KETONES

INTRODUCTION ketones are organic compounds which incorporate a carbonyl functional group, C=O.

Naming ketones The parent compound is named for the longest continuous chain containing the carbonyl group. Ketones take their name from their parent alkane chains. The ending -e is removed and replaced with –one. The chain is numbered beginning at the carbonyl group. The common name for ketones are simply the substituent groups listed alphabetically + ketone. Some common ketones are known by their generic names. Such as the fact that propanone is commonly referred to as acetone.

Examples Write the name of the following compound. 2 – Pentanone Or Pentan – 2 – one

Write the name of this comppound according to IUPAC system. Cyclopentanone

Draw the structure for 3-methylcyclohexanone.

Name the following compound according to IUPAC system. 2 – methyl – 4 – Hexanone

SYNTHESIS OF KETONES From Lithium dialkylcuprates The addition of a lithium dialkylcuprate (Gilman reagent) to an acyl chloride at low temperatures produces a ketone. This method produces a good yield of acetophenone. By Oxidation Of Secondary Alcohol: Secondary alcohols like 2 – propanol can be oxidized in the presence of strong oxidizing agents like potassium dichromate (K 2 Cr 2 O 7 ) to give2 – propanone. OH O ǀ ǁ CH 3 – CH – CH 3 K 2 Cr 2 O 7 CH 3 – C – CH 3 H +

PHYSICAL PROPERTIES OF KETONES ketones are liquids, with boiling points rising as the molecules get bigger. van der Waals dispersion forces in ketones get stronger as the molecules get longer and have more electrons. The small ketones are freely soluble in water but solubility falls with chain length. Ketones also do not have hydrogen bonding but can make hydrogen bonds with water.

REACTIONS OF KETONES (CHEMAICAL PROPERTIES) Addition of hydrogen cyanide: The addition of hydrogen cyanide to a carbonyl group of an aldehyde or most ketones produces a cyanohydrin. Reaction with Grignard’s reagent: Ketones react with Grignard’s reagent to produce tertiary alcohols. OH + CH 3 – CH 2 – Mg – Cl  + Mg Cl

Uses Of Ketones Acetone, a common ketone, is used as a solvent for resins, lacquers, and cellulose Camphor, another ketone, is used in liniments and insecticides and in the manufacture of celluloid and lacquer. ketones, such as civetone, are used in making perfumes. Ketones also are used in making flavorings, dyes, chloroform, and plastics.