34 ALKANES (d) This group contains four carbons in its longest continuous chain. It is named as a butyl group with a cyclopropyl substituent at C-1. It is a 1-cyclopropylbutyl group and is a △ (e, f) a two-carbon group that bears a cyclohexyl substituent is a cyclohexylethyl gi umber from the point of attachment when assigning a locant to the cyclohexyl group CH,CH,一 CH H3 2-Cyclohexylethyl 1-Cyclohexylethyl 2.22 The IUPAC name for pristane reveals that the longest chain contains 15 carbon atoms(as indicated by pentadecane). The chain is substituted with four methyl groups at the positions indicated in the name Pristane(2,6, 10, 14-tetramethylpentadecane) 2.23(a) An alkane having 100 carbon atoms has 2(100)+2=202 hydrogens. The molecular formula of hectane is C1o0H2o2 and the condensed structural formula is CH,(CH,oCH3. The 100 carbon atoms are connected by 99 o bonds. The total number of o bonds is 301(99C-C bonds+ 202 C-H bonds ). (b) Unique compounds are formed by methyl substitution at carbons 2 through 50 on the 100-carbon chain(C-51 is identical to C-50, and so on). There are 49 x-methy lhectanes (c) Compounds of the type 2- x-dimethylhectane can be formed by substitution at carbons 2 through 99. There are 98 of these compounds. 2.24 Isomers are different compounds that have the same molecular formula. In all these problems the safest approach is to write a structural formula and then count the number of carbons and hydrogens (a) Among this group of compounds, only butane and isobutane have the same molecular CH CH,CH,CH CH3 CHCH3 CH3 CHCH, CH3 Cyclobutane Isobutane 2-Methylbutane CH (b The two compounds that are isomers, that is, those that have the same molecular formula, are 2, 2-dimethylpentane and 2, 2, 3-trimethylbutane CH CH CH CH,CCH,CH,CH3 CH3C--CHCH CH Back Forward Main Menu TOC Study Guide Toc Student OLC MHHE Website(d) This group contains four carbons in its longest continuous chain. It is named as a butyl group with a cyclopropyl substituent at C-1. It is a 1-cyclopropylbutyl group and is a secondary alkyl group. (e, f ) A two-carbon group that bears a cyclohexyl substituent is a cyclohexylethyl group. Number from the point of attachment when assigning a locant to the cyclohexyl group. 2.22 The IUPAC name for pristane reveals that the longest chain contains 15 carbon atoms (as indicated by -pentadecane). The chain is substituted with four methyl groups at the positions indicated in the name. 2.23 (a) An alkane having 100 carbon atoms has 2(100) 2  202 hydrogens. The molecular formula of hectane is C100H202 and the condensed structural formula is CH3(CH2)98CH3. The 100 carbon atoms are connected by 99 bonds. The total number of bonds is 301 (99 CGC bonds 202 CGH bonds). (b) Unique compounds are formed by methyl substitution at carbons 2 through 50 on the 100-carbon chain (C-51 is identical to C-50, and so on). There are 49 x-methylhectanes. (c) Compounds of the type 2,x-dimethylhectane can be formed by substitution at carbons 2 through 99. There are 98 of these compounds. 2.24 Isomers are different compounds that have the same molecular formula. In all these problems the safest approach is to write a structural formula and then count the number of carbons and hydrogens. (a) Among this group of compounds, only butane and isobutane have the same molecular formula; only these two are isomers. (b) The two compounds that are isomers, that is, those that have the same molecular formula, are 2,2-dimethylpentane and 2,2,3-trimethylbutane. 2,2-Dimethylpentane C7H16 CH3CCH2CH2CH3 CH3 CH3 2,2,3-Trimethylbutane C7H16 CH3C CH3 CH3 CHCH3 CH3 CH3CH2CH2CH3 Butane C4H10 Isobutane C4H10 Cyclobutane C4H8 CH3CHCH3 CH3 2-Methylbutane C5H12 CH3CHCH2CH3 CH3 Pristane (2,6,10,14-tetramethylpentadecane) CH2CH2 CH CH3 2 1 1 2 2-Cyclohexylethyl (primary) 1-Cyclohexylethyl (secondary) CHCH2CH2CH3 12 3 4 34 ALKANES Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website