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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

Additional information

Physical state: White powder with characteristic odour

Melting Point:  131 deg C

Boiling Point: decomposes in a range of 225 - 235 deg C. Estimated: 321.5 deg C at 101.3 kPa

Relative density: 1.615 at 20 deg C

Particle size distribution:

> 425 μm 0.3%

300 μm 0.4%

250 μm 7.6%

212 μm 39.6%

180 μm 22.8%

150 μm 9.9%

106 μm 10.5%

<106 μm 9.0%

Vapour pressure: 0.000039 Pa at 25 deg C

Partition coefficient (log Pow): –1.26 (undissociated); -6.14 at pH= 8

Water solubility: 647 g/L at 20 deg C

Surface tension: not determined

Flash point: not determined

Auto-flammability: not determined

Flammability: not flammable, but will support combustion

Explosiveness: not explosive

Oxidising properties: not oxidising

Stability in organic solvents: not critical

Dissociation constant: pKa1 = 3.51 and pKa2 = 5.03 at 20 deg C

Viscosity: not determined.

REACH guidance on the identity of substances states that, for substances with chiral centres, in the absence of any indication to the contrary, it is assumed that a substance is an equal (racemic) mixture of the two forms”. As a result the undefined form (CAS 6917-15-7) is regarded as being the same form as the defined (+/-) form (CAS 617-48-1).


In addition it is noted that, in order to provide more accurate descriptions, CAS now registers and names substances with partially defined stereochemistry. Previously, partial stereochemistry was generally ignored. Racemic mixtures of substances having single chiral centers are now indexed, registered, and named as non-stereospecific substances. The decision to discontinue the racemate distinction was based on the observation that most of the chemical substances encountered in the literature are presented without any explicit indications of their racemic nature but which in the majority of the cases are probably racemates.

The distinction that CAS was making between the racemic and non-stereospecific (or relative) forms was judged to cause scattering in indexing and registration, and complications in database searching. Thus, DL-malic acid and malic acid (stereospecificity unspecified) now receive the same CAS Registry Number and CA index name: 6915-15-7, Butanedioic acid, hydroxy-. The Registry Number for the DL-form (617-48-1) will be cross-referred to the Registry Number of the non-stereospecific form (6915-15-7).