Basics of Organic Chemistry

Citation preview

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18



More Examples



I Methanol



H



a



H







3 NH Ammonium ion









removed

one e is

from 5 valence e

N to make it

g

positive charged

of

Lewis structures 2

CHIH

i

f

19

Ufo

Methanol or formaldehyde unpaired

H O

n

n

H

H me

T

Makingone bond

Cand O

between

leaves one unpai

e on each c

ii

fi

O

of CandO they pairupto form a second bond o







4













5

















20 6

Ctej Methylanion inning

a

fg

is

O e

put onto the C

UfNOz

ii

Nitromethane

Unstable

n.fi X H I

H c

Uycoo n

l H

I

Acetate ethanoate ion

µ

O H

N

i

o

N has toe

Q

ms

octetexceeded

i

Not this



Polar Covalent Bonds & Dipoles 1 21

When a covalent bond is formed between atoms of different electronegativity, the bonding pair of electrons is not

shared equally but is attracted towards the more electronegative atom. Such a bond is said to be polarized , or

described as a polar bond, and the charge separation is represented by symbols δ− and δ+ which represent partial

negative and positive charges. Alternatively, we show the direction of bond polarity by an arrow with the

arrowhead pointing toward the negative end and a plus sign on the tail of the arrow at the positive end.

The bond is ionic only when the electronegativity difference is appreciable (typically, >1.8 on the Pauling scale);

otherwise, the bond is covalent.























Bond Dipole Moments 22



Bondpolarities can rangefrom nonpolarcovalent through polarcovalent to totally ionic eg

0

Cte Cte MHz OH Cl Uhs N 6 Ctf Utz Utz

Ionic

NonPolar

Increasing Polarity



an individual bond is measured as its bond dipole moment µ Polarity



St S amount charge at eitherendofdipole µ 8xd

H H U D distance bw the charges

SI unit Debye D k d

30 Coulombmeters

I Debye 3.34 10

a protonand e 9 1.60 1019c were 10 m apart the dipole moment wouldbe

74

1.60 1029 cm 1.60 10 4 8D D

µ 8 0 4.60 1019c x loWm 3 34 1030



H N C N H O C O

c f C y µ c

0.2213 0.86D 1051 D 1.56D 0.3 D 1.3113 l 53 D



of

S­eg

of

If

292

8xd

























23

Molecular Dipole Moments rholeculardipolemoment is the dipole moment of the molecule taken as a whole molecule's overall polarity Its a good indicator Moleculardipolemoment

10N a

eg

120

is the vector sum of individual bond dipolemoments

1All

forceon

this sphere

1240,11200

loaf

of

10N

zero became 3 forces Vectorsum O

up H

C

O

H

c

O

µ 0

Non Polar

µ 2 3D

Molecule

polar molecule















IF

0

similarly

F

g hi

L

14 0

p

If

µ o Nffjepolate

Hisc pH c

F

H

B

H

Non Polar

Molecule

Bfd

Br µ lo9D

Polar molecule



U y



c

4

U U

U

Threepolarbonds polarbonds fourPolarbonds Two

cancel dipoles All All dipolescancel

bothdipolescancel _O MR

Mr 0 µr O





Label thepolarbonds in eachmolecule Indicatethe direction



b Uesufocte

Clea d as a



Br











It

IF

If

401

24

It

at't

17dB

of net dipolecifany g

Bt

Br

MAB

e

a

Br





a

































H C

1 s

s pigsty 9 1

U

d

U

s

qq.BR Br

Br

Mr_0

R

b

o

f II Ms cee

25

Br

7 Mr

c

It I

µ

l

µr O

H

Br

Bothdipoles are equal opposite

Benzene is a planar molecule and both Br are in the

plane of the benzene ring Both dipoles cancel each other

Br

and cancel

each other completely Br

e

11 l

Br

fl I

µ

H

I Mr

Bothdipolespoint in

the

same direction

hence add up togive a resultant dipole



26



Electronegativity allows us to predict the charge distribution in an organic molecule



s S 0 St S St S

I Cee CEN s Ctl OH

eg CSt 11111 C

µ H As µLd



The major factor Influencing the E N is the energy the orbitals that



to rightacross the periodictable the valence the atom uses to acceptelectrons As onemoves

orbitals become lower in energy withinthe same period Going down a group atoms get bigger



in size and valence orbitals are higher in energy E N increases as orbital energy decreases

Then He should have the highest E N as it has the lowestenergyvalenceorbitals but He



can't accept any more e b'coz its a noblegas The atomwith the lowest energyvalence orbitals



that is not a noble gas is F which is the most E N atom







I

I ayy

left

of





















Electrostatic Potential Surfaces

Just for your knowledge no need to memorize

27

Cebu showing the polarity with St and 8 is veryeasy However in more complex molecules there will be manydifferenttypesof bondswithdiffering degrees of polarity and the overall molecule will reflect the sum ofthese Thesimple St S

In

a simple molecule

like HCl

or

symbolism is no longeradequate and we need an alternate way to view the charge distribution in complexorganic molecules





















Example









Example











Example















Classify each bond as nonpolar covalent or polar covalent or state that ions are formed. (a) S 𑁋 H (b) P 𑁋 (c) C 𑁋 (d) C 𑁋 n F mH N Cl

M

Would a bond between each of the following pairs of atoms be covalent or ionic? (a) O, H (b) C, F (c) Li, F (d) C, Mg

Show the polarity of each of the following covalent bonds by partial charges and by a dipole arrow. (a) O–H (b) C–O (c) C–Mg (d) B–H

28



Example









Example











Example















Classify each bond as nonpolar covalent or polar covalent or state that ions are formed. 29 St St S s (a) S8Wa 𑁋 HSt (b) P 𑁋 H (c) C 𑁋 F (d) C 𑁋 Cl b m N EN of P and H Polar Polar Polar NonPolar are very close so covalent covalent covalent covalent there is hardlyany Polarityin P H bond Would a bond between each of the following pairs of atoms be covalent or ionic? (a) O, H (b) C, F (c) Li, F (d) C, Mg

d

DEN to i polarcovalent

de

DEN 1.7

butstill

DEI s 1.7

de

DEN 1.7 Ionic

i Polarcovalent

Polarcovalent as carbondoesn'tformionicbonds

Show the polarity of each of the following covalent bonds by partial charges and by a dipole arrow. (a) O–H (b) C–O (c) C–Mg (d) B–H

8

O

H

St

St

s

C O

s

s1

C Mg

St

S

B H







































30

Group Electronegativities

Its often convenient to consider groups that make up particularportions of a molecule as having their own electronegativity compatible with Pauling Seale Group

Electronegativity

Group

Electronegativity

Utz

2.3

CECH

3.3

Ctfu

2.8

CEN

3.3

Cteclz

3.0

MHz

3.4

cuz

3.0

NHI

3.8

Cfg Ph

3.4

Moz

3.4

OH

307

Ctectez

3.0

3.0



Bonding Patterns & Formal charge 31

Before we start with calculation of formal charge, let’s just understand its importance in chemistry. Suppose you do

a lot of monetary transactions everyday, then how do you keep track of your account balance? You make a ledger.

