What is meant by the following terms ? Give an example of the reaction in each case.
Cyanohydrin
Acetal
Semicarbazone
Aldol
Hemiacetal
Oxime
Ketal
Imine
2, 4 - DNP derivative
Schiff's base
What is meant by the following terms ? Give an example of the reaction in each case.
Cyanohydrin
Acetal
Semicarbazone
Aldol
Hemiacetal
Oxime
Ketal
Imine
2, 4 - DNP derivative
Schiff's base
Cyanohydrin Addition products formed by the reaction of aldehydes and ketones with hydrogen cyanide (HCN) are known as cyanohydrins.
Acetal When an aldehyde reacts with two equivalents of a monohydric alcohol in the presence of dry HCl gas, fem - dialkoxy compounds are formed, which are known as acetals. In acetal, two alkoxy groups are present on the terminal C - atom.
For example :
Semicarbazone The compounds formed on the reaction of aldehydes/ketones with semicarbazide are called semicarbazones.
For example :
Aldol When an aldehyde (or ketone) having at least one α - hydrogen atom undergo a reaction in the presence of dilute alkali as catalyst to form aldol or β-hydroxyaldehydes (or ketals in case of ketones), the reaction is called aldol condensation.
For example :
Hemiacetal When an aldehyde reacts with one molecule of a monohydric alcohol in presence of dry HCl gas, gem-alkoxy alcohols are formed. These are known as hemiacetals.
For example :
Oxime When an aldehyde or ketone reacts with hydroxylamine in weak acidic medium, the product obtained is known as oxime.
Ketal The compound formed by heating a ketone with ethylene glycol in the presence of dry HCl gas is known as ketal (gem - dialkoxy alkane).
For example :
Imine Compounds formed by the reaction of aldehydes and ketones with ammonia derivatives are called imines.
These compounds contain 
group. General reaction is :
Z=Alkyl,aryl,OH,NH2,C6H6H5NH,NHCONH2 etc.
2, 4 - DNP derivative 2, 4 - dinitrophenyl hydrazine reacts with aldehyde or ketone to produce 2,4-dinitrophenyl hydrazones (i.e., 2,4 - DNP derivative). The reaction). The reaction takes place in weak acidic medium.
Uses 2,4- DNP derivatives are used for the identification of aldehydes and ketones.
Schiff's base When an aldehyde or ketone reacts with primary aliphatic or aromatic amines, the formed compoud is called Schiff' base or azomethine.
R−CH=OAldehyde+H2N−R′PrimaryamineH+−−→R−CH≡N−R′Schiff′s base+H2O
Cyanohydrin Addition products formed by the reaction of aldehydes and ketones with hydrogen cyanide (HCN) are known as cyanohydrins.
Acetal When an aldehyde reacts with two equivalents of a monohydric alcohol in the presence of dry HCl gas, fem - dialkoxy compounds are formed, which are known as acetals. In acetal, two alkoxy groups are present on the terminal C - atom.
For example :
Semicarbazone The compounds formed on the reaction of aldehydes/ketones with semicarbazide are called semicarbazones.
For example :
Aldol When an aldehyde (or ketone) having at least one α - hydrogen atom undergo a reaction in the presence of dilute alkali as catalyst to form aldol or β-hydroxyaldehydes (or ketals in case of ketones), the reaction is called aldol condensation.
For example :
Hemiacetal When an aldehyde reacts with one molecule of a monohydric alcohol in presence of dry HCl gas, gem-alkoxy alcohols are formed. These are known as hemiacetals.
For example :
Oxime When an aldehyde or ketone reacts with hydroxylamine in weak acidic medium, the product obtained is known as oxime.
Ketal The compound formed by heating a ketone with ethylene glycol in the presence of dry HCl gas is known as ketal (gem - dialkoxy alkane).
For example :
Imine Compounds formed by the reaction of aldehydes and ketones with ammonia derivatives are called imines.
These compounds contain group. General reaction is :
Z=Alkyl,aryl,OH,NH2,C6H6H5NH,NHCONH2 etc.
2, 4 - DNP derivative 2, 4 - dinitrophenyl hydrazine reacts with aldehyde or ketone to produce 2,4-dinitrophenyl hydrazones (i.e., 2,4 - DNP derivative). The reaction). The reaction takes place in weak acidic medium.
Uses 2,4- DNP derivatives are used for the identification of aldehydes and ketones.
Schiff's base When an aldehyde or ketone reacts with primary aliphatic or aromatic amines, the formed compoud is called Schiff' base or azomethine.
R−CH=OAldehyde+H2N−R′PrimaryamineH+−−→R−CH≡N−R′Schiff′s base+H2O
