INTRODUCTION TO ORGANIC CHEMISTRY; SATURATED HYDROCARBONS
Organic Chemistry – science that deal
generally with compounds of carbon
– fats, proteins, carbohydrates
– fabrics
– wood and paper products
– plastics
– medicinals
Carbon atom is central to all organic
compounds
What makes carbon special?
 unique ability to bond to itself in long
chains and rings;
 ability to form strong covalent bonds
with a variety of elements (H, O, N, S, P,
halogens)
Carbon atom: C
 atomic number 6
 electron structure 1s22s22p2
 stable isotopes
12C
and 13C
 carbon has several radioactive
isotope
Carbon has four valence
electrons
C
1s2, 2s2, 2p2
Carbon forms four single covalent bonds
by sharing electrons with other atoms.
H
HCH
H
Carbon forms four single covalent bonds
by sharing electrons with other atoms.
H
HCH
H
A pair of electrons can be
shared between two carbon
atoms.
One covalent bond can be
formed between two
carbon atoms.
CC
single bond
Single
covalent
bond can be
formed
between two
carbon
atoms
A dash represents a
covalent bond.
C C
single bond
Two covalent
bonds can be
formed between
two carbon
atoms.
C C
double bond
Two covalent bonds
can be formed
between two carbon
atoms.
C C
double bond
Three covalent
bonds can be
formed between
two carbon atoms.
C C
triple bond
Three covalent
bonds can be
formed between
two carbon atoms.
C C
triple bond
Organic
compounds
Saturated
(only single
bonds)
Unsaturated
(double or
triple bonds)
The types of molecular formulas and
molecular models
H
H
CH4
.. .
H ..C . H
..
H
molecular
formula
Lewis
formula
C2H6
CH3CH3
condensed structural formula
H
C
H
H
structural
formula
CLASSES OF ORGANIC COMPOUNDS
CLASSES OF ORGANIC COMPOUNDS (cont.)
HYDROCARBONS
compounds that are composed only of carbon and
hydrogen atoms bonded to each other by covalent
bonds
Hydrocarbons
SATURATED
Aliphatic
(open-chain and cyclic)
Alkanes
Alkenes
Cycloalkanes
Cycloalkenes
Aromatic
(contain the benzene ring)
Alkynes
UNSATURATED
Sources: fossil fuels - natural gas, petroleum, coal
ALKANES (paraffins, saturated hydrocarbons)
straight or branched-chain hydrocarbons with only
single covalent bonds between the carbon atoms
Homologous series – each member of a series differs from the next
member by a CH2 group.
General formula (for open chain alkanes): CnH2n+2; n – number of
carbon atoms in the molecule
ISOMERISM
Isomerism – phenomenon of two or
more compounds to have the same
molecular formula but different
structural arrangement
Isomers – compounds that have the
same molecular formula but different
structural formulas
CH4
There is 1 possible
structure for CH4.
H
line
space
structure
filling
form of
methane
H C H
H
19.4
19.4
CH3CH3
There is 1 possible
structure for C2H6.
H H
space
filling
line
structure
form of
ethane
H C C H
H H
19.4
CH3CH2CH3
There is 1 possible
structure for C3H8.
line
space
structure
filling
form of
propane
H H H
H C C C H
H H H
19.4
CH3CH2CH2CH3
There are 2 possible structures
for C4H10
line structure
space
filling
of
form form
of butane
butane
H H H H
H C C C C H
H H H H
unbranched chain
19.4
CH3
CH2CHCH3
H H
H
H C H
space
filling
line
structure
form of 2-methyl
propane
branched chain
branched chain
H C C C H
H H H
19.4
There are 2 possible structures
for C4H10.
normal butane
(n-butane)
H10
m.p. –138.3Co4C
b.p. 0.5oC
H H H H
H C C C C H
H H H H
Isomers are compounds with
Normal butane and 2-methyl
the same molecular formula but
propane are isomers.
different structural formulas.
2 –methyl propane
o
C
m.p.
4H10–159.5 C
b.p. – -11.7oC
H H
H
H C H
H C C C H
H H H
Pentane (C5H12) has 3 isomers.
Hydrogen
is added
to each
This is the carbon
skeleton
with the
carbon
to form four
bonds.
longest continuous
carbon
chain. It is
the first isomer of pentane.
H H H H H
H C C C C C H
H H H H H
n-pentane
Pentane (C5H12) has 3 isomers.
Hydrogen
added
towrite
each
Add
the fifth
carbon
atom
to either
To form
the is
next
isomer
a fourof
carbon
to carbon
form four
the
middle
atoms.bonds.
carbon
chain.
H
H
H
C H
H C H
H C C C C H
H H H H
2-methylpentane
Pentane (C5H12) has 3 isomers.