Formal charge is also like keeping a track of valence electrons of an atom.



We will be studying lots of reactions and their mechanisms in this course and reactions involve movement of

electrons. When electrons are being moved during reactions, we need to keep a track of this in order to understand

the reaction mechanism.

























Bonding Patterns & Formal charge



































1 32





Assign formal charge



















a

e

te

te Ye

ch E

33

to C N and O atoms in the following molecules b

f

µj teYg

es

y

g

ay

Uy

EN

d

H

pi

NEN















H

BL









a







e









solution



a









S1

34 H

I

He c i

H

teach

O

1H c

b

nµ

p

has 3 e oo

T

H

c

ye

T

has teoc.io

f

T

has 5e

bing.nqe.n.ie

N has 6 e i I formalcharge

o

0

p

1

H og H

d

Cte c N

has

e

o

haste

G

11

n

HY has5 e

hlasse

Ue

g

O

cteg.NO N

T

hasUe

d

Se

X has 55

d

I

L de

Se







































35

Formal charge and Bonding Patterns

In organic chemistry we will be dealing with lots simple and complex molecules so its important of to have a proper understanding bonding patterns of common atoms like C N and O

of

Dueto 4 valence e C

EC

forms four bonds in Neutral state

c

c

A

octet is maintained

E

formal charge

formal charge 0

if

Y

and not

t.g.E

e.EE

I

E

These arrangements for formalcharge 1 are wrong as octetofcarbon is exceeding due to the

unpaired e



Patterns

Formal charge and Bonding

Due to 5 valence E

N forms 3 bonds

and keeps one lonepair

e fc o



Can't form 5 bonds as

octet will be exceeded N

and N doesn't have

empty d orbitas for that Re I





Similarly Oxygen valence 0



1 o 1 o o

0 O O



fC D fc I



hi

ni

36

N

htt

N

of

iii I

Fc

These bonding arrangements ensure octet completion

for

g

I

0 Fc

I



37 shapes organic Molecules

Molecular structure

Molecules have 3Dshapes What do theylook like Why does a moleculehave a particularshape

The search these answers led to the development various bondingtheories These theories

explained the known structures and also allowed chemists to predict structures newly



discovered molecules When a predicted structure was shown tobe wrong theory was refined until



experimental result it could account





Lewis concept concept localized e pair bond Coudritexplain the geometry bondangles

stability



V BT Explains formation bonds through overlap atomic orbitals



vs EPR theory Explains the right arrangement bondpairs and tone pairs in space around

central atom to achieve stability



correct

Allows us to modify the atomic orbitals in such a Hybridization way to explain

bond angles in molecules Assigns geometry bondangles and bond lengths



of

for

of

of

for

of

of

of

of





















Knowledge properties

ofmolecularstructures is critical to understanding of their

Virtually every

molecular structure

physical chemical great extent on the shapes of acidity basicity reactivity ele depend on

biochemical process hinges to a

interacting molecules Properties

like smell flavour

VSEPR Valence shell e pair repulsion

e pairs mean

bondpairs

lonepairs

g

Based on simplefact that e pair repeleachother and want to stay as far awayfrom each that other as possible Electronpairs around central atom arrangethemselves in such a repulsions are

I



38

VS EPR theory

minimum and structure is stable

way



Tetrahedral shapes











z

Pointed

away pointed towards You

fromyou





Y'npitamnesame

a

It

39

µ.gl

or

does amully

5

Pointed

Ball stickModel

you

away fromyou Tetrahedral is one the most of









3D formula

txt

Pointed towards

9

Lewisstructure





or

common geometries

you will

study in organic chemistry Visualize it perfectly

spacefillingmodel







Tetrahedral and Trigonal planar geometries



e

e

z

C

o

1

Ammonia

NH

Pyramidal

shape

Geometry Tetrahedral



Nater Dihydrogenmonoxide

HD

Shape Pyramidal

Tetrahedral

Geometry









Ehr











40







Linear Geometry y

41 S









linear











i















Hy

Ethene

Trigonal Planar Geometries

HCHO

Methanol











Koryo



U

5092



ThionylChloride



Tetrahedral



Seo

42

i

P

6

1

p 304

U

POU

p

a

U

U

Nyo HMOs

Pce

phosphorylchloride

Phosphorous

Tetrahedral

Tetrahedral

trichloride















HO

yo

NitricAcid TrigonalPlanar

Doo

HO

Nyo

HN0z NitrousAcid TrigonalPlanar















Atomic Orbitals and their shapes

43

An orbital of specified energy can bethought ofeither as the space around the

atom available to an e an e

of an

or as a mathematical formulafrom whichthe probability offinding

at a particular location may be calculated

























nucleus

colours whythesedifferent

These two colours represent two different phases The phasing is solely a result the mathematical of colour indicates that the function is positive in this functions describing the orbitals One region of space and the other colour indicates it is negative



















44 There is no other meaning to be given to these phases forinstance the probability of finding an e in the differently phased regions is the same

In atomictheory and quantummechanics an atomic orbital is a mathematicalfunction which describes the location and wave like behaviour of an e in an atom



What is the difference b w orbital



Have function contains all the

and















etc

4

4µm locate an e

wavefunction 4 dynamical info about the e ie its energy coordinates is characterised by 3 quantum numbers n eand m

Havefunction we

define its

a

has all the info about

e

but when we want to

n Land M and then it's called an orbital eg is

2s atomic orbital

42,0





Valence Bond theory

VBT

45

What is a covalent bond, and what characteristic gives it strength? And how can we explain molecular shapes based on the interactions of atomic orbitals? One very useful approach for answering these questions is based on quantum mechanics and called valence bond (VB) theory.





























A covalent bond is formed whenorbitalsoftwo atoms

overlap and a

pairof e overlapof

occupy the overlap region In the terminology of quantum mechanics the two orbitals means their functions are in phase constructiveinterference

VB T assumes that all bonds are localized bonds ie bonding e are fixed b w two This is actually an invalid assumption combining atoms eg A B because w 2atoms many atoms bond using delocalized e e which are not fixed b

Two other key concepts of VBT were developed later For the formationof a bond btw 2 atoms aeet Attractiveforce

Met repulsivetree

e

t

2 Resonance 2 Orbital Hybridization e

Repulsiveforces Aetraceiveforces





Overlapping of Atomic orbitals

When two atoms come close to each other, there is overlapping of atomic orbitals. This overlap may be positive, negative or zero depending upon the properties of overlapping of atomic orbitals. The various arrangements of s and p orbitals resulting in positive, negative and zero overlap are depicted here.

