LOGO
Lecture 3 :
Introduction to Organic Chemistry
Organic Chemistry – FALL 2015
Course lecturer :
Jasmin Šutković
28th November 2015
Contents
International University of Sarajevo
Book chapter 11
11.1 Introduction to Organic Chemistry
11.2 Characteristic Features of Organic
Compounds
11.3 Shapes of Organic Molecules
11.4 Drawing Organic Molecules
11.5 Functional Groups
11.6 Properties of Organic Compounds
11.7 FOCUS ON HEALTH & MEDICINE:
Vitamins
Introduction
 In this lecture we learn about the characteristic
features of organic molecules.
What is organic chemistry?
Organic chemistry is the study of
compounds that contain the element
carbon.
 Clothes, foods, medicines, gasoline, refrigerants,
and soaps are composed almost solely of
organic compounds.
 Some, like cotton, wool, or silk are naturally
occurring; that is, they can be isolated directly
from natural sources.
CHARACTERISTIC FEATURES OF
ORGANIC COMPOUNDS
We will start with smaller molecules, small number of C
atoms.
Mehane (CH4) and Ethanol (C2H5OH)
Ethanol produced in Lab, Methane naturally.
All organic compounds contain carbon atoms and most contain
hydrogen atoms. Carbon always forms four covalent bonds, and
hydrogen forms one covalent bond.
Common fetures ?
Bonding depends on the
atom number around C
The most common multiple bond between C and a heteroatom is
carbon – oxygen double bond.
Carbon forms 4 stable bonds with itself and other elements. Carbon
atoms bind together to fotm RINGS or CHAINS
Shapes of Organic
molecules
Recall section 4.6 = the most stable structural arranement keeps its groups as far
away from each other = VSEPR theory
All carbons having 4 single bonds are tetrahedral !
Exp : ethane
IUPAC name :
ETHYNE = C2H2
IUPAC name :
ETHENE = C2H4
Drawing organic
molecules
Because organic molecules contain many atoms we need to
find the best way to simplify their strucures.
TWO ways are used :
Condensed structures and Skeleton structures
•
Condensed structures used for molecules having a chain
of atoms bound together, rather than a ring.
•
Skeleton structures used for molecules having a both,
chain and ring of atoms.
Condensed structures
Following rules are used :
Skeletal structures
Functional groups
 More than 20 milion organic compounds are
known, most of the have C, H and O atoms.
 Many organic molecules have also other
structural feautures – called functional groups !
 Functional group determines the molecule
shape and therefore its function !
 Functional group in this case in OH
(hydroxyl group)
Hydrocarbons
 Are organic molecules that contain only C
and H elements.




Alkanes – single bonds
Alkenes – double bond
Alkynes – triple bond
Aromatic hydrocarbons – benzane ring (6 C
atoms and 3 double bonds )
 All hydrocarbons other than Alkanes contain multiple
bonds. Alkanes, which have no functional groups and
therefore no reactive sites, are notoriously uncreative
except under very drastic conditions.
 For example, polyethylene is a synthetic plastic and
high molecular weight Alkane, consisting of long
chains of CH2 groups bonded together, hundreds or
even thousands of atoms long.
Polyethylene
 Hydrocarbons that have NO other functional groups – no reactive
sites are very UNREACTIVE in nature.
 Exp :Polyethylene
COMPOUNDS CONTAINING A SINGLE
BOND TO A HETEROATOM
 Several types of functional groups contain
a carbon atom singly bonded to a
heteroatom.
 Common examples include alkyl halides,
alcohols, ethers, and amines, as shown in
Table 11.4.
 Molecules containing these functional groups may be simple or very
complex. It doesn’t matter what else is present in other parts of the
molecule.
Always dissect it into small pieces to identify the functional
groups.
 For example, diethyl ether, the first general anesthetic, is an
ether because it has an O atom bonded to two C’s.
 Tetrahydrocannabinol (THC), the active component in
marijuana, is also an ether because it contains an O
atom bonded to two carbon atoms. In this case the O
atom is also part of a ring.
COMPOUNDS CONTAINING A C=O
GROUP
 Many different kinds of compounds contain a carbon–oxygen double
bond (C=O, carbonyl group), as shown in Table 11.5.
 Carbonyl compounds include aldehydes, ketones, carboxylic
acids, esters, and amides. The type of atom bonded to the carbonyl
carbon—hydrogen, carbon, or a heteroatom—determines the
specific c class of carbonyl compound.
Aldehydes, Carboxylic acid
and Esters
PROPERTIES OF ORGANIC
COMPOUNDS
 Because organic compounds are composed of covalent
bonds, their properties differ a great deal from those of
ionic inorganic compounds.
 This causes lower melting points to organic molecules,
many organic molecules are liquid (some gaseous) in
rooms temperature (ionic molecules are solid)
POLARITY
 Are organic compounds polar or nonpolar ?
 That depends.
 Like other covalent compounds, the polarity of an organic
compound is determined by two factors:
 the polarity of the individual bonds and the overall shape of
the molecule.
 The polarity of an individual bond depends on the
electronegativity of the atoms that form it.
SOLUBILITY
 Understanding the solubility properties of organic compounds allows
us to understand many interesting phenomena.
 One rule governs solubility: “Like dissolves like.”
 Three facts can then be used to explain the solubility of organic
compounds :
 Three compounds—hexane, ethanol, and cholesterol—illustrate
these principles. All of these compounds are organic and therefore
soluble in an organic solvent like diethyl ether (CH3CH2OCH2CH3).
 Their water solubility depends on their polarity and size.
 Since hexane (CH3CH2CH2CH2CH2CH3) is a nonpolar
hydrocarbon, it is insoluble in water.
 Ethanol (CH3CH2OH), on the other hand, is water soluble because it
is small and contains a polar OH group.
FOCUS ON HEALTH &
MEDICINE
Vitamins
 Vitamins are organic compounds needed in small
amounts for normal cell function.
 Our bodies cannot synthesize these compounds, so they must be
obtained in our diet. Most vitamins are identified by a letter, such as
A, C, D, E, and K. There are several different B vitamins, though, so
a subscript is added to distinguish them—for example, B1, B2, and
B12.
 Vitamins are classified on the basis of their solubility properties.
Vitamin A
 Vitamin A, or retinol, is an essential component of the
vision receptors in the eyes.
 It also helps to maintain the health of mucous
membranes and the skin, so many anti-aging creams
contain vitamin A.
 A deficiency of this vitamin leads to a loss of night vision.
Vitamin C
 Although most animal species can synthesize vitamin C,
humans, some animals obtain this vitamin from dietary
sources.
 Citrus fruits, strawberries, tomatoes, and sweet potatoes
are all excellent sources of vitamin C.
 Vitamin C, or ascorbic acid, is important in the
formation of collagen, a protein that forms the
connective tissues of skin, muscle, and blood vessels.
 A deficiency of vitamin C causes scurvy, a common
disease of sailors in the 1600s who had no access to
fresh fruits on long voyages.
Readings
Book Chapter 11
Book Page : 322-354