Hydrogen
added
eachaatoms
To form
Add
the remaining
the is
third
isomer
twotocarbon
write
3
carbon
to form
four
bonds.
carbon
to
the central
chain.
carbon
atom.
H
H
H
H C
H C C C H
H C H
H
H
H
2,2-dimethylpropane
SATURATED
HYDROCARBONS
NAMING ORGANIC COMPOUNDS
Used to: trivial names
Examples:
wood alcohol – methanol;
marsh gas – methane;
alcohol or grain alcohol – ethanol; etc.
Now:
internationally accepted and systematic
method - IUPAC system (International
Union of Pure and Applied Chemistry) established in 1892
Alkyl Groups
Alkyl group - derivative of corresponding alkane
The general formula: R = CnH2n+1. R – any alkyl group.
Alkyl group has 1 hydrogen atom less than the
corresponding alkane.
ALKANES (CnH2n+2)
ALKYL GROUPS (CnH2n+1)
IUPAC RULES FOR NAMING ALKANES
1. The name of the compound consist of the name of the longest
chain prefixed by the names of attached alkyl groups.
2. Select the longest chain.
3. Consider all alkyl groups attached to it.
4. Number the carbon atoms in the carbon chain starting from the
end closest to the first carbon atom that has attached alkyl
group.
5. Name each branch-chain alkyl group and designate its position by
a number (3-methyl means a methyl group attached to carbon 3)
4. If the same alkyl groups occur more than once, indicate this by
prefix (di-, tri-, tetra etc) (dimethyl indicates two methyl
groups). The numbers indicating the positions of these alkyl
groups are separated by comma, followed by a hyphen, and placed
in front of the name (2,3-dimethyl).
5. When several alkyl groups are attached to the parent compound,
list them in alphabetical order.
Name the following compound
2-methylbutane
1. Select the longest chain.
2. Consider all alkyl groups attached to it.
3. Number the carbon atoms in the carbon chain starting from the
end closest to the first carbon atom that has attached alkyl
group.
4. Name each branch-chain alkyl group and designate its position by
a number (2-methyl means a methyl group attached to carbon 2)
Name the following compound
2-methylpentane
Each of the following formulas represent the same compound – 2methypentane
Name the following compound
2,3-dimethylbuthane
1. Select the longest chain.
2. Consider all alkyl groups attached to it.
3. Number the carbon atoms in the carbon chain starting from the end
closest to the first carbon atom that has attached alkyl group.
4. Name each branch-chain alkyl group and designate its position by a
number
5. If the same alkyl groups occur more than once, indicate this by prefix
(di-, tri-, tetra etc) (dimethyl indicates two methyl groups). The
numbers indicating the positions of these alkyl groups are separated
by comma, followed by a hyphen, and placed in front of the name (2,3dimethyl).
Name the following compounds
2,2-dimethylbutane
H3
2,4-dimethylhexane
3-methylhexane
Name the following compound
3-chloro4-ethyl-2,4dimethyloctane
1. Select the longest chain.
2. Consider all alkyl groups attached to it.
3. Number the carbon atoms in the carbon chain starting from the end
closest to the first carbon atom that has attached alkyl group.
4. Name each branch-chain alkyl group and designate its position by a
number (3-methyl means a methyl group attached to carbon 3)
4. If the same alkyl groups occur more than once, indicate this by prefix
(di-, tri-, tetra etc) (dimethyl indicates two methyl groups). The
numbers indicating the positions of these alkyl groups are separated
by comma, followed by a hyphen, and placed in front of the name (2,3dimethyl).
5. When several alkyl groups are attached to the parent compound, list
them in alphabetical order.
Name the following compounds
2,2,4-trimethylpentane
2-methylhexane
5-ethyl-3-methyloctane
Name the following compounds
CH3
CH2
H3C
CH
CH
CH3
Cl
CH2
C
CH3
CH3 CH3
CH3
CH2 CH2
3-chloro-2,5,5-trimethylheptane
CH3
CH3
CH3
C
CH2CH2CHCH3
CH2CH3
3,3,6-trimethyloctane
CH2CH3
CH
CH
CH3
3,4-dimethylhexane
CH3
Write the formula for:
CH2
3-ethylpentane
CH2
CH3
3-bromo-5,6diethyl-2,7dimethyl-5propylnonane
CH3
CH3
CH
CH
Br
CH2
CH
CH3
CH3
CH2
CH2
CH3
C
CH
CH
CH2
CH2
CH3
CH2
CH2
CH3
CH3
Reactions of Carbon
1. Oxidation-reduction reactions
Oxidation of carbon compound
Reduction of carbon compound
2. Substitution reaction
If in a reaction one atom in a molecule is exchanged by
another atom or group of atoms
3. Elimination reaction
If a single reactant is split into two product, and one of
the products is eliminated. Multiple bonds are formed
4. Addition reaction
Two reactants adding together to form a single
product. Reverse of an elimination reaction
Categorize each reaction
CH2
CH2+ H2 O
addition
CH3CH2Cl + H2O
CH3CH2OH
CH3CH2OH+ HCl
substitution
CH3CH2CH2CH3
elimination
CH3CH
CHCH3+ H2
Reactions of alkanes
1. Combustion (with the production of large amount
of heat energy)
CH4(gas) + O2(gas)
CO2(gas) + 2H2O + 191,8 kcal
thermal energy
Mechanical
energy
Electrical
energy
Combustion reactions are the most important for
economics.
