1-Carboxy-1-Methylethoxyammonium Chloride: Lab Handling Guide

1-Carboxy-1-methylethoxyammonium chloride is a stable, water-soluble aminoxy building block used in chemical biology research for selective oxime ligation with aldehyde- and ketone-bearing biomolecules.

Product SKU

C187898

Chemical Class

Aminoxy (O-substituted hydroxylamine) salt

Physical Form

Solid (hydrochloride salt)

Key Reactivity

Selective oxime bond formation with aldehydes and ketones

Solubility

Water-soluble; compatible with aqueous buffer systems

Recommended Storage

Store at 2–8 °C, sealed, away from moisture

Chemical Identity and Properties

1-Carboxy-1-methylethoxyammonium chloride is an O-substituted hydroxylamine reagent presented as its hydrochloride salt. The compound contains a free aminoxy (–ONH₃⁺) functional group rendered stable by protonation, along with a gem-dimethyl-substituted carboxylic acid moiety. This dual functionality makes it a bifunctional building block: the carboxylic acid can be coupled via standard amide-bond chemistry (e.g., EDC/NHS activation), while the aminoxy group is reserved for selective condensation with carbonyl-containing targets. The hydrochloride salt form confers improved aqueous solubility and enhanced bench stability compared with the free base, facilitating straightforward preparation of stock solutions in water or common biological buffers.

Because the gem-dimethyl substitution on the ether oxygen reduces steric strain in an unusual way and because the protonated aminoxy salt is less prone to oxidation than the free base, this reagent typically maintains acceptable purity under standard cold-chain shipping and storage conditions.

Mechanism of Oxime Ligation

The primary application of 1-Carboxy-1-methylethoxyammonium chloride exploits the chemoselective reaction between its aminoxy (–ONH₂) group and an aldehyde or ketone carbonyl. Upon deprotonation under slightly acidic to neutral aqueous conditions (optimal pH ~4.5–6.5), the free aminoxy nucleophile attacks the electrophilic carbonyl carbon, forming a hemiorthoamide intermediate that rapidly collapses with loss of water to yield a stable oxime (–C=N–O–) linkage.

Key advantages of oxime ligation relevant to researchers include:

• Chemoselectivity: The reaction proceeds specifically at aldehyde or ketone sites without requiring protecting groups for amines, thiols, or hydroxyls present elsewhere in the molecule.
• Stability: Oxime bonds are significantly more hydrolytically stable than the Schiff bases (imines) formed by primary amines under equivalent conditions.
• Bioorthogonality: When used in conjunction with ketone- or aldehyde-tagged biomolecules (e.g., periodate-oxidized sugars, unnatural amino acids bearing keto side chains), the reaction is compatible with complex biological environments.

Aniline or other nucleophilic catalysts at low concentrations (10–100 mM) can substantially accelerate the reaction rate when working at neutral pH, which is relevant for labile substrates.

Preparation, Handling, and Storage Guidelines

Reconstitution and Stock Solution Preparation

Weigh the reagent in a low-humidity environment or inside a glove bag if the laboratory atmosphere is highly humid. Dissolve in ultrapure water or an appropriate aqueous buffer (e.g., 50 mM sodium acetate, pH 5.0; phosphate-buffered saline, pH 7.4) to prepare a stock solution at 10–100 mM. Vortex or gently stir until fully dissolved. Filter-sterilize (0.22 µm) if the solution will be used in cell-based assays.

Personal Protective Equipment (PPE)

Handle with standard laboratory PPE: nitrile gloves, safety spectacles, and a laboratory coat. Work in a well-ventilated area or chemical fume hood when weighing powders. Consult the Safety Data Sheet (SDS) for C187898 for full hazard classification details before use.

Storage Conditions

• Store the bulk reagent sealed at 2–8 °C, protected from light and moisture.
• Aliquot stock solutions to minimize freeze-thaw cycles; store aliquots at −20 °C for extended periods.
• Discard solutions showing visible discoloration or precipitation, which may indicate decomposition.

Waste Disposal

Dispose of solutions and solid waste in accordance with local institutional and governmental regulations for nitrogen-containing organic compounds.

