Topic 18 Carbonyl Compounds

18 Carbonyl Compounds

Candidates should be able to:

(a) write the general formula for carbonyl compounds: aliphatic and aromatic aldehydes and ketones;

(b) name aliphatic and aromatic aldehydes and ketones according to the IUPAC nomenclature;

(d) state the physical properties of aliphatic and aromatic aldehydes and ketones;

(e) write the equations for the preparation of aldehydes and ketones;

(f) explain the reduction reactions of aldehydes and ketones to primary and secondary alcohols respectively through catalytic hydrogenation reaction and with LiA1H4;

(g) explain the use of 2,4-dinitrophenylhydrazine reagent as a simple test to detect the presence of >C=O groups;

(h) explain the mechanism of the nucleophilic addition reactions of hydrogen cyanide with aldehydes and ketones;

(i) explain the oxidation of aldehydes;

(j) differentiate between aldehyde and ketone based on the results of simple tests as exemplified by Fehling‟s solution and Tollens‟ reagent;

(k) explain the reactions of carbonyl compounds with the structure CH3C=O with alkaline aqueous solution of iodine to give triiodomethane (iodoform test);

(l) explain that natural compounds such as glucose, sucrose and other carbohydrates which have the >C=O group;

(m) explain the characteristics of glucose as a reducing sugar.

18 Carbonyl Compounds

Candidates should be able to:

(a) write the general formula for carbonyl compounds: aliphatic and aromatic aldehydes and ketones;

(b) name aliphatic and aromatic aldehydes and ketones according to the IUPAC nomenclature;

(d) state the physical properties of aliphatic and aromatic aldehydes and ketones;

(e) write the equations for the preparation of aldehydes and ketones;

(f) explain the reduction reactions of aldehydes and ketones to primary and secondary alcohols respectively through catalytic hydrogenation reaction and with LiA1H4;

(g) explain the use of 2,4-dinitrophenylhydrazine reagent as a simple test to detect the presence of >C=O groups;

(h) explain the mechanism of the nucleophilic addition reactions of hydrogen cyanide with aldehydes and ketones;

(i) explain the oxidation of aldehydes;

(j) differentiate between aldehyde and ketone based on the results of simple tests as exemplified by Fehling‟s solution and Tollens‟ reagent;

(k) explain the reactions of carbonyl compounds with the structure CH3C=O with alkaline aqueous solution of iodine to give triiodomethane (iodoform test);

(l) explain that natural compounds such as glucose, sucrose and other carbohydrates which have the >C=O group;

(m) explain the characteristics of glucose as a reducing sugar.

18 Carbonyl Compounds (Notes for aldehyde and ketones) (Notes 2)

In short, carbonyl compounds can be divided into two major groups
– Aldehydes & Ketones
– Carboxylic Acid & Its derivatives

Candidates should be able to:

(a) write the general formula for carbonyl compounds: aliphatic and aromatic aldehydes and ketones;

(b) name aliphatic and aromatic aldehydes and ketones according to the IUPAC nomenclature;

(d) state the physical properties of aliphatic and aromatic aldehydes and ketones;

(e) write the equations for the preparation of aldehydes and ketones;

Methods of preparation of aldehydes and ketones

By Oxidation of Alcohols

Aldehydes and ketones can be prepared by oxidation of primary and secondary alcohols. Oxidation of alcohols involves the formation of a Carbon – Oxygen double bond with cleavage of an O-H and C-H bonds.

By Dehydration of Alcohols

By dehydration of 2-propanol

CH3CH(OH)CH3−→−−−−Cu/573KCH3COCH3

33From Hydrocarbons

Aldehydes and ketones can be prepared from hydrocarbons by following ways:
1. By ozonolysis of alkenes
2. By hydration of alkynes

From Acids and their derivatives

Preparation of aldehydes and ketones from esters

From Nitriles

(f) explain the reduction reactions of aldehydes and ketones to primary and secondary alcohols respectively through catalytic hydrogenation reaction and with LiAlH4;

(g) explain the use of 2,4-dinitrophenylhydrazine reagent as a simple test to detect the presence of >C=O groups;

(h) explain the mechanism of the nucleophilic addition reactions of hydrogen cyanide with aldehydes and ketones;

(i) explain the oxidation reaction of aldehydes & ketones; (Notes for aldehydes)

(j) differentiate between aldehyde and ketone based on the results of simple tests as exemplified by Fehling’s solution and Tollens’ reagent;

(k) explain the reactions of carbonyl compounds with the structure CH3C=O with alkaline aqueous solution of iodine to give triiodomethane (iodoform test);