Ethyl Propionate (105-37-3) Physical and Chemical Properties
Ethyl Propionate
A volatile aliphatic ester commonly used as a solvent, synthesis intermediate and aroma component in manufacturing, formulation and R&D.
| CAS Number | 105-37-3 |
| Family | Alkyl carboxylate esters |
| Typical Form | Colorless liquid |
| Common Grades | EP, FCC, JP, USP |
Ethyl propionate is a short-chain aliphatic ester (the ethyl ester of propanoic acid) belonging to the C5 monoalkyl esters class. Its molecular formula is \(\ce{C5H10O2}\); the molecule contains a carbonyl-bearing ester functional group (–C(=O)O–) linked to an ethyl and an n-propyl fragment. Electronically the carbonyl is the principal polar site, giving modest dipolarity and the capacity for weak hydrogen-bond acceptance (no hydrogen-bond donors). The ester oxygen lone pairs and the carbonyl π-system determine reactivity in nucleophilic acyl substitution (hydrolysis, transesterification) and susceptibility to acid- or base-catalyzed cleavage.
Physicochemically, ethyl propionate is a low-molecular-weight, volatile, flammable solvent with moderate lipophilicity (log P ≈ 1.2). It displays measurable water solubility but is significantly more soluble in organic media; vapors are heavier than air. Chemically it behaves as a typical short aliphatic ester: stable under ambient conditions but reactive toward strong acids, bases and oxidizing agents; hydrolysis is a relevant degradation pathway under environmental and strongly basic conditions. Industrially it is used as an organic solvent and as a flavor/fragrance ingredient due to a fruity, rum- or pineapple-like odor; it is also used in coatings/lacquers and in food and fragrance formulations.
Common commercial grades reported for this substance include: EP, FCC, JP, USP.
Basic Physical Properties
Density
Reported densities for ethyl propionate include \(0.891\) (USCG, 1999) with the qualitative note "Less dense than water; will float," and \(0.8917\) at \(20\,^\circ\mathrm{C}/4\,^\circ\mathrm{C}\). A narrower literature range is given as \(0.886\)–\(0.889\). These values are consistent with an organic ester less dense than \(\ce{H2O}\).
Melting Point
Reported melting/freezing points: \(-99\,^\circ\mathrm{F}\) (USCG, 1999) and \(-73.9\,^\circ\mathrm{C}\); another reported value is \(-73\,^\circ\mathrm{C}\). These indicate a very low melting point typical for small volatile esters.
Boiling Point
Reported boiling data: \(210\,^\circ\mathrm{F}\) at \(760\ \mathrm{mmHg}\) (USCG, 1999), \(99.2\,^\circ\mathrm{C}\), and a range \(98.00\) to \(100.00\,^\circ\mathrm{C}\) at \(760.00\ \mathrm{mmHg}\). These values are mutually consistent and reflect a normal boiling point near \(99\,^\circ\mathrm{C}\).
Vapor Pressure
Measured vapor pressures reported are \(35.9\ \mathrm{mmHg}\), \(40\ \mathrm{mmHg}\) at \(27.2\,^\circ\mathrm{C}\), and \(35.8\ \mathrm{mmHg}\) at \(25\,^\circ\mathrm{C}\). The relatively high vapor pressure explains its volatility and tendency to exist as a vapor under ambient conditions.
Flash Point
Reported flash points: \(54\,^\circ\mathrm{F}\) (USCG, 1999) and \(12\,^\circ\mathrm{C}\) (closed cup). These low flash-point values indicate that ethyl propionate must be handled as a flammable liquid.
