Trimethyloxonium tetrafluoroborate 95%

Trimethyloxonium tetrafluoroborate, commonly called Meerwein’s salt, is a powerful electrophilic methylating agent with diverse applications in organic synthesis.

Primary synthetic applications:

• Ether cleavage: Selective deprotection of methyl, benzyl, and other ethers under mild conditions
• O-Methylation: Methylation of alcohols, phenols, and carboxylic acids to form ethers and esters
• Carbonyl activation: Converts carbonyls to reactive oxonium species for nucleophilic additions
• Alkylation: Selective methylation of various nucleophiles (amines, sulfides, phosphines)
• Protecting group removal: Critical for MOM and MEM ether deprotection in total synthesis
• Polymerization: Initiator for cationic polymerization reactions

Advantages over other methylating agents:

• Operates at or below room temperature (vs. reflux for MeI)
• Non-toxic BF₄⁻ counterion (vs. toxic iodide or sulfate)
• High selectivity for O-methylation over N-methylation
• Mild conditions preserve sensitive functional groups
• Crystalline, easily handled solid (vs. volatile liquids)

Proper handling and reaction setup are critical for successful results with this moisture-sensitive reagent.

General procedure for ether cleavage:

• Setup: Use oven-dried glassware under argon or nitrogen atmosphere
• Solvent: Anhydrous CH₂Cl₂ or CH₃CN (distilled and stored over molecular sieves)
• Reagent addition: Add 1.1-3.0 equivalents Me₃OBF₄ at 0°C or room temperature
• Reaction time: 1-24 hours (monitor by TLC)
• Quench: Add aqueous base (NaHCO₃ solution) or water
• Workup: Extract, dry (MgSO₄), concentrate, purify

Typical O-methylation procedure:

• Dissolve alcohol or acid in anhydrous CH₂Cl₂
• Add proton sponge or 2,6-lutidine (1.2-2.0 equiv) as base
• Add Me₃OBF₄ (1.2-1.5 equiv) portionwise at 0°C
• Warm to room temperature and stir 2-12 hours
• Quench and work up as above

Important handling notes:

• Weigh quickly in dry box or under argon flow
• Use dry solvents (freshly distilled or from solvent purification system)
• Seal vessel immediately after reagent addition
• Monitor reaction progress by TLC

Trimethyloxonium tetrafluoroborate is highly moisture-sensitive and requires careful storage to maintain activity.

Storage conditions:

• Temperature: 2-8°C in refrigerator
• Atmosphere: Under argon or nitrogen
• Container: Sealed bottle with septum cap or ampules
• Desiccation: Store over P₂O₅ or in desiccator
• Protection: Rigorous exclusion of moisture
• Shelf life: 12 months when stored properly

Handling precautions:

• Dry box: Preferred for weighing and transfers
• Schlenk technique: Use if dry box unavailable
• Minimize exposure: Open container only under inert atmosphere
• Reseal immediately: Close container as soon as possible
• Fresh batches: Order in smaller quantities for frequent use

Signs of degradation:

• Color change from white to yellow/brown
• Reduced reactivity in standard reactions
• Presence of moisture (clumping, stickiness)
• Lower purity by NMR analysis

Safety notes:

• Handle in well-ventilated fume hood
• Wear appropriate PPE (gloves, safety glasses, lab coat)
• Avoid contact with water, alcohols, and moisture
• Refer to SDS for complete safety information

ChemContract supplies trimethyloxonium tetrafluoroborate at ≥95% purity, characterized by multiple analytical methods.

Quality control methods:

• ¹H NMR: Shows characteristic singlet for (CH₃)₃O⁺ group
• ¹⁹F NMR: Confirms BF₄⁻ counterion
• Quantitative NMR: Accurate purity determination
• Acid-base titration: Confirms reactive oxonium content
• Karl Fischer: Verifies anhydrous nature (<0.1% water)

Certificate of Analysis includes:

• Batch number and manufacturing date
• ¹H NMR and ¹⁹F NMR spectra
• Purity determination (≥95%)
• Water content (Karl Fischer)
• Appearance description
• Storage and handling recommendations

Functional testing:

• Reactivity verified in standard ether cleavage reaction
• Methylation activity confirmed by test reactions
• Consistent performance batch-to-batch

Understanding potential issues helps optimize reaction conditions and troubleshoot problems.

