Hex-4-ene-2-ol on treatment with PCC gives ‘A’ on reaction with sodium hypoiodite gives ‘B’, which on further heating with soda lime gives ‘C’. The compound ‘C’ is
Aldehydes, Ketones, and Carboxylic Acids - Chemical Reaction
AChemical reaction is a process in which one or more substances, the reactants, are converted to one or more different substances, the products. Substances are either chemical elements or compounds. A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products.
Types of Chemical Reactions
Nucleophilic Addition Reaction
A nucleophile forms a sigma bond with an electron of other species. These reactions help in the formation of several new organic chemicals.
Nucleophilic Addition Reaction is a type of Addition Reaction in which a nucleophile reacts with a Pi- bond of a compound and results in the formation of a new sigma bond. Nucleophilic Addition reactions are the most important reactions as it allows carbonyl compounds to form various new products with different functional groups.
Reduction
The reaction used for the reduction of aldehydes or ketones to alkanes is known as Clemmensen Reduction Reaction. In a reduction reaction, there is a loss of oxygen atoms from the molecule or gain of electrons.
Clemmensen Reduction Reaction is immensely useful for aryl-alkyl ketones reduction, formed in Friedel Crafts acylation. Acyl Benzene is formed from acylation with the help of Friedel-Crafts acylation. Clemmensen reduction reaction is used for transformation of acyl benzene to alkylbenzene and likewise, reduction of other ketones or aldehydes.
Oxidation
Aldehydes differ from ketones in their oxidation reactions. Aldehydes are easily oxidised to carboxylic acids on treatment with common oxidising agents like nitric acid, potassium permanganate, potassium dichromate, etc. Even mild oxidising agents, mainly Tollens’ reagent and Fehlings’ reagent also oxidise aldehydes.
Reactions due to a-hydrogen
Acidity of α-hydrogens of aldehydes and ketones: The aldehydes and ketones undergo a number of reactions due to the acidic nature of α-hydrogen.
Aldehydes and ketones having at least one α-hydrogen undergo a reaction in the presence of dilute alkali as catalyst to form β-hydroxy aldehydes (aldol) or β-hydroxy ketones (ketol), respectively. This is known as Aldol reaction. The aldol and ketol readily lose water to give α,β-unsaturated carbonyl compounds which are aldol condensation products and the reaction is called Aldol condensation.
Other reactions
The Cannizzaro reaction can be referred to as a scientific process that requires a base-induced disproportionation of two molecules belonging to a non-enolizable aldehyde in order to produce a carboxyl group and a primary alcohol. The Cannizzaro reaction was named by an italian chemist named Stanislao Cannizzaro
Electrophilic substitution reaction: Aromatic aldehydes and ketones undergo electrophilic substitution at the ring in which the carbonyl group acts as a deactivating and meta-directing group.
