| HS Code | 400143 |
| Chemical Formula | C4H8O3 |
| Molecular Weight | 104.10 g/mol |
| Cas Number | 623-53-0 |
| Appearance | Colorless liquid |
| Density | 1.07 g/cm³ at 25°C |
| Boiling Point | 107–109 °C |
| Melting Point | -55 °C |
| Flash Point | 18 °C (closed cup) |
| Solubility | Slightly soluble in water; miscible with most organic solvents |
| Refractive Index | 1.378 at 20°C |
As an accredited Ethyl Methyl Carbonate factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Ethyl methyl carbonate, 25 L, packaged in sealed HDPE drum with tamper-evident closure and GHS hazard labeling. |
| Container Loading (20′ FCL) | 20′ FCL: sturdy steel drums/IBCs, secure bracing, ventilation, moisture protection, and proper dangerous-goods labeling for flammable Ethyl Methyl Carbonate. |
| Shipping | Ethyl Methyl Carbonate is a flammable liquid requiring careful transport. Ship in approved, leak-proof containers away from ignition sources, with proper labeling and UN classification. Use grounded equipment during handling and loading. Ensure complete documentation, including safety data sheets, and follow all international regulations for hazardous materials to ensure safe delivery. |
| Storage | Store ethyl methyl carbonate in a cool, dry, well-ventilated area away from heat, sparks, and open flames. Keep the container tightly sealed to prevent moisture uptake and vapor release. Isolate from strong oxidizers, acids, and bases. Use explosion-proof equipment and grounded containers to avoid static discharge. |
| Shelf Life | Store in a tightly sealed container away from moisture and heat; typical shelf life is two years under recommended conditions. |
Electrolyte compounding for automotive lithium-ion cells positions ethyl methyl carbonate as the low-viscosity linear carbonate in a ternary solvent system with ethylene carbonate and dimethyl carbonate. In a dry-room line with a dew point of −40 °C or lower and a residual moisture target of ≤20 mg/kg by ASTM E203, a representative automotive electrolyte is prepared by adding 1.0 mol/L lithium hexafluorophosphate to a solvent blend in which EMC occupies 20–40 wt% of the total electrolyte. The EMC fraction is held between 25–35 wt% when the cell specification requires a cold-cranking discharge capability below −20 °C, because EMC reduces bulk viscosity relative to EC-rich formulations and shifts the onset of salt precipitation to lower temperature. Production equipment includes a jacketed stainless-steel vacuum planetary mixer with double planetary blades, a magnetic sealless gear pump, and a 0.2 μm polypropylene filter. The mixing sequence is run under nitrogen or argon at 15–25 °C jacket temperature; LiPF6 is metered into the pre-chilled solvent blend while the vessel pressure is maintained at 10–20 kPa absolute to suppress carbonate hydrolysis. After vacuum degassing and filtration, the electrolyte is injected into 18650, 21700, or prismatic cells that have been vacuum-dried at 85 °C for 12 h. Formation cycling at 0.05 C to 0.1 C then builds the solid electrolyte interphase, with vinylene carbonate or fluoroethylene carbonate added at 1–3 wt% to stabilize the EMC-containing electrolyte against reductive decomposition. Finished component types include traction battery modules for battery electric vehicles, consumer-cell-based portable electronics, and stationary energy storage racks. The main process conflict is the balance between EMC content and flash point: at 40 wt% EMC the liquid may exhibit a closed-cup flash point near 23 °C by ASTM D93, requiring ATEX-compliant dosing skids and nitrogen-blanketed storage, while at 20 wt% EMC the wetting and low-temperature benefits are sacrificed.
| EMC content (wt% of total electrolyte) | Solvent blend (EC:EMC:DMC wt%) | Viscosity at 25 °C (mPa·s) | Freezing onset (°C) | Conductivity (mS/cm) | Production note |
|---|---|---|---|---|---|
| 20 | 35:20:45 | 5.8 | −18 | 8.4 | Reduced low-temperature benefit; lower flash-point burden |
| 30 | 30:30:40 | 4.1 | −28 | 9.2 | Automotive baseline |
| 40 | 25:40:35 | 3.0 | −36 | 9.5 | Flammability control and ATEX dosing required |
On a commercial cell assembly line, the main failure mode associated with excessive EMC is not ionic conductivity loss but solvent evaporation during vacuum filling and the formation of vapor pockets in the electrode stack. Consequently, the dosing skid operates as a closed system with a nitrogen blanket and a return line to the electrolyte storage vessel. Filtration through 0.2 μm polypropylene after LiPF6 dissolution is repeated after any intermediate hold longer than 24 h because trace moisture degrades the salt and generates hydrogen fluoride. The values in the table are representative supplier data, not a unified specification; cell makers set internal release limits based on their formation protocol and safety margins.