Chemical Properties
Solubility and Phase Behavior
Ethyl propionate is readily soluble in common organic solvents and miscible with short-chain alcohols and ethers: reports include "SOLUBLE IN MOST ORGANIC SOLVENTS," "Soluble in alcohol and ether," and "Miscible in ethanol and ethyl ether; soluble in acetone." Reported water solubility values include \(19{,}200\ \mathrm{mg}/\mathrm{L}\) at \(25\,^\circ\mathrm{C}\) (equivalently \(19.2\ \mathrm{mg}/\mathrm{mL}\) at \(20\,^\circ\mathrm{C}\)) and a descriptive "Soluble in water (1 mL in 42 mL)." Vapor density is reported as \(3.52\) (Air = 1), indicating vapors are denser than air and can collect in low areas.
In practical formulation contexts, ethyl propionate behaves as a volatile, low-viscosity solvent with partial miscibility in water and good solvation for esters, resins and organic solutes; phase separation from aqueous media may occur depending on concentrations and co-solvents.
Reactivity and Stability
Ethyl propionate is chemically stable under normal storage conditions but undergoes typical ester chemistry under reactive conditions: - Hydrolysis: base-catalyzed hydrolysis is significant; an estimated base-catalyzed second-order hydrolysis rate constant of \(8.9\times10^{-2}\ \mathrm{L\,mol^{-1}\,s^{-1}}\) has been reported, corresponding to estimated aqueous hydrolysis half-lives of 2.5 years at pH 7 and 90 days at pH 8. - Reaction partners: reacts with strong oxidizing agents (can react vigorously), with strong acids and bases (liberates alcohol and acid, exothermic), and with alkali metals/hydrides (generation of flammable hydrogen). Reported reactivity profile states it "Will not polymerize." - Thermal decomposition: "When heated to decomposition it emits acrid smoke and irritating fumes."
Storage and handling should therefore avoid strong oxidizers, strong bases or acids in concentrated contact and exclude ignition sources.
Thermodynamic Data
Standard Enthalpies and Heat Capacity
No experimentally established value for this property is available in the current data context.
Molecular Parameters
Molecular Weight and Formula
- Molecular formula: \(\ce{C5H10O2}\).
- Molecular weight (reported): \(102.13\).
- Exact/monoisotopic mass: \(102.068079557\).
Structural identifiers: SMILES CCC(=O)OCC, InChI InChI=1S/C5H10O2/c1-3-5(6)7-4-2/h3-4H2,1-2H3, InChIKey FKRCODPIKNYEAC-UHFFFAOYSA-N.
Additional computed descriptors: topological polar surface area \(26.3\); complexity \(59.1\); heavy atom count 7; formal charge 0.
LogP and Polarity
Reported partitioning and polarity metrics: \(XLogP = 1.2\) and \(\log K_\mathrm{ow} = 1.21\). Hydrogen-bond counts: hydrogen-bond donor count \(0\), hydrogen-bond acceptor count \(2\). These values are consistent with a moderately lipophilic but polarizable solvent that has limited tendency to bioaccumulate (low estimated BCF).
Structural Features
Ethyl propionate is a simple aliphatic ester (ethyl propanoate). The ester bond confers susceptibility to nucleophilic attack at the carbonyl carbon and to acid- or base-catalyzed hydrolysis; the n-propyl and ethyl groups supply chain flexibility and low steric hindrance. NMR and MS spectral data in the technical literature are consistent with this simple acyclic ester structure.
Identifiers and Synonyms
Registry Numbers and Codes
- CAS: 105-37-3
- EC number: 203-291-4
- UN Number: UN1195
- UN/NA shipping identifier (as reported): 1195 (ETHYL PROPIONATE) / 1195 (Ethyl propionate)
- FEMA Number: 2456
- ChEBI: CHEBI:41330
- UNII: AT9K8FY49U
- DSSTox: DTXSID1040110
- InChI:
InChI=1S/C5H10O2/c1-3-5(6)7-4-2/h3-4H2,1-2H3 - InChIKey:
FKRCODPIKNYEAC-UHFFFAOYSA-N - SMILES:
CCC(=O)OCC
Synonyms and Structural Names
Common synonyms reported include: ethyl propionate; ethyl propanoate; Propanoic acid, ethyl ester; Propionic acid, ethyl ester; Propionate d'ethyle; Ethyl n-propionate; Propionic acid ethyl ester; Ethylpropionate; FEMA 2456. (Multiple additional depositor-supplied synonyms and variant spellings are used in technical supply listings.)