Representative Research Applications

1-Carboxy-1-methylethoxyammonium chloride (C187898) is employed in several research contexts where selective conjugation to carbonyl-bearing molecules is required:

1. Glycoprotein and Glycan Labeling: Periodate oxidation of sialic acid or vicinal diol-containing sugars generates reactive aldehydes. The aminoxy group of C187898 can then be used to attach a carboxylic acid handle, enabling further derivatization, biotinylation, or immobilization.
2. Peptide and Protein Bioconjugation: Genetically encoded or chemically introduced keto amino acids (e.g., p-acetylphenylalanine) provide ketone handles on proteins. Reaction with C187898 introduces a carboxylic acid group suitable for further coupling or as an affinity tag.
3. Surface Functionalization: In materials science and biosensor development, the carboxylic acid moiety can anchor the conjugate to amine-functionalized surfaces (via EDC/NHS), while the oxime bond tethers specific carbonyl-bearing ligands or probes.
4. Linker Chemistry in Drug Conjugates: Researchers designing antibody–drug conjugates (ADCs) or peptide–drug conjugates may use oxime chemistry for site-specific attachment, where C187898 serves as a heterobifunctional spacer unit.

Researchers should optimize reaction time, pH, reagent stoichiometry, and catalyst choice empirically for each specific substrate and application.

Quality, Purity, and Specification Considerations

When ordering or qualifying 1-Carboxy-1-methylethoxyammonium chloride (C187898) from Aladdin Scientific, researchers and procurement managers should consider the following specification parameters:

• Purity: For sensitive conjugation experiments, select lots with purity ≥95% as determined by HPLC or titration methods. The Certificate of Analysis (CoA) accompanying each lot provides lot-specific data.
• Identity Confirmation: Identity is typically confirmed by ¹H NMR, ¹³C NMR, and/or high-resolution mass spectrometry. Request CoA data or spectral data sheets if required for publication or regulatory submissions.
• Moisture Content: As a hydrochloride salt, the reagent may be hygroscopic. Accurate weighing for stoichiometric calculations requires knowing the actual water content; Karl Fischer titration data may be requested for critical applications.
• Lot-to-Lot Consistency: For long-running studies, reserve sufficient material from a single lot or request inter-lot comparability data from Aladdin Scientific customer service.

Contact Aladdin Scientific technical support for custom purity grades, bulk quantities, or application-specific qualification requirements.

Frequently asked questions

What is the recommended pH range for oxime ligation using C187898?

The oxime ligation reaction between the aminoxy group of C187898 and aldehyde or ketone substrates proceeds most efficiently at mildly acidic pH, typically pH 4.5–6.5. At this pH range, the aminoxy nucleophile is sufficiently deprotonated for reaction while the rate of competing hydrolysis is minimized. At neutral to slightly alkaline pH, aniline catalysis (10–100 mM) can be used to accelerate the reaction.

How should I store stock solutions of 1-Carboxy-1-methylethoxyammonium chloride?

Prepare fresh stock solutions in ultrapure water or aqueous buffer and aliquot immediately to minimize freeze-thaw cycles. Store aliquots at −20 °C for extended stability. Bulk solid reagent (C187898) should be kept sealed at 2–8 °C, protected from moisture and light. Discard any solution showing discoloration or precipitate formation.

Can C187898 be conjugated to amine-functionalized surfaces or molecules?

Yes. The carboxylic acid group of C187898 can be activated using standard carbodiimide chemistry (e.g., EDC with sulfo-NHS) to react with primary amine groups on surfaces, proteins, or other scaffolds, forming a stable amide bond. This leaves the aminoxy group free for subsequent selective oxime ligation with aldehyde- or ketone-bearing targets, making C187898 a useful heterobifunctional linker.

Is 1-Carboxy-1-methylethoxyammonium chloride suitable for use in live-cell experiments?

Oxime ligation chemistry in principle is bioorthogonal, but the cytotoxicity and cell-membrane permeability of C187898 specifically have not been established in the source material. Researchers planning cell-based experiments should perform their own cytotoxicity assessments (e.g., MTT assay) and validate that experimental concentrations are non-toxic before proceeding.

References

1. Dirksen A, Dawson PE. Rapid Oxime and Hydrazone Ligations with Aromatic Aldehydes for Biomolecular Labeling. Bioconjug Chem. 2008;19(12):2543-2548. doi:10.1021/bc800310p
2. Kalia J, Raines RT. Hydrolytic Stability of Hydrazones and Oximes. Angew Chem Int Ed Engl. 2008;47(39):7523-7526. doi:10.1002/anie.200802651
3. Aladdin Scientific. Product Certificate of Analysis: 1-Carboxy-1-methylethoxyammonium chloride, SKU C187898. Aladdin Scientific; [date varies by lot].

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.