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Organic Chemistry. Alkenes and Alkynes Geometric Isomers of Alkenes Addition Reactions. Saturated and Unsaturated Compounds. Saturated compounds ( alkanes ) have the maximum number of hydrogen atoms attached to each carbon atom
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Organic Chemistry Alkenes and Alkynes Geometric Isomers of Alkenes Addition Reactions
Saturated and Unsaturated Compounds • Saturated compounds (alkanes) have the maximum number of hydrogen atoms attached to each carbon atom • Unsaturated compounds have fewer hydrogen atoms attached to the carbon chain than alkanes • Unsaturated compounds contain double or triple bonds
Alkenes • Carbon-carbon double bonds • Names end in -ene • H2C=CH2 ethene (ethylene) • H2C=CH-CH3 propene (propylene) • cyclohexene
Alkynes • Carbon-carbon triple bonds • Names end in -yne • HC CH ethyne(acetylene) • HC C-CH3 propyne
Naming Alkenes and Alkynes • When the carbon chain has 4 or more C atoms, number the chain to give the lowest number to the double or triple bond. 1 2 3 4 CH2=CHCH2CH3 1-butene CH3CH=CHCH3 2-butene CH3CH CHCH3 2-butyne
Learning Check HA3 • Write the IUPAC name for each of the following unsaturated compounds: • CH3CH2C CCH3 CH3 • CH3C=CHCH3 2-pentyne 2-methyl-2-butene 3-methylcyclopentene
Cis and Trans Isomers • Double bond is fixed • Cis/trans Isomers are possible
Hydrogenation • Adds a hydrogen atom to each carbon atom of a double bond H H Ni H H • H–C=C–H + H2 H–C–C–H H H ethene ethane
Products of Hydrogenation • Adding H2 to vegetable oils produces compounds with higher melting points • Margarines • Soft margarines • Shortenings (solid)