[souro10]

When both inductive effect and hydrogen bond are in operation, which one do we consider?

Suppose we consider 2-Chlorobutan-1-ol and 2-Fluorobutan-1-ol acidities.
Which shall be more acidic ?

Data says fluoro compound should be more acidic. In that case we can infer that -I effect of F wins over it's hydrogen bonding effect. How can we rationalize this?

[orgopete]

Data says fluoro compound should be more acidic. In that case we can infer that -I effect of F wins over it's hydrogen bonding effect. How can we rationalize this?

What are the pKa values? Since deprotonation of chloro should form epoxide, how were pKa's determined? As I recall, trichloroethanol is more acidic than trifluoro. There was an old discussion about electron withdrawing properties of fluorine. I am seeking any other examples than trifluoroacetic acid. If you wish to use electronegativity arguments, then glycolic acid should be the next most acidic acid after fluoroacetic acid. Is it? I think the acetic acids may be a special case.

[iamback]

When we don't know the pKa values and we have to compare relative acidity of two compounds, we compare the stability of conjugate base.

and conjugate base of 2-Fluorobutan-1-ol is more stable than 2-Chlorobutan-1-ol.

[souro10]

Okay, after comparing pkA values, Chloro-alcohols are more acidic than fluoro alcohols [ i was wrong in my original post ] while Chloro-acetic acids are less acidic than fluoro acetic acids. Why should that be? Why are carboxylic acids a special case?

[iamback]

^^Any idea where I can see the pKa values of these compounds ?

[TheOrganic]

The pkA values are:

2,2,2-Trichloroethanol - pkA = 12.02
2,2,2-Trifluoroethanol  - pkA = 12.40

Chlorine substituted alcohol seems to be more acidic than Fluorine substituted alcohol - the order being the opposite in case of aliphatic carboxylic acids. The factors governing acidity are not explicitly understood yet. If you use electronegativity values, you will find yourself successful at explaining Carboxylic acid acidity order, but the arguments will fail for alcohols. There must be many factors playing together which we do not know yet.

[iamback]

I am asking for the pKa values of 2-Chlorobutan-1-ol and 2-Fluorobutan-1-ol