Use of N,O-Dimethylhydroxylamine HCl in Weinreb Amide Formation
Use of N,O-Dimethylhydroxylamine HCl in Weinreb Amide Formation
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Understanding N,O-Dimethylhydroxylamine Hydrochloride (DMHA HCl): Properties, Uses, and Safety
Introduction
N,O-Dimethylhydroxylamine Hydrochloride, often abbreviated as DMHA HCl, is an important intermediate used in organic synthesis, especially in the pharmaceutical and agrochemical industries. It belongs to a class of compounds known as alkylhydroxylamines, which are characterized by a hydroxylamine group (–NHOH) substituted with alkyl groups.
In its hydrochloride salt form, DMHA is more stable and easier to handle, making it ideal for industrial and laboratory use.
Chemical Information
Chemical Name: N,O-Dimethylhydroxylamine Hydrochloride
CAS Number: 6638-79-5
Molecular Formula: C2H8ClNO
Molecular Weight: 97.55 g/mol
Structure:
Physical and Chemical Properties
| Property | Value |
|---|---|
| Appearance | White to off-white solid |
| Solubility | Highly soluble in water |
| Melting Point | ~142–144°C (decomposes) |
| Odor | Slight amine-like odor |
| Stability | Stable under recommended storage conditions |
| pH (in aqueous solution) | Acidic due to HCl component |
The hydrochloride salt enhances its shelf-life, reduces volatility, and improves its handling compared to the free base.
Applications
1. Pharmaceutical Intermediate
DMHA HCl is primarily used in the synthesis of active pharmaceutical ingredients (APIs). It serves as a building block in:
Drug molecules containing N-methyl hydroxylamine functionality.
Peptide and heterocyclic chemistry.
Selective O-alkylation or N-alkylation reactions.
2. Agrochemical Industry
Acts as a key intermediate in the production of herbicides and insecticides.
3. Chemical Synthesis
Used in formylation and amination reactions.
Plays a role in modifying functional groups via methylation.
Safety and Handling
Hazards
Irritant: Can cause eye and skin irritation.
May be harmful if inhaled or ingested.
Avoid inhalation of dust and contact with skin or eyes.
Protective Measures
Use in a well-ventilated area or fume hood.
Wear gloves, lab coat, and eye protection.
Store in a cool, dry, well-ventilated area, away from oxidizing agents.
Mechanistic Insights
DMHA HCl can undergo various reactions due to the nucleophilic nitrogen and oxygen atoms:
Can serve as a nucleophile in substitution reactions.
Undergoes methylation, acylation, or alkylation depending on reaction conditions.
Its dual N- and O- substitution opens up chemoselectivity in synthetic design.
Environmental Impact
DMHA HCl is generally used in controlled industrial settings, and while it is not highly toxic, proper disposal is important:
Do not release into the environment.
Waste should be treated as hazardous chemical waste and disposed of according to local regulations.
Storage Recommendations
Store in tightly closed containers.
Recommended storage temperature: 2–8°C.
Protect from moisture, air, and heat.
Conclusion
N,O-Dimethylhydroxylamine Hydrochloride is a versatile and valuable reagent in chemical synthesis. Its dual-functionality and enhanced stability in salt form make it essential in the production of pharmaceuticals, agrochemicals, and fine chemicals. With proper handling and safety practices, it offers a robust solution for complex organic transformations.
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