Class-XII Sc
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2
Organic Chemistry Reasoning questions
4
CHLOROFORM is not used as anaesthetic.
Melting point of p-dichlorobenzene is more
than o-isomer
Grignard reagent is prepared in anhydrous
medium
Alkyl halide does not dissolve in water
5
Haloarenes are less reactive than haloalkanes
6
o-and p-nitro phenol is more acidic than
phenol
Propanol has higher b.p than hydrocarbon
o-nitrophenol is more acidic than omethoxyphenol
In Kolbe’sreaction instead of phenol,
phenoxide ion is treated with CO2
During ester formation, ester or water
formed should be removed as soon as it is
formed
3
7
8
9
10
11
pKb of aniline is more than methyl amine
12
Ethyl amine is soluble in water, aniline is not
13
Aniline does not undergo Friedel Crafts
reaction
Amino gr is o-and p- directing ,but on
nitration it gives substantial amount of misomer
Aromatic primary amine can not be prepared
by Gabriel phthalimide synthesis
Amines are less acidic than alcohol
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15
16
17
Primary amines have higher b.p than tertiary
amine
18
Chloroacetic acid is stronger acid than acetic
acid
Aldehydes and ketones are reactive
Aldehydes are more reactive than ketones
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20
Due to formation of toxic phosgene, COCl2
Because p-isomer is more symmetric
A small amount of water produces hydrocarbon.
Water has strong h-bond which is difficult to
break by alkyl halide.
Lone pair electron on halogen are in conjugation
with pi-electron of the ring. Ar-Cl carbon is sp2
hybridised while R-Cl is sp3 hybridised
Due to –R effect by –NO2 group
Strong intermolecular H-bonding due to –OH gr
-NO2 gr is electron withdrawing whereas –OCH3
is electron releasing
CO2 is a weak electrophile. Phenoxide ion is more
reactive towards electophilic substitution rkn
Formation of ester in presence of acid catalyst is a
reversible rkn. As per le-Chatelier principle, with
increase in concentration of product equilibrium
will shift in backward direction.
Aniline is less basic due to conjugation of lone
electron with benzene ring. Higher pKb lower is
the basicity
Ethyl amine is soluble due to H-bonding. In aniline
hydrocarbon part is bulky and conjugation of lone
electron of nitrogen with benzene ring makes the
H-bond weaker.
Aniline is a Lewis base and in FC rkn AlCl3 is a
Lewis acid form an addition complex
In acid medium aniline forms anilinium ion which
is m-directing.
Ar-X bonds acquire some double bond character
which is difficult to break.
N-H bond is less polar than O-H hence difficult to
release H+ ion.
In primary amine intermolecular H-bond is
present. But in tertiary amine there is no N-H
bond , so no H-bond.
Chlro gr exerts –I effect. Higher the –I effect
higher is acidity
Due to presence of polar >C=O
In ketones there are two bulky alkyl gr (+I effect)
attached to >C=O
Arrange the following as per given properties:
S.N
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3
4
5
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12
13
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PROPERTIES
SN-1
SN-2
ACIDITY
BOILING POINT
BOILING POINT
ACIDITY
Acidity
Acidity
Acidity
BOILING POINT
REACTIVITY
acidity
BASIC STRENGTH
in gasphase
BASIC STRENGTH
in solution
BASIC STRENGTH
in solution
ARRANGED IN ASCENDING ORDER
CH3CH2CH2CH2Br<CH3)2CHCH2Br<CH3CH2CH(Br)CH3<(CH3)3CBr
CH3CH2CH2CH2Br>CH3)2CHCH2Br>CH3CH2CH(Br)CH3>(CH3)3CBr
H2O>ROH>HC≡CH
Methanol<Ethanol<Propan-1-ol<Butan-2-ol<Butan-1-ol<Pentan-1-ol
N-Butane<Ethoxyethane<Pentanal<Pentan-1-ol
Acetic acid<Chloroacetic acid<Dichloroacetic acid<Fluroacetic acid
2-Chlorobutanoic acid>3-Chlorobutanoic acid>4-Chlorobutanoic acid
Formic acid>Acetic acid>Propanoic acid
ICH2COOH< BrCH2COOH< ClCH2COOH< FCH2COOH
CH3CH2CH3<CH3OCH3<CH3CHO<CH3CH2OH
Acetophenone<p-Tolualdehyde<Benzaldehyde<p-Nitrobenzaldehyde
C6H5COOH<FCH2COOH<NO2CH2COOH
Ammonia<primary amine<secondary amine<Tertiary amine
NH3<(CH3)3N<CH3NH2<(CH3)2NH
NH3<C2H5NH2<(C2H5)3N<(C2H5)2NH