Organic Chemistry Min
Organic Chemistry Min
Organic Chemistry Min
Chemistry
Organic Chemistry
NEET - UG
S.NO. CONTENT Page
No.
1. 1
2. 15
3. 41
4. 86
5. 129
6. 159
7. 182
8. 207
9. 219
CHAPTER
CHAPTER OUTLINE
Haloalkanes CCl4 Or Pyrene (Carbon-tetra-Chloride)
Teflon (– CF2 – CF2 –)n Chlorobenzene
1
Monohalides The function of ZnCl2 is make cleavage of
Haloalkanes are monohalides; for instance, −C − O– bond by co-ordination with O-
the IUPAC name for C2H5Br is bromoethane. atom.
These molecules may exhibit chain, position, Bromoalkanes
and optical isomerisms. C2H5OH + KBr + H2SO4 C2H5Br + KHSO4 + H2O
Methods of preparation
Facts to Remember
By direct halogenation of alkanes
Conc. n H2 SO4 must not be used in case of
R H X X hv
R X HX
s∘ , 𝑡 o , and neo alcohols as they undergo
Example:
dehydration with it.
CH4 Cl2 hv
CH3Cl CH2Cl2 CHCl3 CCl4
CH3 3 C CH2OH HBr
or 520650K H SO
2
4
2
Follows a free radical mechanism and Like in alkanes branching also decrease B.P.
reduces one C atom number.
The yield of R − X decreases: 𝟏∘ > 𝟐∘ > 𝟑∘ .
In case of iodine, an ester is formed and the
reaction is called Birnbaum-Simonini reaction.
The trend followed for the dipole moment of
2RCOOAg + I2 ⟶ R − COOR + 2CO2 + 2Ag 2 I
various compounds is 𝐑𝐂𝐥 > 𝐑𝐅 > 𝐑𝐁𝐫 > 𝐑𝐈
From ethers
CH3 Cl > CH3 F > CH3 Br > CH3 I
R − O − R + PCl5 ⟶ 2R − Cl + POCl3
R − O − R′ + PCl5 ⟶ R − Cl + R′ − Cl + POCl3 𝜇 → 1.86D 1.847D 1.83D 1.636D
From alkenes: HX reacts with alkenes in The stability of compounds vary in the
accordance with Markovnikov's or following sequence as bond length increases
anti- Markovnikov's to produce haloalkanes in and bond energy decreases.
the following manner: RF > RBr > RCl > RI
According to Markovnikov's rule:- Solubility
Br These are less soluble in water because less
|
energy is released when new attractions are
CH3 CH2 CH2 HBr
CH3 CH CH3
established between the haloalkane and the
In the event that the carbocation formed is less
mater molecules, because these new
stable, a one-time rearrangement via 1,2-shift of
attractions are not as strong as the original
hydride or methyl is performed.
H-bonds in water.
Example:
Their solubility in organic solvents is quite
good due to interactions that are nearly
identical.
1
Solubilities
Mol. wt.
CH3 X > C2 H5 X > C3 H7 X > C4 H9 X
Chemical properties of monohalides
According to Anti-Markovnikov's rule:- Since the C X is polar, these are reactive
CH3 CH CH2 HBr
Benzoylperoxide
compounds.
CH3 CH2 CH2Br The reactivity order is as follows:
From primary amines RI > RBr > RCl
R NH2 NOCl
R Cl N2 H2O R 3 CX > R 2 CHX > RCH2 X
Nitrosyl CH3 X > C2 H5 HX > C3 H7 X > ⋯.
chloride
Nucleophilic substitution reactions: Alkyl
Physical properties of monohalides halides undergo nucleophilic substitution
Lower members (CH3 X, C2 H5 X) are reactions as:
colourless gases, whereas higher members
R X Z R Z X
(C18 and higher) are colorless liquids. Strong
The boiling point and density of a substance nucleophile
increase as its molecular weight increases. This reactions occurs by either SN1 or SN2
C4 H9 Cl > C3 H7 Cl > C2 H5 Cl > CH3 Cl mechanism.
RI > RBr > RCl > RF …
3
Examples: Dehydrohalogenation: It involves 𝛼, 𝛽-
R X R OH HX
Aq. KOH
elimination following E1 and E2 mechanisms.
