6. When two or more substituents are identical indicate this by the use of the prefixes di-, tri-, tetra", and so on CH3 H3 CH 3 3 CH3CH2CCH2CH2CH3 CH3 CH2CHCHCHCH3 CH CH 3 3, 3-dimethylhexane 2, 3, 4-trimethylhexane Not 3-dimethylhexane Not 3, 4.5-trimethylhexane
6. When two or more substituents are identical, indicate this by the use of the prefixes di-, tri-, tetra-, and so on CH3 CH2 CCH2 CH2 CH3 CH3 CH3 3,3-dimethylhexane Not 3-dimethylhexane CH3 CH2 CHCHCHCH3 CH3 CH3 2,3,4-trimethylhexane Not 3,4,5-trimethylhexane CH3
7. When two chains of equal length compete for selection as the parent chain, choose the chain with the greater number of substituents CH 3 CH 3 CH3CH2 CHCHCHCHCH3 CH2 CH3 CH- CH 2, 3,5-trimethyl-4-propylheptanehexane(four subs) Not 4-sec-butyl-2, 3-dimethylheptane(three subs
7.When two chains of equal length compete for selection as the parent chain, choose the chain with the greater number of substituents. CH3 CH2 CHCHCHCHCH3 CH3 CH3 2,3,5-trimethyl-4-propylheptanehexane (four subs) Not 4-sec-butyl-2,3-dimethylheptane (three subs) CH2 CH3 CH2 CH3 4 2 1 7 6 5
8. When branching first occurs at an equal distance from either end of the longest chain, choose the name that gives the lower number at the first point of difference CH3 CH3CH3 CH3CHCH2CHCHCH3 654321 123456 2, 3, 5-Trimethylhexane (not 2, 4,5-trimethylhexane
8. When branching first occurs at an equal distance from either end of the longest chain, choose the name that gives the lower number at the first point of difference. CH3 CHCH2 CHCHCH3 CH3 CH3 CH3 2,3,5-Trimethylhexane (not 2,4,5-trimethylhexane 1 2 3 4 5 6 6 5 4 3 2 1
4.3C Nomenclature of branched alkyl groups Three-Carbon groups CH CHCH Propyl group两基 CHrCH,CH CH2CH or( CH3hCH CH3 1-methylethyl group or isopropyl group 1-甲基乙基(异丙基
4.3C Nomenclature of branched alkyl groups Three-Carbon groups CH3 CH2 CH3 CH3 CH2 CH2 CH3 CH CH3 or (CH3 ) 2 CH Propyl group 丙 基 1-methylethyl group or isopropyl group 1-甲 基 乙 基 （ 异 丙 基 ）
Four-carbon groups Four-Carbon groups CHCH CH Butyl group丁基 CH.CHCH Butane CH2 CHCH I-methylpropyl group or( sec-butyl group) 1-甲基丙基(第二丁基) CH Four-Carbon groups 3 CH CHCH CH. 3 isobutyl group异丁基 CHCHCH 3 CH 3 Isobutane CHC CH 1, I-dimethylpropyl group or( tert-butyl group) 甲基丙基 叔丁基
Four-carbon groups Four-Carbon groups CH3 CH2 CH2 CH3 CH3 CH2 CH2 CH3CH2CH CH3 Butyl group 丁 基 1-methylpropyl group or ( sec-butyl group) 1-甲 基 丙 基 （ 第 二 丁 基 ） Butane Four-Carbon groups CH3 CHCH3 CH3 CHCH2 CH3 C CH3 isobutyl group 异丁 基 1,1-dimethylpropyl group or ( tert-butyl group) 1,1-二 甲 基 丙 基 （ 叔 丁 基 ） Isobutane CH3 CH3 CH3