MIND MAP KESELURUHAN ORGANIC SK025

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SUMMARY MIND MAPPING 1O ALCOHOL SK025

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SUMMARY MIND MAPPING 20 ALCOHOL SK025

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SUMMARY MIND MAPPING 30 ALCOHOL SK025

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BOILING POINT

Factor Alkane Carbonyl/ Amines Alcohol Carboxylic
(Non polar molecule) Haloalkane acid
Hy 1 NH 1 OH
Mr xx (Polar 4C 3C 4C 1 COOH
3C 4C molecule) 2C

x

3C

van S 21 30 20 10 30 20 10
Explanation Linear Branch Branch Linear
(Most (Branch) (Linear) (Most (Branch) (Linear)
Carbonyl (aldehyde and ketone) / Haloalkane &
alkane cannot form hydrogen bond. Only van der branch) branch)
Waals forces exist between the molecule.
Carboxylic acid and alcohol & amines can form hydrogen bonding between the
Dipole-dipole forces in carbonyl (aldehyde/ molecule.
ketone)/haloalkane (polar molecule) stronger
intermolecular forces than London Forces in Hydrogen bonding stronger intermolecular forces than van der Waals forces
alkane (non polar molecule).
Molecule with higher molecular weight has higher Amines have lower boiling point Molecule with higher molecular Carboxylic
boiling point because has greater surface area and compared to alcohol and weight has higher boiling point acid can form
stronger van der Waals forces. carboxylic acid because nitrogen because has greater surface area a stable
atom is less electronegative than and stronger van der Waals hydrogen
For isomeric alkane (molecule with same number oxygen. forces. bonded
of molecular weight), branching makes molecule dimer
more compact, surface area smaller, van der Molecule with higher molecular For isomeric alcohol (molecule between the
Waals forces weaker and less energy to separate the weight has higher boiling point with same number of molecular molecule.
molecule. because has greater surface area weight), branching makes More energy
and stronger van der Waals molecule more compact, surface needed to
forces. area smaller, van der Waals separate the
forces weaker and less energy molecule
10 amines can form more needed to separate the molecule. compare to
hydrogen bonding than 20 amine alcohol.
while 30 amine cannot form If primary amines / alcohols
hydrogen bonding between attachment at different classes of
between their molecules. Carbon; Example: 1-propanol and 2-
propanol. 2-propanol has lower boiling
point due to steric effect. The
formation of hydrogen bond is
hindered since the amino group is
located on the second carbon.

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SOLUBILITY

Factor Alkane Amines Alcohol Carboxylic
acid
Hy x 2C 1 NH 1 OH
Mr 3C 3C 2C 3c 2C 1 COOH
2C

30 < 20 < 10 30 < 20 < 10 30 < 20 < 10 30 < 20 < 10

Explanation Alkane cannot form Carboxylic acid, alcohol and amines can form hydrogen bonding with water per molecule
hydrogen bond with
water per molecule.

2C more soluble in Both can form same number of hydrogen bonded Both can form same number of carboxylic acid
water than 3C because with water per molecule. hydrogen bonded with water per can form more
lower number of alkyl molecule. hydrogen
group and hydrophobic 2C more soluble in water than 3C because lower bonded with
area decrease. Thus, number of alkyl group and hydrophobic area 2C more soluble in water than water per
solubility in water per decrease. Thus, solubility in water per molecule 3C because lower number of molecule than
molecule increase. increase. alkyl group and hydrophobic the others.
area decrease. Thus, solubility
10 amines can form more hydrogen bonding than 20 in water per molecule increase.
amine and 30 amine in water per molecule. Solubility
increase as the number of hydrogen bonding increase. 10 alcohol can form strong
hydrogen bonding than 20 and
If primary alcohols / amines attachment at different classes 30 alcohol in water per molecule
of Carbon; Example: 1-propanaminel and 2-propanamine because stearic effect in
are both primary amines. But 2-propanaminel has lower contact for 10 lower compare
solubility due to steric effect. The formation of hydrogen to 20 and 30 alcohol.
bond is hindered since the amino group is located on the
second carbon.

