Acidic power Order Why ?
1. III < II < I Farther the (–I) group (Cl), lesser the acidic strength
2. I < II < III Farther the (+I) group, greater the acidic power
3. II < I < III —CH3 is electron donating and
— NO2 is electron attracting
4. II < I < III —CH3 is electron repelling; decreases acidic strength of phenol
5. III < I < II — OCH3 group contains +M effect
and decreases acidic poer.
6. I < II < III — NO2 is electron attracting; III is more resonance stabilised than I and also than II. In I, only inductive effect is operative.
7. I > II > III sp2 hybridised carbon of I, II are more el-ectronegative hence acid strength is inc-reased. Benzylic (C6H5CH2) is more stab-ilised than allylic (CH2==CHCH2).
8. I > II > III > IV Effect of one —COOH on the other decr-eases as its distance between them increases, (COOH)2 is maximum acidic.
9. II < III < I —NO2 is electron attracting (–I effect)
10. III < II < I —OH shows electron withdrawing nature at o - and m - and electron repelling at p -, o - isomer due to intramolecular bonding in salicylate ion is stronger than m - isomer
11. III < II < I —do—
12. I < III < II —NH2 is electron donating.
Section B
Basic power Order Why ?
1. I > III > II lone pair on N is not used in resonance of -electrons in I. In II lone pair of the ring is itself used in delocalisation while that of outside ring in III.
2. I > II > III > IV —OCH3 is strong electron donating group. This is due to ortho effect, all the aniline are less basic than p-substituted aniline due to steric hindrance.
3. I > II > III > IV I (hyper conugation and induction) II (induction) IV (ortho effect), ortho effect normally decreases basic nature.
4. II > I > III In II there is sp3 hybridised C, In I, sp2. NO2 is electron withdrawing.
5. III > I > II lone pair on N is used in delocalisation of -electrons in aromatic amines while cyclohexyl is electron repelling (III); in II, lone pair on N is used by two benzene ring.
6. I > II > III > IV NO2 is electron-withdrawing, thus nitro-anilines are less basic than aniline. IV is less basic than III because —NO2 is closer and exerts a stronger inductive effect.
7. III > I > II phenyl and —COCH3 are electronwithdra-wing and —C6H5 < COCH3
8. I < II < III Electron donating nature of C2H5 > CH3 So more basic strength.
9. I < II < III ortho effect in I.
10. I < II < III ortho effect in (I)
General series Order Why ?
1. I > II > III There is intermolecular H-bonding I. III has weak force of attraction and is most volatile.
2. B.P. of o, m, p-nitro phenol o < m < p Intramolecular H-bonding in o-isomer makes it more volatile.
3. Reactivity of ... with Tollen’s reagent
I > II > IV > III —CHO group is easily oxidised compared to keto group due to redusing hydrogen.
4. Reactivity of ... with Fehling’s solution
I > II > IV > III —do—
5. Extent of hydration of
I < II < III < IV Aldehydes are more hydrated than ketones. Halide makes C of carbonyl group more electropositive.
6. Electrophilic nature of ........ for nucleophilic attack
I > II > III CH3 group decreases +ve charge on C hence nucleophilic attack.
7. Reactivity of isomeric 1°, 2°, 3° butyl halide towards elimination (E1 or E2) 3° < 2° < 1° due to stability of intermediate carbocation
8. Dehydration of
IV < I < II < III Alcohol leading to increase in conjugation due to dehydration is more easily dehydration is more easily dehydrated. IV is vinylic, hence least.
9. Stability of
I < II < III < IV
< V < VI Substituted alkenes are more stable.More the alkyl groups are attached to the doubly bonded carbon atom more
is the stability.
10. Stability of
I < III < II II is more substituted than III (More hyperconjugation more stability)
11. Stability of
III > II > I > IV IV is vinylic while in conjugative, II allylic.
12. Stability of
I < IV < II < III III is 3° allylic and II is 1° allylic
13. Dehydration of
1°, 2°, 3° isomeric butyl alcohol
3° < 2° < 1° More the stability of intermediate, greater the reactivity of chemical reaction.
14. Boiling points of
II > I > III I, II have H-bonding but electronegativity of O > N hence H-bonding in II > I
15. Formation of
I > II > III > IV
(easiest I) greater the stability, easier the formation of perticular species.
16. Reactivity of C—H bond (abstraction of H)
I < II < III < IV
< V < VI Vinyl < methyl 1° < 2° < 3° < allylic
17. Leaving nature (tendency) of ... in SN reaction.
I < II < III ~ IV
< V < VI < VII
< VIII If acid is strong, its conjugate base is weak and greater the leaving tendency.
18. Rate of esterification of the following acids with MeOH
I > II > III > IV
> V As the size of the substituents on the —C increases, the tetrahedrally bonded interme. diate becomes more crowded and these slower the rate.
19. Relative reactivity of ... with electrophile in SE reaction
I > II > IV
> III > V —CH3 is o-, p-directing and responsible for activation.
