AB Sir Alcohol phenol and ether part 5

Ajouté : 2026-05-18

[00:00:00]now the next one the reaction involving the cleavage are for each bond which was talking to you here we need to first we need to prove that alcohol is acidic in nature just now I said you are Oh H gives ro - ro - is one alkoxide I'm and it's plus I'm but remember that alkoxide ion is not stable in nature it is not a stable an alkoxide I'm it is not stable because it does not so resonance what it alkoxide ion it does not say resonant so even if it's plus sign is released alcohol is a weak acid it is not as strong as it's a weak and said listen very carefully you can see there on the screen I have given you one example ch3 ch2 edge give ch3 ch2 - + H+ what is that that is on as ethoxide ion we can say that clear an H+ ion is released but that does not mean that alcohol is acidic you can take an litmus solution you will see that blue litmus does not turn red alcohol is neutral in nature rather I should say alcohol is less acidic than water how because the KA value K means acid dissociation constant which is studied last year in ionic equilibrium the acid dissociation constant of water is 10 to the power minus 16 to 10 to the power minus 18 which is less than that of water you know that acid dissociation constant of water is nothing but KW ionic product of water how much it was 10 to the power minus 14 and alcohol is 10 to the power minus 16 to 10 to the power minus 18 which is less got it then 10 to the power minus 14 so alcohol is a weaker acid than water because as I said you that alcohol in case of alcohol it dissociates to give ro - an H+ but ro - is not stable alkoxy range is not stable not it for that purpose alcohol is less acidic than water not it now why it is so we'll explain this I'll explain a little bit then I will come to the equations now water and alcohol possess similar structure that is we have seen it alcohol in the beginning that it is what is that it is bent shape alcohol is venture what is also been shaped we can say that now alkyl group is an electron but he can say donor group so it donates a pair of electron to oxygen but in water are we having an electron donor group HOH no no electron donor group so listen carefully so due to this reason the alkyl group it shows plus I effect upon the oxygen atom the electron density on the oxygen atom increases it shows plus I effect alkyl group electron donor plus I therefore in alcohol the oxygen atom shows lesser tendency to attract the shared electrons from each bond alright oxygen this gaining electron it is getting electron from the electron pumping group our electron donor group there is alkyl group but in what are we having HOH any there any any anything is there electron donor no so what if I decide oxygen is not gaining any electron prominent has got no tendency to gain electron from hydrogen so that for that reason what I find is that the bond between oxygen hydrogen in alcohol does not cleavage easily why because oxygen has got no tendency because it is gaining electron from alkyl group alkyl group is electron donor Roberto plus I effect but in water there is no such group so oxygen has a tendency to gain electrons from hydrogen got it therefore in alcohols oxygen atom shows lesser tendency as I said you attract the shared electrons of H bond now this decreases the polarity of H bond in alcohol it decreases the polarity we can say that thus the H bond in alcohol is less polar as compared to that in water now due to less polarity what it happens due to no clarity or h1 the release of H+ ion as you said you in alcohol becomes more difficult than that of water got it because in a water there is no elect electron donor group there is no plus I effect so it oxygen atom what it does is that it readily gains electrons of hydrogen alcohol is electron donor group attached to oxygen so it does not have any tendency to gain electron from hydrogen due to this h plus sign is not readily releasing alcohol but in water it is readily list due to which alcohol is less acidic in nature then what you can say water I think you got it all of you why alcohol is less acidic in nature all right that is it decreases the polarity of 4h bonding alcohol now as a city due to the presence of plus I effect the electron donor go okay so hence alcohol is less acidic first you remember this particular one what it alcohol is less acidic in nature okay fine now next is if you compare the acidic strength of different kind of alcohol 1 degree 2 degree and 3 degree alcohol what you find one degree alcohol is more acidic than 2 degrees more acidic than 3 degree why because in one degree alcohol there is one electron donor group are ch2 which as you can see on the screen so it is what you can say most polar in nature which bond is most polar image because alkyl group is going to donate to carbon carbon is going to donate to oxygen ultimately now here two donor group is there in case of secondary alcohol are to see a church in case of statutory alcohol what you find is that 3 donor group is there you can you can see are 3 Co H so the polar group what you can say the OS bond is more polar in case of one degree and it is least polar in case of 3 degree alcohol so what do you find now you apply the common sense all right we apply the common sense so here what you find is that in case of tertiary alcohol three alkyl donor group is there Alki crew 3 donor group is there it will donate electron to carbon and carbon will give altima tree to oxygen so will oxygen have a tendency to accept electron from hydrogen no because already is getting from 3 donor group so the cleavage will take place easily in case of primary alcohol because there is only one alkyl you there is only one donor group compared to destory where is 3 donor group so where X plus 1 is readily released primary or tertiary primary so hence primary alcohol is more acidic in nature than in tertiary alkyl so in secondary alcohol $2 rupees left so primary alcohol is more acidic than secondary secondary is more acidic than tertiary because as I said you more number of alkyl group more number of electron donor group more electronegative the oxygen but it's a will it borrow electron from hydrogen it will have less tendency to borrow electron providin so the cleavage will takes place easily in case of primary then secondary then tertiary if suppose apart from primary in the beginning if I would have given you methyl alcohol in methyl alcohol it would have been more easier the primary can be methyl also but primary can be found also ch3 ch2 it can be profile also got it so if I give you if I tell you then I can tell you in this way also primary alcohol is sorry methyl alcohol is more acidic than one degree alcohol primary then secondary then - I think you got this particular thing that why it is more because you can see I effect plus I effect is more in tertiary thought its h plus sign is not readily released because oxygen is gaining electron ultimately from the three alkyl donor group okay so hence in case of primary alcohol h plus one is readily released in secondary and tertiary not it so hence one degree alcohol is more as within two degree and three degrees suppose methyl alcohol would have been there then methyl alcohol is more acidic than one be within two degrees in three degree I hope you understood this thank you very much