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Chemical product profile

HONGKUN / PRODUCT DIRECTORY

5-Fluorocytosine | CAS 2022-85-7

A fluorinated cytosine analogue used as an antifungal active substance and in enzyme-dependent selection research, with qualification centred on pyrimidine identity, related substances and the analytical requirements of the intended use.

CAS2022-85-7
Molecular formulaC4H4FN3O
Molecular weight129.09 g/mol

Product overview

The fluorine at C5 distinguishes flucytosine from cytosine, while its amino-substituted pyrimidinone ring separates it from fluorouracil. CAS 2022-85-7 identifies the free nucleobase without a sugar component. This distinction matters in both pharmaceutical analysis and biochemical selection systems, where the parent compound and its conversion products have different roles. Procurement should identify whether the material is intended for pharmaceutical-source assessment, laboratory selection or analytical calibration. Each use needs its own acceptance criteria: an assay result is only one part of qualification, alongside identity, the related-substance profile and the basis on which content is reported. For solution-based work, define the solvent and concentration used for acceptance testing.

Chemical identity

Chemical name
5-Fluorocytosine
CAS number
2022-85-7
Molecular formula
C4H4FN3O
Molecular weight
129.09 g/mol

Application context

Flucytosine is the active substance in antifungal medicines. Fungal cytosine deaminase converts it to fluorouracil, linking the chemical identity of the starting compound to its biological function. For pharmaceutical procurement, state the applicable monograph and intended manufacturing use so that assay, related substances and source documentation can be assessed together.

In a separate research setting, 5-fluorocytosine is used in negative-selection systems involving expression of cytosine deaminase, including reported work with transgenic plants. Such studies call for qualification within the chosen cell or tissue system and comparison with an appropriate reference lot. Analytical calibration is a third purchasing context: quantitative work requires assigned content and characterization suited to the method. The required analytical standard, research reagent or pharmaceutical input should therefore be identified explicitly in the enquiry.

Chemistry and synthetic role

The molecule retains the cytosine amino group and carbonyl while carrying fluorine on the pyrimidine ring. Enzymatic deamination changes the amino-bearing base into fluorouracil; an identity method should distinguish these two compounds.

Quality review

Separate related pyrimidines

Ask whether the selected chromatographic method resolves fluorouracil and the related pyrimidines relevant to the process or assay.

Define the content calculation

Specify as-received or corrected assay and how water is included in that calculation.

Qualify the intended biological use

For selection experiments, agree solution-preparation criteria and a functional comparison in the target system.

Preparing a specification

Include CAS 2022-85-7, intended use, assay method and calculation basis. List required pyrimidine impurity limits and water testing. For calibration, specify assigned content and uncertainty; for cell-selection work, describe the biological qualification required.

Packaging and storage

Reference handling information in the Sigma-Aldrich F7129 sheet calls for protection from light. Confirm storage conditions, closure and pack size against the selected material’s current SDS and label.

Documentation

Request the proposed specification, batch COA and SDS. Confirm availability of related-substance methods and chromatograms, water results and, where needed, reference-value or manufacturing-source documentation.

Procurement questions

Is 5-fluorocytosine the same as fluorouracil?

No. Flucytosine retains an amino group that is changed during deamination to fluorouracil. Specify the parent compound in the order.

Can the same qualification serve selection and calibration?

Selection requires performance in the target biological system; quantitative calibration additionally needs an appropriately assigned analytical value.

What should pharmaceutical enquiries include?

State the applicable monograph, manufacturing use, assay basis and required source documentation before assessing the proposed grade.

Technical sources
  1. PubChem CAS-resolved identity, CID 3366NCBI / National Library of Medicine
  2. Flucytosine USP reference standard: identityUSP / Sigma-Aldrich
  3. Flucytosine capsules: description and microbiologyDailyMed / U.S. National Library of Medicine
  4. 5-Fluorocytosine F7129 product informationSigma-Aldrich