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it is p-nitro phenol because in 3,5dinitrophenol both are electron withdrawing groups whic are present at m-positions.So it is stabilized.but in p-nitro phenol nitro withdraws the electron density over hydroxy group.so the answer is p-nitro phenol is more acidic than 3,5dinitro phenol.If i am wrong correct me and if i am correct please vote me.
http://www.kayelaby.npl.co.uk/chemistry/3_9/3_9_7.html
see here it is given
for 3,5 dinitro phenol pka1 is 6.69
and p nitro phenol is 7.15 i jst appled the concepts i have studied and frm the help of some frnds i have gained that
higher the pka lesser is the acidic strength now tell me puja singhtwinkle and smarsh where am i makin flaw
in p-nitro phenol the delocalization of electrons takes place which is not possible in 3,5dinitro phenol.Also due to the removal of electron charge over -OH a partial double bond forms between O&C.Hence it is easier to remove H in case of p-nitro phenol.
see it is very tough to say by theortical concepts which is more acidic....bcoz we cant say will 2 strong inductive can overcome the 1 mesomeric effect or not......
but as said by pooja for 3,5 dinitro phenol pka1 is 6.69
and p nitro phenol is 7.15
so 3,5 dintrophenol is more acidic......
remember first practicals are done and then theories are given
ppl i waana no that does stability of the compound has to do any thin with the acidic nature of tho compounds bcuz p-nitro phenol is both resonance stabilised and it also has alt. double and single bond...or is it the stability of the radical formed which matters..
plz tell me..and correct if wrong...
acidic nature of generally O-H COMPOUNDS IS SEEN BY THE EASE WITH WHICH THE RUPTURE OF O-H BOND TAKES PLACE.......THIS CAN BE SEEN BY THE ELECTRON DISPLACEMENT EFFECTS AND THE OTHER WAY TO C WHTHER THE COMPOUND IS ACIDIC OR NOT IS TO REMOVE A PROTON AND CHECK FOR STABILITY OF COMPOUND SO FORMED.............................THIS IS THE WAY OF DETERMINING ACIDIC NATURE..........................................................................................................COMES TO THE STABILITY OF THE COMPOUND ................STABILITY OF A COMPOUND IS DETERMINED BY ITS REACTIONS.......................///.REACTIVE.....-UNSTABLE AND VICE VERSA......











