principle 5)	Hydrolysis is a common degradation route in the environment, where reaction of a substance with water with a net exchange of the X group with an OH at the reaction centre such that RX + H2O →ROH + HX. Hydrolysis is often dependent upon pH as the reaction is commonly catalysed by hydrogen or hydroxide ions. The model uses the principle of linear free energy relationships (LFER) to estimate the aqueous hydrolysis rate.

References

- US EPA (2012). On-Line HYDROWIN User’s Guide, Appendix E: Fragment Substituent Values Used by HYDROWIN.

- ECHA (2012). REACH Guidance Document R.7a, (Nov. 2012). 381 pp.

Identified fragments for the current substance:

If the substance is an ester:	Applicable
R2 substituent is an alkyl carbon or an aromatic carbon.	yes
R1 substituent is either an alkyl carbon, an aromatic carbon or a hydrogen.	yes

Appendix E. Fragment Substituent Values Used by HYDROWIN

Fragment	Es	sigma*	sigma-meta	sigma-para	Fragment identified by HYDROWIN	Substitute fragment (warning by HYDROWIN)	Name of R group according to HYDROWIN
-CH2-CH2-CH2-CH3	-1.43	-0.49	-0.07	-0.16	yes	no	R2
-CH=CH2	-3.19	0.07	0.08	-0.09	yes	no	R1