Combustion reactions are the most active reactions of
alkanes.
In all other reactions alkanes are sluggish and demand
activation (high temperature, catalists)
2. Halogenation (a substitution reaction)
A halogen (Cl or Br) is substituted for a hydrogen
atom in halogenation reactions.
CH3CH3 + Cl2
CH3CH3 + Br2
CH3CH2Cl + HCl
chloroethane
CH3CH2Br + HBr
bromoethane
Alkylhalides are useful as intermediates for
manufacturing of other substances
3. Dehydrogenation (an elimination reactions)
Alkanes lose hydrogen during dehydrogenation
CH3CH2CH3 
propane
CH3CH
CH2 + H2
propene
Alkenes are formed (useful chemical intermediates)
4. Cracking
Breaking up large molecules to form smaller ones
C16H34 
alkane
C8H18 + C8H16
alkane
alkene
4. Isomerization (rearrangment of molecular structure)
CH3CH2CH2CH2CH3
catalist
, pressure
CH3CH2CHCH3
CH3
Halogenation reaction is used for production of
petrochemicals (chemicals derived from petroleum and
used for other purposes than fuel)
Dehydrogenation, cracking and isomerization
reactions are used for production of motor fuels.
Alkyl halides formation
CH4 + Cl2
CH3Cl + HCl
chloromethane
Reaction of methane with chlorine gives the mixture of mono-, di-,
tri-, and tetrasubstituted chloromethanes
CH4
Cl2
CH3Cl
Cl2
chloromethane
CH2Cl2
Cl2
dichloromethane
CHCl3
Cl2
trichloromethane
CCl4 + HCl
tetrachloromethane
The more chlorine the more CCl4.
Monosubstitution product - one hydrogen atom is
substitued by another atom
Di-, tri, tetra- and so on substituted compounds – two,
three, four hydrogen atom are substitued by another atoms
CYCLOALKANES
Hydrocarbons
Aliphatic
(open-chain and cyclic)
Alkanes
Alkenes
Aromatic (contain
the benzene ring)
Alkynes
Cycloalkanes
Cycloalkenes
Cycloalkanes (cycloparaffins, naphthenes) – cyclic,
or close-chain, alkanes.
Cycloalkanes are saturated hydrocarbons.
General formula – CnH2n (two fewer hydrogen atoms
than the corresponding open chain alkane)
Naming of Cycloalkanes
Add prefix cyclo to the name of alkane with the same
number of carbon atom
UNSATURATED HYDROCARBONS
Hydrocarbons
Aliphatic
(open-chain and cyclic)
Alkanes
Alkenes
Cycloalkanes
Cycloalkenes
Aromatic
(contain the benzene ring)
Alkynes
UNSATURATED HYDROCARBONS
Widely used: polymers (plastic things); in medicine,
cosmetics, perfumes, flavorings; detergents,
insecticides, dyes.
Alkenes – double bond
Alkynes – triple bond
Aromatic – benzene ring
Nomenclature of alkenes
1.Select the longest carbon-carbon chain containing
the double bond
2.Name this compound as you would an alkane but
change the –ane ending to –ene. Example: propane
is changing to propene.
3.Number the carbon chain of compound starting
with the end nearer to the double bound.
4.Place the number indicating the location of double
bond in front of the alkene name (example: 3propene)
5.Branch chains and other groups are treated as
for alkanes.
