1559T_ch11_199-21911/02/0521:43Pa9e204 ⊕ EQA 204.Chapter 11 ALKENES:INFRARED SPECTROSCOPY AND MASS SPECTROMETRY olecule everything is accounted for,and the two CH H2C=CH-CH2-CH2OH (e)Ha=6+2 unsaturation=(6-4)/2=1bond or ring 1.7 (doublet.3 H):CHa,next to CH =5.7 (quartet,1 H):alkene CH,next to CH3 29.The multi t8=231s rtet for the 0 CH se of the three neighbors,the CH s additi 心8hg in th TPi6mtpiae In other words.lines 5 and6overlap to give one tall line in the center of the pattem.and lines7and overlap to give the oth 30.(a)Yes.1-Butene>trans-2-butene(which should be zero) (b)No (e)Yes.cistrans(which,again,is zero) As in (c), with only four carbons in the molecule everything is accounted for, and the two CH2 groups must be attached to each other; thus, H2CPCHOCH2OCH2OH (e) Hsat  6  2 2  6; degrees unsaturation  (6 4)/2  1
bond or ring.   1.7 (doublet, 3 H): CH3, next to CH   5.7 (quartet, 1 H): alkene CH, next to CH3 All that’s left is one C and two Cl’s, so the pieces, and two Cl’s, combine to give the answer, CH3OCHPCCl2. 29. The multiplet at   2.3 is a quartet for the C2 CH2 group, because of the three neighbors, the CH2 of C1 and the CH of C3. The signal shows additional very fine splitting, indicating that there is a small coupling to the alkene hydrogens on C4 (J 1 Hz). The multiplet for the hydrogen signal at   5.7 can be interpreted in detail. It corresponds to the CH at C3, which is split by the alkane CH2 on one side and the alkene CH2 on the other. The result is a pattern that can be described as a doublet (for trans alkene coupling) of doublets (for cis alkene coupling) of triplets (for coupling to the alkane CH2), 12 lines total, of which 10 are seen. If we construct a plausible splitting diagram we find that the two “missing” lines are actually “hidden” under the tallest lines in the center of the pattern: In other words, lines 5 and 6 overlap to give one tall line in the center of the pattern, and lines 7 and 8 overlap to give the other. 30. (a) Yes. 1-Butene  trans-2-butene (which should be zero) (b) No (c) Yes. cis  trans (which, again, is zero) 1 2 3 4 5 6 7 8 9 10 11 12 Triplet splitting J  7 Hz Cis doublet splitting J  10 Hz Trans doublet splitting J  16 Hz CH3 CH C 204 • Chapter 11 ALKENES; INFRARED SPECTROSCOPY AND MASS SPECTROMETRY 1559T_ch11_199-219 11/02/05 21:43 Page 204