I need to find 3 bases that are capable of removing the most acidic hydrogen from methanol (CH3OH), ethylene (C2H2), and methylamine (CH3NH2). My problem is that I don't have a good pKa table and to use the one in my book you need to know what exactly what you are looking for. Also, how do you know the pKa of the base and conjugate base since the pKa value only pertains to acids? I think I might be making it harder than it is but I'm really confused.
2007-10-15 05:14:02 · 3 answers · asked by LaLa 1 in Science & Mathematics ➔ Chemistry
You need to find something that is not really acidic, which means its Ka is really small, so the conjugate base of this substance is really a strong acid.
Example, NH2(-), the amide ion, its conjugate acid is NH3, which is really a base, so as an acid, it will be really weak, making the amide ion very basic.
The CH3(-) ion is another very strong base, since its conjugate acid, CH4 is a terrible acid.
Either of this two substances are basic enough to remove protons from methanol, ethylene or methylamine.
2007-10-15 05:53:33 · answer #1 · answered by William Q 5 · 1⤊ 0⤋
Because these compounds are not in a series that one can readily relate to, I suggest looking up the pKa values. From that the order is H3O+ (-1.7), HN3 (4.6), HONH3+ (5.97), CH3SH (10.4), CH3OH (15.5). All pKa values from Wikipedia. I would be cautious about using electronegativity in predicting acidity as it requires some absurd predictions, such as HF is ionic, but doesn't ionize while HI is covalent, but completely ionizes. The larger the nuclear charge, the more electrons are attracted to it works for me.
2016-05-22 18:24:50 · answer #2 · answered by Anonymous · 0⤊ 0⤋
You need a strong base like K-tBuO (Potassium tert- Butoxide)
Actually it should be pKb.
2007-10-15 05:49:31 · answer #3 · answered by ag_iitkgp 7 · 0⤊ 0⤋