1559T_ch11_199-21911/02/0521:43Page202 ⊕ EQA 202.Chapter 11 ALKENES:INFRARED SPECTROSCOPY AND MASS SPECTROMETRY of the most stable alkene (the ther 0m100% CHsCH-CH-CHaBrK-OCCH(CH.COH CH:CH2CH=CH2 CHCH-CHBICHCH,CH-CH-CH2+CHCH-CHCH Major Minor,cis and trans CH.CH-CHBCH CH,CH.CH-CHCHCH-CHCH Maior cis and trans Either 1-or 2-butanol CHCH.CH-CH+CH,CH-CHCH Additional information pertaining to this process is presented in Chapter 12. Solutions to Problems HO、 OCH (HO (d) (e) 27.(a)cis-or Z-2-Pentene (b)3-Ethyl-1-pentene (c)trans-or E-6-Chloro-5-hexen-2-ol (d)Z-1-Bromo-2-chloro-2-fluoro-1-iodoethene (Priorities are I Br on CI and Cl F on C2.) (e)Z-2-Ethyl-5.5.5-trifluoro-4-methyl-2-penten-1-ol (f)1.1-Dichloro-1-butene (g)-1.2-Dimethoxypropene (h)-2.3-Dimethyl-3-heptene 28.(a)H.at =8+2-1=9:degrees of unsaturation =(9-7)/2 =1 bond or ring present.The functional group 8=4.0(s,2 H):CH2,most hed to Cl 1 H):Two alkene hydrogens of the most stable alkene (the thermodynamic product). Alcohol dehydrations are susceptible to rearrangement processes. A classic example is encountered in attempted syntheses of terminal alkenes such as 1-butene. The only 100% reliable method is base-promoted E2 elimination of a suitable 1-butyl compound (e.g., 1-bromo￾butane, 1-butyl tosylate). Any other method will give mixtures: Additional information pertaining to this process is presented in Chapter 12. Solutions to Problems 26. (a) (b) (c) (d) (e) 27. (a) cis- or Z-2-Pentene (b) 3-Ethyl-1-pentene (c) trans- or E-6-Chloro-5-hexen-2-ol (d) Z-1-Bromo-2-chloro-2-fluoro-1-iodoethene (Priorities are I  Br on C1 and Cl  F on C2.) (e) Z-2-Ethyl-5,5,5-trifluoro-4-methyl-2-penten-1-ol (f ) 1,1-Dichloro-1-butene (g) Z-1,2-Dimethoxypropene (h) Z-2,3-Dimethyl-3-heptene (i) 1-Ethyl-6-methylcyclohexene. This name is better than 2-ethyl-3-methylcyclohexene, because the first number is smaller. 28. (a) Hsat  8  2 1  9; degrees of unsaturation  (9 7)/2  1
bond or ring present. The integrated intensities reveal the pieces.   1.8 (s, 3 H): CH3, attached to an unsaturated functional group   4.0 (s, 2 H): CH2, most likely attached to Cl   4.9 and 5.1 (singlets, each 1 H): Two alkene hydrogens HO OCH3 Cl HO Cl Cl Cl I Br Conc. H2SO4, Either 1- or 2-butanol Minor Major, cis and trans CH3CH2CH CH2  CH3CH CHCH3 NaOCH2CH3, CH3CH2OH CH3CH2CHBrCH3 Minor Major, cis and trans CH3CH2CH CH2  CH3CH CHCH3 K OC(CH3)3, (CH3)3COH  CH3CH2CHBrCH3 Major Minor, cis and trans CH3CH2CH CH2  CH3CH CHCH3 K OC(CH3)3, (CH3)3COH  The only elimination product CH3CH2CH2CH2Br CH3CH2CH CH2 202 • Chapter 11 ALKENES; INFRARED SPECTROSCOPY AND MASS SPECTROMETRY 1559T_ch11_199-219 11/02/05 21:43 Page 202