Senior High School
General
Chemistry 1
Quarter 2 Week 2 Module 2
Arenes and
Hydrocarbon Derivatives
General Chemistry 1 – Grade 11
Alternative Delivery Mode
Quarter 2 Week 2 Module 2: Arenes and Hydrocarbon Derivatives
2nd Edition 2021
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What I Need to Know
This module was designed and written with you in mind. It is here to help you
master the nature of Chemistry. The scope of this module permits it to be used in
many different learning situations. The lessons are arranged to follow the standard
sequence of the course. The module consists of one lesson, namely:
• Lesson 1 – Arenes and Hydrocarbon Derivatives
After going through this module, you are expected to:
1. write names and formulas for simple arenes
2. describe the different functional groups (STEM_GC11OCIIg-j-87)
3. identify the functional group in each of the following: organic halide, alcohol,
phenol, ether, amine, aldehyde, ketone, carboxylic acid, ester and amide.
What I Know
I. Choose the letter of the correct answer. Write your answers in a separate sheet of
paper.
1. Cortisone belongs to ________ group.
A. aldehyde
B. amide
C. ester
D. ketone
2. Methylacetate belongs to the class of _________.
A. aldehyde
B. amide
C. ester
D. ketone
3. What is the name of the following compound?
A. 1, 2-dimethylbenzene
B. meta-xylene
C. ortho-xylene
D. para-xylene
For numbers 4 to 7, identify the class of compound for the given hydrocarbon
derivative based on its structure.
4.
A. alcohol
B. ester
C. ether
D. organic halide
A. aldehyde
B. amide
C. amine
D. ether
A. alcohol
B. aldehyde
C. amide
D. amine
5.
6.
7.
A. alcohol
B. carboxylic acid
C. ester
D. ether
8. The general formula for amines is _________.
A. R-CH2
B. R2CH
C. R-NH2
D. R-COOH
9. Compounds in which one hydrogen atom of an alkane is substituted by one
halogen atom are called _______.
A. ethers
B. phenols
C. alcohols
D. organic halides
10. A _________ is characterized by the presence of the -OH group attached to a
hydrocarbon chain.
A. ether
B. phenol
C. alcohol
D. organic halide
11. The general formula for carboxylic acids is _______.
A. R-OH
B. R-O-R
C. R-NH2
D. R-COOH
12. Hydrocarbons and their derivatives are called ________.
A. isomers
C. organic compounds
B. isotopes
D. inorganic compounds
13. Groups of atoms that can occur within organic molecules are called ________.
A. alkane groups
C. functional groups
B. cyclic compounds
D. homologous groups
14. A group of atoms obtained by removing one hydrogen atom from an alkane is
a/an __________.
A. alkene
B. alkyne
C. alkyl group
D. functional group
15. ____________ is an example of ester.
A.
C.
B.
D.
Lesson 1
Arenes and Hydrocarbon Derivatives
What’s In
In the previous module, we have already been acquainted with alkyl groups.
In this lesson, we will revisit alkyl groups and become familiar with another kind of
substituent in organic chemistry – the aryl groups. Such will then be followed by the
topic on arenes or aromatic hydrocarbons. These are unsaturated hydrocarbons that
have one or more planar six-carbon rings called benzene rings to which hydrogen
atoms are attached with the general formula C nHn. Lastly, we shall deal with
hydrocarbon derivatives which are offshoots of hydrocarbons.
What’s New
The stamp at the right commemorates
Kekulé’s proposal for the cyclic structure of
benzene in 1865.
Benzene, a molecule with the chemical
structure of C6H6, has a molar mass of just
over 78 grams/mole. At room temperature,
benzene tends to exist in a liquid state. It is
colorless and has a very distinctive gasoline-like
Figure 2.1. August Kekulé stamp
odor. Benzene is soluble in water and has a
(Source: Corwin, C. H. (2018). Introductory
Chemistry Concepts and Critical Thinking
melting point of 5.33 degrees Celsius. It also
8th ed. USA: Prentice Education, Inc.)
has a boiling point of 80.1 degrees Celsius.
This aromatic hydrocarbon is also highly
flammable. It is carcinogenic and tends to be used as an additive to gasoline,
plastics, synthetic rubbers, dyes, and industrial solvents. It is also the parent
compound for numerous other aromatic compounds.