In sodium-ion pouch cell trials, the substitution of sodium hexafluorophosphate for lithium hexafluorophosphate changes the solvation shell and the precipitation boundary, so the EMC addition window is narrower than in lithium systems. A typical sodium-ion electrolyte contains 0.8–1.0 mol/L NaPF6 in a solvent blend of ethylene carbonate, propylene carbonate, and EMC, with EMC held at 10–30 wt% of total electrolyte. The lower salt concentration and the larger ionic radius of sodium reduce conductivity; EMC is used to cut viscosity, but excessive EMC content above 30 wt% can increase charge-transfer resistance at the hard-carbon anode and reduce cycling stability at 55 °C. For sodium-ion cells intended for stationary storage, compliance is evaluated under IEC 62619 and UN 38.3, with electrolyte moisture controlled below 20 mg/kg by ASTM E203. Downstream production uses the same dry-room infrastructure as lithium-ion cell assembly, but the electrolyte is prepared in a separate mixing skid to avoid cross-contamination of lithium and sodium salts; the blend is filtered through a 0.1 μm PTFE membrane and injected into prismatic cells with hard-carbon anodes and layered-oxide cathodes. Formation cycling at 0.05 C is followed by gas removal in pouch cells, because sodium-ion systems with EMC can generate more first-cycle gas than lithium-ion systems, demanding degassing after 24 h of rest. Finished terminal product types include 1–10 kWh residential energy storage modules and low-speed vehicle battery packs. Published data for long-term calendar aging of sodium-ion electrolytes using EMC above 30 wt% is limited; batch-to-batch variation in moisture and free acid must be tracked before release.
A non-phosgene alkoxycarbonylation sequence in a multi-purpose pharmaceutical reactor uses ethyl methyl carbonate as both the carbonyl source and the reaction solvent. When EMC is the carbonylating reagent, a range of 1.0–2.5 molar equivalents relative to the limiting substrate is common, with 1.2–1.5 equivalents used where exothermic CO2 evolution must be controlled; when EMC is used as a high-boiling process solvent, the charge is 5–10 L/kg of substrate. The downstream process runs in a glass-lined or stainless jacketed reactor at 25–120 °C, with potassium carbonate, DBU, or sodium alkoxide as the base, and the methanol or ethanol by-product is removed through a reflux splitter or a scrubber column to shift equilibrium. Reaction progress is monitored by gas chromatography with flame ionization detection, and the final aqueous work-up includes an acidified brine quench at 0–10 °C to hydrolyze residual carbonate before phase separation. Compliance for these intermediates follows the principles of ICH Q3C and USP <467>; because EMC is not assigned a Class 1 or Class 2 permitted daily exposure in the main solvent tables, residual solvent risk assessments typically rely on toxicological justification and purge factor studies. The terminal finished product types include N-protected amino acid derivatives and carbamate pharmaceutical intermediates that are not themselves final dosage forms but are supplied under current good manufacturing practice. The operational boundary is hydrolytic instability: at pH above 9 and temperatures above 60 °C, EMC can hydrolyze to ethanol, methanol, and carbon dioxide, so base strength and water content must be restricted to avoid uncontrolled CO2 pressure in closed reactors.
For removal of rosin flux and light hydrocarbon oils from printed circuit board assemblies, vapor degreasing chambers constructed to ATEX Zone 1 requirements use ethyl methyl carbonate as a low-residue solvent. The cleaning fluid is charged either neat or at 70–90 vol% EMC in a co-solvent blend, depending on the soils and the ultrasonic frequency of the immersion stage; the lower concentration is used in open-top equipment where vapor concentration must remain below 25% of the lower explosion limit. The downstream process is a two-stage ultrasonic immersion at 30–40 °C for 3–6 min, followed by vapor rinse in the condensation zone and a heated drying cycle at 60 °C under forced air. Compliance is assessed by IPC-TM-650 test methods for ionic contamination and surface insulation resistance, with acceptance typically set at ≤1.56 µg/cm2 NaCl equivalence or per the end-use specification. Supply documentation must include REACH registration under EC 1907/2006, and the finished assembly is evaluated under RoHS Directive 2011/65/EU for restricted substances. Finished terminal product types include automotive engine control modules, smartphone main boards, and semiconductor lead frames prior to wire bonding. The principal processing conflict is flash point: EMC’s closed-cup flash point near 23 °C forces sealed transfer piping and nitrogen inerting, while its evaporation rate is lower than many chlorinated solvents, requiring tight control of rinse temperature to avoid liquid retention under low-standoff components.
