A Guest Gives a PepTalk from a "Pure" Perspective

By Yoav Luxembourg

OxymaPure® is an additive used in carbodiimide-mediated (DIC or EDAC-HCl) reactions in the conversion of carboxylic acid to amide, with increased yield and decreased side reactions.


Synonyms: Ethyl(hydroxyimino)cyanoacetate; Ethyl cyanoglyoxalate-2-oxime; Ethyl isonitrosocyanoacetate; 2-cyano-2-(hydroxyimino)acetate
Purity: ≥99.5%
pKa = 4.60
(M.W. 142.11 g/mol) C5H6N2O3     [3849-21-6]

White to off-white crystalline powder
Store in a cool and dry place (2-8oC)

 OxymaPure® has the following benefits and applications:

  1. It is safer than other benzotriazole additives (HOBt, Cl-HOBt). It is considered to be less sensitive to friction, spark, and electrostatic discharge and is not classified as a hazardous material, making it easier to transport.
  2. OxymaPure® is non-toxic. HOBt, on the contrary, may not only cause skin irritation and contact dermatitis, but also sensitization and can cause an allergic reaction in the respiratory tract.
  3. OxymaPure® is considered an excellent replacement for HOBt, HOAT, HOOBt, HOPO, Cl-HOBT and other analogues (without the need to change synthesis protocol). It gives results comparable to HOAt in step-wise Solid Phase Synthesis. It is ideal for peptide synthesizers using microwave heating.
  4. OxymaPure®-derived products are extensively adopted in pharmaceutical platforms for the synthesis of various scaffolds such as Weinreb Amides, Oligobenzamides, ester bond formation, and more.
  5. OxymaPure® is an ideal additive used with carbodiimide coupling methodology, for amide bond formation.  The 2-cyano-2-(hydroxyimino)acetate displays a remarkable capacity to suppress racemization and an impressive coupling efficiency in both automated and manual synthesis. It causes less epimerization than HOBt in fragment condensation reactions.
  6. Suppresses the formation of side products, in comparison to HOBt (see Table 1).
  7. Increased coupling yield, compared to HOBt (see Table 2).


Coupling Reagent

DL (%)





Table 1. Racemization of His during synthesis of H-Gly-His-Phe-NH2 in solid-phase peptide synthesis


Pentapeptide (%)

des-MeGly (%)

des-Tyr (%)

Tripeptide (%)











 Table 2. Percentage of H-Tyr-MeGly-MeGly-Phe-Leu-NH2, solid-phase assembly

  1. Can be used as a pH modulatory agent in the prevention of base-driven side reactions and its effect on 2-Chlorotrityl Chloride Resin.
  2. Has high solubility in a broad spectrum of solvents. The highly polar nature of OxymaPure® influences the water solubility, which is essential to removing the coupling byproducts in solution-based acylations. On the other hand, the great solubility of OxymaPure® in organic solvents has prompted its use in the evaluation of green alternatives to DMF.
  3. The combination of TFFH and OxymaPure® raised the percentage of the target Aibpeptide in comparison to TFFH alone (98% vs 95%).
  4. In a TFE–DCM (1:1) system, OxymaPure® plus DIP is an effective additive in cyclization (lowest yield of intermolecular coupling product).
  5. OxymaPure® almost completely eliminates proline-based overcoupling during solid-phase elongation of Pro-enkephalin (H-Tyr-Pro-Pro-Phe-Leu-NH2).
  6. OxymaPure® is a registered trademark of Luxembourg Bio Technologies Ltd. The product is produced by a unique technology which was developed by Luxembourg Biotechnologies R&D. This technology produces a product free of salts with more than 99.5% purity and a controlled ratio between the active Oxim to non-active Nitroso.  Peptides International is an official distributor of OxymaPure®.
  7. OxymaPure® is undergoing the process of REACH registration due to its popularity.

References using OxymaPure®:

Industry News , Tools for Peptide Synthesis , Peptides International News

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