CHEM 2211 1st Edition Lecture 3 Outline of Last Lecture I Br nsted Lowry Acid Base Theory II Ka value III Factors that affect Ka IV Conjugate Acids and Bases V Resonance Structures Outline of Current Lecture I Alkyl group formation II Addition of Functional groups III Naming of Iso structures IV Naming of sec and tert butyl structure V Naming Alkanes Vocabulary Alkyl group Secondary Carbon Tertiary Carbon Functional group Butyl Alkane Primary Carbon Isobutyl Parent Chain Propyl Sec butyl Isopropyl Tert butyl Current Lecture I An Alkyl group is formed by removing one hydrogen from an Alkane CH3 CH3CH2 CH3CH2CH2 Methyl group Ethyl group Propyl group R is used to denote a methyl group II Different functional groups can be added to an alkyl substituent R OH an alcohol R NH2 an amine R X III an alkyl halide X F Cl Br I R O R an ether There are two molecules with a three carbon chain propyl and isopropyl A A propyl group is a group with a hydrogen removed from the primary carbon i Primary Carbon a carbon bonded to only one other carbon CH3CH2CH3 CH3CH2CH2 Propane a Propyl Group B An isopropyl group has a secondary carbon bonded to one hydrogen and to two CH3 groups i Secondary Carbon a carbon bonded to two carbons CH3CH2CH3 CH3CHCH3 Propane an Isopropyl Group C EXAMPLE Figure 1 Propyl Chloride Figure 2 Isopropyl Chloride IV There are four alkyl groups with four carbons butyl isobutyl sec butyl and tert butyl A While butyl and isobutyl follow the same rules as propyl and isopropyl above sec butyl and tert butyl are different i Sec butyl has a hydrogen removed from a secondary carbon ii Tert butyl has a hydrogen removed from a tertiary carbon 1 Tertiary Carbon a carbon bonded to three Figure 3 Butyl Group Figure 4 Isobutyl Group Figure 5 Sec butyl Group Figure 6 Tert butyl Group V Naming Alkanes A Rules i Determine the longest continual chain of carbons known as the parent chain 4 methyloctane 4 ethyloctane ii Number the chain in the direction that give the substituent the lowest number possible 1 REMEMBER only systematic names have numbers 2 methylpentane NOT 4 methylpentane 3 ethylhexane NOT 4 ethylhexane iii If more than one substituent is attached to the parent hydrocarbon the chain is numbered in the direction that will produce the name containing the lowest of the possible numbers Substituents are listed in alphabetical order not numerical order Bruice 2014 5 ethyl 3 methyloctane NOT 4 ethyl 6 methyloctane 1 The prefixes di tri tetra etc indicate the number of identical substituents are on the parent chain 2 4 dimethylhexane iv If the same number is obtained in both directions for differing substituents then the group listed first receives the lowest number 2 2 4 trimethylpentane v When the substituents receive the same number when numbered both ways the substituent that is labeled first gets the lowest number 2 bromo 3 chlorobutane NOT 3 bromo 2 chlorobutane vi In a highly branched compound where the substituent also has branched portions the substituent s name is in parenthesis and is accompanied by a number indicating a position on the substituent 4 1 methylethyl heptane vii In the case that two hydrocarbon chains have the number of carbons choose the one with the most substituents 2 ethyl 2 methylhexane
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