Acetone Formula: Structure, Preparation, and Properties

Acetone Formula: Do you know the main component of a nail polish remover? It is Acetone \(\left( {{\rm{C}}{{\rm{H}}_3}{\rm{COC}}{{\rm{H}}_3}} \right),\) also known as \(2\)-propanone or dimethyl ketone. It breaks down nail polish, making it easy to remove with a cotton swab or cloth. It is the simplest and most important of the aliphatic (fat-derived) ketones. It is used as a solvent in the chemical industry and as an antiseptic in medicines.  It is widely used in the textile industry for degreasing wool and degumming silk. It is also a precursor to many organic syntheses.

Structure Formula of Acetone

The IUPAC name of Acetone is \(2\)-propanone with a condensed chemical formula \({{\rm{C}}_3}{{\rm{H}}_6}{\rm{O}}.\) Acetone is made up of three carbon atoms, six hydrogen atoms, and one oxygen atom. It is considered a ketone since there is a carbonyl group present in it.  It is a methyl ketone that consists of propane bearing an oxo group at \({\rm{C – 2}}\) carbon atom. The chemical formula of Acetone is \(\left( {{\rm{C}}{{\rm{H}}_3}{\rm{COC}}{{\rm{H}}_3}} \right).\)

CLEAR YOUR CONCEPTUAL DOUBTS ON ACETONE

Molar Mass of Acetone

The molar mass of Acetone, \(\left( {{\rm{C}}{{\rm{H}}_3}{\rm{COC}}{{\rm{H}}_3}} \right)\) is:

\({\rm{3x}}({\rm{The}}\,{\rm{atomic}}\,{\rm{mass}}\,{\rm{of}}\,{\rm{carbon}}){\rm{ + 6x}}({\rm{The}}\,{\rm{atomic}}\,{\rm{mass}}\,{\rm{of}}\,{\rm{hydrogen}}){\rm{ + Atomic}}\,{\rm{mass}}\,{\rm{of}}\,{\rm{Oxygen}}\)

\(= 3(12.01) + 6\left( {\left( {1.007} \right) + 15.999 = 58.08{\mkern 1mu} \,{\rm{g}}\,{\rm{mo}}{{\rm{l}}^{ – 1}}} \right.\)

Hence, one mole of Acetone weighs \({58.08}\) grams.

Hybridization of Acetone

Acetone has two terminal methyl groups attached to a \(\left( {{\rm{C = O}}} \right)\) group at the \({\rm{C – 2}}\) position. The carbon of the terminal methyl groups are \({\rm{s}}{{\rm{p}}^{\rm{3}}}\) hybridized, whereas the carbon atom of the carbonyl group at the \({\rm{C – 2}}\) position is \({\rm{s}}{{\rm{p}}^{\rm{2}}}\) hybridised.

Steric factor of the carbonyl carbon atom \( = \) Number of atoms attached \( + \) Lone pairs

\( = 3 + 0 = 3\)

The carbon atom of the carbonyl group is \({\rm{s}}{{\rm{p}}^{\rm{2}}}\) hybridised \(\left( {{\rm{1s + 2P = 3s}}{{\rm{p}}^{\rm{2}}}} \right)\). This means the atomic orbitals of the carbon atom undergo intermixing to form \({{\rm{3s}}{{\rm{p}}^{\rm{2}}}}\) hybridized orbitals.

The \({\rm{s}}{{\rm{p}}^{\rm{2}}}\) hybridized carbon of the carbonyl group forms \(3\) sigma bonds (two \({\rm{C – C}}\) sigma bonds and one \({\rm{O – C}}\) sigma bond). The formation of \(3\) sigma bonds gives the carbonyl group a basic trigonal shape. Only two out of three p orbitals participate in hybridization; hence, one p orbital remains unhybridized. This unhybridized p orbital of the carbon atom forms a pi bond with the unhybridized p orbital of the carbonyl oxygen atom. This p orbital is directed above and below the plane of the paper. The oxygen atom of the carbonyl group has two lone pairs.

Molecular Geometry of Acetone

The centre of the acetone molecule consists of the carbonyl group. The carbon of the carbonyl group is planar-trigonal due to the \({\rm{s}}{{\rm{p}}^{\rm{2}}}\) hybridization, while the terminals have methyl groups with tetrahedral geometry.