Common challenges:

• Moisture sensitivity: Water reacts rapidly, generating dimethyl ether and destroying reagent
  • Solution: Use rigorously dry solvents and glassware
  • Test: Add small amount to dry solvent, should not effervesce
• Over-alkylation: Excess reagent can cause multiple methylations
  • Solution: Use 1.1-1.5 equiv, add slowly, monitor by TLC
  • Control: Stop when starting material consumed
• N-methylation: Can compete with O-methylation in substrates with amines
  • Solution: Protect amines or use selective conditions
  • Alternative: Use different methylating agent for N-methylation
• Decomposition: Old or improperly stored reagent shows reduced activity
  • Solution: Use fresh reagent, store properly under argon at 4°C
  • Test: Yellow/brown color indicates decomposition

Troubleshooting tips:

• Low yield: Check reagent freshness, verify anhydrous conditions
• No reaction: Confirm reagent activity with test reaction
• Side products: Reduce equivalents, lower temperature, shorter time
• Decomposition during reaction: Work at lower temperature, exclude moisture rigorously

Trimethyloxonium tetrafluoroborate offers unique advantages compared to other methylating agents.

Common methylating agent comparison:

• Methyl iodide (MeI):
  • Advantages: Inexpensive, readily available
  • Disadvantages: Toxic, volatile, requires harsh conditions (heat, base)
  • When to use: Simple methylations, cost-sensitive applications
• Dimethyl sulfate (Me₂SO₄):
  • Advantages: Powerful methylating agent
  • Disadvantages: Highly toxic, carcinogenic, safety concerns
  • When to use: Industrial scale (with proper safety measures)
• Diazomethane (CH₂N₂):
  • Advantages: Mild conditions, selective
  • Disadvantages: Explosive, toxic, must be prepared fresh
  • When to use: Small scale, when mildest conditions required
• Trimethyloxonium tetrafluoroborate (Me₃OBF₄):
  • Advantages: Mild conditions, high selectivity, non-toxic counterion, stable solid
  • Disadvantages: Moisture-sensitive, more expensive
  • Best for: Sensitive substrates, ether cleavage, selective O-methylation

Recommendation guide:

• Use Me₃OBF₄ when: Sensitive functional groups present, mild conditions needed, ether cleavage required, selective O-alkylation desired
• Use MeI when: Simple substrate, cost is primary concern, harsh conditions acceptable
• Use CH₂N₂ when: Extremely mild conditions mandatory (e.g., epoxide-containing substrates)

We offer multiple pack sizes suitable for various research needs.

Available quantities (in stock):

• 1 g – For method development and small-scale synthesis
• 5 g – Standard research quantity
• 10 g – For multiple reactions or scale-up
• 25 g – Process development or larger campaigns
• Custom quantities: Available for kilogram-scale needs

Usage estimates:

• 1 g = ~6.8 mmol (sufficient for 5-10 reactions at 1 mmol scale)
• 5 g = ~34 mmol (sufficient for 25-50 reactions)
• Typical usage: 1.1-3.0 equiv per reaction

Delivery times:

• Stock quantities: Ships within 24-48 hours
• Domestic USA: 2-3 business days with cold packs (FedEx/UPS)
• International: 5-7 business days with temperature control (DHL/FedEx)
• Custom quantities (>25g): 2-3 weeks

Packaging:

• Sealed glass bottle under argon atmosphere
• Packaged with desiccant in moisture-proof bag
• Shipped with cold packs in insulated container
• Certificate of Analysis included
• Safety Data Sheet included
• Handling instructions provided