nucleophilic addition reaction of α, β–unsaturated carbonyl compounds

,4-Addition, also known as conjugate addition, is a nucleophilic addition reaction of α, β–unsaturated carbonyl compounds and α, β–unsaturated nitriles.

eg:  Two nucleophilic addition reaction could occur between methylvinyl ketone (1) and methanethiol in basic medium.

mechanism of Reaction 1:

The net reaction from 1 to 4 is the addition of two ligands to atoms 1 and 4 in 1. Hence, the reaction is called 1,4-addition, or conjugate addition, and its product (2) 1,4-adduct.

mechanism of Reaction 2:

The net reaction from 1 to 3 is the addition of two ligands to atoms 1 and 2 in 1.  Hence, the reaction is called 1,2-addition, or direct addition, and the product (3) a 1,2-adduct.

The overall reaction between an α, β–unsaturated compound and a nucleophile is regioselective. Whether the dominant process is 1,4-addition or 1,2-addition depends on several factors, such as the alkene-containing reactant (the α, β–unsaturated compound), nucleophile, solvent, concentration, temperature, reaction time, and catalyst, if any, making if difficult to make a generalization. Most resonance-stabilized carbon nucleophiles, such as enolate ions and enamines overwhelmingly prefer 1,4-addition to 1,2-addition.

مواضيع ذات صلة

مركبات الآزو متجانسة الحلقة Homocyclic azo compounds

تصنيف مركبات الآزو Classification of azo compound

أصباغ الآزو Azo Dye

تفاعلات الازدواج Reaction Coupling

أملاح الدايازونيوم الاروماتية      Aromtic Diazonium Salt    

أهمية الكواشف العضوية reagents Importance of organic

الثايوزبينات Thiazepines

الدايازبينات Diazepines

الاوكسازبينات Oxazepines

المركبات الحلقية غير المتجانسة Heterocyclic Compounds

نبذة عن مظاهر كيمياء الكلورامين-T الحيوية واهميته

بعض مظاهر كيمياء الكلورامين-T