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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Oxidising properties

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Link to relevant study record(s)

Description of key information

The ASA Category comprises 5 aromatic sulphonic acids:

TSA, Toluene-4-sulphonic acid (EC 203-180-0, CAS 104-15-4)

XSA, (Xylenes and 4-ethylbenzene) sulphonic acid (EC 701-247-3, CAS -) Former EC 246-839-8:

CSA, p-cumene sulphonic acid (EC 240-210-1, CAS 16066-35-6)

BSA, Benzene sulphonic acid (EC 202-638-7, CAS 98-11-3)

HBSA, 4-hydroxybenzensulphonic acid (EC No. 202-691-6, CAS No. 98-67-9)

The susbtances in the ASA category does not have any oxydizing properties based on oxygen balance calculation and based on the availbale test on on Hydrotrope (SXS).

The oxygen balance is calculated using the formula: 

                     2 ( x ) + (y / 2)  + M – (z)

OB = -1600 * __________________________



X = number of atoms of carbon

Y = number of atoms of hydrogen

Z = number of atoms of oxygen

M = number of atoms of metal (metallic oxide produced).

The Oxygen balance of Hydrotropes substances are:

TSA (C7H8O3S, MW = 172.20 g/mol): OB = - 162.60

XSA (Former EC 246-839-8, C8H10O3S, MW = 186.22 g/mol): OB =  -154.66

CSA (C9H13O3S, MW = 200.25 g/mol): OB = -171.79

BSA (C6H6O3S, MW = 158.17 g/mol): OB = - 122.16

HBSA (C6H6O4S, MW = 174.17 g/mol): OB = -101.05

A negative oxygen balance is an indication that substance contains less oxygen than is needed; therefore it is not expected that substance may, generally by yielding oxygen, cause, or contribute to the combustion of other materials. Based on the oxygen balance values, no oxidizing properties are expected for ASA substances.

In accordance with column 2 of REACH Annex VII, the study does not need to be conducted since the substance is incapable of reacting exotermically with combustible materials based on the chemical structure.

Key value for chemical safety assessment

Oxidising properties:

Additional information

Justification for classification or non-classification

No classification for oxidizing properties is warranted under or Regulation EC 1272/2008