Overlapb w same phases

1 PositiveOverlap ie constructive interference



Overlapbtw opp phases

2 Negative overlap ie destructive interference



No effective overlap

3 Zero overlap

orbitals

of



46

















Natureof Covalent bonds SigmaBond

formed by axial

T or

and IT bonding

47

end toend overlap ofatomicorbitals

Leads to greater overlap b w orbitals and hence is a stronger bond

Is

Is





Internuclear axis



Two Hatoms

f­









Overlapping of orbitalstakes placealong the internuclear axis

the axis connecting the nuclei combining atoms of





Overlapping

ie Greater e density in b w the nuclei

Of S orbitals o

or

H H













Natureof Covalent bonds IT Bond

formed

r

and 1T bonding

by parallel orsideways overlapofatomicorbits

Extentof overlap is less



























Exampleof pit pit bonding

If Example of

us

so IT bond is weaker than

bond

s orbitals don't form it bonds

day

881 dry

2 lobes

only d orbital are in overlap

p of each participating

gfgffemanfiutoietibeasueo.es of each d orbital are PIT dit bonding

participating

in overlap







































formation of Ctly molecule

4g

as per VBT

A bond is formed between two atoms when both contribute one electroneach ie At 1B AMB Two half filled orbitals overlap to

1B Dl

G's configuration of C

Es

C

IS

Dt

25

ftp

off

give a bonded

2P

t H

can form only 2 bonds in ground state

9 9 9 t

pair

It hasonly 2 halffilledorbitals so it

4 f f

e

t

t

H H H

One e is excited from as Ip to give 4 unpairedorbitals toform 4bonds

4 halffilledorbitalsof Cand 4H overlap

Onebond is formed by Is 25 overlap threebonds are Is ap overlap

This means that all 4 bonds are not same 3 are similar and one is different







































50

But it's

experimentally confirmed that all C H bonds of Ulu are alike So in situations like this normal VBT is not successfuland we introduce a new concept

called Hybridization

t.TL

BEBEE P orbital

If

Mixing

iir

EEEEo EESE EEEEEEEEOEESE.no orbital 3 sp orbitals p orbital 2

s

I mix 2 bowls rice with 1 bowl dal and dothe cooking

I get

palace

So different orbitals

rice and dal when mixedtogether give a new set of equivalentorbitals Cpulao

Hybridization is the process where orbitals

ofslightly differentenergies like s Pd

intermix

to generate a new set of orbitals which are equivalent in energies shapeand size known as

hybrid orbitals like Pulao in the aboveexample







































52

Now let's discuss the formation of Ctly once again Is

c CGS C CES

25

ft ft off f

2p 9 t g g g

Ones andthree p orbitals mix to generate a new set of 4 hybrid orbitals sp'sorbitals

Hybridize

off

1

Is

These 4

Nowthese are

9 f f f t

Is

t

Is

no longer S or

p orbitals but are

sp3 orbitals having similarenergy and shape

t

Is

four hydrogen atoms ready to overlap with 4 sp3 orbitals of C atom to give Uty

sp orbitals axially overlap with Is orbitalsofH to form a

tetrahedral arrangement







































52

No of hybrid orbitals formed Hybridization

Stp

No

of participating orbitals

Noof hybridorbitalsformed

Bond angle

Geometry

sp

2

Linear

St Ptp

3

TrigonalPlanar

1200

St

sp2 p Ptp sp

4

Tetrahedral

109.50

of S character

sp3

sp

sp

501

33.39

Electronegativity

sp sp2 sp

Relative Overlap

sp

sp

sp

25

As

180

S orbital is closer to thenucleus the

greather the soloof a hybrid orbital

the lower its energy the smaller its size

p

higher its

Electronegativity







































53 Hybrid orbitals undergo better overlap compared to pureatomicorbitals this results in stronger and more stable bonds Geometry of a molecule is governed by hybridization bonds and not IT bonds Hybrid orbitals form

O S

A

t

CA

t

CA

t

S

O s

of

t

t

Be

Be Be

Sp Hybrid Orbital

CS

D

Ry

CA Ry

t

A

B

As p character increases the hybridorbital becomeslonger

sp2 Hybrid Orbital

I

sp3 Hybrid Orbital

























54 Totalenergy ofthe orbitals is not changed by the hybridization and energy each hybrid orbital of in a set is the mean of the energies of constituent Aos L

f

Unhybridized Orbitals

















formation 55 Ethane



H H

I l

H C H c

I 1

H H



Hoo



bonds

Each C atom has

like Chey it needs hybrid orbitals



axis

This bond is symmetrical along the internuclear

C C Now I hold one carbon atom fixed and rotate the

the carbonatoms

other it will not affect the overlap b w

bond ie rotation about c c is allowed

in yourhands formed BY

can visualize this byholding a pen withcaps

sp3 sp overlap and rotate the pen while keeping the cap pen fixed



of

four Usps

I

T

T

X

just

µ

if

you

of



formation Ethane



c

eg



holdthepenbody





H H



Cii

µ H

y

H



H

what you

see









of

GHG

56

c

This pen can be considered an example of bond here

g

12 HC

th

11

b

f

TH

rotate

the cap

to Youdidn't faceany problem ie

Rotation about a single bond is allowed 2 we will use this concept in stereochemistry

OD

eye Carbon

pear n or

I

Goo

Hold the front

at

cartebaornfansdonrobtyategoo

front carbon

j







formation

of

Ethene

57

Hy

































Each Carbonforms 4 bonds 2 bonds C H Require 3 orbitals is a bond C C Hybrid f it bond c C J Requires 1 p orbital

J

I se

be will excited

to2P

aroundState

I

these 3 orbitals will form

3 o bonds cloud is above the plane bond e IT halfof it molecule rest half is below

7 of

entire GHy molecule is

in one plane becamethe

shape of sp2 hybridization is trigonal planar Noofatoms in sameplane 6







































formation

of

Ethene

58

Hy

2porbitals

t

b

H

H e

Overlap oftwosp2hybridorbitals

forms the C C

Overlap

r bond

of sp2and

torms the

c H

Is orbital bond

H

H

f

cu

T H

ITbond

c

c C

H

H

of two 2p orbitals formsthe bonds are in the plane the of

Overlap

C C itbond

5 molecule but ITbond extends above and below the plane ofthe molecule

e density of ITbond is not concentrated on the

axis joining the two nuclei

Because the e density in a 7Tbond is fartherfrom

the two nuclei IT bonds are usually weaker







































59

Restricted Rotationabout IT bond

we have already learnt that rotation about bond is allowed Now let's understand what happens when we try to rotate about a T bond p orbitals ie sideways overlap IT bond is formed

of

by

As we start rotating

Rotate

f

gg

d

C

got

fixed the overlap blue p orbitals is

f

destroyed So rotationabout a it bond is restricted

d Cz

Fcf

by keeping a

Doublebonds are rigid and can't be

twisted

Rotateabout bond

bykeeping

one carbonfixed

of

Motagua

Neill use this concept

in geometrical

isomerism Sovisualise it clearly





60



















Does it mean that we can never rotate about it bond

IT bond results from sidewaysoverlapof porbitals When the two porbitals are parallel the overlap is maximum If one of the carbons is rotated about the c c bond the 900 when there can be no overlap between P orbitals decreases and becomes zero at

