Question

When methyl alcohol is treated with NaH, the product is CH3O -Na+ (and H2) and not Na+ -CH2OH (and H2). Explain why this is so.

Answer 1

The simple reason can be stated as:

Because the proton attached to the highly electronegative oxygen atom of CH3OH is much more acidic than the protons attached to the much less electronegative carbon atom.

Further, NaH is an ionic bond between Na+ and H- and CH3OH is entirely covalent, meaning that the hydrogen is not an anion. Methanol is actually a weak acid because the oxygen pulls the electrons toward itself from the other atoms, but more strongly from the hydrogen than from the carbon, which makes the oxygen more negatively charged and the hydrogen less negatively charged. This allows the H-, which is a strong nucleophile (molecule that attracts less negatively charged atoms), to pull the hydrogen from the oxygen as H+, creating H2. Since the hydrogen came off as a positively charged ion, the oxygen attached to the carbon has a negative charge, which allows the sodium cation to bond to it.