Chapter 11: Problem 71
What is the degree of unsaturation in cyclobutane? (a) Zero; (b) one; (c) two; (d) three
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Chapter 11: Problem 71
What is the degree of unsaturation in cyclobutane? (a) Zero; (b) one; (c) two; (d) three
These are the key concepts you need to understand to accurately answer the question.
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Write the most likely major product(s) of each of the following haloalkanes with sodium ethoxide in ethanol or potassium tert-butoxide in 2-methyl-2-propanol (tert-butyl alcohol). (a) Chloromethane; (b) 1-bromopentane; (c) 2-bromopentane; (d) 1-chloro-1-methylcyclohexane; (e) (1-bromoethyl)-cyclopentane; (f) \((2 R, 3 R)-2\) -chloro-3-ethylhexane; (g) \((2 R, 3 S)-2\) -chloro-3ethylhexane; (h) \((2 S, 3 R)-2\) -chloro- 3 -ethylhexane.
Spectroscopic data for three compounds with the molecular formula \(\mathrm{C}_{5} \mathrm{H}_{8}\) are given below; \(\mathrm{m}\) denotes a complex multiplet. Assign a structure to each compound. (Hint: One is acyclic; the others each contain one ring.) (a) IR \(910,1000,1650,3100 \mathrm{~cm}^{-1} ;{ }^{1} \mathrm{H}\) NMR \(\delta=2.79(\mathrm{t}, J=8 \mathrm{~Hz})\), 4.8-6.2 (m) ppm, integrated intensity ratio of the signals \(=1: 3\). (b) IR \(900,995,1650,3050 \mathrm{~cm}^{-1}\); \({ }^{1} \mathrm{H}\) NMR \(\delta=0.5 1.5(\mathrm{~m}), 4.8-6.0(\mathrm{~m}) \mathrm{ppm}\), integrated intensity ratio of the signals \(=5: 3\). (c) IR \(1611,3065 \mathrm{~cm}^{-1} ;{ }^{1} \mathrm{H}\) NMR \(\delta=1.5-2.5(\mathrm{~m}), 5.7(\mathrm{~m}) \mathrm{ppm}\), integrated intensity ratio of the signals \(=3: 1\). Is there more than one possibility?
You have just entered the chemistry stockroom to look for several isomeric bromopentanes. There are three bottles on the shelf marked \(\mathrm{C}_{5} \mathrm{H}_{11} \mathrm{Br}\), but their labels have fallen off. The NMR machine is broken, so you devise the following experiment in an attempt to determine which isomer is in which bottle: You first treat a sample of the contents in each bottle with \(\mathrm{NaOH}\) in aqueous ethanol, and then you determine the IR spectrum of each product or product mixture. Here are the results: (i) \(\mathrm{C}_{5} \mathrm{H}_{11} \mathrm{Br}\) isomer in bottle \(\mathrm{A} \stackrel{\mathrm{NaOH}}{\longrightarrow} \mathrm{IR}\) bands at \(1660,2850-3020\), and \(3350 \mathrm{~cm}^{-1}\) (ii) \(\mathrm{C}_{5} \mathrm{H}_{11} \mathrm{Br}\) isomer in bottle \(\mathrm{B} \stackrel{\mathrm{NaOH}}{\longrightarrow} \mathrm{IR}\) bands at 1670 and \(2850-3020 \mathrm{~cm}^{-1}\) (iii) \(\mathrm{C}_{5} \mathrm{H}_{11} \mathrm{Br}\) isomer in bottle \(\mathrm{C} \stackrel{\mathrm{NaOH}}{\longrightarrow} \mathrm{IR}\) bands at \(2850-2960\) and \(3350 \mathrm{~cm}^{-1}\) (a) What do the data tell you about each product or product mixture? (b) Suggest possible structures for the contents of each bottle.
Convert each of the following IR frequencies into micrometers. (a) \(1720 \mathrm{~cm}^{-1}(\mathrm{C}=\mathrm{O})\) (b) \(1650 \mathrm{~cm}^{-1}(\mathrm{C}=\mathrm{C})\) (c) \(3300 \mathrm{~cm}^{-1}(\mathrm{O}-\mathrm{H})\) (d) \(890 \mathrm{~cm}^{-1}\) (alkene bend) (e) \(1100 \mathrm{~cm}^{-1}(\mathrm{C}-\mathrm{O})\) (f) \(2260 \mathrm{~cm}^{-1}(\mathrm{C} \equiv \mathrm{N})\)
The molecular formulas and \({ }^{13} \mathrm{C}\) NMR data (in ppm) for several compounds are given here. The type of carbon, as revealed from DEPT spectra, is specified in each case. Deduce a structure for each compound. (a) \(\mathrm{C}_{4} \mathrm{H}_{6}: 30.2\left(\mathrm{CH}_{2}\right), 136.0(\mathrm{CH}) ;\) (b) \(\mathrm{C}_{4} \mathrm{H}_{6} \mathrm{O}: 18.2\left(\mathrm{CH}_{3}\right), 134.9(\mathrm{CH}), 153.7(\mathrm{CH})\), \(193.4(\mathrm{CH}) ;(\mathrm{c}) \mathrm{C}_{4} \mathrm{H}_{8}: 13.6\left(\mathrm{CH}_{3}\right), 25.8\left(\mathrm{CH}_{2}\right), 112.1\left(\mathrm{CH}_{2}\right), 139.0(\mathrm{CH}) ;(\mathrm{d}) \mathrm{C}_{5} \mathrm{H}_{10} \mathrm{O}: 17.6\left(\mathrm{CH}_{3}\right)\) \(25.4\left(\mathrm{CH}_{3}\right), 58.8\left(\mathrm{CH}_{2}\right), 125.7(\mathrm{CH}), 133.7\left(\mathrm{C}_{\text {quatemary }}\right) ;(\mathrm{e}) \mathrm{C}_{5} \mathrm{H}_{8}: 15.8\left(\mathrm{CH}_{2}\right), 31.1\left(\mathrm{CH}_{2}\right), 103.9\left(\mathrm{CH}_{2}\right)\) \(149.2\left(\mathrm{C}_{\text {quaternary }}\right) ;\) (f) \(\mathrm{C}_{7} \mathrm{H}_{10}: 25.2\left(\mathrm{CH}_{2}\right), 41.9(\mathrm{CH}), 48.5\left(\mathrm{CH}_{2}\right), 135.2(\mathrm{CH}) .\) (Hint: This one is difficult. The molecule has one double bond. How many rings must it have?)
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