What is It
Alkyl and Aryl Groups
When a hydrogen atom is removed from an alkane, an alkyl group (symbol R-)
results. Because an alkyl group is missing a hydrogen atom, it can bond to another
atom or molecule. The name of the alkyl group is formed by changing the suffix -ane
of the alkane to the suffix -yl. For example, methane becomes a methyl group.
Similarly, removing a hydrogen atom from ethane gives an ethyl group.
Removal of a hydrogen atom from propane can occur in two ways—from the end of
the molecule or from the middle carbon atom. The structural formula of propane,
CH3–CH2–CH3, shows that there are six hydrogen atoms on the end carbons and two
hydrogen atoms on the central carbon. Since the end carbon atoms are identical, we
can remove any one of the six hydrogen atoms to produce a propyl group.
Since the middle two hydrogen atoms are equivalent, we can remove either of these
atoms to form an isopropyl group.
It is easy to see that we can substitute a chlorine atom onto a propane molecule at
two different positions. If the chlorine is attached to an end carbon, the result is
“propyl chloride,” CH3–CH2–CH2–Cl. If the chlorine atom is attached to the central
carbon, the result is “isopropyl chloride,” CH 3–CH(Cl)–CH3. “Propyl chloride” and
“isopropyl chloride” are isomers, and thus have different properties.
When a hydrogen atom is removed from an aromatic hydrocarbon, the result is an
aryl group (symbol Ar – ). The most common aryl group results from removal of a
hydrogen atom from a benzene ring. The resulting aryl group is called a phenyl
group.
Now, let us summarize
the structures of
alkyl groups. The names and formulas of selected alkyl and aryl groups are shown
in Table 2.1.
Table 2.1 Alkyl and Aryl Groups
Arenes
In 1825, the English scientist Michael Faraday (1791–1867) isolated a
substance from the fuel oil used in lamps. After analysis, the formula of the
compound was determined to be C6H6. A few years later, the same compound was
isolated from the natural product benzoin, a topical antiseptic. This compound, C 6H6,
was originally called benzin, but the name evolved into benzine, and eventually
benzene.
Arene Family of Compounds
As other organic compounds were isolated and identified, chemists observed
that those containing a benzene structure often had a fragrant odor. Thus, these
compounds were termed aromatic because of their pleasant aroma. Further analysis
revealed that the benzene structure and the fragrant odor were not related. The term
persisted, however, and today an aromatic hydrocarbon is one that usually contains
the benzene structure. Arenes are a family of aromatic hydrocarbon compounds
whose names end in the suffix -ene.
In 1865, German chemist August Kekulé (1829–1896) proposed that benzene,
C6H6, had a cyclic structure with three double bonds. He suggested that six carbon
atoms formed a ring with alternating single and double bonds. The structure is called
the Kekulé structure of benzene. Since the double bonds are not in fixed positions
and shift between carbon atoms, the electrons are said to be delocalized. Because of
this phenomenon, and for simplicity, the benzene ring is usually shown by a hexagon
enclosing a circle to represent C6H6.
Isomers
Benzene
of
Using the delocalized electron model of benzene, we can represent the
structure of dichlorobenzene as follows:
Notice that the two chlorine atoms are next to each other on the benzene ring.
When two groups are adjacent on a benzene ring, their positions are indicated by the
prefix ortho–. If the groups are separated by a carbon, their positions are indicated
by the prefix meta-. If the groups are opposite each other on the benzene ring, their
positions are indicated by the prefix para-. Since ortho-, meta-, and para- compounds
have the same molecular formula but are different, they are structural isomers.
Recall that isomers have different physical properties. We can illustrate these
isomers as follows:
Example
Example Exercise:
Exercise:
Give
for the following:
Drawthe
thesystematic
structural IUPAC
isomer name
for meta-dimethylbenzene.
Solution:
The compound contains a benzene ring. It also has two –CH3 groups on the
benzene ring
in the meta position.
Answer:
para-fluoroiodobenzene
Hydrocarbon Derivatives
In the 1800s, chemists began to realize that there was a huge number of
organic compounds. As more compounds were identified and studied, the subject
became overwhelming. According to the German chemist Friedrich Wöhler, organic
chemistry seemed to be a “dreadful endless jungle.” Gradually, chemists began to
realize that organic compounds could be classified into only a few categories. Each
of these categories is referred to as a class of compounds and all the compounds in
each class have similar names and properties.
