Potassium acetate structure, properties, uses, production

The potassium acetate is an organic compound formed by a potassium K ion⁺ and an acetate ion CH₃COO^-. Its chemical formula is CH₃COOK, or KCH₃COO, or also C_twoH₃KO_two. It is a colorless or white crystalline solid, very soluble in water..

It is used to regulate the acidity of certain industrially processed foods. Due to its great affinity with water, it is used in laboratories or in certain processes to absorb water from other compounds, such as to dehydrate alcohol..

Potassium acetate participates in some chemical reactions as an accelerator of these and in the synthesis of organic compounds. It also allows to increase the formation of antibodies (natural substances that fight infections) in industrial methods to produce them..

Its very low temperature properties make it a good candidate for use in ice melting mixes on concrete roads in very cold climates. According to consulted sources, it is also used in fire fighting equipment and in assemblies to observe cells in microscopes..

Article index

• 1 Structure
• 2 Nomenclature
• 3 Properties
  • 3.1 Physical state
  • 3.2 Molecular weight
  • 3.3 Melting point
  • 3.4 Density
  • 3.5 Solubility
  • 3.6 pH
  • 3.7 Other properties
  • 3.8 Behavior when heating up
• 4 Obtaining
• 5 Uses
  • 5.1 In various applications
  • 5.2 In the polymer industry
  • 5.3 In scientific and medical research laboratories
  • 5.4 In the industrial production of antibodies
  • 5.5 In antifreeze mixtures
  • 5.6 How it works as antifreeze
• 6 References

Structure

Potassium acetate is made up of a potassium K cation⁺ and an acetate anion CH₃COO^-. The latter is the conjugate base of acetic acid CH₃COOH. The acetate ion CH₃COO^- consists of a methyl -CH₃ attached to a carboxylate -COO^-.

The union between both ions is electrostatic or ionic, that is, the union between a positive and a negative ion.

Nomenclature

• Potassium acetate
• Potassium ethanoate
• Potassium salt of acetic acid
• AcOK
• KOAc

Properties

Physical state

Colorless or white crystalline solid.

Molecular weight

98.14 g / mol

Melting point

292 ºC

Density

1.6 g / cm³

Solubility

Very soluble in water: 256 g / 100 mL at 20 ° C.

pH

A 5% aqueous solution of potassium acetate has a pH of 7.5-9.0.

Other properties

Sometimes it has a faint vinegar smell. In 10% solution it does not attack aluminum at room temperature but at 60-70 ° C the metal darkens and suffers pitting.

At concentrations of 20% or more, surface attack on aluminum occurs at any temperature.

Potassium acetate (AcOK) is highly soluble in water. It has a hydrate: KCH₃COO.1,5H_twoOr, which is the solid that is obtained by crystallizing it from the aqueous solutions of AcOK.

Behavior when heated

If the hydrated potassium acetate (AcOK) (KCH₃COO.1,5H_twoO) when it reaches 40 ° C it begins to lose the water of hydration.

KCH₃COO.1,5H_twoO → KCH₃COO + 1.5H_twoOr ↑

If anhydrous potassium acetate (without water: KCH₃COO), upon reaching 340 ° C it begins to decompose forming potassium carbonate K_twoCO₃ according to the following reaction:

2 KCH₃COO + 4 O_two → K_twoCO₃ + 3 H_twoO + 3 CO_two↑

Obtaining

It can be prepared by the action of potassium hydroxide KOH on various compounds, such as acetic acid CH₃COOH, acetic anhydride (CH₃CO)_twoO and ammonium acetate CH₃COONH₄.

KOH + CH₃COOH → CH₃COOK + H_twoOR

It can also be obtained by reacting potassium carbonate K_twoCO₃ or KHCO potassium bicarbonate₃ with acetic acid CH₃COOH.

KHCO₃ + CH₃COOH → CH₃COOK + H_twoO + CO_two↑

Potassium acetate can be crystallized from aqueous solution to obtain high purity.

Applications

In various applications

Potassium acetate is used in the processed food industry as an acidity regulator. It is used as a desiccant in chemical methods to measure the water vapor permeability of some fabrics..

It serves as a dehydrating agent for ethanol in the production of this alcohol starting from lignocellulose, a material derived from wood..

