NFTF WEEK 1,2,3

Write a condensed structural formula for
2–methylbutane.

HHHH

H CCCCH

H C H H
H H

H

Write 5 different ways to write the structure.

51

Write a condensed structural formula for
2,3–dimethylpentane.

H

HCH

HH HH

H CC CC CH

H HHH
HC H

H

Write five different ways to write the structure.

52

MULTIPLE BONDS IN CONDENSED STRUCTURE

Show double bond and triple bond

EXAMPLE: propene (C3H6)

H CH2═CHCH3
HCCCH condensed structure

HHH

expanded structure

53

Write a condensed structural formula for
isoprene (C5H8).

HH
H

H CCCC

H CH H

H

54

Convert each condensed formula to an
expanded structure:

a) (CH3)2CHOCH2CH2CH2OH 55

b) H H
C

H OH
CC

HH

SKELETAL STRUCTURE

C chains are drawn zigzag, and
rings are drawn as polygons

C atoms are usually not shown

C atom assumed to be at each intersections
of two lines (bonds) and at the end of each
line

H atoms bonded to C are not shown

Functional groups are shown

56

EXAMPLE: skeletal structure

expanded structure : C atom
HHHH
Cl
H CCCCH
H HH 57
HCH
H
H HH

H C C C C Cl
HH
HC H
H

EXAMPLE: skeletal structure
expanded structure
OH
HH : C atom

H C O–H N
CC
58
HH

H HH

H CNCCH

HH H
HC H

H

(CH3)2C═CHCH2Cl Good technique:
Outline the carbon
skeleton first!

C C C C Cl Cl
C
59

CARBON SKELETON

Good technique:
Outline the carbon skeleton first!
(determine the longest C chain)
Then, draw the proper structures

60

Outline the C skeleton of the following 61
condensed structure formula and then
write each as a skeletal structure:

a) (CH3)2CHCH2CH3
b) (CH3)2CHCH2CH2OH
c) (CH3)2C═CHCH2CH3
d) CH3CH2CH2CH2CH3
e) CH3CH2CHOHCH2CH3
f) CH2═C(CH2CH3)2
g) CH3COCH2CH2CH2CH3
h) CH3CHClCH2CH(CH3)2

Convert OH into a:

Expanded and a condensed structure.

62

CLASSIFICATION OF C ATOMS

Focus only for sp3 C atom (all single bonds)

CC C C
C

primary carbon (1o) secondary carbon (2o)

Number of C atoms Number of C atoms
attached to it = 1 attached to it = 2

C C

CC C CC

C C

tertiary carbon (3o) quaternary carbon (4o)

Number of C atoms Number of C atoms
attached to it = 3 63

attached to it = 4

EXAMPLE:

How many 1o, 2o, 3o and 4o carbon in the following
alkane?

ANS: 4o 3o
1o C = 6 3o
2o C = 2
3o C = 2
4o C = 1

64

Identify the kinds of carbons (1o, 2o, 3o, or 4o)
in the following molecules. Label at each C atom.

(a) CH3 (b) CH3 (c) CH3

CH3CHCH2CH3 (CH3)3CCH2CH2CH

CH3

(d) (e)

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No classification for C atoms in methane and
in multiple bonds

EXAMPLE: 1o H correct
C 1o
H H3C
C
1o
H CH3
H CH
2–butene

H H3C 2o 2o H
CC
methane
H2–buteneCH3
66

CLASSIFICATION OF H ATOMS

Depending on type of C atom it attached to:
 H atom (1o) attached to C atom (1o)
 H atom (2o) attached to C atom (2o)
 H atom (3o) attached to C atom (3o)

No such thing as quaternary H (4o)!

C quaternary carbon (4o)

C CC No hydrogen!
C
67

EXAMPLE:

How many 1o, 2o, 3o hydrogen in the following
alkane?

CH3CHCH2CH3

CH3

H (3o) (CH) H (2o) (CH2)

H H HH H (1o) (CH3)

H (1o) (CH3) CC CC H

H H HH 68
HCH
ANS:
1o H = 9 H H (1o) (CH3)
2o H = 2
3o H = 1

Identify the kinds of hydrogens (1o, 2o or 3o)
in the following molecules.
Label at the H atoms.

