Electrophilic addition reaction

Japanese: 求電子付加反応 - きゅうでんしふかはんのう

...The main step in a reaction is when an electrophilic reagent, such as a cation (hydrogen ion H ⁺ or nitronium ion _NO2 ⁺ ) or a Lewis acid (aluminum chloride _AlCl3 or boron fluoride _BF3 ), attacks the unsaturated bond or unshared electron pair of the substrate. Electrophilic reactions are broadly divided into (1) electrophilic substitution reactions, in which (part of) the reagent replaces part of the substrate, and (2) electrophilic addition reactions, in which the reagent is added to the multiple bond of the substrate. Electrophilic substitution reactions are likely to occur in aromatic compounds. ...

From [Organic Chemical Reactions]

...These are known as the substituent effects.
[Electrophilic Addition Reaction]
Alkenes, like benzene, are electron-rich and susceptible to electrophilic attack. Therefore, in the reaction of alkenes with electrophilic reagents, addition of to the multiple bond occurs first. …

*Some of the terminology that refers to "electrophilic addition reaction" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…一般に陽イオン(水素イオンH^＋やニトロニウムイオンNO₂^＋など)やルイス酸(塩化アルミニウムAlCl₃やフッ化ホウ素BF₃など)の求電子試薬が基質の不飽和結合や非共有電子対を攻撃する段階が反応の中心となる。　求電子反応は，(1)試薬(の一部)が基質の一部と置換する求電子置換反応と，(2)試薬が基質の多重結合に付加する求電子付加反応に大別される。求電子置換反応は芳香族化合物に起こりやすい。…