R X
AgOH
R OH AgX Here, the following, α,β-elimination reaction
takes place:
R X
Alc. KCN
R CN KX
R − CN is the major product as KCN being In the case of t∘and s∘ halides, elimination
ionic, provides CN − ions. Therefore, the predominates over substitution, whereas
attack occurs from the carbon atom side. substitution predominates in the case of p∘
halides. In addition to high temperature and
R X
AgCN
R NC AgX
solvent polarity, the strength of the base also
The major product is R − NC as AgCN being
favours elimination over substitution.
covalent cannot furnish CN − ions. Therefore,
the attack occurs from nitrogen atom (lp e-
side) to give R − NC.
R X
AgNO2
R NO2 AgX
Nitroalkane
R X
KNO2
R O N O KX
Alkyl nitrite
R X
NaN3
R N3 NaX
Azides
R X
NASH
R SH NaX
Thiols
R X
R'COOAg
R'COOH AgX
R X
R'ONa
R' O R NaX Saytzeff's Rule
The above reaction is called Williamson According to Saytzeff's rule, the removal of β-
synthesis (Method to prepare all kind of H-atoms from β-carbon atoms with a greater
ethers. (R − X must be p∘ or s° halide). number of alkyl groups results in the
R X R'SNa
R' S R NaX formation of a more stable alkene.
C2H5OH/H2O
Thioether
Example:
R X R S R 2NaX
Na2S
CH3 CH CH2 CH3
KOH
CH3 CH CH CH3
R X C6H6
C6H5 R HX | But 2 ene major
Anhyd. AlCl3
Cl
The above reaction is called Friedel-Crafts CH2 CH CH2 CH3
reaction. minor
R X
R OH
Moist Ag2O
2R X Ag2O
R O R 2AgX
Dry Ether In the case of a fluoro-alkane or other s o halide
R X NaC CR'
R C C R' NaX reacting with a very strong base, such as
Alkyne (CH3 )3 COK or C2 H5 ONa, the predominant
X R
R X
NH3
HX
R NH2
HX
product (Alkene) is determined by the
p Hoffmann Rule. According to this theory, 𝜷-H-
atom is eliminated from 𝜷-C-atom with less H-
atom or less acidic 𝜷-H-atom, resulting in less
stable alkene.
4
Dihalides
CH3 CH CH2 CH3 KOH
Always
CH2 CH CH2 CH3
Hoffmann Major
| Gem or geminal halide or alkylidene halides
F
CH3 CH CH CH3
Minor
CH
CH3 CH CH2 CH3 CH2 CH CH2 CH3
3 3 COK
| Major
Methods of preparation of geminal halides
X 1. From aldehyde or ketone
CH3 CH CH CH3
Minor
Isomerination
5
3. Reaction with KCN
3.
5. Haloform reaction
(A) It is given by >C = O having –COCH3 group.
For example,
6
This substance is insoluble in water, but
soluble in organic solvents. Additionally, it
is a useful solvent for lipids, resins, etc.
CHBr3
It is a colourless liquid and its boiling point
is 149.5∘ C.
CHI3
It occurs as yellow, hexagonal plate like
crystats.
Its melting point is 119∘ C.
It can be used as an antiseptic (due to the
CH3CHO is the only aldehyde to show the liberation of free I2 ).
reaction.
Test of Purity of CHCl3
For example,
No precipitate is produced when chloroform
and silver nitrate react. Due to the fact that
CHCl3 is covalent, it cannot provide Cl-ions.
Chemical properties of chloroform (𝐂𝐇𝐂𝐥𝟑 )
1. Nitration
CH3CHO + 3I2 + 4NaOH CHI3 + HCOONa +
CHCl3 HO NO2
CCl3 .NO2 H2O
3NaX + 3H2O
Chloropicrin (insecticide)
CH3COCH3 + 3I2 + 4NaOH CHI3 +
It is used in the manufacture of tear gas
CH3COONa + 3NaX + 3H2O
[C6 H5 COCH2 Cl], phenacyl chloride.
(B) Alcohol having CH3 CH OH group shows 2. Reduction
| 6[H]Zn H2O
CHCl3 CH4 3HCl
haloform reaction.
