Propionic

Chemical Properties

Propionic anhydride is a colorless liquid. Strong, pungent, unpleasant odor. Soluble in methanol, ethanol, ether, chloroform and alkali, decomposes in water.

Uses

Propionic anhydride is used as a esterifying agent for certain perfume oils, fats, oils, and especially cellulose and as a reagent in organic synthesis. In the production of alkyd resins, dyestuffs and drugs. Has been used as a dehydrating agent in some sulfonations and nitrations.

Application

Propionic anhydride was previously used in the preparation of α and β-1-propionyl derivatives of glucopyranose tetra-acetate.

General Description

Propionic anhydride is an organic compound with the molecular formula (CH3CH2CO)2O. it is an colorless acid anhydride that is widely used as a reagent in organic synthesis.

Air & Water Reactions

Decomposes exothermically in water to form a corrosive solution of propionic acid [Merck, 11th ed. 1989].

Reactivity Profile

Propionic anhydride reacts exothermically with water. The reactions are sometimes slow, but can become violent when local heating accelerates their rate. Acids accelerate the reaction with water. Incompatible with acids, strong oxidizing agents, alcohols, amines, and bases.

Hazard

Strong irritant to tissue.

Health Hazard

Inhalation causes irritation of eyes and respiratory tract. Contact with liquid causes burns of eyes and skin. Ingestion causes burns of mouth and stomach.

Fire Hazard

Combustible material: may burn but does not ignite readily. Substance will react with water (some violently) releasing flammable, toxic or corrosive gases and runoff. When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion hazards. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapors may travel to source of ignition and flash back. Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water.

Flammability and Explosibility

Non flammable

Safety Profile

Moderately toxic by ingestion. Mildly toxic by skin contact. A corrosive irritant to skin, eyes, and mucous membranes. Combustible when exposed to heat or flame; can react with oxidizing materials. To fight fire, use CO2, dry chemical. When heated to decomposition it emits acrid smoke and irritating fumes. Used as an esterifyng agent and dehydrating agent. See also ANHYDRIDES.

Safety

Propanoic anhydride is strong smelling and corrosive, and will cause burns on contact with skin. Vapour can burn eyes and lungs.

Synthesis

Propanoic anhydride has been prepared by dehydration of propanoic acid using ketene :
2 CH₃CH₂CO₂H + CH₂= C= O → (CH₃CH₂CO)₂O + CH₃CO₂H.

Potential Exposure

Used in the manufacture of perfumes, flavorings, alkyd resins; dyestuffs, pharmaceuticals; as an esterifying agent for fats, oils, and cellulose; dehydrating medium for nitrations and sulfonations.

Shipping

UN2496 Propionic anhydride, Hazard class: 8; Labels: 8-Corrosive material.

Purification Methods

Shake the anhydride with P2O5 for several minutes, then distil. [Beilstein 2 IV 722.]

Incompatibilities

Vapors may form explosive mixture with air. Incompatible with oxidizers (chlorates, nitrates, perox- ides, permanganates, perchlorates, chlorine, bromine, fluo- rine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides, reducing agents; alcohols and metals. Contact with water forms heat 1 flammable propionic acid. Compounds of the carboxyl group react with all bases, both inorganic and organic (i.e., amines) releasing substantial heat, water and a salt that may be harmful. Incompatible with arsenic compounds (releases hydrogen cyanide gas), diazo compounds, dithiocarbamates, isocyanates, mercap- tans, nitrides, and sulfides (releasing heat, toxic and possibly flammable gases), thiosulfates and dithionites (releasing hydrogen sulfate and oxides of sulfur).

Waste Disposal

Use a licensed professional waste disposal service to dispose of this material. Dissolve or mix the material with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber. All federal, state, and local environmental regulations must be observed.