BrCH2CH2Br+NaOH== BrCH=CH2+NaBr+H2O
BrCH2CH2Br+2NaOH ==CH≡CH+2NaBr+2H2O
箭头,上面条件略
BrCH2CH2Br+NaOH ==CH2═CH—Br+NaBr+H2O (消去1分子HBr)
BrCH2CH2Br+2NaOH ==CH≡CH+2NaBr+2H2O (消去2分子HBr)
等号是箭头
BrCH2CH2Br+NaOH =BrCH=CH2+NaBr+H2O
-------------------有烯键
BrCH2CH2Br+2NaOH=C2H2+2NaBr+2H2O
------------------乙炔