Acidic comparison of 2-nitrophenol, 2,4-dinitrophenol,2,4,6-trinitrophenol( For 12th JEE NEET B Sc)

Added: 2026-05-06

[00:00:01]Hello everyone. The next acidic comparison will be this.

[00:00:08]This is two nitrofenol already discussed with you in previous video. First position will be this given to main function group. Second position will be given to side chain two nitro and this is whole portion two nitrofenol or we can call it orthonitrofenol.

[00:00:27]Similarly, if I number 1 2 3 4 to 2 4 D nitro phenol UC naming its name will be 2 4 6 tr nitrophenol and this compound's common name is also pic acid.

[00:00:52]Picric acid common names are always very very important in organic chemistry. So make a separate notebook and write down all the common names of the compounds with their chemical formula. This is pic acid. This is orthopera nitrofenol and this is ortho nitrofenol.

[00:01:09]If I talk about common names. So let's compare their acidic nature.

[00:01:21]Again I'm using the second method to compare their acidic nature means I'm checking stability of the anion which is left after removal of H positive ionine. I have removed H positive and I have made anine there.

[00:02:23]This one aligns are made there. And now let's check whether they are getting stable or unstable. Which atom is unstable? Oxygen because it is carrying a negative charge. Now which factor its negative charge is increasing or decreasing? Let's check. Factor number one this resonance which we used to call plus R of oxygen.

[00:02:52]Yes, it is showing plus R effect because due to resonance it is donating electrons in a benjene ring and as already I told you what is plus r effect loss of ox loss of electrons due to resonance.

[00:03:05]So with plus r the negative charge of oxygen will finish draw resonance by yourself first structure at least this factor is also available here.

[00:03:23]This factor is also available here.

[00:03:30]So only this factor can't decide the acidic comparison or stability order.

[00:03:34]Second factor from orthoposition you know nitro group can absorb electrons which are coming from resonance. So means from orthop position nitro will show minus r effect.

[00:03:56]Now in this molecule nitro is present on ortho as well as on para and we know from both positions it can show minus r effect.

[00:04:11]So I will write minus r effect two times.

[00:04:14]minus R minus R. And here you can check nitro group is present on three positions. This is ortho, this is para and this is ortho. And from all three positions it can show minus r effect means it can absorb electrons which are coming during resonance. This resonance because during resonance the lawn pairs will generate on ortho and parapositions. Please check previous videos. So here minus R effect will be how many times? Three times of which group? Nitro group. And nitro group is substituent here.

[00:04:58]Third factor.

[00:05:00]Nitro group is more electrogative than carbon. Nitrogen is more electrogative than carbon. So it will attract electrons. And as it will attract electrons this effect will be operated up to here due to which the negative charge of oxygen will decrease means minus I effect. This effect is known as minus I of NO2.

[00:05:27]Attracting electron due to electro negativity difference is known as minus I effect. Losing electron due to electro negativity difference that is known as plus I effect. Here minus I factor is also there. How many times? Two times you can check because two nitrogen groups are there.

[00:05:55]In this case how many times minus I effect will be there? Three nitrogen groups are there. Nitrogen atoms are there which are attracting electrons due to higher electro negativity as compared to carbon. So 3 * - I that's it all the factors we have written now it's the time to conclude okay so if I say in which case the negative charge of oxygen is decreasing most the answer will be this case third case it's the first one it is second one and it's the third Because you can check the oxygen negative charge is decreased by three factors. Number one plus R of oxygen.

[00:06:46]Number two minus R three times. Here also we have minus R effect in these cases. But here only two times and here only one time. So three times.

[00:06:57]Number third minus I effect three times from three positions. two orthopositions and one from para position. So obviously the negative charge of oxygen is decreased most in this case followed by second you can check here 3 * minus r effect here now we have 2 * minus r effect here 2 * minus I effect here the negative charge of oxygen is decreasing but less than third one so third is most stable followed by second and least stable anion will be first one. No doubt negative charge of oxygen is decreasing by these factors but as compared to this it is less decreased and if I talk about this one negative charge is decreasing but as compared to this it is decreasing less.

[00:07:53]So the stability order if I write I'm rubbing it in this fashion always write down the factors.

[00:08:03]So stability order of anion increasing order if I write the first one is least stable second one is more stable than first and third is most stable and if I write acidic nature of their molecules means those molecules which have generated them by the loss of H positive like this was orthonitenol.

[00:08:37]This was orthoperitenol and this is pic acid.

[00:08:50]So which is most uh acidic? Third one will be most acidic because it knows that after loss of h positive the anion which it is getting it is most stable anion. So obviously everybody wants stability. So it is the happiest molecule to release H positive because it knows that after release of H positive I will get stability. I will get stable anion most stable anion. So it is ready to release H positive easily. If it is ready to release H positive easily means it is most acidic.

[00:09:22]So first will be least acidic compound means orthonitenol.

[00:09:29]Second, orthoperan nitrofenol will be more acidic than orthonitrofil. And third, pic acid will be the most acidic compound among all these three.

[00:09:41]I have applied the second method. I am checking the stability of annions which is left uh which is left after removal of H positive. Uh you will you can apply the first method also. Check the strength of O bonding and you will find same order.

[00:09:56]Please try it. As a students you must try all the ways to solve the questions because you are very new in the concepts. Thank you very much. In next video, next comparison.