Module 6: Cycloalkenes
Pharmaceutical Organic Chemistry (Lecture)
PChem 1202 | Kristine Chesley D. Dullan | BS Pharmacy 1A | Prof. Taytayon
CYCLOALKENES
Cycloalkenes
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also called cycloolefin
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type of alkene HC which contains a closed ring of C atoms
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prefix -cyclo comes from ancient Greek meaning round
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whenever the ends of a C chain are joined together, that
molecule is said to be cyclic & alkenes are no different from
other C chains in that respect
PHYSICAL PROPERTIES
Physical Properties
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Unsaturated = have fewer H atoms & fewer bonds
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as opposed to open-chain alkenes
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less internal energy within the molecule
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uses Van der Waals force to bond (like cycloalkanes)
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Macroscopically, liquid at room temperature
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Very low solubility in water
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Only first few cycloalkenes are gas
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Rarely solid at room temperature
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Have similar physical properties to alkenes & cycloalkenes
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Cycloalkenes have at least 1 double bond
CHEMICAL PROPERTIES
Chemical Properties
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contain double bonds
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Benefit from enhanced stability if double bonds are
conjugated
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If it contains a total of 3 double bonds; it is no longer a
cyclohexene
Benzene
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6 C ring w/ 3 alternating (and conjugated) double bonds
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stable molecule that displays completely different chemistry
than other non-aromatic cycloalkenes
USES
Cycloalkenes
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most important organic substances for biological &
industrial purposes
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used in production of molecules essential to a broad
spectrum of applications
ADDITION REACTION
5 addition reaction of cyclohexene
NOMENCLATURE
RULE 1: Number the C atoms in the ring so that double bond is
between C atom 1 & C atom 2
RULE 2: Give lower numbers to the group/branch encountered first
RULE 3: Number & list groups in alphabetical order
Addition reaction of open chained alkene
Structural differences between
open chained alkenes & cycloalkenes
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