To comprehend the vast subject of organic chemistry, chemists have divided
a massive amount of information into divisions of organic compounds. The first
division separates hydrocarbons and their derivatives. A hydrocarbon contains only
hydrogen and carbon. A hydrocarbon derivative is derived from a hydrocarbon, but
contains other elements, such as oxygen, nitrogen, or halogen (F, Cl, Br, I).
We will study 10 classes of hydrocarbon derivatives. Our task is simplified by
the fact that each member in a class has similar names and properties. The classes
are organic halides (R―X), alcohols (R―OH), phenols (Ar―OH), ethers (R―O―R′),
amines (R―NH2), aldehydes (R―CHO), ketones (R―COR′), carboxylic acids
(R―COOH), esters (R―COOR′), and amides (R―CONH2). The use of R and R′ indicates
that the groups may or may not be the same.
Hint: The symbol R represents an alkyl group and Ar represents an aryl group. The
designations R and R′ indicate different alkyl groups.
The structural feature in a molecule that characterizes a class of compounds
is called the functional group. For example, in an alcohol (R―OH), the functional
group is ―OH attached to a carbon atom. For an ether (R―O―R′), the functional
group is the oxygen atom between two carbon atoms.
Hint: An organic compound may contain more than one functional group. Thus, an
organic compound may represent two or more hydrocarbon derivatives.
We can further divide these 10 hydrocarbon derivatives into five classes that
have a carbon atom double bonded to an oxygen atom (C=O), and five classes that
do not. A carbon atom joined to an oxygen atom by a double bond is
called a carbonyl group. The presence of a carbonyl group gives distinct properties
to a given class of compounds, such as amides that have a carbonyl group and
amines that do not.
Figure 2.2. Hydrogen Derivatives (without carbonyl)
(Source: Corwin, C. H. (2018). Introductory Chemistry Concepts and Critical Thinking 8th ed. USA: Prentice
Education, Inc.)
For organic halides, X can be F, Cl, Br or I. For alcohols, R can be any alkyl
group that is not an aryl (Ar); for phenols, the ―OH group must be attached directly
to an aryl group.
Figure 2.3. Hydrogen Derivatives (with carbonyl)
(Source: Corwin, C. H. (2018). Introductory Chemistry Concepts and Critical Thinking 8th ed. USA: Prentice
Education, Inc.)
Aldehydes, ketones, carboxylic acids, esters, and amides all contain a
carbonyl group with different attached groups. The symbol R can be any alkyl group,
and Ar can be any aryl group. (R can also be a hydrogen atom except in ketones.)
Table 2.2 Summary of Hydrocarbon Derivatives
Example Exercise: Classifying Hydrocarbon Derivatives
Indicate the class of hydrocarbon derivative for each of the following
compounds:
(a)
(b)
(c)
(d)
Solution:
Let us first identify the functional group in each compound. We can then refer to
the general formulas to determine the class of compound.
(a) This hydrocarbon derivative does not have a carbonyl group. Since the
functional group is a halogen (―Br),
CH3―Br is an organic halide.
(b) This hydrocarbon derivative does not have a carbonyl group. Since the
functional group is an amine (―NH2),
CH3―CH2―NH2 is an amine.
(c) This hydrocarbon derivative has a carbonyl group. Since the functional
group has a carbonyl attached to a H atom,
is an aldehyde.
(d) This hydrocarbon derivative has a carbonyl group attached to a benzene
ring. Since the functional group has a carbonyl attached to an OH,
is a carboxylic acid.
Example Exercise: Hydrocarbon Derivatives
Identify each of the following compounds as an organic halide, alcohol, phenol,
ether, or amine based on the name of the hydrocarbon derivative.
(a) caffeine
(b) choloroform
(c) cholesterol
(d) diethylether
Solution:
(a) Caffeine has an ―ine suffix; thus, the compound is an amine.
(b) Chloroform has ―chloro in the name; thus, it is an organic halide.
(c) Cholosterol has an ―ol suffix; thus, it is an alcohol, or phenol.