20. Relative reactivity of these compunds with electrophile inSE reaction
II > I > III > IV —CH3 is o-, p-directing due to activation while —COOH is m-directing and deactivating group.
21. Relative reactivity of ... with electrophile in SE reaction.
II > I > IV > II As the number of sp3 hybridised C atoms separating the ring from the positively charged substituent increases, deactivating effect decreases due to less electronegativity.
22. Activating effects of the following o, p-directors.
II > I > III is best able to donate electrons there by giving a very stable uncharged intermediate. In cross conjugation diminished its ability to donate electrons to an arenium ion.
23. Relative reactivity of ... towards SN1 reaction
II > I > III Intermediates are benzylic cations. So CH3O(electron repelling) gives greater stability through delocalisation while NO2 (electron attracting) decreases stability.
24. Relative reactivity of ... towards SN1 and SN2 reaction
SN1 :
III > II > I
SN2 :
II < II < I SN1 : 1° < 2° < 3° alkyl halide
SN2 : 3° < 2° < 1° alkyl halide
25. Relative reactivity of ... with E+ (electrophile) in SE reaction. II > I > III —NO2 deactivates benzene ring for SE
26. Order of SN2 reactivity of alkoxide nucleophiles
I < IV < V < III
< II SN2 reactivity is suseptible to steric hindrance by the nucleophile as well as by the size of alkyl group.
IMPORTANT ORDER AND FACTS OF ORGANIC CHEMISTRY
1. RCOCl > RCOOCOR > RCOOR > RCONH2 Nucleophilic substitution reaction.
2. HI > HBr > HCl > RCOOH > C6H5OH > H2O > CH CH > NH3 (Acidic nature).
3. CCl3CHO > HCHO > CH3CHO > CH3COCH3 Nucleophilic addition reaction.
4. CH2 = CH2 > CH CH > C6H6 Electrophilic addition reaction.
Electrophilic Substitution Reaction
Nucleophilic Substitution Reaction
Nucleophilic Substitution Reaction
10. (CH3)2C = C(CH3)2 > CH3 - CH = C -(CH3)2 > CH3 - CH = CH - CH3 > CH3 - CH = CH2 (Stability)
(Heat of Hydration)
13. NI3 > NBr3 > NCl3 > NF3 (Basic strength)
14. Br2 > Cl2 > I2 (Selectivity for halogenation)
15. Halogenation of alkenes by cyclic halonium state, so anti attack takes place.
16. Hydroboration followed by oxidation is always anti markownikoff’s addition due to steric effect.
17. Oximercuration - demercuration is m.K. addition of water because some carbocation character in cyclic mercurium state.
18. CHCl3 in the presence of strong bases forms biradical : CCl2 which undergo addition with double or triple bonds.
19. When conjugated diene reacts with alkene or alkyne it is known as diel’s elder synthesis.
20. Ozonolysis of cyclo alkene forms one mole dialdehyde while ozonolysis of cyclo alkadiene forms two moles of dialdehyde.
21. Ozonolysis with (CH3)2S is known as reductive ozonolysis.
22. Hydration of alkyne occur’s in HgSO4 and dil H2SO4.
24. Cis-2-butene reacts with Br2 to forms dl() pair of enantiomers of 2,3-dibromobutane while in case of trans-2-butene forms meso-2,3-dibromo butane due to anti addition always.
25. Haloform test given by species with CH3CO-group but not in case of A.A.E. and tert. Butyl alcohol.
26. Chloral reacts with chloro benzene in con. H2SO4 to form insectiside DDT.
27. NBS is used for free radical allylation.
28. Rate for SN1 reaction is 3° > 2° > 1° in protic polar solvent.
29. Rate for SN2 reaction is 1° > 2° > 3° in polar aprotic solvent like DMSO, DMF, HMPT.
30. Chemical reactions like Hoffmann carbylamine and Reimer Tiemann’s reaction active species is biradical CCl2.
31. If cyclo 1,3-penta diene reacts with CHCl3 and potassium tert. butoxide to form chlorobenzene.
32. Alkyl halides reacts with AgCN to form isocyanides due to ambident nature of nucleophile, other ambident nucleophiles are and SO3-2.
33. In dehydration of alcohols active species is carbocation so rearrangement occurs like hydride shift or alkyl shift.
34. Dehydration of cyclobutyl methyl alcohol ring expansion takes place, formation of cyclo pentene occurs.
35. In esterification where acid reacts with alcohol to form ester, - OH given by acid while - H by alcohol
36.Ether’s reacts with HI to form alcohol and halide where fission of lower ether by SN2 mechanism while higher ethers like ter. butyl methyl ether or alkyl methyl ether by SN1 mechanism.
37. Quantitative estimation of ethers is done by ziesal’s method.
38. If unsym. cyclic ether undergo fission it depends upon medium weather it is acid or basic like in acidic medium some character of carbocation so nucleophile goes to carbon where more alkyl groups are there while reverse in basic medium due to steric factor.
39. Aldehydes are reducing agent while ketones are not.
40. Aldehydes and ketones are separated by tollenâ€
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