PROPERTIES OF KETONES with respect to BSC physics

in this you will guide yourself about ketones

1. PROPERTIES OF KETONES: SUBMITTED TO: ISHA GOYAL SUBMITTED BY: MARIUM ZAKIR Bsc BIOTECH 1 ST YEAR

2. PROPERTIES OF KETONES PHYSICAL PROPERTIES: CHEMICAL PROPERTIES :  State $ Appearance Polarity Boiling Points Solubility Density $ Refractive Index Nucleophilic Addition Reaction Reduction Oxidation Reaction with α-carbon Formation of Hydrazones /Oximes  Tollen’s and Fehling’s Tests

3. PHYSICAL PROPERTIES OF KETONES STATE $ APPEARANCE: Lower ketones (like acetone , propanone ) are colorless liquids with a sweetish odor . Higher ketones (longer chains) are oily liquids or solids. POLARITY: The C=O (carbonyl) group is highly polar. This makes ketones more polar than alkanes but less than alcohols. BOILING POINTS: Boiling points are higher than alkanes/ethers of similar molecular mass (due to dipole-dipole interactions). Lower than alcohols (since ketones lack hydrogen bonding between their own molecules). 1) 2) 3)

4. PHYSICAL PROPERTIES OF KETONES SOLUBLITY: Low-mass ketones are miscible with water because the oxygen atom of the carbonyl can form hydrogen bonds with water. As molecular mass increases, water solubility decreases. Ketones are good solvents for many organic compounds (oils, fats, resins). DENSITY $ REFRACTIVE INDEX: Most ketones are less dense than water but denser than hydrocarbons. They have moderate refractive indices. 4) 5)

5. CHEMICAL PROPERTIES OF KETONES NUCLEOPHILIC ADDITION REACTION:  The carbonyl carbon is electrophilic, so nucleophile attack it. Addition of HCN  Cyanohydrin formation . Addition of bisulfite(NaHSO 3 )  Bisulfite adduct . Addition of Grignard reagents  Tertiary alcohols. EXAMPLES :- ( i ) (ii) (iii)

6. CHEMICAL PROPERTIES OF KETONES REDUCTION: -Ketones are reduced to secondary alcohols by LiAlh 4 or NaBH 4 . -Catalytic hydrogenation (H 2 /Ni or Pt) also gives secondary alcohols. 2) By LiAlH 4 : CH 3 C=OCH 3 + 2[H]  CH 3 CH(OH)CH 3 ( i ) EXAMPLES:- OXIDATION: -Ketones are harder to oxidize than aldehydes. -Strong oxidizing agents (KMnO4 + conc.H2SO4 ,K2Cr2O7) cleave ketones to give carboxylic acids or a mixture of acids. 3) EXAMPLES:- CH 3 C=OCH 3 + 4[H]  CH 3 COOH + CO 2 + H 2 O (ii)

7. CHEMICAL PROPERTIES OF KETONES 4 ) REACTION AT THE α-CARBON : - Halogenation : In presence of acid/base, halogens substitute at the α-carbon. EXAMPLES:- ( i ) - Aldol Condensation : Two molecules of a ketone react in base to form a ß- hydroxy ketone, w hich dehydrates to an α,ß-unsaturated ketone. EXAMPLES:- (ii)

8. CHEMICAL PROPERTIES OF KETONES 5) FORMATION OF HYDRAZONES/OXIMES: -Reaction with hydrazine  hydrazones . ( i ) EXAMPLES:- -Reaction with hydroxylamine  Oximes EXAMPLES:- ( ii)

9. CHEMICAL PROPERTIES OF KETONES 6 ) TOLLEN’S AND FEHLING’S TEST: -Ketones generally do not react, because Tollen’s reagent is weak oxidizing agent which cannot break C-C bond of ketone, it can break only C-H bond of aldehyde (these are for aldehydes). -Some α- hydroxy ketones may give a positive Tollen’s test because they can be easily oxidized. -This reaction is used to distinguish between aldehyde and ketone.