Acetone Bond Angle

The \(\left( {{\rm{C = O}}} \right)\) group at the \({{\rm{C – 2}}}\) position is \({\rm{s}}{{\rm{p}}^{\rm{2}}}\)  hybridized, and the terminal methyl groups are \({\rm{s}}{{\rm{p}}^{\rm{3}}}\)  hybridized. The \({\rm{C – C – C}}\) bond angle at \({{\rm{C – 2}}}\) should be \({\rm{12}}{{\rm{0}}^{\rm{o}}}\) but is found to be \({\rm{11}}{{\rm{6}}^{\rm{o}}}\) due to lone pair-bond pair repulsion. As the terminal methyl groups are in tetrahedral shape, the bond angle within the methyl groups is \({\rm{109}}{\rm{.}}{{\rm{5}}^{\rm{o}}}\).

Dipole Moment of Acetone

In Acetone, the main component of the dipole moment is the \({\rm{C = O}}\) bond. This is because-

1. The dipole moment in the terminal methyl groups is zero.
2. Dipole does not exist in similar atoms, i.e. \({\rm{C – C – C}}\) bond.
3. Only the \({\rm{C = O}}\) bond is polar in nature.

Hence, no cancelling out can happen, and the dipole moment of the entire acetone molecule is due to oxygen’s electronegativity. The dipole moment of Acetone is found to be \(2.69\) Debye.

Lewis Structure of Acetone

Acetone consists of a ketone functional group present at the centre of the molecule. In the Lewis structure for Acetone, there are a total of \(26\) valence electrons. These electrons are distributed as shown below:

Skeletal Formula of Acetone

Acetone is a three-carbon containing compound with the ketonic functional group at the \({\rm{C – 2}}\) position. The central carbon atom is connected to its neighbouring carbon atoms through single bonds and to the oxygen atom through a double bond. It has nine sigma bonds and one pi bond. The skeletal structure of Acetone is shown below:

Three-dimensional Representation of Acetone

The Wedge-dash method is used to represent the \({\rm{3 – D}}\) structure of an organic compound. The \({\rm{3 – D}}\) structure of acetone has the following aspects-

1. A solid wedge is used to represent a bond that protrudes out of the plane of paper towards the viewer.
2. A dashed wedge used to represent the bond that projects away from the viewer or below the plane of the paper, and
3. A line is used to represent the bond that lies in the plane of the paper.

Considering the above factors, Acetone can be represented as below-

Preparation of Acetone

Laboratory Preparation of Acetone

1. By the dehydrogenation of isopropyl alcohol promoted by a copper catalyst.

2. By the oxidation of isopropyl alcohol

Industrial Preparation of Acetone

Acetone is widely manufactured through the oxidation of Cumene. It is a two-step process.

Step 1: Cumene, also known as isopropyl benzene, is obtained by the Friedel-Crafts alkylation of benzene with propylene.

Step 2: Air oxidation of Cumene leads to the production of Cumene hydroperoxide. On treating cumene hydroperoxide with dilute acid, Phenol along with Acetone is obtained.

Physical Properties of Acetone

1. Acetone is a colourless liquid with a sweetish odour.
2. It is a highly volatile liquid.
3. Its melting and boiling points are \({\rm{ – 94}}.{\rm{9}}{\,^{\rm{o}}}{\rm{C}}\) and \({\rm{56}}.{\rm{08}}{\,^{\rm{o}}}{\rm{C}}.\)
4. Its density is \(50.785\;{\rm{g}}\;{\rm{m}}{{\rm{L}}^{ – 1}}\).
5. Acetone is miscible with water, alcohol, benzene, dimethylformamide and ether.

Chemical Properties of Actone

Acetone is polar due to the \({\rm{ – C = O}}\) bond present at its centre. Due to the presence of a positively charged centre, nucleophilic molecules attack the electrons deficient carbonyl carbon.

Uses of Acetone

1. It is the active ingredient in nail polish removers and paints thinners.
2. The chemical and petroleum industries extensively use it to produce adhesives and sealants, solvents, coats, plastic and rubber, agricultural products, etc.
3. Acetone is produced and disposed of in the human body through normal metabolic processes. It is normally present in blood and urine.

Summary

Acetone is a widely used organic solvent. When our liver breaks down stored fat, it makes chemicals called ketones. Acetone is the main ketone. It is also found as a compound in food additives, food packaging and in acne treatment. Through this article, we learnt about the formula of Acetone, its structure and various properties. We also learnt its various uses in our day-to-day life.

FAQs on Acetone Formula

The commonly asked questions about Acetone formula are answered here:

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