Ketones are family of carbonyl compounds with the structure RC(=O)R', where R and R' bonded onto the carbonyl carbon(C=O) are both alkyl groups. R may be the same or different from R'. Acetone is the simplest ketone. It is commonly used as an industrial solvent. Nail polish remover contains acetone.
Preparation of ketones:
Oxidation of secondary alcohols in presence of oxidizing agents like K2Cr2O7
/ H2SO4, KMnO4, CrO3 gives ketones.
Ozonolysis of Alkenes
By ozonolysis of alkenes:
Ozonolysis of alkenes followed by reaction with zinc dust and water gives aldehydes, ketones or a mixture of both depending on
the substitution pattern of the alkene.
By hydration of alkynes:
Hydration of alkynes other than acetylene yield ketones.
Addition of water to ethyne in the presence of H2SO4 and HgSO4 gives acetaldehyde, which is also known as Markovnikov addition. Addition of H2O2 to ethyne gives ketones and this addition is known as Anti Markovnikov addition.
Friedel–Crafts acylation reaction
Preparation of aromatic ketones:
When benzene or substituted benzene is treated with acid chloride in the presence of anhydrous aluminum chloride, it affords the
corresponding ketone. This reaction is known as Friedel–Crafts acylation reaction.
Uses:
- In chemical industry carbonyl compounds(aldehydes and ketones) are used as solvents, starting materials and reagents for the synthesis of other products.
- Acetone and ethyl methyl ketone are common industrial solvents. Acetone is a common fingernail polish remover and is a solvent. Acetone is very flammable.
- 2 – Butanone is used as a solvent and paint stripper but is very flammable
- (–) – Carvone(2–Methyl–5–(1–methylethenyl)–2–cyclohexenone) is used as spearmint flavoring and (+) – Carvone is used as caraway seed flavoring.