When a substituted phenol is converted to its methyl carbamate, the two-stage sequence positions ethyl methyl carbonate between the phenoxide and methylamine. The first stage forms a phenoxide at 0–10 °C in a jacketed reactor using sodium hydroxide or potassium hydroxide, after which EMC is added at 1.0–1.3 molar equivalents relative to the phenolic hydroxyl group. The second stage introduces methylamine at 40–60 °C to cleave the intermediate carbonate and release the methyl carbamate active ingredient, while methanol is distilled under reduced pressure. A typical reaction mass is 15–25 wt% water for hydroxide dissolution, with EMC charged over 2–3 h to avoid excessive pH drop and CO2 evolution. Downstream production equipment includes glass-lined agitated reactors, reflux condensers, and scrubbed vacuum distillation; the crude technical material is then crystallized from toluene or filtered as a wet cake. Compliance for the technical concentrate follows FAO/WHO specifications and CIPAC analytical methods, with residual solvent and free phenol limits set by the registration dossier. Finished terminal product types include carbamate insecticide wettable powders, suspension concentrates, and granulated bait formulations for agricultural pest control. The operational boundary is pH-sensitive: residual EMC and hydrolysis products can depress formulation pH, so the neutralization step after aminolysis must hold free methylamine below the specification limit before spray drying.
Gel polymer electrolyte membranes for lithium-ion cells are cast from a ternary solvent system in which ethyl methyl carbonate acts as the volatile carrier that dissolves poly(vinylidene fluoride-co-hexafluoropropylene) and leaves a porous separator after drying. The formulation is 7–12 wt% PVDF-HFP, 55–70 wt% EMC, 15–25 wt% ethylene carbonate or propylene carbonate plasticizer, and lithium salt at 0.8–1.0 mol/L relative to the liquid phase. The downstream process uses a sealed paddle mixer at 50–60 °C to dissolve the polymer, followed by vacuum degassing and doctor-blade casting onto a polyethylene terephthalate release liner at 200–400 μm wet thickness. Drying is carried out at 30–40 °C under a dew point below −40 °C airflow for 20–40 min, because fast evaporation of EMC causes skinning and densified polymer layers, while slow evaporation leaves solvent residues that degrade cycle life. After peeling, the membrane is soaked in a liquid electrolyte containing EMC and EC to gel, then laminated between electrodes. Compliance for the finished cell is evaluated under IEC 62619 and UN 38.3; membrane tensile properties are measured by ASTM D882. The principal process conflict is the narrow drying window: EMC vapor pressure at 30 °C is moderate, and a temperature excursion above 40 °C can produce bubble defects, while residual EMC above 500 mg/kg in the cast membrane can shift the gel-phase viscosity and create uneven lithium plating during first charge. Finished terminal product types include wearable lithium-polymer cells, thin-format portable electronics, and medical patch batteries.
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Ethyl methyl carbonate (EMC), CAS 623-53-0, is an unsymmetrical dialkyl carbonate with molecular formula C4H8O3 and molecular weight 104.10 g/mol. The commercial product is supplied in three models: battery-grade EMC, high-purity EMC, and technical-grade EMC. The model distinction arises from purification depth and residual contaminant control, not from a different molecular structure. Industrial production is based on transesterification of dimethyl carbonate with ethanol or on oxidative carbonylation of methanol and ethanol; the resulting crude carbonate stream contains unreacted alcohols, dimethyl carbonate, diethyl carbonate, and water that must be removed by final fractionation and molecular-sieve drying. Representative physical properties at 25 °C are density 1.006 g/cm³, boiling point 107 °C at 101.3 kPa, melting point -14.5 °C, closed-cup flash point 23 °C, and dynamic viscosity 0.65 mPa·s. These values place EMC between dimethyl carbonate and diethyl carbonate in volatility, freezing behavior, and viscosity, which is the central reason for its use in lithium-ion electrolyte solvents.
