Chemical properties of glacial acetic acid

Acetic acid is a saturated carboxylic acid with two carbon atoms in its molecule. Molecular formula CH3COOH. As it is the main component of vinegar, it is also known as acetic acid. It is widely found in nature; for example, in fruits or vegetable oils it exists mainly in the form of its ester compounds ； It exists in the form of a free acid in animal tissues, excretions, and blood. Colorless liquid with an irritating odor. Melting point: 16.6°C, boiling point: 117.9°C, relative density: 1.0492 (20/4°C), refractive index: 1.3716. Pure acetic acid can form an icy solid at temperatures below 16.6°C, which is why it is often referred to as glacial acetic acid. Soluble in water, ethanol, ether, and carbon tetrachloride. When water is added to acetic acid, the total volume of the mixture decreases and its density increases, until the molecular ratio reaches 1:1, corresponding to the formation of the monoprotic acid protoacetic acid, CH3C(OH)3; further dilution results in no change in volume. 　　Molecular weight: 60.05 Molecular structure: O ‖ CH3—C—OH – Glacial acetic acid. It is an organic compound and a typical fatty acid. It is recognized as the source of the sour taste and pungent odor in vinegar. Pure anhydrous acetic acid (glacial acetic acid) is a colorless, hygroscopic liquid with a freezing point of 16.6 °C (62 °F); it forms colorless crystals upon freezing. Although it is a weak acid due to its ability to dissociate in aqueous solution, acetic acid is corrosive, and its vapors are irritating to the eyes and nose. Acetic acid is a simple carboxylic acid and an important chemical reagent. Acetic acid is also used to produce cellulose acetate needed for movie film, polyvinyl acetate in wood adhesives, as well as many synthetic fibers and fabrics. In households, dilute acetic acid solutions are often used as descalers. In the food industry, acetic acid is a specified acid regulator in Food Additive List E260. Glacial acetic acid is still quite corrosive, but not as strong as formic acid ； Using 316L material is fine.

As a supplementary note, for glacial acetic acid at temperatures of 120–150 degrees, what material would be suitable?

Acetic acid corrosion is very severe. Two-phase steel can be considered.

Acetic acid corrosion is very severe. Two-phase steel can be considered.

Aluminum can be used for storage at room temperature (note that its crystallization temperature is around 16°C); TIMO2 is used for distillation columns

