Module No.
05(Q2)
Structure and nomenclature of Hydrocarbon compounds
Describe functional groups and distinguish each properties.
Specific Objectives
At the end of this module, learners are expected to:
1. compare and contrast the structures of the major classes of substituted
hydrocarbons.;
2. show the general formula of each functional group; and
3. site some of its uses and examples.
Materials
•
•
•
Pen
Bond paper or intermediate paper
Any Chemistry book or Laboratory Manual
Lesson
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Figure 16 Freshly baked strawberry cake
Doesn’t that strawberry cake look good and fresh out of the oven?
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Looking at the picture, you can almost smell the sweet strawberry aroma
together with the other ingredients used in this freshly baked cake. What
causes these ingredients to have aromas? Certainly, all ingredients contain
molecules with a distinctive group of atoms located at the end of the molecule.
This atomic arrangement imparts a pleasant aroma to the molecule.
The part of a molecule having a specific arrangement of atoms that is
largely responsible for the chemical behavior of the parent molecule is called a
functional group. Functional groups can be atoms, group of atoms or bond
arrangements. (John P.,Strozak and Cheryl Wistrom,Chemistry,p. 640) As you
study these functional groups, notice the similarities among molecules
containing a given functional group that leads to the use of members of that
group for similar purposes.
Functional Groups
1. Halogenated Compound
Structure: R-X, where X = F,Cl,Br, or I
Functional group: halogen atoms
Properties: high density
Uses: refrigirants, solvents,pestisides, moth repellents, some plastics
Biological functions: thyroid hormones
Examples: chloroform, dichloromethane,thyroxin, freon, DDT,PCBs, PVC
2. Alcohols
Structure: R—- 0-— H
Functional group: hydroxyl group (— OH); hydrogen atom bonded to an
oxygen atom, which is bonded to the hydrocarbon part of the molecule
Properties: polar, so water molecules are attracted to it; high boiling
point; alcohols with low molecular weights are water-soluble
Uses: solvents, disinfectants, mouthwash and hair-spray ingredient,
antifreeze
Biological functions: reactive groups in carbohydrates, product of
fermentation
Examples: methanol, ethanol, isopropanol (one type of rubbing alcohol),
cholesterol, sugars
3. Carboxylic Acids
Structure:
Functional group: carboxyl group bonded to a carbon, and the
hydrocarbon part of the molecule
Properties: acidic, usually water-soluble, strong unpleasant odors, form
metal salts in acid-base reactions
Uses: vinegar, tart flavoring, skin-care products, production of soaps and
detergents
Biological functions: pheromones, ant sting toxin; causes rancid-butter
and smelly-feet odors
Examples: acetic acid (in vinegar), formic acid, citric acid (in lemons),
salicylic acid
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4. Esters
Structure:
derived from carboxylic acids in which the —OH of the carboxyl group
has been replaced with an —OR from an alcohol
Properties: strong aromas, volatile
Uses: artificial flavorings and fragrances, polyester fabric
Biological functions: fat storage in cells, DNA phosphate-sugar
backbone, natural flavors and fragrances, beeswax
Examples: banana oil, oil of wintergreen, triglycerides (fats)
5. Ethers
Structure: R—O—R'; oxygen atom bonded to two hydrocarbon groups
Properties: mostly unreactive, insoluble in water, volatile
Uses: anesthetics, solvents for fats and waxes
Examples: diethyl ether
6. Ketones and Aldehydes
Structures:
Ketones
Aldehydes
Functional group: carbonyl group(-- CO); carbon atom double bonded to
an oxygen atom
Properties: very reactive, distinctive odors
Uses: solvents, flavorings, manufacture of plastics and adhesives,
embalming agent
Examples: acetone; formaldehyde; cinnamon, vanilla, and almond
flavorings
7. Amines and Amides
Structures:
Amine
Amide
Functional group:
amine: amino group (--NH2); two hydrogen atoms bonded to a nitrogen
atom, which is bonded to the hydrocarbon part of the molecule
amide: amino group bonded to a carbonyl group (—CONH2)
Properties: amines: basic, ammonia-like odor
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amides: neutral, most are solids
Uses: solvents, synthetic peptide hormones, fertilizer, nylon synthesis
Biological functions: in amino acids, peptide hormones, and proteins;
distinctive odor of some cheeses
Examples: urea, putrescine, cadaverine, Nutrasweet
Directions
Directions: Classify the following compounds based on the presence
of functional group.
1.
2.
3.
4.
5.
Agreement:
Explain how ethanol is being produced and enumerate its usefulness.
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References
Chang, Raymond and Jayson Overby…General Chemistry The Essential
Concepts 6Th Edition. New York: The McGraw Hill Companies Inc, 2011
Key to Correction
1.
2.
3.
4.
5.
Halogenated compounds
Carboxylic acid
Alcohol
Esters
Ketone
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