Question

I am wondering about a conceptual question:

In an acid/base reaction is there a way to know for sure when an H2O is going to stay with the larger molecule or break off and form water? here are my two examples:

R=cyclohexane
R-C=-(triple bonded to)CH + KOH <---> cyclohexane=-(triple bonded to)C:- + K+ + H2O

while..

CH3CH2OH + HBr <---> CH3CH2OH2 + Br-
my question is why the H2O doesnt break off in this reaction to make water

thanks for the help!!

Answer 1

I think I understand the question. In an acid/base neutralization the H^+ and OH^- ALWAYS "break away" to form water.
The H in R-CtriplebondC-H is acidic. The H in CH3CH2OH is acidic, also, although not as acidic as the acetylenic H is. But if you react the alcohol with HBr don't you obtain CH3CH2Br? and the H and OH still form water? I know that isn't the reaction mechanism because the primary process isn't about forming water but the alkyl bromide.