(d) Diethylether has ―ether in the name; thus, it is an ether.
What’s More
I. Read and answer the following on a separate sheet of paper.
1.
2.
3.
4.
Draw and name the 3 isomers of the solvent xylene, C 6H4(CH3)2.
Draw and name the 3 isomers of dinitrobenzene, C6H4(NO2)2.
What are the 2 products from the complete combustion of benzene?
Identify the class of compound for each of the following hydrocarbon
derivatives.
4.1.
4.2.
4.3.
4.4.
4.5.
4.6.
4.7.
4.8.
4.9.
4.10.
What I Have Learned
Fill in the blanks with the correct term(s).
_________ are hydrocarbons that contain a benzene ring. If there are two
groups attached to the ring, there are three possible isomers: _____-, ______-, and
_______-. A ________________ contains carbon, hydrogen, and an additional element
such as O, N, or a halogen. The hydrocarbon derivatives can be
divided into families, each of which is called a _______________. There are 10
classes of hydrocarbon derivatives, five of which have a ___________ group (C=O)
and five of which do not. The atom or group of atoms that characterizes a class of
compounds is referred to as a ____________ group.
What I Can Do
Read the following carefully and follow the procedures given.
You are a member of the creative design team in a chemical factory. Your task
is to create an advertisement about your chosen class of organic compound. Begin
your advertisement with a creative slogan. Then give a background information on
the properties, reactions, and uses of the organic compound. Your team should
design a four-page brochure. Your brochure will be evaluated based on the following:
•
•
•
•
creativity
accuracy of information
originality
visual impact
Total
20%
45%
20%
15%
100%
Assessment
Choose the letter of the correct answer. Write down your answer on a separate sheet
of paper.
1. Based on the name of the hydrocarbon derivative, identify the class of compound
of cinnamal.
A. aldehyde
B. amide
C. ester
D. ketone
2. The name of the compound below is _________.
A. meta-dinitrobenzene
B. ortho-dinitrobenzene
C. para-dinitrobenzene
D. 1,4-dinitrobenzene
3. Sulfanilamide belongs to the ________ class of compound.
A. aldehyde
B. amide
C. ester
D. ketone
For numbers 4 to 7, identify the class of compound for the given hydrocarbon
derivative based on its structure.
4.
5.
6.
A. aldehyde
B. amide
C. amine
D. phenol
A. ester
B. ether
C. ketone
D. phenol
A. amine
B. ester
C. ether
D. phenol
7.
A. alcohol
B. amide
C. ester
8. Ethers are formed by the attachment of ___________.
A. four alkyl groups to one oxygen atom
B. two alkyl groups to same oxygen atom
C. three alkyl groups to one oxygen atom
D. two alkyl group to different oxygen atoms
9. An example of an amide is _________.
A.
C.
B.
D.
10. Methanoic acid is classified as a/an ____________.
A. ether
B. ketone
C. aldehyde
11. ___________ is a ketone.
A.
D. ketone
D. carboxylic acid
C.
B.
D.
12. A/an __________ has two hydrocarbon groups bonded to the carbonyl carbon
atom.
A. ether
B. ketone
C. aldehyde
D. carboxylic acid
13. The term ________ is used for an atom or group of atoms that provide a family of
organic compounds its characteristics properties.
A. alkyl group
C. structural group
B. hydrocarbon
D. functional group
14. When compounds have an -OH attached to a benzene ring, they are classified as
_________.
A. ethers
B. phenols
C. alcohols
D. halo alkenes
15. A/an _________ has at least one hydrogen atom or two hydrogen atoms attached
to the carbonyl carbon atom.
A. ether
C. aldehyde
B. ketone
D. carboxylic acid
References
Corwin, C. H. (2018). Introductory Chemistry Concepts and Critical Thinking 8th ed.
USA: Prentice Education, Inc.
Guzman, D. F. et. al. (2012). Discover Science: Chemistry. Philippines: Diwa
Learning Systems, Inc.
byjus.com/chemistry/aromatic-hydrocarbons/
https://interestingengineering.com/what-is-benzene-and-why-is-it-so-useful
https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modul
es_(Organic_Chemistry)/Arenes/Nomenclature_of_Arenes
https://en.wikipedia.org/wiki/Dinitrobenzene
Answer Key
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