CHCl3 CH2Cl2 HCl
2[H]Zn/HCl
Example:
CHCl3 4(H) Zn
CH3Cl 2HCl
alc. HCl
3. Oxidation
1
CHCl3 O2
hv
COCl2 HCl
2 Phosgene
(poisonous)
To prevent oxidation or the formation of
phosgene, chloroform is stored in a dark,
completely filled, securely sealed bottle with
a small amount of ethyl alcohol (a negative
For example, catalyst).
CH3 – CH2 – OH + 4I2 + 6NaOH CHI3 + Phosgene is converted to non-poisonous
HCOONa + 5NaX diethyl carbonate by ethyl alcohol.
CHCl3
It is a colourless liquid with sweet smell.
Its boiling point is 61∘ C.
7
4. Reaction with hot NaOH 𝐂𝐂𝐈𝟒 OR PYRENE (Carbon Tetra-Chloride)
Cl
|
Cl C Cl
|
Cl
5. Reaction with hot C2H5ONa
Tetrahedral structure
sp3 hybridization
Bond angle 109∘ 28 ′
𝜇 is zero
6. Carbylamine reaction: It is a test of primary
amine. Here, the primary amine reacts with Methods of preparation
chloroform and base KOH, to give bad 1. CH4 4Cl2
hv
CCl4
4HCl
8
Uses of CCl4: From benzene diazonium chloride or Sand
(i) As a solvent for oils, fats, Resins etc. Mayer's reaction
(ii) Under the pyrene it is used as a fire
extinguisher.
Teflon (– CF2 – CF2 –)n Gatterman reaction
Teflon is a polymer of tetrafluoroethylene.
It is a thermoplastic that is chemically inert
and used for electrical insulation and gasket
Physical properties of Chlorobenzene
materials.
800C
It is a colourless liquid with a pleasant odour
CHCl3
SbF3
CHF2Cl
HCl
CF2 CF2
HF
and a boiling point of 132∘ C.
CF2 CF2 n
nCF2 CF2 It is heavier than water and insoluble in it.
Tetrafluoroethylene Teflon
Chemical properties of Chlorobenzene
Chlorobenzene Due to benzene ring
Methods of preparation The Cl-atom present in the ring renders the
ring inactive, but it is both o- and p-directing.
Electrophilic substitution occurs at a slower
rate than benzene.
Here, the electron (e–) density increases at the o
From benzene
and p positions due to resonance, but the -X
atom tends to withdraw electrons from the
benzene ring due to the -I effect. It indicates that
the rate of electrophilic substitution decreases
due to ring deactivation.
cannot be obtained by direct
From alcohol
9
Sulphonation Substitution by-OH group
Acylation
sp3
In while in R CH2 X it means Substitution by NH2 group
10
This reaction proceeds with Benzine Uses and Effects of Polyhalogen Compounds
on Environment and Human Health
formation. (i) Chloroform
It is used primarily in the production of
Substitution by CN group
the R-22 Freon refrigerant and as a
solvent for lipids, alkaloids, iodine, etc.
Substitution by –OR group It results in dizziness, headache, and
fatigue.
Chronic chloroform exposure can
Reaction with magnesium result in liver and kidney injury.
(ii) Iodoform
It is primarily employed as an
antiseptic because it releases free
Wurtz Fittig Reaction iodine.
However, it is no longer used due to its
foul odour.
Fittig reaction
(iii) Freon
Freon is used as a refrigerant in
refrigerators and air conditioning
units.
However, its use has been
discontinued because it depletes the
Ullmann reaction
ozone layer.
(iv) DDT
DDT, a popular pesticide consisting of
an off-white crystalline substance, is
exceedingly toxic to fish.
Reaction with chloral It is not swiftly metabolised by
DDT is produced when chloral is heated with animals; instead, it is deposited and
chlorobenzene in the presence of retained in fatty tissues.
concentrated H2SO4 (p, p-dichlorodiphenyl Since its residues are non-
trichloroethane). Due to the fact that both biodegradable, they accumulate in the
Cl-atoms are linked to the benzene ring, it is environment and are toxic to
not biodegradable. mammals, etc.