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ACIDITY

Alcohol Water Phenol Carboxylic Acid
R-OH H-OH Ar-OH R-COOH

No resonance stabilisation because the Phenoxide ion is resonance stabilised because the Carboxylate ion is resonance stabilised because
negative charge is localised on the negative charge is delocalised into the benzene ring the negative charge is delocalised between two
oxygen atom of alkoxide ion formed. (delocalization between carbon atom). oxygen atoms.

CH3CH2OH CH3COOH

CH3CH2O- < - < CH3COO-
increasing acidity
O

C
HC CH

HC CH
CH

• The ethoxide ion is least stable because no resonance ion formed. The negative charge is localized on oxygen atom. The presence of alkyl
group, which is an electron-donating group, increasing electron density on the oxygen atom therefore destabilizing the ion.

• The phenoxide ion is more stable than ethoxide ion because it is resonance stabilized. The negative charge in phenoxide ion is delocalized
between carbon atom in benzene ring.

• The ethanoate ion is more stable than phenoxide ion because it is resonance stabilized. The negative charge in ethanoate ion is delocalized
to a far greater extent since it is distributed over two electronegatively charges oxygen atoms. Oxygen is more electronegative than carbon
atom.

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ACID STRENGTH OF CARBOXYLIC ACIDS

RESONANCE EFFECT INDUCTIVE EFFECT

Delocalization of π electrons between two Movement of electron density along the σ bonds
oxygen atoms
- Electron withdrawing group Electron donating group
O (EWG) (EDG)
O
RC RC The presence of electron withdrawing The presence of electron donating group
group/atom (EWG), for example Cl, will (EDG), for example -CH3, will decrease the
- O increase the acidity of carboxylic acids. acidity of carboxylic acids.

O O O

EWG C EDG C

- -

O O
The negative charge on oxygen atom The density of negative charge on oxygen
delocalize, thus stabilizes carboxylate ion atom increase, thus destabilizes carboxylate
and increase the acidity. ion and decrease the acidity.

Electron withdrawing group (EWG)

Position of halogens Number of halogens

Acidity decrease as halogen is further away from the carboxyl group. The presence of more halogens increase the acidity of the carboxylic
acids.

H3C CH2CH O 2-chlorobutanoic is O 2-chloropropanoic acid is
Cl C more acidic because Cl less acidic because it has only
atom is nearer to H3C CH C one Cl atom.
OH carboxyl group Cl OH

O 4-chlorobutanoic is less Cl O 2,2-dichloropropanoic acid is
acidic because Cl atom C more acidic because it has
H2C CH2CH2 C is further away from H3C C two Cl atom.
Cl OH carboxyl group Cl OH

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BACISITY OF AMINES

BASICITY OF AMINES

Inductive effect Resonance effect

i) Electron donating group (EDG) • Aromatic amines are less basic than aliphatic amines.

• EDG increase electron density on the nitrogen atom of • The lone pair electrons of nitrogen atom are delocalized into the

amine and stabilize alkylammonium ion. aromatic ring, and less available for bonding to H+.

•  amines are easier to accept proton / H+. • In resonance terms, arylamines are stabilized relative to aryl

• Example: alkyl group ammonium ion because of the four resonance structures.

ii) Electron withdrawing group (EWG)
• EWG reduce electron density on the nitrogen atom
of amine destabilize alkylammonium ion.
•  amines are more difficult to accept proton / H+.
• Example: halogen, NO2

Basicity of Amines
(Gaseous Phase)

(CH3)3N > (CH3)2NH > CH3NH2 > NH3

• 3°amine > 2° amine > 1° amine > ammonia
• For 3°amine, there are more alkyl groups attached to the nitrogen atom.
• Alkyl group act as electron donating group (EDG)
• Basicity increase as number of EDG increase.
• The electron density is greater around the nitrogen atom making it easier for protonation and stabilize alkylammonium ion.
• So the basicity increases.

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