烯类和炔类可以和亲电子試剂,如HCl,HBr,H_2SO_4等等发生加成反应,最后生成飽和化合物。关于这些反应的特点、规律和应用,在一般的有机化学书中都有了比较詳細地阐述。现在这里所要介紹的是一个新的亲电子加成反应,其加成試剂是甲硼烷及其烃基衍生物,R_2BH(R=烷基,芳香基,H)。硼是周期表第三类的第一个元素,它的原子有三个最外层电子。所以在三价的硼化合物,如R_2BH中,尚有和未共享电子对发生配价,生成八电子层結构的 Alkenes and acetyles can react with electrophiles, such as HCl, HBr, H 2 SO 4 and the like, and finally form saturated compounds. The characteristics, laws and applications of these reactions are described in more detail in the general Organic Chemistry book. What we are going to introduce here is a new electrophilic addition reaction. The addition reagent is borane and its alkyl derivative, R_2BH (R = alkyl, aryl, H). Boron is the first element of the third type of the periodic table, its atoms have the three outermost electrons. Therefore, in the trivalent boron compounds, such as R_2BH, there are still and unshared electron pairs occurred in valence, generating eight electronic layer structure