(a) (b) H H
H
CH3 H3C CC

CH3CHCHCH2CH2CH3 H2C CH2
CH2CH3 H2C
CH
C CH3

H3C H

69

ISOMERISM

The existance of chemical compounds that have
same molecular formula but different molecular
structure or arrangement in space

ISOMERISM

(different compound with
same molecular formula)

constitutional stereoisomerism
isomerism
(same connectivity, but
(different in connectivity)
different arrangement

in space) 70

CONSTITUTIONAL ISOMERISM

Compounds with same molecular formula
whose atoms are connected differently
Also called structural isomerism

Type of structural isomerism
chain isomerism
functional group isomerism
positional isomerism

71

CHAIN ISOMERISM

due to different in carbon skeleton

EXAMPLE:

Molecular formula = C4H10

CH3

C1 H3 C2 H2 C3 H2 C4 H3 C1 H3 CH C3 H3

butane 2

2–methylpropane

72

EXAMPLE: Check the location
Molecular formula = C6H14 of alkyl groups!

Longest C chain = 6 C
CCCCCC

Longest C chain = 5 C

1 23 45 1 23 45

CCCCC CCCCC

CC

Longest C chain = 4 C

1 23 4 C

CCCC 12 3 4

CCCC

CC 73

C

ANSWER: Total five
Constitutional isomers

CH3—CH2—CH2—CH2—CH2—CH3

hexane

CH3—CH—CH2—CH2—CH3 CH3—CH2—CH—CH2—CH3

CH3 CH3

2–methylpentane 3–methylpentane

CH3—CH—CH—CH3 CH3
CH3 CH3 CH3—C—CH2—CH3

2,3–dimethylbutane CH3

2,2–dimethylbutane74

You must be able to recognize when
two different–looking structure are actually

the same molecule written in different way!

EXAMPLE: Molecular formula = C5H12

CH3—CH—CH2—CH3 CH3 CH3
CH3 CH3—CH—CH2—CH3

CH3—CH2—CH—CH3 CH3
CH3—CH2—CH—CH3 CH—CH2—CH3
CH3
CH3

All is the structures is actually 2–methylbutane75 !

How many structural isomers (chain isomer)
does pentane, C5H12, have?

Draw all the five constitutional isomers of
cycloalkanes with formula C5H10.

76

POSITIONAL ISOMERISM

due to different position of functional group

EXAMPLE:

Molecular formula = C3H8O

32 1 32 1

CH3 C H2 CH2 OH CH3 C H CH3

1–propanol OH
2–propanol

Both isomers have same

carbon skeleton. They are only different
in the position of –OH group!

77

FUNCTIONAL GROUPS ISOMERISM

due to different functional group
EXAMPLE:
Molecular formula = C2H6O

CH3 CH2 OH CH3 O CH3

ethanol dimethyl ether

Molecular formula = C3H6O
OO

CH3 CH2 CH CH3 C CH3 78
propanal propanone

General Classes of
Formula compounds
CnH2n+2O
CnH2nO Alcohol and ether
Aldehyde and
CnH2n ketone
Alkene and
CnH2nO2 cycloalkane
Carboxylic acid
and ester

79

Draw all isomers that have molecular formula
C5H11Br ( Hint: There are eight isomers ).

Write the structural formula for constitutional
isomers with molecular formula:

a) C3H6O2
b) C4H8O

80

CH3—CH2—CH2—CH2—OH CH3—CH—CH2—CH3

1–butanol OH

2–butanol

CH3—CH—CH2—OH CH3—O—CH2—CH2—CH3
methyl propyl ether
CH3

2–methyl–1–propanol

The word ―chain isomerism‖, ―position isomerism‖
and―functional group isomerism‖ describe the

relationship between two or more isomers

In general, they all called constitutional isomers

81

82

1.4 Basic Reactions In Organic Compounds
State the type of reactions in organic:

i. free radicals
ii. electrophiles
iii. nucleophiles

Addition Elimination

GENERAL TYPES OF
ORGANIC REACTIONS

Substitution Rearrangement

INFO

Arrow types in chemical reactions:

 reaction (reactant  product)
 equilibrium
 resonance structures
 movement of an electron pair
 movement of a single electron

4 main types of chemical reactions

Elimination Rearrangement
Substitution
Addition
electrophilic electrophilic
nucleophilic
nucleophilic