(v) Carbon tetrachloride
CCl4 or carbon tetrachloride is
primarily employed in the synthesis of
chloroflourocarbons.
It may induce human liver cancer.
It may result in migraines, nausea, and
nerve injury.
It may contribute to the depletion of
the ozone layer.
11
(vi) Benzene Hexachloride (B.H.C)
12. The order of chemical reactivity of alkyl
It is commonly called as Gammexene
halides is
or 𝛾-Lindane or 6,6,6[C6 H6 Cl6 ]. RI > RBr > RCl
It is a popular pesticide for killing of 13. The order of reactivity of an alkyl halides
Thermites (white ants) from soil. is
Tertiary > Secondary > Primary
Facts to Remember This is due to the inductive effect of alkyl
1. As a treatment for hookworms, CCl4 is groups, which increases the polarity of
used as a medication. the C-X bond, making it more reactive.
2. CFCl3 is freon-11, while CF4 is freon-14, 14. Despite their higher positive ionisation
CF3Cl is freon-13 and CF2Cl2 is freon-12. energy, it has been observed that the
presence of bulky groups in primary
3. Perfluorocarbons have a standard
halides causes steric hindrance and
chemical formula- C𝑛 F2n+2.
makes them less reactive towards the
C6H14 14F2
573K, COF2
C6 F14 14HF SN2 mechanism.
4. Halothane (CF3CHClBr) is employed as The reactivity follows the order CH3 X >
an inhalational anaesthetic. C2 H5 X > C3 H7 X.
5. Chloretone is a substance that induces 15. Antiseptic action of CHI3 is due to the
hypnosis or sleep. liberation free I2 .
6. Westron is composed of 16. Perfluoro carbons (PFCs) have a general
formula Cn H2n+2
tetrachloroethane while Westrosol is 573K
C7H16 16F2
Vapour Phase N2C0F2
C7F16 16HF
trichloroethylene. Perfluoro heptane
CHCl2 These substances are odourless, non-
| Westron polar, stable, and non-toxic. They are
CHCl
2 resistant to U.V and other types of
CCl2 radiation, so they do not deplete the U3
|| Westrosol layer. They can be utilised as lubricants,
CHCl
in skin-care medications, in medical
7. The boiling point have the following diagnosis, etc.
order: 17. Halogen derivatives of aromatic
Alkyl iodides > alkyl bromides > alkyl hydrocarbons with a halogen atom in
chlorides > alkyl fluorides the side chain are known as aryl alkyl
halides or aralkyl halides.
R − I > R − Br > R − Cl > R − F
Examples: Ar − CH2 − X.
8. The volatility has the following order:
18. Bond strength and stability decreases as
R − Cl > R − Br > R − I
R − F > R − Cl > R − Br > R − I
9. Dipole moment has the following order: 19. The relative nucleophilicity order for
CH3 Cl > CH3 F > CH3 Br > CH3 I SN 1 Reaction:
10. The order of the boiling points in a RS̅ > C̅N > I̅ > R − O̅>O ̅H
group of isomeric alkyl halides is 20. The leaving group tendency for SN 2
Primary > Secondary > Tertiary Reaction:
11. The order of the densities of alkyl p CF3C6H5SO3 p CH3C6H4 SO3 I Br
Tf Ts
halides is
Cl H O F CH3COO NR3 R O
R − I > R − Br > R − Cl > R − F 3
CH3 Cl < CH2 Cl2 < CHCl3 < CCl4 R2N NH2
12
(R) : Reactivity depends upon the
21. Decreasing order of Reactivity of
Nucleophilic Substitution Reaction: nature of the nucleophile and the
solvent.
5. (A) : Isopropyl chloride is more reactive
than CH3 Br in SN2 reactions.
(R) : SN2 reactions are always
accompanied by inversion of
configuration.
6. (A) : o-dichloro benzene has higher
metlting point than p-dichloro-
benzene.
22. R-Br and R-I cannot be derived using (R) : Stronger the Van der Waal's forces
Dorzen's approach since SOBr2 is
of attraction, higher is the melting
unstable and SOI2 does not exist.
point.
NEET AND AIIMS ESSENTIALS 7. (A) : Addition of Br2 to cis-but-2-ene is
stereoselective.