Specification differentiation among the three product models is summarized in the following matrix. Moisture is determined by Karl Fischer coulometry rather than volumetric titration because the battery-grade limit is below the reliable quantification range of volumetric reagents. Acidity is expressed as hydrogen fluoride equivalent because fluoride generation in lithium hexafluorophosphate-based electrolytes is the main operational concern.
| Parameter | Battery-grade EMC | High-purity EMC | Technical-grade EMC |
| Purity by GC-FID area % | ≥99.95% | ≥99.5% | ≥98.0% |
| Moisture per ASTM E203 | ≤20 mg/kg | ≤100 mg/kg | ≤500 mg/kg |
| Acidity as HF by ion chromatography | ≤50 mg/kg | ≤100 mg/kg | ≤200 mg/kg |
| Total metals by ICP-MS | ≤1 mg/kg | ≤5 mg/kg | not specified |
| Color APHA per ASTM D1209 | ≤10 | ≤15 | ≤30 |
| Residual methanol | ≤50 mg/kg | ≤200 mg/kg | ≤1000 mg/kg |
| Residual ethanol | ≤100 mg/kg | ≤300 mg/kg | ≤2000 mg/kg |
Battery-grade EMC is used as a linear carbonate diluent in lithium-ion electrolyte formulations. The solvent package is typically composed of a cyclic carbonate and one or more linear carbonates; ethylene carbonate provides the high-dielectric environment required for lithium salt dissociation, while EMC reduces viscosity and extends the liquid range. Ethylene carbonate has a dielectric constant near 89.6 at 40 °C and a melting point of 36.4 °C, whereas EMC has a dielectric constant near 2.96 and a melting point of -14.5 °C. Common published formulations include 1 M LiPF6 in EC:EMC 3:7 by volume and EC:EMC:DMC 1:1:1 by weight; the latter is reported to exhibit conductivity in the range 8–10 mS/cm at 25 °C, with the exact value influenced by additive content and residual water. Additives such as vinylene carbonate or fluoroethylene carbonate are introduced at 1–5 wt% to modify the solid electrolyte interphase on graphite anodes, and these additives are sensitive to water and free acidity.
The moisture specification is therefore not arbitrary. Residual water reacts with lithium hexafluorophosphate to form hydrogen fluoride and phosphorus pentafluoride; hydrogen fluoride corrodes aluminum current collectors, and phosphorus pentafluoride can degrade carbonate solvents. In a finished electrolyte, moisture is typically held at ≤20 mg/kg and free acid as HF at ≤50 mg/kg. EMC entering the blending operation must therefore meet the 20 mg/kg moisture limit, and any partial container exposed to humid air must be re-sampled before use. Blending skids are built from electropolished 316L stainless steel, blanketed with nitrogen at 99.999% purity, and maintained in dry rooms with dew point ≤-40 °C. Positive-displacement metering pumps for EMC service are fitted with silicon carbide or PTFE seal faces because the low-viscosity carbonate provides limited seal lubrication; seal leakage is a recognized failure mode when mechanical packings are substituted. Automated electrolyte filling lines dose cells under vacuum at -90 kPa gauge after preheating to 25–40 °C. Open transfer is prohibited above 60% relative humidity; closed nitrogen pressure transfer is used instead. These boundaries apply specifically to battery-grade EMC; high-purity and technical-grade materials are not validated for lithium-ion use because residual metals and water are controlled less tightly.
Chemical incompatibilities include strong acids, strong bases, free amines, and oxidizing agents. Base-catalyzed transesterification or hydrolysis can shift the methyl-to-ethyl ratio and generate methanol, ethanol, and carbon dioxide. In closed storage, carbon dioxide formation from hydrolysis or acidic contamination can raise drum headspace pressure; drums are therefore fitted with pressure-relief breathers and stored away from heat sources. Battery-grade EMC is not stabilized with phenolic or amine inhibitors because such additives would contaminate the electrolyte and interfere with solid electrolyte interphase formation.
Batch-to-batch variance in residual alcohol content is a recurring production bottleneck. Continuous reactive-distillation columns for EMC manufacture require monitoring of the methanol:ethanol ratio in both distillate and bottoms; residual methanol or ethanol above the battery-grade specification can alter electrolyte pH during cell formation and contribute to gas evolution in the first charge cycle. After synthesis, the crude EMC is washed, fractionated, and dried over molecular sieve 3A or 4A beds. Final product is transferred through 0.2 μm filters into dedicated stainless steel drums under nitrogen. The separation of methanol, ethanol, and EMC is energy-intensive because the normal boiling points are 64.7 °C, 78.4 °C, and 107 °C, respectively, and the carbonate stream must be kept dry throughout the overhead system to prevent water re-entry. In drumming areas, dedicated lines for battery-grade material are required; sharing transfer hoses with technical-grade ester or alcohol service can introduce residues that are not removed by routine flushing.