Free radical 85

POLARITY OF REACTION

Reactions in which a nucleophile reacts
with an electrophile

EXAMPLE:
electrophile nucleophile
CH3CH2Cd+H2—Bd–r + CN–  CH3CH2CH2CN + Br–

86

ADDITION REACTIAONreaction in which atoms or gro
add to adjacent atoms of a multi
All parts of the adbdoinndg (rdeaoguebnlet aoprpteriaprleinbtohned).
product

Two molecules become one

Characteristic reaction of compounds with
multiple bonds

• involve breaking of one p bond

to form two sigma bonds

ELECTROPHILIC ADDITION

Reactions involving C═C and C≡C

p bonds are electron–rich and located above
and below the plane of the bond
 susceptible to attack by electrophiles

Example: HH
HCCH
HH + Br Br
Br Br
CC

HH

H H + H Cl HH
C C HCCH

H H H Cl

NUCLEOPHILIC ADDITION

Most common reaction of aldehydes and
ketones

Nucleophile approach to the electrophilic
C of carbonyl group

d+ ●●Nu

C O d–

or

Example: ●●O●●●●– H+ OH
RCH RCH
●●O ●●
R C R’ + H– R’ R’

ketone/aldehyde alcohol

nucleophile

O CH3OH O + HCl

C C OCH3
CH3 Cl CH3

an acid chloride ester

SUBSTITUTION REACTION

Two reactants exchange parts to give new
products

Characteristic reaction of saturated and
aromatic compounds

Example: light H
H C Cl + H Cl
H
H C H + Cl Cl H

H

methane chloromethane
(an alkane) (an alkyl halide)

ELECTROPHILIC SUBSTITUTION

The characteristic of all aromatic compounds
Benzene has six p electrons delocalized in
six p orbitals that overlap above and below
plane of the ring (electron–rich)
 susceptible to attack by electrophiles

benzene

Example:

+ Br Br FeBr3 Br H Br
+

benzene bromobenzene

NUCLEOPHILIC SUBSTITUTION

Most common reaction of alkyl halides
(haloalkanes)

Nu:– + d+ d– R–Nu + X–

R–X

Example:

HO– + CH3–I  CH3–OH + I–
I– + CH2CH3–Cl  CH3CH2–I + Cl–

FREE RADICAL SUBSTITUTION

 Most common reaction of alkanes

EXAMPLE:

Cl2 Cl
light chlorocyclohexane

cyclohexane

ELIMINATION REACTION

Opposite of addition reaction

A single reactant splits into two products

Method for preparing compounds with double
and triple bonds

Example: base HH + H Br
CC
H Br small
HH molecule
HCCH eliminated
ethylene
HH (an alkene)

bromoethane
(an alkyl halide)

REARRANGEMENT REACTION

A single reactant undergoes a reorganization of
bonds and atoms

Example:

CH3CH2 H acid catalyst H3C H
C C C C

H H H CH3

1–butene 2–butene

SUMMARY OF TYPES OF ORGANIC
REACTIONS

Electrophilic addition  alkenes, alkynes

Electrophilic substitution  aromatic
compounds

Nucleophilic addition  aldehydes,
Nucleophilic substitution ketones
Free radical substitution
alkyl halides,
derivatives of
carboxylic acids

 alkanes

Addition Elimination Substitution Rearrangement
(R-OH, RX  (Rxn involve C+ / C
alkene) intermediates)

electrophilic electrophilic
(alkene/alkyne) (aromatic ring)

nucleophilic nucleophilic
(aldehyde/ketone) (R-OH, R-X)

Free radical 99
(alkane)

Classify each of the following reactions as an
addition, elimination, substitution, or
rearrangement:
a) CH3Br + KOH  CH3OH + KBr
b) CH3CH2OH  H2C═CH2 + H2O
c) H2C═CH2 + H2  CH3CH3
d) CH2═CHOH  CH3CHO
e) CH3C≡CH + HCl  CH3CCl═CH2
f) (CH3)2C═O + HCN  (CH3)2C(OH)CN
g) CH3CH2CH2Br  CH3CH═CH2 + HBr
h) CH3CH2CH2Br + NaCN  CH3CH2CH2CN + NaBr

100