Acetic acid is a saturated carboxylic acid with two carbon atoms in its molecule. Molecular formula CH3COOH. As it is the main component of vinegar, it is also known as acetic acid. It is widely found in nature; for example, in fruits or vegetable oils it exists mainly in the form of its ester compounds ； It exists in the form of a free acid in animal tissues, excretions, and blood. Colorless liquid with an irritating odor. Melting point: 16.6°C, boiling point: 117.9°C, relative density: 1.0492 (20/4°C). Pure acetic acid can form an icy solid at temperatures below 16°C, which is why it is often referred to as glacial acetic acid. Soluble in water, ethanol, ether, and carbon tetrachloride. When water is added to acetic acid, the total volume of the mixture decreases and its density increases, until the molecular ratio reaches 1:1, corresponding to the formation of the monoprotic acid protoacetic acid, CH3C(OH)3; further dilution results in no change in volume. Chinese name: Acetic acid. English name: Acetic acid. Alias: Acetic acid ； Glacial acetic acid. CAS No.: 64-19-7. Molecular formula: C2H4O2 ； CH3COOH。 Molecular weight: 60.05. Hazard label: 20 (Acidic corrosive). Packaging method: small-opening aluminum drum ； Ordinary wooden box or semi-grilled wooden box outside the glass bottle or plastic barrel (jar) ； Ordinary wooden box outside the frosted-mouth glass bottle or threaded-mouth glass bottle ； Ordinary wooden box outside threaded-mouth glass bottles, iron-cap pressed-mouth glass bottles, plastic bottles, or metal drums/tanks ； Threaded-mouth glass bottles, plastic bottles, or tin-plated thin steel sheet drums (tanks), enclosed in floor-grid boxes, fiberboard boxes, or plywood boxes. Acetic acid possesses the typical properties of carboxylic acids, which are manifested in the following two aspects: ① Acidity: Acetic acid is highly acidic and can release some hydrogen ions in aqueous solution; it is a weak acid. The ionization constant Ki of acetic acid is 1.8×10-5 (at 25°C), making it more acidic than carbonic acid (whose first-order Ki at 25°C is 4.3×10-7). Acetic acid exhibits the general properties of acids. For example, it can turn blue litmus paper red ； It can react with metals, as well as with bases, sodium carbonate, and sodium bicarbonate. CH3COOH + NaOH → CH3COONa + H2O
2CH3COOH + Na2CO3 → 2CH3COONa + CO2↑ + H2O
CH3COOH + NaHCO3 → CH3COONa + CO2↑ + H2O
② Esterification reaction: Acetic acid reacts with ethanol in the presence of concentrated sulfuric acid upon heating to produce ethyl acetate, which has a fragrant odor. Using oxygen isotope tracing, it can be determined that during the aforementioned esterification reaction, the hydroxyl group in the acetic acid molecule combines with the hydrogen atom on the hydroxyl group of the alcohol molecule to form water, while the remaining parts combine to form an ester. The reaction in which an acid reacts with an alcohol to produce an ester and water is called esterification. The esterification reaction is a reversible reaction; not only organic acids can undergo esterification, but inorganic acids such as nitric acid and sulfuric acid can also react with alcohols to form esters. For example, the ester formed when concentrated nitric acid reacts with glycerol is called nitroglycerin, which is a raw material for **production. Acetic acid can neutralize alkali metal hydroxides, and it can form salts with reactive metals; these metal salts all have important uses. Acetic acid can also yield various derivatives, such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, etc., which serve as excellent solvents in the coatings and paints industry. Cellulose acetate, produced by the reaction of acetic anhydride with cellulose, can be used to manufacture film, spray paint, etc. It is also an essential raw material in industries such as dyes, fragrances, and pharmaceuticals, and is widely used as a solvent. It can also be used as a solvent and as a raw material for producing acetates, acetates (ethyl acetate, vinyl acetate), and vinylon fibers. Anhydrous acetic acid is almost non-conductive; as it is diluted with water, its degree of ionization increases, and thus the concentration of H ions also rises. However, even when diluted to below 2 mol/L, the degree of ionization continues to increase gradually, while the concentration of H ions decreases slowly. Reaction with carbonates produces carbon dioxide, indicating that its acidity is stronger than that of carbonic acid, and it exhibits the general properties of a weak acid. It can undergo esterification reactions with alcohols, requiring concentrated sulfuric acid and heating; it can be used to synthesize various fruit-acetic acid ester fragrances ； When acetylene reacts with acetic acid in the presence of a zinc acetate catalyst at temperatures between 170 and 250°C, vinyl acetate is produced, which can be polymerized to form polyvinyl acetate for use in latexes and to manufacture vinylon fibers: CH≡CH + CH3COOH → CH3COOCH=CH2. Under certain conditions, dehydration occurs to yield ethylene, which then reacts with acetic acid to form acetic anhydride: CH3COOH → CH2=C=O + H2O. Acetic anhydride can undergo esterification with cellulose to produce cellulose acetate, which is used in the production of photographic film and movie film. Additionally, it can be used to synthesize pharmaceuticals such as chloroacetic acid, acetylsalicylic acid, and acetanilide.

This post was last edited by mopeizhi on 2009-11-23 at 19:07. When the temperature reaches 120–150 degrees, acetic acid containing halogens can easily cause pitting corrosion on 316L. Epoxy coating or titanium, as well as other materials, can be used. I suggest you check out this post. They had a lively discussion. http://bbs.hcbbs.com/thread-268218-2-1.html

I have information here regarding the materials to be used for acetic acid production equipment, but I was unable to upload it for some reason. Please leave your email address, and I’ll send it to you. Excerpt from the Handbook of Corrosion Data and Material Selection

I wonder whether the original poster deals with storage containers or reaction vessels? If the temperature reaches 120-150, it is recommended to use the Hars type, HC276.