Name the following compounds
1-butene
2-butene
3-methyl-1-butene
3-propyl-1-hexene
Write a structural formula for:
4-methyl-2-pentene
7-methyl-2-octene
IMPORTANT: in naming of alkenes the double bond
must be included in the chain even if there is
longer chain in this compound
the longest carbon
chain contains six
carbons
We must include the double bond in the chain
the carbon chain
containing the
double bond has
five carbons
2-ethyl-1-pentene
Name the following compounds
3-methyl-2-pentene
2-methyl-1-butene
2,4-dimethyl-2-pentene
2-methyl-2-butene
Name the following compounds
CH3
3-methyl-3-heptene
CH2
CH3
CH2
CH2 CH
C
CH3
CH2
CH
CH3
CH2
CH2 CH2 CH
3-methyl-1-heptene
CH3
CH2
CH
CH3
CH2
CH2
CH2
C
CH2
CH3
CH3
3-ethyl-3-methyl1-heptene
Write a structural formula for:
CH3
4,5-dichloro2,3-dimethyl1-pentene
CH2
C
CH
Cl
Cl
CH
CH2
CH3
CH3
CH2
4-chloro-5,6diethyl-2,7dimethyl-5propyl-2-nonene
CH3
CH3
C
CH
Cl
CH2
CH
C
CH3
CH
CH2 CH2
CH3 CH3
CH
CH2
CH3
Nomenclature of alkenes containing
more than one double bond
Compounds with two (di) double bounds are called dienes, with three
(tri) – trienes.
Name the following compounds
1,4-pentadiene
2-methyl-1,3-butadiene
Name the following compounds
Cl
CH2
C
C
C
Cl
4,5-dichloro-3-methyl1,2,4-pentatriene
CH
CH3
CH3
CH3
CH2
CH2
CH2
CH2
CH
CH3
CH
CH2 5-methyl-4-pentyl2,5-octadiene
CH
CH
C
CH3
Geometric Isomerism in Alkenes
these two compounds are identical
1,2-dichloroethane
carbon atoms can rotate freely
about the single bond
carbon atom can not
rotate about the
double bond
Restricted rotation of carbon atom around the bond
with other carbon atom results in the phenomenon
known as geometric isomerism
these compounds are different
Geometric isomers (cistrans isomers) compounds that differ
from each other only in
the geometry of their
molecules and not in the
order of their atoms
Cis- isomer has
substituent groups on
the same side of the
double bond
cis-1,2dichlorethene
trans-1,2dichlorethene
Trans- isomer has
substituent groups on
the opposite sides of
the double bond
An alkene shows cis-trans isomerism when each carbon atom
of the double bond has two different kinds of groups attached
to it
A
A
C
B
B
A
C
cis-isomer
C
C
B
B
trans-isomer
A
An alkene doesn’t show cis-trans isomerism if one carbon atom
of the double bond has two identical groups attached to it
H
H
C
H
H
C
C
H
H
C
CH3
H
Write geometric isomers for: 2-butene
CH3
cis-2-butene
CH
CH
CH3
trans-2-butene
Chemical properties of alkenes
Addition
So far as alkenes have double bonds they are more reactive
than alkanes and undergo addition reactions.
Some of the reagents that can be added to alkenes:
hydrogen, halogens, hydrogen halides, water, sulfuric
acid, etc.
C
C
Brown color of Br2 disappears in this reaction.
As result of addition alkenes are converted to saturated
molecules.
Addition reactions are reverse to the elimination reactions.
Markovnikov’s rule
When an asymmetrical molecule HX (HCl) adds to a
carbon-carbon double bond, the hydrogen from HX
goes to the carbon atom that has the greater number
of hydrogen atoms.
Write the formulas for the organic compounds formed
when 2-methyl-1-butene reacts with (a) H2, (b) Cl2,
(c) HCl, (d) H2O
2-methyl1-butene
(a)
(b)
1,2-dichloro-2methylbutane
(c)
(d)
Alkynes
Hydrocarbons
Aliphatic
(open-chain and cyclic)
Alkanes
Alkenes
Cycloalkanes
Cycloalkenes
Alkynes
Aromatic
(contain the benzene ring)
Alkynes –
unsaturated
hydrocarbons
containing triple
bond
Widely used: plastic things; in medicine, cosmetics,
perfumes
Naming of alkynes
1. Select the longest carbon-carbon chain containing the triple
bond.
2. Name this compound as for alkene but change the –ene ending
to –yne.
3. Number the carbon chain of compound starting with the end
nearer to the triple bound.
4. Place the number indicating the location of triple bond in front
of the alkyne name (example: 3-propyne)
5. Branch chains and other groups are treated as for alkanes.
Chemical properties
Addition Reactions
Positive Bayer’s test with potassium permanganate
(disappearance of purple-pink color)
Reactions with halogens. Either one or two molecules of
halogens can be added.
Reactions with hydrogen halides.
Vinyl chloride is widely used in chemical industry, for
example for production of plastic polyvinyl chloride
This reaction follows Markovnikov’s rule.
These reactions follow Markovnikov’s rule.
Acetylene is the most important industrially.
Many different polymers are manufactured from acetylene
(production of clothes, superabsorbents (disposable
diapers, soil additives))
Aromatic hydrocarbons
Structure
Benzene and its derivatives are classified as aromatic
hydrocarbons.