In the following questions, two statements
Assertion (A) and Reason (R) are given. Mark (R) : SN2 reactions are stereospecific as
(a) if 𝐴 and 𝑅 both are correct and 𝑅 is the well as stereoselective.
correct explanation of 𝐴 8. (A) : SN2 reaction of an optically
(b) if 𝐴 and 𝑅 both are correct but 𝑅 is not the activealkyl halide with an aqueous
correct explanation of 𝐴 solution of KOH gives an alcohol
(c) 𝐴 is true but 𝑅 is false with opposite sign of rotation.
(d) A is false but 𝑅 is true (R) : SN2 reactions proceed with
(e) A and R both are false inversion of configuration.
1. (A) : The effect of electron withdrawing 9. (A) : Benzyl chloride is more reactive
group at ortho and para position than p-chlorotoluene towards
increases the reactivity of aqueous NaOH.
haloarenes but at meta position (R) : The C − Cl bond in benzyl chloride
(R) : As at meta position negative charge is more polar than C − Cl bond in p-
can not be stabilized by such a chlorotoluene.
group in any resonating structure 10. (A) : Tertiary haloalkanes are more
2. (A) : Alkyl iodides darken on standing. reactive than primary haloalkanes
(R) : Alkyl iodides are prepared by
towards elimination reactions.
Finkelstein reation.
(R) : The +I-effect of the alkyl gropus
3. (A) : 2-chloro-3-methylbutane on
weakens the C − X bond.
treatment with alcoholic potash
11. (A) : Rate of reaction is dependent only
gives 2-methyl-butene-2 as major
on the concentration of
product.
nucloephile in SN1 reactions.
(R) : The reaction occurs according to
(R) : Polar solvent favours SN1 reaction.
Saytzeff rule.
4. (A) : Primary benzylic halides are more 12. (A) : The carbon halogen bond in an aryl
reactive than primary alkyl halides halide is shorter than the carbon
towards SN1 reactions. halogen bond in an alkyl halide.
13
(R) : A bond formed of an sp3 orbital (R) : Front side attack of nucleophile is
should be shorter than the hindered due to the presence of
corresponding bond involving an leaving group in the vicinity.
sp2 orbital. 15. (A) : Bromobenzene upon reaction with
13. (A) : SN2 reaction of CH3 − Br is faster in Br2 /Fe gives 1, 4-dibromobenzene
DMSO than in H2 O. as the major product.
(R) : DMSO has greater capability to (R) : In bromobenzene, the inductive
solvate nucleophile. effect of the bromo group is more
14. (A) : In SN1 mechanism, the product dominant than the mesomeric
with inversion of configuration is effect in directing the incoming
obtained in higher amount electrophile.
compared to the product with the
retention of configuration.
ANSWER KEY
1. (a) 2. (c) 3. (a) 4. (b) 5. (d) 6. (d) 7. (b) 8. (a) 9. (a) 10. (b)
11. (d) 12. (c) 13. (c) 14. (a) 15. (c)
14
CHAPTER
CHAPTER OUTLINE
Alcohols Ethyl Glycol
Glycerol or Glycerine Phenols
Ethers (R–O–R) Epoxy Ethers
ALCOHOLS
Alcohols are hydroxy derivatives of alkanes or alkyl derivatives of water obtained by replacing one
or more H atoms by –OH group.
General formula of the alcohol is 𝐑 − 𝐎𝐇.
Types of Alcohols
Monohydric alcohols Dihydric alcohols Trihydric alcohols
Alcohols with only one −OH Alcohols that have two-OH groups. Alcohols having three −OH
group with their general groups
formula Cn H2n+1 OH
Types of Monohydric Alcohol Example: Example:
(a) Primary alcohol (1°) Glycol, Propan 1, 2 diol
RCH2OH
Example: CH3 OH methyl
alcohol (Methanol)
(b) Secondary alcohol (2°)
R2CHOH
Example: (CH3 )2 CHOH
isopropyl alcohol (Propan-
2-ol)
(c) Tertiary alcohol (3°) R3C.OH
Example: (CH3 )3 COH −
tertiary butyl alcohol (2-
methyl-propan-2-ol)
15