It is used to produce antibiotics and is widely used in fire fighting equipment.

In the polymer industry

It is used to recycle polyurethanes as it serves to catalyze or accelerate the hydrolysis and glycolysis reactions of said polymers so that they become alcohols and amines.

It is also used in the production of organic silicone resins.

In scientific and medical research laboratories

High purity potassium acetate is used in laboratories as a reagent in analytical chemistry. Also to carry out medico-scientific research.

In histopathology laboratories, it is used to ensure a neutral pH medium in microscope setups..

It is used for the synthesis of heterocyclic organic compounds, which are compounds with cycles of different sizes..

Certain microelectrodes used to study the electrical properties of cells are filled with a concentrated solution of potassium acetate..

In the industrial production of antibodies

Potassium acetate is used for the large-scale production of monoclonal antibodies (which are those that come from the same stem cell) in cell cultures. It allows to stimulate the synthesis or formation of antibodies.

Antibodies are substances produced by some cells in the blood to fight infections from viruses or bacteria..

Although potassium acetate (AcOK) inhibits or slows cell growth and decreases cell density, the productivity of antibodies per cell increases.

In antifreeze mixtures

Potassium acetate has been used in antifreeze mixtures. anti-icing) in order to use them to melt ice on roads and cement pavements and thus allow the safe use of these.

The selection of potassium acetate (AcOK) for this application is due to the fact that a 50% by weight aqueous solution of AcOK is eutectic and has a melting point of -62 ° C. This means that even at temperatures as low as -62 ° C the solution remains molten..

A eutectic is a homogeneous mixture of components that has the lowest melting point of all possible mixtures of these, including that of the pure components..

How it works as an antifreeze

Potassium acetate (AcOK) has a very good ability to melt ice.

At -5 ° C it is capable of melting 11.5 kg of ice for each kg of AcOK. This property decreases as the temperature decreases, but even at -50 ° C it has the ability to melt 1.3 Kg of ice for every Kg of AcOH..

At -5 ° C this capacity is comparable to that of sodium chloride or table salt (NaCl), while from -30 ° C it far exceeds it.

However, in the tests carried out with AcOK together with other compounds, a certain degree of corrosion of the cement surfaces was observed, for which reason it was considered to add anticorrosive agents to the antifreeze mixtures..

On the other hand, the mixture of potassium acetate (CH₃COOK) with potassium formate (HCOOK) is an excellent antifreeze and does not require anticorrosive.

References

1. Baker, F.J. et al. (1976). Staining Procedures. Aqueous mountants. In Introduction to Medical Laboratory Technology (Fifth Edition). Recovered from sciencedirect.com.
2. Hassan, A.A. et al. (2018). Indazoles: Synthesis and Bond-Forming Heterocyclization. In Advances in Heterocyclic Chemistry. Recovered from sciencedirect.com.
3. U.S. National Library of Medicine. (2019). Potassium acetate. Recovered from pubchem.ncbi.nlm.nih.gov.
4. Das, A. and Alagirusamy, R. (2010). Moisture transmission. Desiccant inverted cup method. In Science in Clothing Comfort. Recovered from sciencedirect.com.
5. Vargel, C. (2004). Carboxilic Acids and their Derivatives. Acetates. In Corrosion of Aluminum. Recovered from sciencedirect.com.
6. Cuevas, J. (2014). Electrophysiological Recording Techniques. Intracellular Recording Techniques. In Reference Module in Biomedical Sciences. Recovered from sciencedirect.com.
7. Fink, J.K. (2018). Poly (urethane) s. Recycling. Solvolysis. In Reactive Polymers: Fundamentals and Applications (Third Edition). Recovered from sciencedirect.com.
8. Fong, W. et al. (1997). Optimization of monoclonal antibody production: combined effects of potassium acetate and perfusion in a stirred tank bioreactor. Cytotechnology 24: 47-54. Recovered from link.springer.com.
9. Danilov, V.P. et al. (2012). Low-Temperature Anti-Icing Reagents in Aqueous Salt Systems Containing Acetates and Formiates. Theoretical Foundations of Chemical Engineering, 2012, Vol 46, No. 5, pp. 528-535. Recovered from link.springer.com.
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