Methyl Ethyl Ketone

What is Methyl Ethyl Ketone (MEK) or Butanone?

Methyl Ethyl Ketone (MEK), also known as butanone, is an organic chemical with the formula CH3C(O)CH2CH3. This dialkyl ketone is a colourless liquid that has a sharp and sweet odour. It occurs in nature in a small amount. However, due to its various applications, the industrialists produce this chemical on a large scale. The other popular name of methyl ethyl ketone is methyl acetone. This chemical liquid is soluble in water, which makes it an excellent industrial solvent.  It is an isomer of the tetrahydrofuran, which is also a popular solvent. 

Production of Methyl Ethyl Ketone

The oxidation of 2-butanol leads to the production of butanone. The dehydrogenation of 2-butanol takes place using a catalyst like copper, zinc, or bronze. The reaction for the production of MEK from 2-butanol is as follows:

CH3CH(OH)CH2CH3 → CH3C(O)CH2CH3 + H2

The industrialists use this process to manufacture approx 700 million kilograms of MEK annually. The other method that is not much popular but can yield methyl acetone is Wacker oxidation of isobutyl benzene and 2-butene. The modification of the cumene process can lead to the production phenol and a mixture of butanone and acetone. The liquid-phase oxidation of Fischer-Tropsch and heavy Napthla reaction can generate mixed oxygenate streams, which can lead to the extraction of methyl ketone using fractionation. 

MEK is an organic compound that exists in the liquid state at room temperature. It has a unique and sweet odour, which is similar to acetone. This colourless solvent is flammable, and it has a low boiling point that is 79.64oC. It has a fast evaporation rate and has excellent solvent properties. Methyl acetone is miscible with almost all organic solvents. It makes this compound excellent for a variety of resin systems in various industries. It forms an azeotrope with many organic solutions that makes it an excellent solvent. The vapours of MEK are even heavier than ordinary air. In the below table, we have provided the various MEK properties.

Physical Properties of Methyl Ethyl Ketone

Butanone Formula

C4H8O

Methyl Ethyl Ketone Boiling Point

79.64oC

Methyl Ethyl Ketone Melting Point

-86oC

Density 

0.8050 g/ml

Molecular weight

72.107 g/mol

Dielectric constant

18.51

Critical temperature

260oC

Critical pressure

43 atm

Heat of combustion

8084 cal/g

Heat of vaporization

106 cal/g

Heat of fusion

24.7 cal/g


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The above image shows the structure of Methyl Ethyl Ketone.

Chemical Properties of MEK

Methyl Ethyl Ketone is a highly reactive compound that can undergo various chemical reactions under proper conditions. The reactivity of this compound centres around its adjacent hydrogen atoms and the carbonyl group. 

Two moles of MEK can undergo aldol condensation to yield hydroxyl ketone. Then, it can readily dehydrate to form an unsaturated ketone. This reaction is as follows.

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Methyl Ethyl Ketone can also react with aldehydes to give cyclic compounds, ketals, and higher ketones depending upon the conditions. It also condenses with organic oxides and glycols to yield derivatives of dioxolane. Moreover, the reaction of MEK with aqueous ammonia and hydrogen yields sec-butylamine. 

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In the above reaction, the use of MEK in excess amounts can give di-sec-butylamine.

The oxidation of MEK with oxygen leads to the production of diacetyl that is a flavouring material. Chlorination of this compound yields a mixture of dichloro and monochloro derivatives in several percentages. MEK can also react with hydrogen peroxide to give a mixture of peroxides. 

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The other chemicals that can react with MEK to form resins include phenol, formaldehyde, acetaldehyde, etc. These resins are useful in moulded products as well as electric insulation. Moreover, the reaction of methyl acetone with acrylonitrile will give di-nitrile, which can undergo hydrogen to produce amines. 

Applications and Uses of Methyl Ethyl Ketone 

MEK is an excellent solvent due to which it has numerous applications in many industries. This compound is beneficial in the production of resins, gums, cellulose acetate, etc. The manufacturing of vinyl films also requires the use of this compound. For these reasons, MEK is also helpful in producing textiles, plastics, and paraffin wax. 

The production of various household products like paint remover, lacquer requires MEK due to its solvent properties. It is also used as a denaturing agent for glues and denatured alcohol. Butanone can dissolve many plastics, including polystyrene. Hence, it is also a part of many scale model kids to connect different components. The adhesive property of methyl acetone makes it a welding agent in plastic products. Butanone can also work as a cleaning agent. 

MEK acts as a precursor to methyl ethyl ketone peroxide that is a significant catalyst for many polymerization reactions. It can also lead to the production of dimethylglyoxime by reacting with ethyl nitrile. This reaction first yields diacetyl monoxime, which then converts into di-oxime to give the desired product. MEK is also required for the production of petroleum.

FAQ (Frequently Asked Questions)

1. What are the health effects of methyl ethyl ketone on human beings and animals?

Ans. MEK is a constituent of the smoke produced by tobacco during the smoking of cigarettes. It can also act as an irritant, which can cause irritation to the nose or eyes of humans. This compound can be even more dangerous if inhaled with other harmful chemicals. Animals that had swallowed or breathed MEK in large amounts show severe side effects. Sometimes, it can also lead to fainting and death of animals. However, drinking MEK by animals in a small amount doesn't have any severe effects. It doesn't affect the ability to reproduce in animals or humans, as seen in recent studies.

2. How is MEK different from the acetone?

Ans. Methyl Ethyl Ketone is a stronger compound as compared to acetone. However, it has a much slower evaporation rate and has a higher boiling point. Hence, it acts as a stronger cleaning agent than acetone. MEK can form an azeotrope with water, which is not possible in the case of acetone. The drying rate of MEK is slower than acetone, which makes it excellent for dry-erase markers. However, acetone is much cheaper as compared to MEK. Hence, many people prefer to use acetone in nail polish and similar products because of its lower cost.