1T bond In other words rotation about the does not take place at normal temperature

















What is the meaning of

and

e

is a

high energy process which

in the lobes of orbitals

These lobes don't refer to positive or negative charges since bothlobesof an e cloud orbital must be negatively charged These are the signs of wave function 4 when two parts of an orbital are separated by a node 4always has oppsigns on the two sides of the node This also explains why s orbital has only or sign and not both like p orbitals



Ethyne Cs

formation

H C C H



180



carbon forms 4 bonds Each

I C H bond Requires 2



bond hybridorbitals I C c

2 C C ITbonds Requires 2



P orbitals

















Hz

of

Gl

y

f

se be

will

excited

4 atoms are linear Two IT bonds extendout from the axisof

the linear molecule







1

62

Trick for calculating Hybridization 1800

A

TRICK for Hybridization







Calculate no

E 1200 v

109.50

3



I

bonds

free lonepairs

Moreclarity on free lonepairs will comeafter nanee so don't worry if youdon't YYntifgyur.es



2

of











T

1 Free L P

2

3













4

sp

linear

sp2 Trig Planar sp3

5

sp3d

6

sp d2

Tetrahedral

TBP Octahedral

This is an easiermethod Detailedtheory is covered in chemical Bonding topic and dsp2

hybridization is covered in coordination compoun

topic







Trick for calculating Hybridization

63

TRICK for Hybridization







Calculate no













bonds

free lone pairs

Moreclarity on free lonepairs will comeafter don't Yeventingthrees.onance so don't worry if you T

Free L P

2

3















of

4

sp

linear

sp2 Trig Planar sp3

5

sp3d

G

sp3d2

Tetrahedral

TBP Octahedral





Calculating Hybridization in

H H

eg µ c q

µ c c H

µ I l



c 4

i s sp3



sp2



Cee _UL



Cte







Ut Sp a

p

U





G

ay ay

ay

As

cha ausps

64

organic molecules c

H

H

to LD

f

I

c H

N H

3

n

sp2

H

2

sp O p

Utz dps

I

Io zLp y i

I

11

H

spz

11

20 10 L P

4

I LP

3

attacks 2

Ips

2LP 3

sp2

o

P y

sp2 40 06 5

U a

Fps

sps

ab

Ips

ut cha 2

at

Vsp

I

at

at

Tey

or

t

thatyaall care sp2







































65

0 i

H or

Cte

30 0 up

stp3

Cee

or

y

CHP

i

µ

µqq

sp3

te

or

sp

ite

30 0LP

i sp2

the odd e isin pure p orbital

iii Vf

cee

Asp3

oteff

Vhf

Sps

Restallaresp

carbons

sp

dP

y

Restallaresps can

Sps

3ot2LP 4

E

Utz Slp Isps

sp2

o

µ

UF

O

o

08 spa0 o H

S OH 0 1 OH

To spa sp

µ O

sped

N

O 0

sp2













as CH CECH



























Determine the hybridization around the highlighted atoms in each molecule

b

c

Ctf

c

Utz

Seldane is a major drug forseasonalallergies Relenza is a common antiviral

I a

p

b

66

t

I

b Seldane

O

OH OH

throat Tf OH NH NH

0

Draw all the lonepairs of e in bothstructures

fd

7 MHz

NH

Relenza

Which orbitals overlap to form the covalent bonds indicated by arrows a b c and d







































67 as CH CECH

sp3 sp

b

NO

ttbcjcHz

pz ctez­jprVsp yo

no

sp sp Seldane

I i

Ipa

T.N.ie µµ O

Tsp

Il

ao

I

c

fd

T.N.tl

1.7142

Ipa

spa sp sp2 sp2 Relenza





Place















possesses

it in the following structures

CEC

c

N

a

es



















formal charge over any atom that

yO

b

H CEO

Q

Y

off NH

EJ't

US

Molecule

and

A

11

rub

N

Ctb

A contains

sp

carbons

d

UtzNH

t 0

I

Q

68

un

0

Ttb

Tan

t

4 Ctl

theobromine

sp2

Howmany lonepairs in theobromine

MHz

I

wane Il t µµTNXNHz 2 Melamine

Howmany lonepairs in

melamine





Solution to

Practice Problems



a













es



















CEC

0

b

69

t

y o.info Ill

yo

I

s

u

O

IX

NH

Hes

Molecule

and

A

N

A contains

6 sp's

carbons

0

8 sp2

Q

d

CtlzNHz

EI O

ab

ab

N

c

H CEO

Hq

Il X

II Mil

its No t

Uts Lonepairs _8

ivies in

I X

qq.HN

N

iiiiq

Lone pairs _6







































Quick Recap of MOT

70

MOT is very important theory to understand the phenomenon which involve molecular energy covered levels Its also based on quantum mechanical model atom and you must have of this in detail during chemical bonding getback here

If not

then brushup the basicsofMOTand then

Atomicorbitals Aos combine to give Mos

In phaseinteractions out ofphase

constructive interference

destructive interference

Bonding MO Antibonding

orbitals that contain pairof e which are not bonding bond Axial overlap sideways overlap

IT bond

Brno

MO

ABMO

or antibonding

higherenergy lower energy

Nonbonding orbital







































BondingOrbital

Antibonding Orbital

of

fo

Sigma overlap

Dt

f f t

f

it overlap



Molecular Orbitals 72

According to molecular orbital (MO) theory, when two AOs overlap, they combine to form two new orbitals called

molecular orbitals (MOs), and the electrons from the original AOs are now accommodated in the new MO(s).

Whereas AOs are localized on atoms, MOs are associated with molecules and sometimes extend over a whole

molecule.

The simplest example is the formation of the H–H bond

of a hydrogen molecule (H ), which involves the 2

interaction of the singly occupied 1s AOs of two H atoms.

When the two AOs of equal energy overlap, two MOs are

produced. One is lower in energy than the original AOs,

while the other is higher and the new MO of lower

energy becomes occupied by the two electrons (as per

Aufbau Rule) which were originally in the two AOs.

It is this pair of electrons which constitutes the covalent

bond . The H2 molecule is lower in energy (more stable)

than the two separate H atoms, and the energy

difference, which is liberated as heat, is the bond energy

of the H2 molecule.