Molecular formula of benzene: C6H6
Kekule’s formula:
carbon atoms in a benzene molecule
are arranged in a six-membered ring
with one hydrogen atom bonded to
each carbon atom and with three
double carbon-carbon bonds.
Benzene doesn’t react as a typical alkene (doesn’t decolorize bromine
solution, negative Bayer’s test).
Benzene behaves chemically like a typical alkane (substitution
reactions).
Structure of benzene can be represent by
different formulas
Kekule structures
Kekule formulas are classical however such
structures actually doesn’t exist
Formulas C or D more accurately represent the real
benzene structure
Naming of aromatic compounds
Monosubstituted benzenes
1. Add the name of a substitutent group as a
prefix to the word benzene
2. Write the name as one word
3. Position of substituent is not important
Name the following compounds:
F
CH2CH2CH3
fluorobenzene
CH2CH3
ethylbenzene
propylbenzene
HO
hydroxybenzene
Some monosubstituted benzenes have special
(trivial) names.
These names should be memorize.
The group
(C6H5) is called phenyl group
The name phenyl can be used to name compounds that
can not easily be named as benzene derivatives
3-chloro-2-phenylpentane
diphenylmethane
Disubstituted Benzenes
In disubstituted benzenes the prefixes ortho-,
meta- and para- (o-, m-, p-) are used for
naming.
In ortho- disubstituted
compounds, the two
substituents are located on
adjacent carbon atoms
In meta- disubstituted
compounds, the two
substituents are one carbon
apart
In para- disubstituted
compounds, the two
substituents are located on
opposite points of ring
Name the following compounds:
ortho-dichlorobenzene
CH2CH3
CH2CH3
meta-dichlorobenzene
CH2CH3
CH2CH3
ortho-diethylbenzene
meta-diethylbenzene
para-dichlorobenzene
CH2CH3
CH2CH3
para-diethylbenzene
When the two substituents are different the names
of two substituents are given in alphabetical order
o-bromochlorobenzene
m-ethylnitrobenzene
CH3
CH2CH3
p-ethylmethylbenzene
CH2CH2CH2CH3
CH2CH3
o-butylethylbenzene
Sources and using of aromatic
hydrocarbons
Sources:
 Coal tar (by-product of the manufacture of
coke)
 Alkanes found in petroleum
Using: in the production of
- drugs,
- dyes,
- detergents,
- explosives,
- insecticides,
- plastics,
- synthetic rubber.
ALCOHOLS
Alcohols – a class of compounds containing the hydroxyl
(-OH) functional group
General formula – ROH
Alcohols are derived from aliphatic hydrocarbons by
the replacement of at least one hydrogen atom with a
hydroxyl group
Classification of Alcohols
Primary – carbon atom to which the –OH group is
attached is directly bonded to one other carbon atom
Secondary – carbon atom to which the –OH group is
attached is directly bonded to two other carbon atom
Tertiary – carbon atom to which the –OH group is
attached is directly bonded to three other carbon atom
If two or more –OH groups are attached to the same
carbon atom such compound is not stable
If two or more –OH groups are attached to the different
carbon atoms such compounds is stable
Alcohols can be also classified as
 monohydroxy-,
 dihydroxy-,
 trihydroxy-,
 tetrahydroxy-, and so on.
polyhydroxy alcohols
The formulas of alcohol can be written as
follow:
2-butanol
or
2-butanol
Naming of alcohols
1.Select the longest chain of carbon atoms containing
the hydroxyl groups
2.Number the carbon atoms in this chain so that the
one bearing the –OH group has the lowest possible
number
3.Form the parent alcohol name by replacing the final
–e of alkane by –ol.
4.Locate the position of the –OH by placing the number
of corresponding carbon atom before the alcohol
name.
5.Name each side chain and designate its position by
number
Name the alcohol CH3CH2CH2CH2OH
1. The longest carbon chain has 4 carbons
2. Number the carbon atoms (carbon bonded to –OH
must have number 1)
3. Four carbon alkane is called butane. Change –e to –ol
butanol
4. OH group is on carbon 1, so place 1 before butanol
Result: 1-butanol
Name the following compounds
CH3
CH2
CH2
OH
CH3
CH3
CH
1-propanol
OH
cyclohexanol
2-propanol
CH3
CH
CH2 CH2OH
OH
CH3CH2CHCH2CHCH3
CH3
CH3
3-methyl-1-butanol
OH
4-methyl-2-hexanol
CH3
3-methylcyclopentanol
CH3CH2CHCH2CH2CH3
CH2OH
2-ethyl-1-pentanol
OH
Br
CH3CH2CHCH2CCH3
OH
CH3
5-bromo-5-methyl-3-hexanol
Write the structural formulas for:
3,3-dimethyl-2-hexanol
2-chloro-4-methylcyclopentanol
CH3
CH3CH
OH
C
OH
CH2CH2CH3
Cl
CH3
CH3
4-phenyl-2-butanol
CH2 CH2
CH
2,3,4-trichlorocyclobutanol
CH3
Cl
OH
Cl
Cl
OH
Nomenclature of alkohols containing
more than one -OH groups
Compounds with two (di) –OH groups are called diols, with
three (tri) – triols.
