Acyl Chloride · Acylating Agent · Organic Acid Chloride
Propanoyl Chloride
(Propionyl Chloride / Propionic Acid Chloride / Propanoic Acid Chloride)
| CAS No. | 79-03-8 |
| IUPAC Name | propanoyl chloride |
| Common Name | propionyl chloride, propionic acid chloride, propanoic acid chloride |
| Molecular Formula | C₃H₅ClO / CH₃CH₂COCl |
| Molecular Weight | 92.52 g/mol |
| Functional Group | Acyl chloride (–COCl) / Propanoyl group (CH₃CH₂CO–) |
| HS Code | 2915901000 |
| Grade Available | Industrial ≥99.0% Pharmaceutical ≥99.5% Reagent Grade ≥98.0% |
What Is Propanoyl Chloride? Structure, Formula & Overview
Propanoyl chloride (IUPAC name; common name: propionyl chloride; CAS 79-03-8) is a colorless, highly volatile liquid with a pungent, suffocating odor. Its structural formula is CH₃CH₂COCl - a three-carbon acyl chain terminated by a highly reactive C–Cl bond. The functional group is an acyl chloride (–COCl), which makes it one of the most reactive acylating agents in organic synthesis. The propanoyl group (CH₃CH₂CO–) it delivers is a three-carbon carbonyl fragment that introduces propionyl substituents into target molecules.
The displayed formula of propanoyl chloride shows: H₃C–CH₂–C(=O)–Cl, with the carbonyl carbon bearing both the ethyl chain and the chlorine leaving group. On reaction with nucleophiles (water, alcohols, amines, Friedel-Crafts conditions), the C–Cl bond breaks and the propionyl group is transferred to the nucleophile with release of HCl. This high electrophilicity makes propanoyl chloride significantly more reactive than propionic anhydride or propionic acid for acylation reactions, though it requires more careful handling due to HCl evolution.
We partner with leading Chinese manufacturers using advanced propionic acid – phosphorus trichloride (PCl₃) condensation technology and multi-stage rectification purification to supply Industrial (≥99.0%), Pharmaceutical (≥99.5%), and Reagent Grade (≥98.0%) propanoyl chloride with competitive pricing, comprehensive quality documentation, and flexible packaging from glass bottles to IBC totes.
Physical & Chemical Properties of Propanoyl Chloride (Propionyl Chloride)
CH₃CH₂COCl + H₂O → CH₃CH₂COOH + HCl
Yields propionic acid + HCl. Violent reaction - avoid all contact with moisture.
CH₃CH₂COCl + 2 NH₃ → CH₃CH₂CONH₂ + NH₄Cl
Gives propanamide. Two equivalents of ammonia needed to neutralize HCl.
CH₃CH₂COCl + CH₃NH₂ → CH₃CH₂CONHCH₃ + HCl
N-methylpropanamide; key route in pharmaceutical synthesis.
CH₃CH₂COCl + C₆H₆ → C₆H₅COCH₂CH₃ + HCl (AlCl₃ cat.)
Gives propiophenone; important synthetic intermediate.
CH₃CH₂COCl + C₂H₅OH → CH₃CH₂COOC₂H₅ + HCl
Ethyl propanoate (flavor ester). Fast esterification without catalyst.
CH₃CH₂COCl + CH₃CH₂COONa → (CH₃CH₂CO)₂O + NaCl
Synthesis of propionic anhydride from propanoyl chloride.