Molecular Orbitals























why Bonding MO is more stable Because



is greater which reduces the repulsion b w



e cloud

btw 2 nuclei





73

in BMO e density blew the nuclei nuclei and provides stability



Molecular Orbitals



























why Antibonding MO are unstable

and hence repulsion b w the nuclei





74

In ABMO the

e density b w

the two nuclei is zero

is maximum This makes the ABMO Unstable



Molecular Orbitals













c





In a 1T bond the 2 e

and ABM0

stay in BMO

is empty



this empty DBrno will be

used in upcoming chapters

concepts like

to define etc

hyperconjugation in alkene



a

y

O

o

0

75



Bond strength

Bond length and

atoms comecloser to form a covalent

As 2 bond potentialenergy the system

decreases and reaches a minimum Point3

This point represents max stability

lowest energy and distance b w the

atoms at this point is called Bond

length



atoms comecloser than point3

the repulsiveforces b w their e clouds

become stronger than attractiveforces

system becomes unstable This

pushes the two atoms apart towards

3

point again

Bondlength

H H





of

If

of

76





77





4 Bond length 9 as we move down the group as distance b w

the nuclei 4



Bond

Energy The strength a covalent bond depends on the

the attraction b w the nuclei and shared e

magnitude of

The energy required to break the bond a particulartype is

known as bond energyCB E

Bored its an endothermic process breaking always requiresenergy



heat is

9 A BCgs absorbed Cgs A AH se KTImol



Bond energy

Greater the B E

strongerthe bond

of

of

Big















Average BondEnergies Kamel and bond lengths pm

Noneed to memorise gust for your reference

78















Bond length and Bond strength

2g BondOrder No bonds b w 2 atoms of

Increasing Bond length

g

yeah Increasing Bond Strength

Bonding e

c

eg

N

c

2

c

c

BO I BO 3 B0 _2



As bondorder 9 increases bond length

and bond becomes stronger

All C C don't have some bond length

as hybridization plays an importantrolehe



Clsp3 c ClspDtclsp2



Utz Utz eg Us at _Utz



1 53 1.55 Ao 1 Ug 1.52 Ao

same trend we find in c H bondlengths

sp



Antibonding e

in the table

As







































Bond length and Bond strength H

UtsUta H

f

Sp

80

I 111

PM

Ctf_qµ

This again confirms that s

f

spz

110pm

Asthe soloof carbon 4

Cte C H

I

sp

electrons are closer to

109PM

the nucleus

in the hybridization the bond length d





81









































82 shorter

sp

f















a

sp 3

shorter Shorter

I

Shorter

sp





















Br as

Br

II

pc

IIH

µ

PolarMolecule

b

IF

th

CpBr

H

Polar Molecule

F

IT

C

F

gt F

MR 0

sp3 4

p d's

f

c

U

Y

PolarMolecule

te e

UH

c

U H

µr

O







































83

Polarizability a

molecules that

very important property of

youmust havestudied during

Rajan's rules in

mical bonding let's have a quick recap ofthis as well

they respond to electricfields In particular e in molecules are so their positions can shift to different extents when any external

Since e are charged particles

mobile to varying degrees

electric field dueto a charge is nearby

g

e e

e

e

e

a simple representation

of a neutral atom

e

Red

Blue

recharge e

cloud

e density has shifted duetothe presence of ve charge nearby This is called polarization ie development of ve

It has a symmetrical

distribution of charge in the absence

ofany external electricfield

St

e

Place a

cation

near this

atom

s e

e

e

t

e

e

PositivePole

and ve poles

NegativePole

F







































84 So polarization is distortion or shifting of e density due to an electricfield nearby In the previous example the neutralatomgot polarized by the cation So cation has a polarizing power and the neutralatom has ability to get polarized ie polarizability Now its the size of atom anion is bigthen its outermost e easy to visualise that

very if cloud is far from the nucleus and loosely bound So it has higher tendency to get polarized ie higher polarizability Whereas in smalleratomsfanions the e cloud is more tightly held

thus making them less polarizable Upon polarization

a dipole is induced in

the moleculeadding to

any permanentdipolealready

present

This polarization caused byexternalinfluence is temporary ie as soon as i remove that external electricfield the atom goes back to original state symmetrical distribution of e cloud

of







































85 We define the polarizability of a molecule as the magnitude of the dipoleinduced by one unit of field gradient Bigger the size ofatomlanion smaller the cation Atomic Polarizability

e

higher the polarizing power N S O

C

O 80

loIO

1076

I

higherthe polarizability

7 Br

47

P 3 13

7 U

3.05

s 2.90

2 18

H 0.66

F 7 He 0.55 0.20

asperCRChandbook

A 0.55

polarizability

across a

period

4 down the group







































86 Polarizability hasprofound consequences whichyou'll encounter in induced dipole nucleophilicity etc water is a very polarmolecule However methane is much more polarizable than water

This explains the difference b w

µ

fo O

H

I HR

polarity

and polarizability

H

i

II

H

o_0

n

St S E bonds are much more reactivethan C Cl bonds in reactions like

St S

C

t

Lesspolar

Morepolarizable

Alkenes

t

MorePolar

Snf and

EZ

which you will study later

lesspolarizable

arenes with themore E N sp2carbons are lesspolarizablethanalkanes withonly sp3

carbons











Differentmethodsof representing molecularstructures

gy

Wecan represent molecularstructuresthroughdifferent ways lewisstructure structuralformula condensed formula or

