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Chemical product profile

HONGKUN / PRODUCT DIRECTORY

6-Maleimidohexanoic acid | CAS 55750-53-3

A bifunctional linker combining a thiol-reactive maleimide with a free carboxylic acid across an aliphatic spacer, used in conjugation development and preparation of functional maleimide monomers.

CAS55750-53-3
Molecular formulaC10H13NO4
Molecular weight211.21 g/mol

Product overview

6-Maleimidohexanoic acid connects two different reaction handles through a chain of five methylene groups. The maleimide double bond provides a conjugation site, while the terminal carboxyl can be converted into an ester or amide. The material is the free acid and should be distinguished from its activated esters and from linkers with a different spacer length.

Chemical identity

Chemical name
6-Maleimidohexanoic acid
CAS number
55750-53-3
Molecular formula
C10H13NO4
Molecular weight
211.21 g/mol

Application context

Bioconjugation development uses the maleimide group to connect thiol-bearing partners, with the acid end providing a separate route for attachment to another component. The molecule is also used as an intermediate for ester- and amide-linked maleimide monomers. Qualification should establish the intended order of functionalization and assess intact maleimide content, because ring-opened or already-reacted species have different functionality.

Chemistry and synthetic role

The electron-deficient maleimide alkene and terminal acid serve distinct reaction families; the spacer separates these functions.

Quality review

Preserve the maleimide structure

Use identification and chromatography that distinguish intact maleimide from ring-opened related substances.

Confirm the free acid

Specify acid functionality rather than an NHS ester or pre-conjugated form.

Match spacer and residuals

Confirm five methylene units and set residual-solvent or water requirements for the intended coupling.

Preparing a specification

Specify 6-maleimidohexanoic acid, intact maleimide assay, free-acid identity, ring-opened related substances and residuals relevant to the conjugation or monomer route.

Packaging and storage

Confirm container compatibility, closure and net weight for the selected grade and destination. Follow the actual supplier SDS and batch label for storage and transport.

Documentation

Request the batch COA, SDS and analytical methods covering the agreed purchasing specification. Confirm which supporting chromatograms and application-specific records are available from the selected manufacturer.

Procurement questions

Is the acid already activated for amines?

No; select an appropriate activation strategy or request the required activated derivative.

What reacts with the maleimide end?

Thiol-bearing partners are a principal conjugation context.

Why review ring-opened impurities?

They change the reactive functionality and can affect coupling consistency.

Technical sources
  1. PubChem CAS identity lookupNCBI / PubChem
  2. 6-Maleimidohexanoic acidFisher Scientific
  3. 6-Maleimidohexanoic acid heterobifunctional crosslinkerCreative Biolabs
  4. Functional Additives selector guide MM-211Designer Molecules