Propionyl Chloride Specifications - All Grades
| Specification | Industrial Grade Agrochemical / Fine Chemical |
Pharmaceutical Grade API Synthesis / GMP |
Reagent Grade Lab / R&D |
|---|---|---|---|
| Purity (GC) | ≥ 99.0% | ≥ 99.5% | ≥ 98.0% |
| Boiling Point (bp) | 77–80 °C (1013 hPa) | 78–79 °C (1013 hPa) | 77–79 °C (1013 hPa) |
| Flash Point | 6 °C (dangerously flammable) | 6 °C | 6–11 °C |
| Specific Gravity (20 °C) | 1.060–1.065 g/cm³ | 1.062–1.064 g/cm³ | 1.060 ± 0.005 g/cm³ |
| Refractive Index (20 °C) | 1.402–1.405 | 1.403–1.404 | 1.4020–1.4050 |
| Phosphate (PO₄³⁻) | ≤ 0.02% | ≤ 0.01% | ≤ 0.01% |
| Heavy Metals / Free Acid | - | Heavy metals ≤ 0.001% | Free acid ≤ 0.1% |
| Storage Stability | 2 months (sealed, <30°C) | 3 months (N₂-sealed, dark) | 6 months (sealed, cool) |
| Packaging | 200 kg PTFE-lined drum 1000 kg IBC tote |
20 L HDPE drum 200 L N₂-sealed drum |
100 mL / 500 mL glass bottle 20 L HDPE drum |
Complies with Q/320281NGY03-2021, REACH & TSCA. COA, SDS/MSDS available on request.
Propionyl Chloride Uses & Applications
1. Pharmaceutical Industry - API Synthesis & Drug Intermediates
Propanoyl chloride (propionyl chloride) is a core acylating agent in pharmaceutical synthesis, valued for its speed and completeness of reaction compared to propionic anhydride. It is used in the synthesis of anti-epileptic drugs (e.g., methylphenytoin), choleretic agents, and anti-infective drugs, and serves as a protective group reagent and propionylation agent for hydroxyl and amino groups in complex molecule synthesis.
A widely searched regulatory topic is propionyl chloride and fentanyl: propionyl chloride is listed as a DEA-monitored chemical because it can be used in the synthesis of fentanyl analogues. We supply propanoyl chloride exclusively for legitimate industrial, pharmaceutical, and agrochemical applications with full end-user documentation and compliance with export control regulations.
Pharmaceutical-grade propionyl chloride (≥99.5%) meets GMP and ICH Q3C guidelines. By-product HCl is managed by using base scavengers or operating in the presence of a tertiary amine (e.g., triethylamine).
Reference: PubChem - Propanoyl Chloride (CAS 79-03-8) · NIH ↗
2. Agrochemical Industry - Herbicide & Pesticide Synthesis
In agrochemicals, propanoyl chloride is a key raw material for manufacturing propionamide-based herbicides - most notably propanil (3,4-dichloropropionanilide), a selective post-emergence herbicide widely used in rice cultivation. The acyl chloride route offers significantly faster acylation of aniline intermediates compared to propionic anhydride, with better conversion rates for large-scale continuous production.
It is also used as an intermediate in the synthesis of propionyl hydrazine derivatives (fungicide intermediates) and other propionamide crop protection actives with high selectivity and low environmental toxicity.
3. Flavor & Fragrance Industry - Propionate Ester Synthesis
Propanoyl chloride is used to synthesize propionate esters - ethyl propanoate, butyl propanoate, and other fruit/creamy esters - used as flavor ingredients in food, beverages, and cosmetics. Its high reactivity enables near-quantitative ester yields under mild conditions. The reaction with ethanol (propanoyl chloride + ethanol → ethyl propanoate + HCl) is one of the fastest esterification routes, important for continuous-process flavor manufacturers.
4. Fine Chemicals, Dyes & Analytical Chemistry
In fine chemicals, propanoyl chloride participates in Friedel-Crafts acylation (with benzene → propiophenone), synthesis of dyes, pigments, and specialty surfactants. It is used as a derivatization reagent in GC/HPLC analytical chemistry to convert hydroxyl- and amino-bearing analytes into volatile, chromatographically separable propanoyl derivatives for trace quantification.
It is also a reagent for making propionic anhydride from propanoyl chloride + sodium propanoate, and for synthesizing organic peroxide initiators and pharmaceutical excipients.
How Is Propionyl Chloride Made? Synthesis Methods
The primary industrial route is the reaction of propionic acid with phosphorus trichloride (PCl₃): 3 CH₃CH₂COOH + PCl₃ → 3 CH₃CH₂COCl + H₃PO₃. The reaction proceeds at moderate temperature (50–80°C) with continuous distillation of propanoyl chloride from the reaction mixture. PCl₃ is preferred over thionyl chloride (SOCl₂) for large-scale production as it produces phosphorous acid (recoverable) rather than SO₂ and HCl gas as by-products.