HOCH2
CH2OH
1,2-ethanediol
CH2 CH
CH2
OH
OH
OH
1,2,3-propanetriol
Name the following compounds
OH
CH3
CH
CHOH
CH2OH
OH
1,3-cyclohexanediol
CHOH
CH
CH3
CH2CH3
2,5-dimethyl-1,3,4-heptanetriol
Alcohols:
 relatively high boiling
point (depends on the
hydrogen bonding between
alcohol molecules)
 alcohols containing up to
three carbon atom are
soluble in water (solubility
depends on hydrogen
bonding between alcohol
molecules and water)
 alcohols with 5-11 carbons
are oily liquids, 12 or more
carbon atoms – waxlike
solids
 two or more –OH groups
increase boiling point and
solubility
Chemical properties of alcohols
Acidic and basis properties (similar to water properties)
a) In acidic solution alcohols accept a proton
oxonium ion (protonated alcohol)
b) Alcohols react with alkali metals to release hydrogen
alkoxide ion (strong base)
1. Oxidation
The hydroxyl group gives an alcohol the capability of
forming an aldehide, ketone or carboxylic acid
Tertiary alcohols
don’t have a
hydrogen on the –
OH carbon and
can not react with
oxidizing agents
Oxidation
occurs at
the carbon
atom bonded
to the –OH
group and
this atom
becomes an
aldehyde or
carboxylic
acid.
The rest of
the molecule
remains the
same.
Oxidation of ethanol in organism (in liver)
Toxic compound, can cause the
liver damage (liver cirrhosis)
Can be used as sourse of energy
for the organism
2. Dehydration (elimination of water)
a. Intramolecular dehydration (the alkenes are formed)
Saytzeff’s rule. If there is the choice of positions for double bond
the preferred location is the one that gives the more highly
substituted alkene – that is, the alkene with the most alkyl groups
attached to double-bond carbons.
Remove the hydrogen from the carbon with fewer hydrogen.
b. Intermolecular dehydration (the ethers are formed)
This type of reaction occurs only between primary
alcohols.
Such type of reactions is called condensation
reaction (two molecules are combined with removing
of small molecule).
3. Esterification (convertion of alcohols to esters)
Alcohol reacts with carboxylic acid to form an ester
and water.
Utility of the Hydroxyl Group
Common Alcohols
Methanol (wood alcohol)
Preparation:
- heating of wood to high temperature without oxygen (distructive
distillation)
- hydrogenation of carbon monoxide under the high pressure
methanol
Physical properties:
 highly flammable liquid
 poisonous, can cause
blindness and death
Using:
-convertion to formaldehyde
–manufacture of esters and
other chemicals
–production of denaturing
ethyl alcohol
-industrial solvent
Ethanol (ethyl alcohol, spirit)
Preparation:
-fermentation. Starch is converted to sugar, then sugar is
converted to ethanol. The enzymes of yeast are used.
-acid-catalyzed addition of water to ethylene (ethylene
can be obtain from petroleum)
Using:
-intermediate in the production of other chemicals
-solvent for many organic substances
-ingredient for pharmaceutical, perfumes, flavorings
-ingredient of alcoholic beverages
Glycerol (1,2,3-propanetriol, glycerine)
Contains three –OH groups.
Preparation:
-by-product of processing fats to make
soap and other products
-it is synthesized from propene
Physical properties:
-liquid with a sweet, warm taste
-hygroscopic (is able to hold water
molecules by hydrogen bonding)
Using:
-manufacturing of polymers
-manufacturing of explosives
-emollient in cosmetics
ETHERS
General formula R-O-R’.
R and R’ can be saturated, unsaturated or aromatic hydrocarbons.
R and R’ can be alike or different.
Naming ethers
A. Common names (only for naming simple ethers)
Common names are formed from the names of groups
attached to oxygen atom
Name the following compounds using
common names
OCH3
CH3CH2-O-CH2CH3
diethyl ether; ethyl ether or ether
methyl phenyl ether
O
CH3CH2CH2
CH
O
divinyl ether
CH
CH2CH2CH2CH3
butyl propyl ether
diphenyl ether
CH2
O
CH2
CH3
CH3CH2 O
CHCH3
ethyl isopropyl ether
B. Naming according to IUPAC system
Group R-O- is called alkoxy group (consist of alkyl group
R- and oxygen atom).
