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CHAPTER 44.2 Nomenclature of Alkanes●Systemic names○Names produced by IUPAC rules●Substituents○Groups connected to the parent chain●If there is a competition between two chains of equal length -- chose the chain with the greater number of substituents●Cycloalkanes○“Cyclo-” indicates the presence of a ringNaming Substituents●Named with the same terminology as naming parents but add “-yl”●Alkyl Groups○Substituent with two carbon atoms (ethyl)Naming Complex Substituents●Place numbers going awayfrom the parent chain●Treat complex substituents as if it has a miniparent with it’s own substituents●Assembling the Systematic Name of an Alkane●Locant○Location of the methyl group clearly identified with a number●Naming Alkanes1.
Identify the parent chain2.
Identify and name the substituents3.Number the parent chain and assign a locant to each substituent4.Arrange the substituents alphabetically
Naming Bicyclic Compounds●Bridgeheads:two carbon atoms where the rings are fused together○For each path, count the # of carbons (excluding bridgeheads)■○To number the parent - start at one of the bridgeheads and begin numbering along the longest path, then go to the 2nd longest path, finally go along the shortest pathStrategy For Naming Complex Compounds1.
Identify the parent2.
Identify and name substituents3.Assign locants
4.Arrange substituents alphabeticallyConstitutional Isomers●Number of possible constitutional isomers increase with increasing molecular size○Tip for not drawing same molecule - compare namesRelative Stability (Heat of Combustion)●Change in enthalpy:heat given off during the reaction (H°)△●For a combustion process -H° is called the △heat of combustion○Increases with each CH2group○Compare rings of different sizes by dividing the HOC by # of CH2groups in the compound■Gives HOC per CH2group●Differences in H° can be found by comparing stability of alkanes△○Compare amount of heat given off by each combustion process○Compare potential energy that each isomer had beforecombustion○Branched alkanes are LOWER in energy (MORE STABLE) than straight-chain alkanes■Branched = more stable = lower energyNewman Projections●Conformations:3D shapes●Steps to drawing