Saturated and Unsaturated Compounds

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 • Contain carbon-carbon double bonds • Names end in -ene H2C=CH2 ethene (ethylene) H2C=CH-CH3 propene (propylene) cyclohexene

Alkynes • Contain carbon-carbon triple bonds • Names end in -yne HCCH ethyne (common name: acetylene; fuel for torches) HCC-CH3 propyne

Naming Alkenes and Alkynes When the carbon chain has 4 or more C atoms, number the chain that has the double or triple bond in itto 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 Write the IUPAC name for each of the following unsaturated compounds: A. CH3CH2CCCH3 CH3 B. CH3C=CHCH3 C.

Solutions Write the IUPAC name for each of the following unsaturated compounds: A. CH3CH2CH=CHCH3 2-pentyne CH3 B. CH3C=CHCH3 C. 2-methyl-2-butene3-methylcyclopentene

Cis and Trans Isomers • Double bond is fixed • Cis/trans isomers are possible CH3 CH3 CH3 CH = CH CH = CH cis trans CH3

Hydrogenation • Adds a hydrogen atom to each carbon atom of a double bond H H H H Ni 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)

Learning Check What is the product of adding H2 (Ni catalyst) to 1-butene?

Solution What is the product of adding H2 (Ni catalyst) to 1-butene? Ni CH2=CHCH2CH3 + H2 CH3CH2CH2CH3

Adding Halogens Halogens also add to the double bond of an alkene. H2CCH2 +Cl2

Learning Check Write the product of the following addition reactions: CH3CH=CHCH3 + H2

Solution Write the product of the following addition reactions: CH3CH=CHCH3 + H2 CH3CH2CH2CH3

Saturated and Unsaturated Compounds