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Diss Factsheets

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

Toxicity of 2-methylbutyl acrylate to aquatic organisms was assessed in single tests to each taxonomic level.  Results of these assays were considered reliable without restriction.  The 2-MBA data are suitable for Risk Assessment, Classification & Labelling, and PBT Analysis.  Supporting aquatic toxicity studies using n-butyl acrylate give results in a similar range to 2-MBA.  n-Butyl acrylate is of similar molecular weight to 2-MBA (MW 128.2 and 142.2 for n-BA and 2-MBA, respectively) and lipophilicity (log Kow 2.38 and 2.90 for n-BA and 2-MBA, respectively).  The toxicity of acrylates with log Kow < 4(1)is due to electrophilic interactions (Michael addition) to cellular nucleophiles(2,3), causing glutathione depletion(2)and protein inactivation(3).  Detoxification is by ester hydrolysis followed by downstream conversion and entry of acrylic acid to the citric acid cycle(4).While the biodegradation screening study result for isooctyl acrylate was used to support ready biodegradability of 2-MBA, read-across of aquatic toxicity data from isooctyl acrylate (IOA) to 2-MBA is generally not supported due to IOA’s substantially higher molecular weight (MW 184.3) and lipophilicity (log Kow 4.5-4.7).  Substantially greater toxicity of IOA than 2-MBA or n-BA is generally found.  However, all three acrylates are readily biodegradable, which limits their potential for chronic toxicity.


References:

1. USEPA Office of Pollution Prevention and Toxics. 2002.  TSCA New Chemical Program (NCP) Chemical Categories. 

2. A. P. Freidig, H. J. M. Verhaar, J. L. M. Hermens.  1999.  Comparing the Potency of Chemicals with Multiple Modes of Action in Aquatic Toxicology:  Acute Toxicity Due to Narcosis versus Reactive Toxicity of Acrylic Compounds.  Env. Sci. Technol. 33 (17): 3038–3043.

3. K. Chan & P. J. O’Brien.  2008. Structure–activity relationships for hepatocyte toxicity and electrophilic reactivity of a,b-unsaturated esters, acrylates and methacrylates.  J. Appl. Toxicol. 28 (8): 1004–1015.

4. H. Greim, J. Ahlers, R. Bias, B. Broecker, H. Hollander, H.-P. Gelbke, S. Jacobi, H.-J. Klimisch, I. Mangelsdorf, W. Mayr, N. Schön, G. Stropp, P. Stahnecker, R. Vogel, C. Weber, K. Ziegler-Skylakakis, E. Bayer.  1995.  Assessment of structurally related chemicals: Toxicity and ecotoxicity of acrylic acid and acrylic acid alkyl esters (acrylates), methacrylic acid and methacrylic acid alkyl esters (methacrylates). Chemosphere 31 (2): 2637–2659. 

Data matrix – Analog approach (all data experimental except as noted)

Target substance

Source substance

CHEMICALNAME

2-methylbutyl acrylate

n-butyl acrylate

CAS#

44914-03-6

141-32-2

Molecular formula

C8H14O2

C7H12O2

Molecular Weight

142.2

128.2

PHYSICO-CHEMICAL DATA 

Melting Point

≤ -75 °C

Not available

Boiling Point

161.7 °C at 1013hPa

147 °C at 1013hPa

Density

0.8886 g/cm3 at 25 °C

0.9 g/cm3 at 20.0 °C

Vapour Pressure

1.7 hPa at 20°C

5 hPa at 22.2°C

Partition Coefficient (log Kow)

2.9

2.38 (at 25°C)

Water Solubility

316 mg/L at 23 °C

Not available

ENVIRONMENTAL FATE and PATHWAYS

Photodegradation

DT50 1.04 d (QSAR: AOPWIN v1.92)

Not determined

Stability in Water

Adaptation, readily biodegradable

DT50, 1100 day at pH 7, 25 °C (40CFR796.3500)

Aerobic Biodegradation

60% after 11 days (OECD 301D)

80 - 90% after 28 days (OECD 310)

Bioconcentration

Not bioaccumulative
(Low log Kow, extensive metabolism)

Not bioaccumulative
(Low log Kow, extensive metabolism)

Transport and Distribution

Koc 263 – 302 (Calculated by TGD method)

Koc 40-148 (EPA OTS 796.2750)

Henry's Law constant

96 Pa*m3/mol at 23.1 °C

Not determined

ENVIRONMENTAL TOXICITY

Acute Toxicity to Fish  (P. promelasunless noted)

96-hour LC50 1.09 mg/L (OECD 203)

96-hour LC50 5.2 mg/L (S. gairdneri,

EPA OTS 797.1400);

96-hour LC50 2.1 mg/L (C. variegatus, OECD203)

Chronic Toxicity to Fish

Adapted (readily biodegradable)

Not determined

Acute Toxicity to Aquatic Invertebrates (D. magna)

48-hour EC50 (mobility) 5.65 mg/L (OECD 202)

48-hour EC50 (mobility) 8.2 mg/L (EPA OTS 797.1300)

Long-Term Toxicity to Aquatic Invertebrates (D. magna)

21-day NOEC (growth) 0.249 mg/L (OECD 211)

21-day NOEC (reprod) 0.136 mg/L (OECD 211)

Toxicity to Algae and Aquatic Plants (P. subcapitata)

72-hour ErC50 1.15 mg/L (OECD 201)

96-hour EbC50 2.65 mg/L (OECD 201)

Toxicity to Microorganisms (activated sludge respiration)

3-hour EC50 >1000 mg/L (OECD 209)

3d EC50 >150 mg/L (ASTM STP 528)