Phenol is acidic or basic and Which is stronger acid phenol or cresol ?

Phenol is acidic or basic?

Phenol is an aromatic alcohol, which contain – OH group.The lone pair electron on oxygen atom of phenol participate in resonance with the pi electron of benzene 

nucleus.

As a result, the electro negative oxygen atom gets partially positive charge . Consequently, oxygen atom pull the O – H bonded electrons towards itself. Hence O – H bond becomes more polar and more weak.

Therefore, the O – H bond breaks easily and phenol leave proton ( H + ) in aqueous solution . So phenol is acidic in nature. It is not a base.

Which is stronger acid phenol or cresol?

There are three type of cresol such as o-cresol, m-cresol and p-cresol. They are all positional isomers to each other . Each of them contains one methyl group.

Now, due to +I effect and hyper conjugative effect of methyl group , the density of electron towards oxygen atom increases. 

As a result , a repulsion force acts among the electrons.  Hence the acidity of all the cresol decreases with respect to phenol.

Consequently, phenol is stronger acid than cresol ( o-cresol, m-cresol and p-cresol )

Why m-cresol is more acidic than o-cresol?

Both m-cresol and o-cresol contains one methyl group in their respective position.

If this group is in o-position ,then due to hyper conjugative effect of methyl group the density of electron on carbon atom as well as on oxygen atom increases.

But, if this group is in m-position , then hyper conjugation does not effective. Hence , m-cresol becomes more acidic than o-cresol.

Why m-cresol is more acidic than p-cresol?

Both m-cresol and p-cresol contains one methyl group in their respective position.

If this group is in p-position ,then due to hyper conjugative effect of methyl group the density of electron on carbon atom as well as on oxygen atom increases.

But , if this group is in m-position,then hyper conjugation does not effective . Hence , m-cresol becomes more acidic than p-cresol.

Why p-cresol is more acidic than o-cresol?

Both m-cresol and p-cresol contains one methyl group in their respective position. But, if this group is present in o-position , then + I effect is more effective  than p-position . 

So, in case of o-cresol the density of electron on oxygen atom via carbon atom increases more extent with respective to p-position.

Consequently, o-cresol has less tendency to give up proton ( H+ ) than p-cresol .

For the above said reason , p-cresol is more acidic than o-cresol.

Why p-nitro phenol is more acidic than o-nitro phenol ?

o- nitro phenol can form intra molecular hydrogen bond . Due to formation this intra molecular hydrogen bond , o-nitro phenol is more stable than phenoxide ion.

Consequently, o-nitro phenol can not leave proton ( H+ ) in solution and hence  p-nitro phenol is more acidic than o-nitro phenol.

Summary

• Phenol is acidic or basic ?
• Which is stronger acid phenol or cresol ? 
• Why m-cresol is more acidic than o-cresol ?
• Why m-cresol is more acidic than p-cresol ? 
• Why p-cresol is more acidic than o-cresol ? 
• Why p-nitro phenol is more acidic than o-nitro phenol ?

Why most of transition metals are used as catalyst?