line angledrawing



Uts

Ues Ut ut

U





CteCte U Ut Ut3 z









U





Uf

b

te

H





t

Carbon







































88



Determine the geometry around









a

Uy

di Ctb

b

all

second row elements in

Ctf Cte OH

c

d

MHz

Predict the indicated bond angles in each compound









a

un H Utz CEC nu

b

Clea

nu

c

Cee

a

e

TI

b

t

I

c

g

µ

N

les C Br

HH

convert each skeletal structure into a complete structure

showing















Utz

89

H

H

les c Br

eachof following compounds

all C's H's and lonepairs d

me

quo N.lk X

h































Determine the geometry around



sp2

a

Ue n

I

116 If Uab

Isps

sp

Trigonal Planar about central carbonatom

by

all

second row elements in

Do

SP

sps

fo N

c

Maginn l te

Tetrahedral around

both C andoxygen

n't

1800

ay

Br

sp2 TrigonalPlanar

H

d

O

H te

H

sp

I

µ

sp

SP3

Tetrahedraland

Tetrahedral

linear



Predict the indicated bond angles in each compound

1800 1200

If b c Cees H as 58421200

A

90

eachof following compounds

H 09.50

I

Uy

fH

Br ale angle are 7109.50 Slight

deviation will be because of different groups





a

































ctfu de de

o

Utz

b

l

92

l UI

Utz

I

cee

91

c

cuz

ab

ai

I

ab ii Macey

I

O 11

µ

H

C te

e

ai

okayEmme

Cee

lay

eee

9

h

equine.ie

t

dnue

o

I

H

Ig

Hi

u o

g

cygni H

Ue

o

d

91

OH

te

0

Utz H







orbitals What

a UtzBelt

Predict

the hybridization and







a

I

b

of

geometry aroundeach highlighted atom

d

c



a



















92

are used to form each bond in the followingmolecules C Uy O Ctb b W B

Amoxicillin

Nate

Predictthe hybridization and geometryaround each

highlighted atom b Label 5 polar bonds using c

e

Howmany

St and 8

and it bonds does amoxicillinhave





ay











I

µ

11C

1

s overlap

sp

H

c

2

Bee

H

2

sp3 sp overlap Be c

3

s overlap

SP

Be H























H

y

uf

nel care sp Tetrahedral

are

Till LF

ai

O Ctl

00

I

B

ab

sp3

g sp

Ttb

c

sp3

G H

I

H

H H

All care sp2 Trigonal Planar

Ut

Utz

c µ bonds

c te bonds are sp3 s B C bonds are sp2 sp

cee

Tetrahedral

2

e

O

nee cand 0

sp

by

H

b

c Haug 8cg

Cys

sp

c O bonds

H d

HY

SP

sp3

s

sp

Tetrahedral

c

sp linear

µ





sp2

a

f































sp3

sp

P

I

2

sp

Esp2

Polarbonds are highlighted in green bonds 46





IT bonds

6

94



forces 95

Intermolecular

Tries to keep molecules closer between molecules Intermolecular



Intramolecular within same molecule 7 Holds atoms together to make a molecule eg



Intermolecularforces AHect the MetallicBond covalentBond Strength IonicBond

KUMM 400 4000

and chemical properties physical 150 1100 75 1000

molecules point example Nau eg melting boiling Fe Ni Hz Uz Cay

etc reactivity basicity acidity

Cary Ctey etc Ag Pt

behavior the threestate is Physical

Bondingforces ionic covalent metallic are intramolecular because the strength intermere

different are much stronger than intermolecular forces b'coz

cellar forces differfrom stateto state

the e density involved in bonding is veryclosebut in

intermolecular forces thedistance b w the e Ion dipole

density is large

rebond



Dipole dipole

DipoleInduceddipole



Dispersion Londonforces

of

of

of







































Intermolecular forces

Ion Dipole forces

96

M be attractive or repulsive but repulsiveforces come into playonly when molecules come so close that their

e clouds start overlapping

forces they are attractiveforces These forcesaffect physical properties St

St

S

S

t St

g

s

8

g g

This is why most time when we discuss intermolecular of

of organic

molecules

St Attractive forces b w cation

polarmolecules

etc

molecules

g

s

St St

St

g

g St

S

S

8

H2O molecule

Nat

8

U

ions are surrounded by H2O St S

mp

eg boilingpoint meltingpoint solubility

simplest example there of forces is when we dissolve

Nacl in water Nat g

bp

U

Attractive forces b w anion

polarmolecules







be



through solubility water



in easily

solids Understood forces



dipole

ion













creditsErebor Mountain

Shutterstock





97 S

ionic of can

St

H

s

u

0

Na

ly si St

S

O

U

st

H

s

O

H

s1

g

O

test

H

H

Watermolecules polar attract the ions from the crystal and hydrate savate

them The forces b w water molecules and ions are won dipole forces

Thetotal energy released during the interaction water and ions is called

of

the HydrationEnergy



Dipoleforces 98

Dipole



These are electrostatic interactions b w moleculeswhich St S St S St S

have permanentdipoles eg Chaz HI MHz HCl etc

oppositely charged ends attractandalign

stronger than London dispersionforces but weakerthan

5 25 KHmol strength ion ion ion dipoleforces as only partial charges are



involved



When oppositely charged ends are aligned the attraction A and P E 14



Nonpolarmolecules don't engage in dipole dipole interactions eg coz Cay etc



strong dipole dipoleforces result in higher boiling meltingpoints and also affect other properties



St St St

S St S S St St S S S H H

H

eg U U U H U H U H G

H H H





I

9

µgc

µgC

µqc

















These forces depend on the magnitude

similar Mol wt BP K

ainolar mass

46

Abusing

Uhs o Ue 248

50.48

Uy U 249

Source: chem.libretexts.org



for compounds of

gg

the greater the molecular dipolemoment greater the dipole dipoleforces

Uh 231

ofthe

molecular dipole moment

44 Cee

I

294

41 H

Uy EN 355



100 Hydrogen Bond



Its a special case dipoledipoleforces strongerthan ordinary dipoledipoleforces



It requires H atom bonded to a small highly E N atom specifically 0 N F



S St St S

A H 01h11F B Notany random H can form H bonds Hydrogen which is



Hbond already part a dipole can participate in tebonding with



N O or F St

S S St O H

N H St S S S St S S St S g St S

S g si g g Sf Sf f N H H

St S St

S Ho F H

O

c Hoo o O H X it U also has E.nl comparable to N but



doesn't normally participate in te bonding Nopolarity in this

bond

High E N and small size of NO F create greater St

charge on their covalently bonded H



of

T

of

why



lol

Unique properties Hydrogen that facilitate this uniqueinteraction are electropositivity smallsize



absenceof inner e shells These properties allow X and D to approach eachother closely

without experiencing

X H D any severe repulsion



Intramolecular H bonding tebonding that exists within the same molecule



Intermolecular H H bonding that exists between 2 ditt molecules bonding



ar H D 90

O I O Hoo N µ

e H F I 11 d



o

H H H I o

N XO H O O

µ 0 17 Every water molecule can

para nitrophenol

4 H bonds form



Intermolecular H bonding Intramolecular H bonding



of

g

Neo

If

ie

Enke

no

EIl







































102 bonding EHectsofH

Melting and boilingpoints H2O

H2S L Hase

HF 77 HU C HBR PHz

AsHz

Nitze MHz

Urea is

NHS

Hate HI

SbHz

Boiling Point H2O UtzOH 76450 Utz 100C

63C

T

5C

Y

3 H bonds y µ bonds permolecule permolecule

solid while Uts

E Cte

acetone is

Hf CtbUf F ROOM ROH

No H bonding b w ethermolecules

liquid

Amines are more watersoluble than alcohols of comparable mol wt bcoz aminesact as a better donor group in

H bonding solubility

H bonding with water

4 viscosity and

affects acidity

µ

µ

qµ

stronger

H

R

H

Oy

weaker



London Dispersionforces Intermolecular forces 103



So we've discussed the forces between polar molecules but what about the forces that

operate between non polar molecules eg noble gases alkanes Uz Br etc

Intermolecular force blue non polar molecules is Londondispersionforces or weak VanDer



