13-9 continued (x d Q cx>=c 3H H '-':: H I b I .& b 1 1 The electron-withdrawing H H The chemical shift Q � carbonyl group deshields the O�C"'OH of -COOH is variable. It is 2H 2H protons adjacent to it, moving TMS usually a broad them downfieid from their a peak. usual position at 8 7.2. 1 I I I I I I I I I I I 10 9 8 7 6 5 4 3 2 o 8 (ppm) 1 3-10 The formula C3H2NCI has three elements of unsaturation. The IR peak at 1650 cm-I indicates an alkene, while the absorption at 2200 cm-I must be from a nitrile (not enough carbons left for an alkyne). These two groups account for the three elements of unsaturation. So far, we have: \ IC N C = C / \ + 2 H + Cl H C = N The NMR gives the coupling constant for the two protons as 1 4 Hz. This large J value shows the two protons as trans (cis, J = 10 Hz; geminal, J = 2 Hz). The structure must be the one in the box. \ 1-C = C I \ Cl H 13- 1 1 (a) C3H7CI-no elements of unsaturation; 3 types of protons in the ratio of 2 : 2 : 3 . abc Cl - CH2CH2CH3 a = <5 3.8 (triplet, 2H); b = <5 2. 1 (multiplet, 2H);
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