Product name: Propionic acid
CAS number: 79-09-4
Molecular formula: C3H6O2
EINECS number: 201-176-3

Introduction to Propionic Acid

Propionic acid, also known as primary oleic acid, is a saturated monocarboxylic acid containing three carbon atoms and one of the typical volatile low-level fatty acids. Chemical formula: CH3CH2COOH. Molecular weight: 74.08. Colorless, clear, oily liquid with an unpleasant rancid odor. Melting point: -20.8℃, boiling point: 140.99, 41.65 (1330Pa), relative density: 0.9930, refractive index: 1.3869. Ka=1.34×10-5. Miscible with water. Soluble in alcohol, chloroform and ether. Active chemical properties, acidic, can undergo salt formation, esterification, reduction and other reactions.

Content analysis

Take 3g of the sample (accurate to 0.1mg), put it into a 250ml flask, add 50ml of water, and mix. Add a few drops of phenolphthalein test solution (TS-167), and titrate with 1mol/L sodium hydroxide until a slight red color appears and lasts for more than 30s. Each milliliter of 1mol/L sodium hydroxide is equivalent to 74.08mg of propionic acid (C3H6O2).

Chemical properties

Colorless liquid with pungent odor. Miscible with water, soluble in ethanol, acetone and ether.

Propionic acid Chemical Properties

Uses

Used as organic reagent, esterifying agent and plasticizer, also used in the preparation of food flavors

Uses

Preservative; mildew inhibitor; flavoring agent. Used as a sticky substance inhibitor in beer, etc.

Uses

As a feed mildew preventer. Dosage 0.15%-0.25%.

Uses

Propionic acid is an important chemical raw material, an intermediate for fungicides such as metalaxyl and bensulfuron, herbicides such as propanil, quizalofop-p-butyl, oxazolidinone, fluazifop-p-butyl, thiazolin-butyl, fluazifop-p-butyl, lactofen-p-butyl, pretilachlor, and naproxen. It is also a pharmaceutical intermediate and can be used as a preservative in the food industry and a preservative for green fodder.

Uses

Propionic acid is an important fine chemical and an intermediate for many other fine chemicals. It is mainly used as a food and feed additive, and secondly as a household herb, medicine, and spices. In terms of grain and feed additives, propionic acid has a significant effect and its consumption is growing rapidly.

(1) Food additives. Calcium propionate and sodium propionate can prevent food from spoiling due to microbial action, extend the shelf life of food, and are effectively used in the preservation of bread and pastries.

(2) Grain preservatives. Propionic acid has been successfully used to prevent grain from mildew and caking, providing a new method for long-term storage and preservation of grain.

(3) Beverage preservatives. Experiments have shown that propionic acid, sodium propionate, and calcium propionate are all good feed preservatives, mostly used to preserve pig, cattle, sheep, and poultry feed, among which calcium propionate has the best effect. Zinc propionate and cadmium propionate in propionate salts are catalysts for the production of polyester terephthalate; there are many varieties of propionate esters, each with its own uses, such as solvents, fragrances, pharmaceutical intermediates, cosmetic additives, resin modifiers, cigarette filter plasticizers, gas oil anti-explosion agents, antibacterial agents, etc. The intermediates of propionic acid derivatives, 2-chloropropionic acid, lactic acid, 2,2-dichloropropionic acid, 2-bromopropionic acid, 3-chloropropionic acid, propionitrile, and propionyl chloride, are used in the production of many drugs, pesticides and herbicides, food fortifiers, fragrances, and other products.

Uses

Used in the preparation of propionate esters for fragrances, and used as solvent and plasticizer for cellulose nitrate, etc.

Uses

Intermediate of food preservatives; used in esterification reactions; used in the modification of alkyd resins; used in the production of synthetic lubricants and hydraulic fluids.

Uses

Determination of aromatic diamines, gas chromatography analysis standard.
Insect cell culture grade is used to inhibit the growth of mold in insect cell culture.

Production method

Propionic acid exists in fermented or corrupted dairy products, molasses and starch. In the early days, propionic acid mainly came from the by-products of certain products, such as paraffin nitration, molasses or starch fermentation, wood distillation, light hydrocarbon oxidation to acetic acid, etc., all of which produced a small amount of propionic acid. At present, the main methods for industrial production of propionic acid are propionaldehyde oxidation, ethanol carboxylation, and recovery as a by-product when light hydrocarbon oxidation to acetic acid.
1. Propionic acid is easily oxidized to propionic acid by air or other oxidants. The oxidation process can use salts such as cobalt, manganese and copper as catalysts, or it can be carried out without a catalyst at normal pressure or slightly increased pressure. The yield of this method can reach more than 95%, and more than 90% of the propionic acid production in the United States is produced by this method.
2. Light hydrocarbon oxidation is one of the main methods for producing acetic acid. For every 100t of acetic acid produced, 25t of formic acid and 10t of propionic acid can be produced as by-products.
3. The method of ethanol carboxylation is to use ethanol, carbon monoxide and water as raw materials, and catalytic carboxylation is carried out at high temperature and high pressure to obtain propionic acid. DuPont of the United States uses this method to build a production unit with an annual output of 5,000 tons. This method has harsh process conditions and high requirements for equipment materials, and its development is limited.
4. The direct oxidation method of low-carbon hydrocarbons can produce formic acid and propionic acid when oxidizing acetic acid with low-carbon hydrocarbons as raw materials, and propionic acid can be obtained after separation.
5. The Reppe method synthesizes propionic acid in one step by reacting ethylene with carbon monoxide and water under the catalysis of carbonyl nickel. The reaction conditions are 250-320℃ and 10-30MPa.
6. The hydrolysis method of propionitrile is obtained by hydrolysis of propionitrile under the catalysis of concentrated sulfuric acid.
7. The acrylic acid method is obtained by hydrogenation reduction of acrylic acid.

Production Method

The Preparation Method Is to Use Ethylene, Carbon Monoxide and Hydrogen as Raw Materials, React in a Polar Solvent at 100-200°c and 20-30mpa in the Presence of a Catalyst Such as Cobalt Cyclopentaneate to Produce Propionaldehyde, Which Is Further Oxidized by Air or Oxygen. The Catalyst Is Cobalt Cyclopentaneate, Manganese Cyclopentaneate, Copper Acetate, Etc. The Reaction Temperature Is 60°c, And the Oxidation Reaction Is Carried out at Normal Pressure to Produce Propionic Acid. The Conversion Rate of Propionaldehyde Is 95%-98%. Reaction Equation: Ch2＝ch2+co+h2→ch3ch2cho2ch3ch2cho+o2→2ch3ch2cooh

Production methods

(1) Propionaldehyde oxidation method. Propionaldehyde can be oxidized to propionic acid by air under the catalysis of cobalt, copper or manganese salts. The yield is more than 95%.
(2) Light hydrocarbon oxidation method. Light hydrocarbon oxidation is one of the main methods for producing acetic acid, and it also produces formic acid and propionic acid as by-products.
(3) Ethanol carboxylation method. Using ethanol, CO and water as raw materials, catalytic carboxylation is carried out under high temperature and high pressure to obtain propionic acid.

Production method

Obtained by the reaction of ethanol and carbon monoxide under the catalysis of boron difluoride. Obtained by the reaction of carbon monoxide with acetylene and water vapor under high temperature and high pressure with iron or nickel as catalyst. Obtained by oxidation of acetaldehyde. Obtained by purification of wood pulp waste liquid after fermentation with Propionibacteria.

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