Industrial and Commercial Applications
Representative Uses and Industry Sectors
Ethyl propionate is used across several industrial sectors: - Solvent for cellulose ethers/esters, lacquers, resins and coatings. - Flavoring and fragrance ingredient in foods, beverages and personal-care products (notes described as apple, pineapple, rum, strawberry in flavor profiles). - Formulation solvent and processing aid in coatings and adhesives. - Reported use as a cutting agent for pyroxylin and in selected specialty chemical processes.
It is produced industrially by esterification of ethanol with propionic acid (or propionic anhydride) and is available in grades suitable for technical, food and pharmaceutical applications.
Role in Synthesis or Formulations
In synthesis and formulations ethyl propionate functions primarily as a volatile organic solvent and as a flavor/fragrance constituent. Its low polarity and good solvency for many organic resins make it useful in lacquer and coating formulations; its fruity odor makes it valuable at low concentrations in flavor and fragrance blends. It may also serve as a reagent or intermediate in acylation/transesterification chemistry when ethyl esters are required.
Safety and Handling Overview
Acute and Occupational Toxicity
- Acute toxicity values reported include LD50 (rat, oral) \(8732\ \mathrm{mg/kg}\); LD50 (rat, i.p.) \(1200\ \mathrm{mg/kg}\); LD50 (mouse, i.p.) \(1300\ \mathrm{mg/kg}\); LD50 (rabbit, oral) \(3500\ \mathrm{mg/kg}\) and \(5.7\ \mathrm{g/kg}\) (alternate report).
- Inhalation exposures to saturated vapor under experimental conditions produced lethality with LT50 values reported as \(35\) (26–47) minutes (males) and \(32\) (23–44) minutes (females) in one study; survivors exhibited transient respiratory and neurological signs.
- Primary irritation: eye and skin irritation reported (eye irritation resolved within 48 hours in test animals), and exposure to high concentrations may produce central nervous system depression, dizziness, headache, nausea and respiratory irritation.
- Ecotoxicity: aquatic toxicity tests (Daphnia) indicate 24‑hr EC50 values in the hundreds of mg·L⁻¹ range and a 21‑day NOEC around \(6.3\ \mathrm{mg/L}\) for sensitive endpoints in reproduction tests.
Hazard classification entries reported include H225: Highly flammable liquid and vapor; additional notifications include skin and respiratory irritation and environmental aquatic hazard statements in certain notifications.
Storage and Handling Considerations
- Flammability control: ethyl propionate has a low flash point (reported \(54\,^\circ\mathrm{F}\) / \(12\,^\circ\mathrm{C}\)), LEL approximately \(1.8\)–\(1.9\%\) and UEL approximately \(11\%\) by volume in air. Eliminate ignition sources, use grounding/bonding for transfer operations and store in a cool, well-ventilated area.
- Incompatible materials: strong oxidizers, strong acids and strong bases; avoid contact with alkali metals and hydrides.
- Personal protective equipment: use appropriate chemical-resistant gloves and eye/face protection; in the presence of vapor or mist, use appropriate respiratory protection. For firefighting and emergency response, positive-pressure self-contained breathing apparatus and full protective clothing are recommended.
- Spill response: eliminate ignition sources, dike and absorb with inert non-combustible material, collect with non-sparking tools, ventilate confined spaces. Vapors heavier than air can accumulate in low areas—ventilate accordingly.
- Disposal and regulation: handle waste and emissions per applicable local regulations and product-specific Safety Data Sheet (SDS).
For detailed hazard, transport and regulatory information, users should refer to the product-specific Safety Data Sheet (SDS) and local legislation.
