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HONGKUN / PRODUCT DIRECTORY

Thiodiacetic acid | CAS 123-93-3

A sulfur-containing dicarboxylic acid whose thioether and carboxylate donor sites support metal-coordination research, with ligand form and background metal content central to reproducible evaluation.

CAS123-93-3
Molecular formulaC4H6O4S

Product overview

A central thioether links the two acetic acid arms of thiodiacetic acid. This arrangement combines a sulfur donor with two carboxylic acid groups that can form carboxylate donors upon deprotonation. The result is a flexible ligand precursor with coordination behaviour that depends on the metal and chemical environment. It differs structurally from thioglycolic acid, which has a free thiol, and from disulfide-linked diacids. CAS 123-93-3 refers to the free acid rather than a thiodiacetate salt or preformed metal complex. For coordination work, qualification should address the acid form, assay basis and any background metals or ions that could interfere with the intended complexation study.

Chemical identity

Chemical name
Thiodiacetic acid
CAS number
123-93-3
Molecular formula
C4H6O4S

Application context

Published coordination studies use thiodiacetic acid to prepare metal complexes and extended structures. Samarium and europium thiodiacetate systems have been examined for crystal structure, solution speciation and solid-state luminescence. Other work reports palladium and platinum complexes in which sulfur participates in coordination. These examples demonstrate that the molecule can provide different donor arrangements depending on the metal system; they do not assign a single coordination mode to every application. In purchasing ligand feedstock, the relevant questions are its protonation or salt form, chemical composition and background contamination. Luminescent behaviour belongs to the studied metal complex and its structure, rather than to a universal property of the free acid.

Chemistry and synthetic role

The structure is HOOC–CH2–S–CH2–COOH. Sulfur is a thioether donor; the two carboxyl groups offer oxygen-donor sites after deprotonation. There is no thiol or disulfide bond.

Quality review

Confirm free acid or salt

State whether the required input is H2tda or a specific thiodiacetate salt, including any counterions and water content.

Match metal screening to the study

For coordination experiments, agree limits for metal contaminants capable of altering the intended system.

Review acid assay and sulfur identity

A total-acid result should be supported by identification and related-substance data for the requested thioether diacid.

Preparing a specification

Specify the free acid CAS 123-93-3, assay and identity methods, water basis, and relevant inorganic-ion or metal limits. Name any desired salt explicitly rather than quoting it as the free acid.

Packaging and storage

Packaging, closure and net weight are agreed for the selected grade, order quantity and destination. Confirm storage and transport requirements against the actual supplier SDS.

Documentation

Request a batch COA, specification, identity data and SDS. Confirm the availability of the analytical methods and any application-specific impurity results with the proposed supplier.

Procurement questions

Does this molecule contain a free SH group?

No. Its sulfur lies between two carbon atoms as a thioether.

Is thiodiacetate the same purchasing form?

Thiodiacetate is the deprotonated ligand; a supplied salt or complex requires its own full composition.

Must every application use trace-metal limits?

Set them according to the sensitivity of the intended coordination or analytical work.

Technical sources
  1. 2,2-Thiodiacetic acid T30007Sigma-Aldrich
  2. Lanthanide(III) complexes with thiodiacetato ligandCrystals / MDPI
  3. Coordination compounds of Pd(II) and Pt(II) with thiodiacetic acidPolyhedron / Elsevier