Glycollic acid

Endpoint summary

Description of key information

A complete dataset of experimental studies is available on the pure (solid) substance. Some tests were also conducted on the 70% solution as placed on the market.

Glycolic acid (CAS No. 79-14-1) is a solid, described as a colourless to white, crystalline powder, odourless. Glycolic acid 70% solution is a light yellow liquid. Additional physico-chemical properties, in accordance with REACH Annex VII, are summarized below as appropriate.

The substance has a melting point of 79,1ºC and undergoes ambiguous decomposition, without clear boiling transition, from ca 145ºC. Freezing was measured at a lower temperature of ca 31,4°C, meaning that the melted substance may exist as a supercooled liquid. It is much more dense than water, with a relative density of 1,47 and 1,26 for the solid and the solution, respectively.

With 0,1 Pa at 25°C, it is considered of low volatility (based on volatility bands criteria for occupational exposure (Chesar / ECETOC TRA), << 500 Pa).

The partition coefficient is low (logKow < -1,2) consistent with a solubility higher than 852 g/L at 20°C. No effect of pH was observed, which is consistent with a measured pKa of 3,77, but this could not be fully assessed in the low pH range, due to technical limitations in the determination of both logKow and solubility (only limit values were derived).

The substance is not considered as surface-active according to EC criteria (73 mN/m at 1 g/L); however the solution is slightly below the threshold of 60 mN/m (57 mN/m at 70%; DuPont-16983-1649).

Solubility in organic solvents increases with polarity: <10 g/L for n-heptane, p-xylene and 1,2-dichloroethane; > 50 g/L ethyl acetate; 160 – 200 g/L propan-2-ol; >250 g/L acetone. The stability in organic solvents is not considered critical, so this study does not need to be conducted, in accordance with REACH Annex XI Section 2; this would be assessed in individual studies where organic solvents are used.

Granulometry measurements have been conducted on the powder: none of the particles were less than 180 µm by sieving (DuPont-18754-1692). 

The viscosity of the solution is 6.149 mm2/s at 23°C.

A 1% solution is acidic, with a pH of 2,34; however, the substance is not classified for metal corrosion (UN-GHS, EU-CLP, UN-TDG and ADR criteria).

 

Flammability:

The flammability of the solid form of glycolic acid (>99%) was investigated according to EC method A.10. As the substance failed to ignite, it is NOT classified as a flammable solid, according to both UN-GHS and EU-CLP criteria.

The flash point of glycolic acid 70% solution was determined using a method based on ASTM D 56 (Tag Closed Cup). No flash point was observed up to 100°C. Therefore, it is NOT classified as a flammable liquid, according to both UN-GHS and EU-CLP criteria.

As a low melting solid (< 160°C), an auto-flammability (relative self-ignition) study is not necessary. However, a self-heating study was conducted according to UN N4 method (relevant for UN-GHS and EU-CLP), and found negative.

 

Explosivity and Oxidising Properties:

In accordance with Column 2 adaptation statement of REACH Annex VII, information requirement section 7.11, explosivity testing does not need to be conducted since structural examination shows that there are no chemical groups associated with explosive properties present in the glycolic acid molecule. However, a study conducted according to the previous reference method EU A14 is available, and shows that the substance is not sensitive to heating, impact or friction.

In accordance with Column 2 adaptation statement of REACH Annex VII, information requirement 7.13, a study on oxidising properties does not need to be conducted based on structural assessment of the substance. Glycolic acid contains no oxidising groups and all oxygen atoms are bonded directly to carbon and/or hydrogen atoms. However, a study conducted according to the previous reference method EU A17 is available, and shows that the substance was not classified according to DSD criteria; though the reference substance differs from the UN O1 test, relevant for UN-GHS/EU-CLP and TDG criteria, the negative result supports the low potential for oxidising properties.

For details on references see the IUCLID dataset.

Additional information

The report with study reference number CLS3_0461_0002 (test item as solid) is attached in this endpoint summary record to avoid multiple attachments in the following endpoint study summary records:

• Appearance


• Melting/Freezing point


• Boiling point/Decomposition temperature/Thermal stability


• Relative density


• Vapour pressure


• Partition coefficient


• Water solubility


• Solubility in organic solvents


• Surface tension


• Self-heating


• pH and acidity


• Dissociation constant


• Corrosion to metals


• Analytical information