Waal's forces



Theseforces are weakest and exist in all substances polar or nonpolar But since they



are very weak we don't normallymention them in polarsubstances



These forces result from the motion e so they are present between all particles atoms



Ions and molecules Atanyinstant e density on one side atom

of

No inherent polarity can be than the e greater

density on opp in this atom side



But the e in an atom this will create a momentary dipole

are moving randomly all in the atom and this momentary

the time

dipole will polarize the neighbouringatom



far

of







































104

This process spreads through all

atoms in the sample

and weak attractive forces b w these

induced dipole come into action These are dispersionforces or weak V D W forces

S

St ooo

Nodipole

ooo

a momentary

ooo

ooo

S

St ooo

9

dipole is created due to randomlymoving e cloud

S

St

Adipole

is induced

in this atom

eventually theseatoms induce dipole in other nearby particles

when particles are close very weak forces and are effective only at low temperature and have less thermal energy to escape from attractiveforces

These are

Londonforces

9 with polarizability

ie biggermolecules or the ones with more surface area have stronger London forces







































105 strength

of

London dispersion forces

Polarizability of the particles

I

depends on no

ofe

which is greaterin particle

with highermolar mass Dispersionforces

9 with mol wt

ie

Ho L C Hg L CyHo He L Ne s Ar L Kr L Xe

Chey

Fz

U

Brz

L Iz

Exceptforthe forces b w small highlypolarmolecules or blue molecules forming Hbonds the dispersion force is the dominant intermolecularforce e.g In HCl

85 attraction is dueto dispersionforces and 15

due to dipoledipoleforces





106

what

if two































e.g

molecules non

polar havesame molarmass

like isomers

one with greater surface area has greater dispersion forces n pentane

and

neo pentane

Branchingi reduces surface area

same

molar mass

straightchain has greater surface area among isomers

Neopentane n pentane

Hawk ayub bp 36.1 C

GreaterSurfaceArea

Uts Joab

f

Utz

Utz

bp g 5 C lessersurface area







































107

Geckos

How walls on stick Vander Wallsforces

A Gecko's foot has toepadsconsisting of about half a million setae made keratin Eachofthesefinehairs hashundreds of of even smaller projections

protruding

of nanoscale diameterscalledspatulae

fromtheir ends

The VanderWaals forees created b w

the spatulae and the surface In the case of geckofeet the spatulae are

so small and get so close to the surface that an attractive VanderWaals

forceofaround 0 UµN develops b w a singlespatulaand a surface

Credits marimalShutterstock





































each substance for identify the



has the higher boilingpoint

MgUz

a

a

Mga

or

Pcl3

consists

of Mg

b

108

keyintermolecularforceIs and predictwhichone ofthe pair CtlNHz Or

Uff

c

UtzOH

b

Utz

and U ions held togetherbyionic bonding forces Pcl

polar molecules so intermolecular dipole dipole forces are present stronger so

or

H

consists

of

Theforces in Mgelz are

it should have a higher boiling point

AGNHz and Uff both consist of polarmolecules ofabout the same molarmass UtsMHz has N H bonds so it can form H bonds but Utz f can'tform H bonds









would

Both

BE or II be expected tohave the higher boilingpoint moleculeshavesame no of e but IU has a dipole moment ofthese



a Can a molecule havedipolemoment









b How is it a No

possible

b

if it has no polarcovalentbonds

for a molecule tohave polar bonds but

If the

various polarbonds are symmetrically placed and their vector sum



down a fewproperties list of water that





High m p

bp

highspecificheat



Which





no dipolemoment

is coming out to be zero then the molecule will be non polar eg coz Cay etc

ay

Og

originate because of

H bonding

highheat of vaporization lowdensityofice compared to water

makeswater a good coolant

of followingmolecules can exhibit

H bonding

etc

a

CtesuezOH

b

Utz o Utz





























c ClyNHz

ctbUfOH

it

8

UtzNHz as 2 Hare bonded to N

CMU

and

e

UHH

h

CHU

110

OH

has no H directly bonded to an EN atom but still it shows H bonding Hydrogen atom should have ve polarity on it to participate in H bonding This

Although Clea

bcoz

can also be achieved

eg

U

UTC I

Q



Calculate







f

d LettsgN

OH

a

c atom is bonded to multiple EM atom as in case of Cetus

if

St

H

p

s O

This example shows

1413

c

Hbond

H bonding blue chloroform

ab

Ulcers

and

acetone

the max number of atoms that are planar in the following molecules

Ctf Utz

b

Ctfu

c

Cte

Cte

Utz

d

Benzene

e

Ctf 1

642





a





F pnfjrnee7 mn





1 c

CIC

y H



atoms in

one plane

X Hl

42

C



H

c

by

H

G H

o

Hd

ttI

C BACK

H H

outofPlane H







FRONT



c c

C

c c

c

H

3patfnns.in

H

6 carbons and

6 hydrogens are in sameplane

one

H

e

Ht C

H

All

H

Importance

H

d

y

111

yBackoftheplane

pyke

afonmssanaYepianar

H5

H

pFanne

SH

Z

C u

C s

H

H

b atomsare planar

This moleculebelongsto Allene family





the hydrogens on end carbonatoms in uy why



































µ

C

g

TH

C

lµ

The p orbital overlapping

verticalPlane

C CHz

sp has 2purep

orbitalsformaking 2 IT bonds

C

ay d

pz

d d

p2

IT bonds

Py

Utz

O d

Py

In adjacent 1Tbond systems Callenes adjacent ITbonds in 1 planes

C

ie

T

q

for IT bond is 1 to the sp2carbonatoms

4

C

2

Uk are in 1 planes

this C forms 2

1C

Uy

c

942 c Ctez

HorizontalPlane

Uj

c

c

cHz

this figureclearly explains that 21T bonds formed by central Catom have to be in 1 planes c te bonds are present in the plane 1 to the 1T e cloud Utzgroups are in 1 planes