Alternative laboratory routes include: reaction of propionic acid with thionyl chloride (SOCl₂) - CH₃CH₂COOH + SOCl₂ → CH₃CH₂COCl + SO₂ + HCl; or reaction with oxalyl chloride for very high purity applications. The PCl₃ route is standard for industrial manufacture.
Our partner manufacturers use continuous condensation production lines with multi-stage fractional distillation, strict phosphate control (≤0.02%), and nitrogen blanketing throughout, ensuring consistent purity and minimal HCl residuals in the finished product.
Regulatory Status: Propionyl Chloride, DEA Monitoring & Export Compliance
Propionyl chloride (CAS 79-03-8) is monitored by the U.S. DEA as a List II chemical due to its potential use as a precursor in the synthesis of fentanyl analogues. All export shipments to DEA-regulated markets require complete end-user documentation, including end-use certificates and importer declarations confirming legitimate industrial use.
We supply propanoyl chloride exclusively for legitimate industrial, pharmaceutical, and agrochemical applications in compliance with REACH, TSCA, and applicable national export control regulations. Comprehensive export documentation, customs declarations, and compliance support are provided for all international shipments. Buyers are required to disclose end-use information at order placement.
Storage, Stability & Safety Handling
Storage Requirements
Store below 25°C (preferably 5–20°C) in a cool, dry, well-ventilated explosion-proof warehouse. All containers must be nitrogen-sealed - propanoyl chloride reacts with atmospheric moisture. Use PTFE-lined drums or HDPE drums; avoid metal containers susceptible to HCl corrosion. Segregate from water, strong oxidizers, strong bases (NaOH, KOH), and food materials with minimum 10 m separation or incombustible barriers. Maximum stack: 2 layers for 200 kg drums. Warehouse must be equipped with explosion-proof electrical fittings, forced ventilation, and dry-powder / CO₂ fire suppression.
Stability
Stable under dry, sealed, cool conditions. Hydrolyzes immediately on contact with water to propionic acid and HCl. Shelf life: 2 months (industrial, <30°C); 3 months (pharma, N₂-sealed, dark); 6 months (reagent, cool sealed). Yellowing indicates hydrolysis/oxidation - discard if discolored.
Safety & Handling (SDS / MSDS Summary)
GHS classification: Flammable Liquid Category 2 (flash point 6°C), Acute Toxicity (inhalation) Category 3, Skin Corrosion Category 1A, Eye Damage Category 1.
PPE required: Anti-static clothing, triple-layer nitrile gloves, chemical safety goggles + face shield, organic vapor respirator (SCBA for confined spaces). Ground all containers during transfer to eliminate static electricity. Operate in fume hood at all times.
Spill response: Cut ignition sources immediately. Do NOT use water. Absorb with dry sand, dry lime, or inert absorbent. Collect in sealed containers. Neutralize residue with dry sodium carbonate. Evacuate to upwind area.
First aid: Skin - remove clothing, flush with water ≥15 min. Eyes - flush with water ≥15 min, seek emergency eye care. Inhalation - fresh air immediately; HCl fumes cause acute respiratory irritation. Full SDS/MSDS from sales@sinolookchem.com.
Propionyl Chloride Price - 2025 Market Reference
The propionyl chloride price (propanoyl chloride price) is driven by propionic acid and PCl₃ feedstock costs plus production capacity. Reference prices for China-origin product (ex-works, 2025):
Frequently Asked Questions about Propanoyl Chloride / Propionyl Chloride
Q: What is propanoyl chloride? What is the IUPAC name vs common name?
Propanoyl chloride is the IUPAC name for the compound CH₃CH₂COCl (CAS 79-03-8). Its common name is propionyl chloride. Both names are used interchangeably in industry and academia - "propionyl" is the traditional name based on propionic acid, while "propanoyl" follows IUPAC systematic nomenclature. Other synonyms include propionic acid chloride, propanoic acid chloride. The functional group is an acyl chloride (–COCl), and the leaving group transferred in acylation reactions is the propanoyl group (CH₃CH₂CO–).
