4-hydroxybutan-2-one

Phototransformation in air

Administrative data

Endpoint:

phototransformation in air

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable, well-documented publication which meets basic scientific principles.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2013

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

The reaction of the OH radicals with 4-hydroxy-2-butanone was investigated in the gas phase using an absolute rate method at room temperature and over the pressure range 10−330 Torr in He and air as diluent gases. The rate coefficients were measured using pulsed laser photolysis (PLP) of H2O2 to produce OH and laser induced fluorescence (LIF) to measure the OH temporal profile.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

4-hydroxybutan-2-one

EC Number:

209-693-6

EC Name:

4-hydroxybutan-2-one

Cas Number:

590-90-9

Molecular formula:

C4H8O2

IUPAC Name:

4-hydroxybutan-2-one

Details on test material:

- Name of test material (as cited in study report): 4‑Hydroxy-2-Butanone (4H2B)
- Purity: >95%. After receivng the sample, it was further purified to 98.5% by fractional distillation under a pressure of 15 Torr by using a Vigreux Column.
- Impurities: impurities were mainly 4-(acetyloxy)-2-butanone, 4-hydroxy-4-methyl-2-pentanone, and methyl vinyl ketone at the following concentrations: 0.90%, 0.48%, and 0.13%, respectively.

Study design

Light source:

other: 266 nm pulsed laser

Light spectrum: wavelength in nm:

266

Details on test conditions:

RATE COEFFICIENT MEASUREMENTS:
Kinetic decays were determined by recording the variation in the LIF signal as a function of the time delay between the pulses from the photolysis and probe lasers. These measurements were carried out at 294 ± 1 K and over a wide range of pressure varying from 10 to 330 Torr with helium and purified air bath gases. Kinetic decays were observed by recording the variation in the LIF signal as a function of the time delay between the pulses from the photolysis and probe lasers. The profiles were fitted to single exponential functions leading to the extraction of pseudo-first order rate coefficients related to the rate of loss of OH radicals. The pseudo-first order rate coefficients varied linearly with the 4H2B concentration and the value of k is obtained as the slope of least-squares fits of these data. The second-order rate coefficient k was determined by measuring approximately 10 pseudo-first order rate coefficients spanning more than a factor of 10 in 4H2B concentration.

DETERMINATION OF LIFETIME:
The experimentally determined rate coefficient was combined with the average tropospheric concentration of OH radicals to assess the major atmospheric loss process of 4H2B and its atmospheric lifetime. The lifetime was calculated by using a 24 h daytime average global tropospheric OH radical concentration of 1E+06 molecules cm−3.

VAPOUR PRESSURE:
The investigated kinetic study required accurate measurements of the vapor pressure of 4-hydroxy-2-butanone, which was measured using a static apparatus. The vapor pressure was found to range from 0.056 to 7.11 Torr between 254 and 323 K.

Reference substance:

not specified

Results and discussion

Test performance:

The overall error in the rate coefficient values reported in this work is estimated to be about 25% arising from both statistical and systematic errors.

Quantum yield (for direct photolysis):

0.3

Any other information on results incl. tables

TROPOSPHERIC LIFETIMES:

For the reaction of OH radicals with 4H2B a troposperic lifetime of 2.4 days was calculated through the Arrhenius equation by using the experimentally determined average rate constant (4.8±1.2 E-12 cm3· molecule-1·s-1) with a 24-h average OH concentration of 1E+06 molecules cm−3.