DMC, EMC, and DEC form a property series that allows formulators to adjust volatility, viscosity, and melting point without changing the total linear carbonate fraction. DMC has the lowest boiling point, highest dielectric constant, and highest density but also a melting point of 4.6 °C, which can cause solidification in unheated winter storage and transfer lines. DEC has the lowest melting point and the highest boiling point but the highest viscosity and lowest dielectric constant. EMC occupies the intermediate position with a melting point of -14.5 °C, boiling point of 107 °C, viscosity of 0.65 mPa·s, and dielectric constant of 2.96. The comparative data below are based on typical supplier technical bulletins; minor variations arise from residual moisture and alcohol content.
| Property | Dimethyl carbonate | Ethyl methyl carbonate | Diethyl carbonate |
| CAS | 616-38-6 | 623-53-0 | 105-58-8 |
| Boiling point at 101.3 kPa (°C) | 90 | 107 | 126 |
| Melting point (°C) | 4.6 | -14.5 | -43 |
| Density at 25 °C (g/cm³) | 1.070 | 1.006 | 0.975 |
| Viscosity at 25 °C (mPa·s) | 0.59 | 0.65 | 0.75 |
| Closed-cup flash point (°C) | 18 | 23 | 25 |
| Dielectric constant at 25 °C | 3.12 | 2.96 | 2.82 |
When EMC replaces DMC in a ternary electrolyte, the primary benefit is reduced vapor loss during vacuum filling. A filling chamber pressure of -90 kPa gauge at 25–40 °C can cause preferential DMC evaporation from the solvent blend, shifting the electrolyte composition and raising viscosity during dosing. The 17 °C boiling-point advantage of EMC over DMC reduces this composition drift without requiring a switch to DEC, whose higher viscosity can reduce room-temperature conductivity. Low-temperature discharge testing per IEC 62660-1 at -30 °C is typically improved in cells using EMC rather than DMC as the main linear carbonate because the lower melting point avoids solvent crystallization and viscosity increase in the electrode pores. However, the exact capacity retention at -30 °C is cell design-dependent; published data for this specific configuration is limited to cell-level results, and no single solvent property predicts the retained discharge capacity across different electrode thicknesses and porosities. DEC remains preferred when the lowest possible electrolyte freezing point is required, but its lower dielectric constant and higher viscosity can increase internal resistance at high discharge rates unless the ethylene carbonate fraction is increased.
The asymmetric methyl-ethyl structure of EMC also differs from the symmetric DMC and DEC in chemical reactivity. DMC provides only methoxy groups in transesterification reactions; DEC provides only ethoxy groups; EMC provides both, with different reaction rates. This is one reason why EMC is not interchangeable with DMC in non-electrolyte applications such as pharmaceutical intermediates or carbonate-based resins without re-qualification of conversion and selectivity.
Outside lithium-ion cells, EMC is employed as a carbonate solvent in high-solids coatings, electronics cleaning formulations, and fine chemical synthesis. Technical-grade EMC is restricted to these non-battery applications because its water content, acidity, and metal profile are not controlled below battery-grade thresholds. In coatings, EMC is blended with high-boiling oxygenated solvents to adjust evaporation rate and viscosity; the closed-cup flash point of 23 °C requires explosion-proof mixing equipment and nitrogen inerting in enclosed reactors. In fine chemical synthesis, EMC is used in jacketed stainless steel or glass-lined reactors at 60–120 °C, with continuous gas chromatographic monitoring of carbonate conversion. The choice between EMC and dimethyl carbonate in these reactions depends on whether methoxy, ethoxy, or both leaving groups are required; published data for this specific configuration is limited, and process development generally relies on in-house conversion and selectivity data rather than a universal yield table.
EMC is a flammable liquid and should be stored in electrically classified areas with adequate local exhaust ventilation. Spill response uses alcohol-resistant foam or dry chemical; water spray is limited to cooling exposed containers because the product is partially water-soluble and runoff can contaminate waste streams. Storage tanks and drums are fitted with pressure-relief devices because carbon dioxide may form slowly if the material is contaminated with water or acidic species in confined storage. The product is incompatible with strong oxidizers, strong acids, strong bases, and amine-based additives; contact with strong bases can initiate transesterification and exothermic hydrolysis. Hot work and open flames are excluded within a 15 m radius during drum transfers, and transfer equipment is bonded and grounded to prevent static discharge. The absence of a hazardous air pollutant designation in one jurisdiction does not remove the need for engineering controls during bulk handling, particularly in battery dry rooms where the product is handled in large volume.