Q: What is the structure (displayed formula) of propanoyl chloride?
The displayed formula (full structural formula) of propanoyl chloride is: H–C–C–C(=O)–Cl with the full hydrogen expansion: CH₃–CH₂–C(=O)–Cl. The carbonyl carbon is bonded to: (1) the ethyl chain (–CH₂CH₃), (2) a double-bonded oxygen (=O), and (3) the chlorine atom (–Cl). The C–Cl bond is the reactive site - it is highly polar due to the adjacent carbonyl group, making the carbonyl carbon strongly electrophilic. The structural formula is CH₃CH₂COCl or C₂H₅COCl, molecular formula C₃H₅ClO.
Q: What is propanoyl chloride subjected to reduction with H₂ (Rosenmund reduction)?
When propanoyl chloride is subjected to reduction with H₂ in the presence of a Pd/BaSO₄ catalyst (Rosenmund reduction conditions), it selectively yields propanal (propionaldehyde, CH₃CH₂CHO). The BaSO₄ support poisons the catalyst sufficiently to prevent over-reduction to propanol. This is a classic A-level and undergraduate exam reaction: acyl chloride + H₂/Pd(BaSO₄) → aldehyde. Full reduction to the alcohol (propan-1-ol) requires a stronger reducing agent such as LiAlH₄ (which reduces acyl chlorides → primary alcohols via an aldehyde intermediate) or NaBH₄ in combination with specific conditions.
Q: What is propanoyl chloride and sodium propanoate reaction?
The reaction of propanoyl chloride with sodium propanoate (CH₃CH₂COCl + CH₃CH₂COONa) yields propionic anhydride [(CH₃CH₂CO)₂O] and sodium chloride (NaCl). This is one of the standard laboratory methods for preparing symmetric acid anhydrides from acyl chlorides and carboxylate salts. The reaction is fast and clean, proceeding at room temperature in an inert solvent (e.g., DCM or diethyl ether).
Q: Is propionyl chloride a DEA-monitored / regulated chemical?
Yes - propionyl chloride (CAS 79-03-8) is a U.S. DEA List II chemical because it is a known precursor in the illicit synthesis of fentanyl analogues. This means that U.S. importers must register with the DEA and report transactions above threshold quantities. International exports to the U.S. require DEA import permits. Other jurisdictions (EU, China) have analogous precursor control regulations. We rigorously comply with all applicable export control laws - all buyers must provide end-use declarations confirming legitimate pharmaceutical, agrochemical, or industrial use. We do not supply to unlicensed parties or for undisclosed end-uses.
Q: How does propanoyl chloride compare to propionic anhydride as an acylating agent?
Both propanoyl chloride and propionic anhydride introduce propionyl groups, but they differ in reactivity and by-products. Propanoyl chloride is more reactive (faster acylation), but generates corrosive HCl - requiring a base scavenger (e.g., Et₃N, pyridine) to neutralize HCl and prevent side reactions. Propionic anhydride is milder, generates only propionic acid as by-product (non-corrosive, easily removed), and is therefore preferred for acid-sensitive substrates, pharmaceutical GMP settings, and food-grade applications. For large-scale agrochemical production where cost and speed dominate, propanoyl chloride is often preferred. For pharmaceutical API synthesis with strict impurity profiles, propionic anhydride is typically the safer choice.
Industry References & Standards
Comprehensive physicochemical data, NMR/IR spectra, toxicology, GHS classifications, and regulatory information.
EU REACH dossier: hazard classifications, occupational exposure limits, and regulatory status.
Global reference for reagent-grade propanoyl chloride quality benchmarks and spectral data.
Official DEA list of monitored precursor chemicals including propionyl chloride; import/export regulatory requirements.
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Request Propanoyl Chloride Pricing & Supply
We supply Industrial, Pharmaceutical, and Reagent Grade propanoyl chloride (propionyl chloride, CAS 79-03-8) with full export compliance documentation. Contact us for a tailored quote, COA, SDS/MSDS, or DEA/REACH compliance guidance.
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