H2 Properties of alkenes and alkynes ■Alkynes structure olinear with the triple bond carbons being sp hybridized The triple bond is made up of one o bond and twoπbonds o bond sp centers 180° R-c=C⊥R R一C三C一R R-C三C-R R-C=C-R Linear xbond bond Fig.2.Structure of an akyne functional group
College H2 Properties of alkenes andof Science alkynes Alkynes structure zlinear with the triple bond carbons being sp hybridized z The triple bond is made up of one σ bond and two π bonds
H2 Properties of alkenes and ■C=C alkynes .An alkyne triple bond is stronger than a C-C single bond or a C=C double bond. ●The twoπbonds present in the triple bond are weaker and more reactive than the o bond Nucleophilic center Nucleophilic center R一C三C一A Fg.3. Nucteophilic centers of an aikene and an alkyne
College H2 Properties of alkenes andof Science alkynes C=C zAn alkyne triple bond is stronger than a C-C single bond or a C=C double bond. zThe two π bonds present in the triple bond are weaker and more reactive than the σ bond
Reactions of alkenes 双键上 烯烃反应 -H上 亲电加成； 氧化， 自由基取代
Reactions of alkenes 双键上 烯烃反应 σ -H 上 亲电加成； 氧化; 自由基取代
Electrophilic Addition Step 1:Pi electrons attack the electrophile Step 2:Nucleophile attacks the carbocation Nuc +:
College Electrophilic Addition of Science Step 1: Pi electrons attack the electrophile C C + E + C E C + C E C + + Nu c: _ C E C Nu c Step 2: Nucleophile attacks the carbocation
Electrophilic Additions Hydrohalogenation using HCl,HBr,HI Hydration using H2O,H2SO4 Halogenation using Cl2,Br2 Halohydrination using HOCl,HOBr Oxymercuration using Hg(OAc)2,H20
College Electrophilic Additions of Science Hydrohalogenation using HCl, HBr, HI Hydration using H 2O, H 2SO 4 Halogenation using Cl 2, Br 2 Halohydrination using HOCl, HOBr Oxymercuration using Hg(OAc) 2, H 2 O