Alkoxy group is named by dropping the ending –yl of the
alkyl name and adding the suffix –oxy.
Examples:
CH3O-, alkyl is called methyl, replace ending –yl to –oxy.
Group is called methoxy.
CH3CH2O- - is called ethoxy (eth + oxy).
- is called phenoxy (phen + oxy).
Rules for naming ethers
1. Select the longest carbon chain and label it with the name
of corresponding alkane.
2. Change the –yl ending of other hydrocarbon group to –oxy.
3. Combine the two names giving the alkoxy name and its
position on the longest carbon chain first.
metoxyethane
Name the following compounds
O
OCH3
CH3CH2-O-CH2CH3
methoxybenzene
ethoxyethane
phenoxybenzene
CH3
CH3CH2CH2
O
CH2CH2CH2CH3
1-propoxybutane
CH3CH2CH2 O
2-propoxybutane
CH3
CH3
CH3CH2 O
CHCH3
2-ethoxypropane
CHCH2CH3
CH2
CH3CH2CH2CH2 O
CHCH2CH3
3-butoxypentane
Name the following compounds
CH3 O
OCH3
CH2CHCH3
CH3
1-methoxy-2-methylpropane
OCH2CH2CH3
Cl
Cl
1,2-dichloro-4propoxybenzene
Cl
m-chloromethoxybenzene
CH3
CH3
CH3CH
O
CH3
CHCH2CHCH3
2-isopropoxy-4methylpentane
Physical Properties of Ethers
The shape of molecule is similar to water and alcohol molecules
Ethers are more polar than alkanes (alkanes don’t conatain
oxygen atom)
Ethers are less polar than alcohols or water (ethers don’t
contain hydrogen)
Ethers form hydrogen bonds with water molecules or acids
 Solubility and boiling point of ethers
depend on the carbon chain structure
 Ethers with long carbon chain are insoluble in
water
 Ethers with small carbon chain are very little
soluble in water and acids
 Ethers – very good solvents for organic
compounds
 Some polar compounds (water, alcohols) can be
dissolve to some extent in ethers
 Ethers are highly flammable
 Vapors can form with air explosive mixture
Chemical Properties
 Ethers have little chemical reactivity
 Ethers can slowly react with oxygen from
air to form peroxides (explosive substances).
Preparation of ethers
1. Intermolecular dehydration of alcohols
2. Williamson synthesis. Alkyl halides react with sodium
alkoxides or sodium phenoxides to form ethers. This is
the substitution reaction.
Thiols
Thiols (mercaptants) – organic compounds
containing –SH group.
Naming of thiols
The principle of naming is as for alcohols but except
the ending –ol the ending –thiol is used.
CH3SH
CH3CH2CHCH3
methanethiol
SH
2-butanethiol
SH
cyclohexanethiol
CH3
CH3CH2CHCHCH2CH3
SH
4-methyl-3hexanethiol
Properties
1. Foul odours (natural gas is odorized by methanethiol
to be detectable)
2. Oxidation to disulfides
Functions
Disulfide structures in proteins.
Constituent of coenzyme A (metabolism).
ALDEHYDES AND KETONES
Structure of aldehydes and ketones
Both aldehydes and
ketones contain
carbonyl group
C
O
Differerence:
-aldehydes contain hydrogen atom bounded to carbonyl group
-ketones have only alkyl or aromatic groups attached to carbonyl group
Methanal is the smallest
aldehyde (the first member
from the homologous series)
methyl group
on 4 carbon
the longest chain is hexane
4-methylhexanal
Ethanal is the second member
of the homologous series
Name the following compound
O
CH3CH2CH2CH2C
pentanal
CH3
O
CH2ClCHCH2CH2C
H
5-chloro-4-methylpentanal
O
H
OH
OH
O
CH
CCH2CHCH2CHCH3
3,5-dihydroxyhexanal
H
CHC
H
3-phenyl-2-propenal
CH2CH3
O
CHCHC
H
CH3
2-methyl-3-phenylpentanal
Naming of Ketones
1.Select the longest chain containing the
ketone group.
2.Drop the ending –e from the corresponding
alkane name and add the suffix –one.
3.If the chain is longer than four carbons, it
is numbered so that the carbonyl group has
the lowest number possible. This number is
prefixed to the parent name of the ketone.
4.Name other groups attached to parent
chain as usual.
Name the following compounds
O
O
CH3 C
CH3 CH3 C
propanone
CH2 CH3
CH3 C
butanone
O
CH3 CH2 C
O
CH
CH2
CH3
CH3 CH
OH
CH3
4-methyl-3-hexenone
O
2-pentanone
CH
C O
CH3
CH3
4-hydroxy3-methyl-2pentanone
CH3
CH3
H3C
CH2 CH2
O
O
CH3
cyclohexanone 2,4,6trimethylcyclohexanone
CH2 CH2 CH2 C
CH2OH
1-hydroxy-5-phenyl2-pentanone
Alternative Names of Ketones
It is used to name simple ketones.