113

Howdoes molecular polarity affect physical properties

of compounds































Molecule having higher polarity

has higher boilingpoint

More energy is required to separatethem

Greater the intermolecular attractive forces

More polarity 9 the solubility in polarsolvents

like dissolves like

less polarity In the solubility in less polar1nonpolar solvents

He

leads to higher melting a boilingpoint





what type



114

of intermolecular forces are present in eachcompound







a

In

b

c

Note

d

e

which compound in each pair has the higher boilingpoint

























a

C

e

N

or

or

koµ

7 or

H

b

d

0

Iko

ay

f

dy

or

OH

d

W

or

free

or

M

Az

ace



115



a











c

Koµ

H bonding

d

lesser

dispersionforces

higher bp

e

or

koµ

b

compact

greater Dispersionforces

dipole dipole

Higher bp or

Hbonding GreaterBp

omg

i

Dipole Dipoleforces

Dipole Dipole e

Te

highersurfacearea C

there is some polarity

y µ

or

f

Due to presenceof N

b

Dispersionforces

dipole dipole



a





















No polarity

d

f

onlydipoledipole

w

free

h

Dipole Dipoleforces

or

OH

K

q

onlydispersion forces

higher b p

o

or

bonding i Higher b p

Biggermolecule greater dispersionforces

I higher B P

has biggeratom I i

Greater dispersionforces



116

Functional Groups in Organic chemistry

Most c bonds These bonds are strong non polar and not organiccompounds have C and C H

brokeneasily But apartfrom C and H organic compounds sometimes have 0 N S P and

halogens Atoms other than C and H are called Heteroatom

T

different



S OH Cte 692 0 H NH

eog



what differentiates these molecules

to

structural

features like heteroatoms it bonds carbon chain etc



These structural features decide the geometry reactivity physicalproperties molecules



Coote group

eg carboxylicacids are acidic due to





Utz

Utz

Utz

Clb

di

ay

di Utz

I

of



117



Functional the characteristic physical chemical group is a group atoms that is responsible

properties the compound In simple words F G decideshow a particular class compounds

alcohols are due to OH group

react OH is functional group Typical reactions

COOH carboxylicacids are due to COOHgroup







Functional Group

Onecompound can have more than one f G as well R



carbon ReactivePart

N OH µ

Skeleton

OH 0

11

2

Br



HO

CHO

Highlighted groups are AG

of eg

for

of

of

of

T

tycoon

I

f

INCOOR

T







































Typeof Compound

GeneralStructure

Example

Alkane

R H

Alkene

4 4

Uez cH Utz

Alkyne

CEC

Hec Cte

AlkylHalide

functional Group

Uy UtzUes c

c c

R X

ay ay

Alcohol

R OH

cte5UyOH

OH CHydroxygroup

Ether

RO R

Ues O Utz

OR Alkoxy group

Amine

R NHz RzNH

UtzMHz

MHz aminogroup

Ryn

G 3N

Thiol

X f U Br I

R SH

118

Br

UtzzMH

Uhs SH

X Halogroup

SH

MercaptoGroup







































Sulphide

R S R

Utz Stetz

0 11

O 11 Uys C H

O

O 11 Cee C cute

Aldehyde

r C H

Ketone

11 R C R

Carboxylicacid

11 R C OH

0

0

Esler

11

RC o R

O

11

cage o te O C Cee O Ub 11

O

Amide

R

11 c MHz

O

Acidchloride

11 R c a

O

Utz

11 C

MHz

O

11

chest a

SR alkylthiogroup O

11 c H

die O 11 C

ote

O

11 C o

O 11 C

O

11 C

Y u

carbonylgroup

carboxy group

119



carbon and Hydrogen atoms 120

Types

Based on the number carbonatom connected to a particular carbonatom we classify it as

primary lo secondary120 tertiary 5 or quaternary Cli



which is bonded to only 2 carbonatom

10 or Primary carbon

e.g 20 or secondarycarbon 2 which is bonded to only 2 carbonatoms

C c

I 1 30 or tertiary carbon 2 which is bonded to

c only 3 carbonatoms

10 or Primary U or Quaternary carbon which is bonded to 4 carbonatoms 20orsecondary



lo C C Uy

lo Gt3 l lo Cte f lo 20

I lo I CC CC Ctl c Cc c Uf

l 30 so l

e e

61220 40 orQuaternary

5 or Tertiary

Utz to





of

of

d

d

Ctf

yes quoth Uy ab 1







Degree



CHS



























121

of

H atom

Ctf 20

CH 10

Degreeof Catom to which 10 Hydrogen

20 Hydrogen

6

it is

go

2

connected

to

Cle

Utz de 8

µ

Uf Ctl 20

10Hydrogens

g

20 Hydrogens

2

30 Hydrogen

I



122

Solubility



called solvent the extent towhich a compound called the solute dissolves in a



ie Pandit dissolve

Like dissolves like ie polarcompoundsdissolve in polarsolvents and nonpolarsolutes in non polar

solvents



Polar solvent as it has polarity can form H bonds Haler



Organicsolvents Mostly are non polar e.g Cay hexane benzene or are weaklypolar

e

g UtzO Ctb Oil

oil acetone



oil layer



water water

organicsolvent



dissolves oil non polar oil non polar

Nacl ionic

dissolves in doesn't dissolve in water bothare polar organicsolvent nonpolar

in water bcoz

if

liquid

IHT

Nacl

f

f







































123 students sometimes wonder that

it

dissolves in water so easily

if

NaCl hasionic bonding which is

and

breaks

strongestthen how come

the ionic bonds b w Nat and I

No doubt that ion ion interactions in ionic solid like NaCl are strong but when added to water each icon is surrounded by so many water molecules through iondipole

interactions Though these forces ion dipole are weaker there are so many ofthem

that they compensate for the stronger ionic bonds H

St

St

H

H OS

St

H

1

l

s 0

8O

1

st

H

St H

O H

1st St l H

H

solvation hydration

o

l

St

ofcation

H

StHl s

s

St

S O

St

S St O µ h

St

H

g1

H og

H

St

l

H ft

Solvation hydration

of anion







































Mostorganiccompounds are soluble in organic solvents is water solubleonly

five carbon atoms

if

it contains one polarfunctional group

p

Non polar

Nonpolar Hydrophobic

Anorganiccompound

Nor 0 containing

110

OH

Hydrophilic

waterloving

4

Hydrophobic

waterhating

Hydrophilic

Carbonchain hydrophobic should not be verylong

the substance has to dissolve in water

Cay

Soluble

Insoluble

forevery

polarhead can form H bond with water

if

Cay

f

Polarhead

Tail

Hydrophobic

Butane

124

it contains COOH

water hating

like

dissolveslike

Acetone

f

H2O

Soluble

Soluble







































O 11

Acetone has

125

carbons and a polar in functional groups which makes it capable only 3 of H bonding with water In fact acetone is so soluble in water that acetone and water are miscible they form solution in all proportions with each other

s

s1

H

S

o

µ

Ls

0

H

HO

Utz OH

slightlysoluble very in water b'coz carbonchain hydrophobic is small as Cchaingetsbigger

OH

Insoluble in water as c chain is very

big

04

Khao boy

NOH

soluble inwater

µ bond

OH

but

St

note

Glucose

is

far

carbon chain is bigger but we

have 5 OH groups

f Benzoicacid

water Insoluble Bigcarbon chain

we

d

OH

Aceticacid WaterSoluble







































That's it

for organic

the

basics of

chemistry

but

dost abhi mere Picture hai See u baaki

in next book