2-methylbutyl acrylate

Phototransformation in air

Administrative data

Endpoint:

phototransformation in air

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

March 28, 2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Structurally, 2-MBA contains moieties that have experimental group rate constants utilized by the software (AOPWIN) to calculate the OH radical reaction rate constants. Additionally, comparative evaluation with the experimental value of the analogous compound ethyl acrylate (also in the training set) indicates the conservative nature of this estimate. Thus, it is within the domain.

Justification for type of information:

QSAR prediction: migrated from IUCLID 5.6

Data source

Reference

Reference Type:

other: QSAR simulation report

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: QSAR Results

Principles of method if other than guideline:

AOPWIN v1.92 as implemented through EPI Suite v4.10

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-MBA

IUPAC Name:

2-MBA

Constituent 2

Reference substance name:

2-methylbutyl acrylate

EC Number:

256-170-3

EC Name:

2-methylbutyl acrylate

Cas Number:

44914-03-6

Molecular formula:

C8H14O2

IUPAC Name:

2-methylbutyl prop-2-enoate

Details on test material:

CAS No. 44914-03-6
SMILES: O=C(OCC(CC)C)C=C

Study design

Estimation method (if used):

EPI Suite module AOPWIN (v1.92) utilizes experimentally determined group rate constants to estimate the overall OH radical reaction rate constant for a chemical. EPI Suite is a valid QSAR and this substance is within the applicability domain since there are analogous substances in the training set.

Light source:

other: Not Applicable (QSAR)

Details on light source:

Not applicable

Details on test conditions:

QSAR

Results and discussion

Dissipation half-life of parent compound

DT50:

1.04 d

Test condition:

QSAR simulation

Any other information on results incl. tables

Validity of Model (OECD 5 principles):

1) Defined endpoint: Photodegradation rate

2) Unambiguous algorithm: The predicted value of the rate constant for reaction with hydroxyl radicals is

calculated through the following equation: overall OH rate const = ∑F(x)k{group}

where F(x) is the substituent scale factor and k{group} is the hydroxyl radical reaction rate constant for each individual chemical group in the test species.

3) Applicability domain: the software's training set contains several alkyl ester acrylate compounds and numerous other esters which are structurally related to the test substance. This is not an exhaustive list of all chemical species in the reference data, merely those which may be grouped with the test compound. The test substance is therefore within the applicability domain of the model.

4) Statistical characterization: Statistical variation of 25 pairs of experimental and predicted photodegradation rates for alkyl esters and alkyl acrylates indicates that there is a 0.966 correlation coefficient (r-squared), a standard deviation of 0.120 and an absolute mean error of 0.107.

5) Mechanistic interpretation: The primary mechanism of photolysis is through indirect photodegradation by reaction with hydroxyl radicals which are produced during the daylight hours.

Please see attached QMRF and QPRF for justification of model and applicability.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

This model conforms with the 5 principles set forth by OECD for validation of QSAR models.

Conclusions:

The half life of 2-methylbutyl acrylate, assuming a 24 hour day and hydroxyl radical concentrations in the atmosphere of 5.0E5 OH radicals / cm3, is estimated to be 1.04 days. This indicates that the test material is not expected to be persistent in the atmosphere and long range transport is not expected.

Executive summary:

Photolysis of 2-metylbutyl acrylate (2-MBA) was estimated utilizing the AOPWIN v1.92 module of EPISuite v4.10.  Structurally, 2-MBA contains moieties that are part of the training set of the software and is thus, within the predictive domain of the software.

The half-life/DT50 (50% decline times) of the test substance, assuming a 24 hour day and hydroxyl radical concentrations in the atmosphere of 5.0E5 OH radicals / cm3, was predicted to be 1.04 days. This indicates that the test material is not expected to be persistent in the atmosphere and long range transport is not expected.

This study is classified as an acceptable QSAR and satisfies the requirements for photolysis study. It is pertinent to the fate of 2-methylbutyl acrylate