List the names of the alkyl or aromatic groups attached
to carbonyl carbon together with the word ketone.
methyl methyl ketone
(propanone)
methyl ethyl ketone
(butanone)
Propanone and butanone are the most widely used
ketones.
They have the special (common) names: acetone
(propanone) and MEK (butanone).
Name the following compounds
O
CH3CH2 C
CH2CH3
ethyl ethyl ketone
(diethyl ketone)
O
C
dicyclohexyl ketone
O
CH3
CH3CH2 C
CH
CH3
ethyl isopropyl ketone
CH3 O
CH3
C
CH
CH
CH3
CH3
diisopropyl ketone
Naming of Aromatic Ketones
Aromatic ketones are named similarly to the aliphatic
ketones and can have the special names as well.
O
O
C
C
CH3
1-phenylethanone
(methyl phenyl ketone)
O
CH3
C
CH
CH2
CH3
1-phenyl-1-propanone
(ethyl phenyl ketone)
CH2 CH3
2-methyl-1-phenyl1-butanone
Naturally occurring aldehydes and ketones
Many aldehydes have a specific odour and can be used in
flavoring and perfumes
Benzaldehyde (oil of bitter almonds)
Cinnamaldehyde (oil of cinamon)
Carvone (chief component of spearmint oil)
Muscone (gland of male musk deer, used in perfumes)
Civetone (secretion of the civet cat, used in perfumes)
Camphor (from the camphor tree)
Cortisone (hormone; produced by epinephrine glands;
regulate metabolism in organism; widely used in medicine)
Glucose
Ribose
Fructose
Sugars; energetic and plastic material for organism
Citral (oil of lemon)
Vitamin K (antihemorrhagic vitamin)
Chemical Properties of
Aldehydes and Ketones
Chemical properties of aldehydes and
ketones are determined by the functional
carbonyl group
C
O
1. Oxidations
Aldehydes are oxidized to carboxylic acids by different
agents (K2Cr2O7+H2SO4; Ag+; Cu2+; oxygen of air)
orange
green
Ketones are not oxidized by such agents.
Ketones can be oxidized under drastic conditions (hot
potassium permanganate). Carbon-carbon bonds are broken
under these conditions and variety of products are formed.
The Tollens test (silver-mirror test)
Silver ions oxidizes ammonia (Tollens’ reagent is formed)
Ag+ ions are reduced to metallic silver by aldehydes
O
O
CH3 C H
+ 2 Ag(NH3)2OH
CH3 C ONH4 + 2 Ag + 3 NH3 + H2O
Tollens’ Reagent
Add into tube aldehyde, silver nitrate and
ammonia
The silver mirror appears on the inner wall of
the tube
Fehling test
Fehling solutions contain Cu2+ ions in alkaline medium.
Cu2+ has blue color. During reaction it is reduced and brickred copper oxide is formed.
Before
reaction
(blue color
of Cu2+)
After
reaction
(brick-red
color of
Cu2O)
Ketones don’t give a positive Tollens or
Fehling tests
Tollens or Fehling test can be used to distinguish
between aldehydes and ketones
2. Reduction
Aldehydes and
ketones are
reduced to alcohols
Reducing agents:
-hydrogen
(catalyst Ni);
-litium aluminium
hydride (LiAlH4);
-sodium
borohydride
(NaBH4).
Aldehydes yield
primary alcohols;
ketones yield
secondary alcohols
Common Aldehydes and Ketones
Formaldehyde (methanal)
Can be obtained in the oxidation of methanol by
oxygen (silver or copper are catalysts)
Properties:
-gas
-poisonous
-very irritating (ingestion can cause death)
-soluble in water
-37 % solution of formaldehyde is called
formalin
Using:
 manufacture of
polymers;
 preservation of
biological specimens
Acetaldehyde (ethanal)
Can be obtained in
the oxidation of
ethanol
Volatile liquid with pungent odor
Using: intermediate in the production of other
chemicals (for example, acetic acid)
Three or four molecules of ethanal can polymeraze to form
cyclic compounds paraldehyde and metaldehyde, which can
be used for production of sedative drugs and pesticides
Acetone (methyl methyl ketone) and MEK
(methyl ethyl ketone)
Using: solvents, manufacturing of drugs, chemicals,
explosives, in plastic industry; for removal of paints
Acetone and MEK can be obtained by oxidation of
secondary alcohols:
Acetone is formed in human body
In some diseases (diabetes mellitus, starvation) the
concentration of acetone is increased in blood and urine.