2. The following eight structures are all isomers of C6H14O. Each structure corresponds to one of the predicted ¹H NMR spectra pictured on the next two pages of this document. The integral values for each peak are next to that peak. Indicate which structure matches each spectrum by drawing the structures in the boxes along the right side of the pages. Use the letter codes provided to label the chemically equivalent hydrogens on the structures. One example is provided. A 2H A 4H < 1H OH B 2H tox PPM PPM 3 PPM B 12H DE C 2H 2H 1H B 4H 6H ха ло мон 6H B B

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Use the spectral information given below to derive a structural formula for unknown II. Its molecular formula is C4H100. LO0 IR Spectrum of Unknown II 80 %T 60 40 20 2000 Wavenumbers (cm-1) 4000 3000 1500 1000 400 HNMR Spectrum of Unknown II 9H S S 1H 5 3 2 PPM C13NMR Spectrum of Unknown II 70 60 50 40 PPM 30 20 10

From the 13C spectrum of a compound, one can assign signals to specific carbon atoms of the compound and determine the number of protons on each of those carbon atoms. Such information in conjunction with the DEPT C-13 chart will allow the appearance of the corresponding DEPT spectrum of the compound to be predicted. There are five signals (I – V) in the 13C spectrum of compound A as shown below. At the exactly same location of each of these five signals, "a peak", "no peak", or "an inverted peak" may appear in the corresponding DEPT-135 spectrum. Predict the DEPT-135 spectrum of compound A by selecting the expected signal appearance at each of these five locations in the DEPT-135 spectrum. - II II IV V in HO A 100 PPM 180 160 140 120 80 60 40 20 v At the location of signal I A. no peak v At the location of signal IIl В. а рeak v At the location of signal IIl C. an inverted peak v At the location of signal IV v A the location of signal V

Part A Draw C4HgBr₂ that has the following ¹H NMR spectrum: 1.97 (s, 3H), 3.89 (s, 1H). Hint: Draw C4H₁0 (there are two isomers), and then replace two H atoms with Br atoms. NOTE NOTE! C4H8Br2 has 8 H's! But the integral is 3H and 1H!!! How will you fix that? Draw the molecule on the canvas by choosing buttons from the Tools (for bonds), Atoms, and Advanced Template toolbars. The single bond is active by default. H 12D EXP L CONT 1

You measured the carbon-carbon bond lengths of four different compounds in Experiment 8 (Molecular Modeling and IR spectroscopy). Which of the following compounds has the shortest average C-C bond length? Benzene Cyclohexene Cyclohexane O Cyclohexadiene Which of the following statement(s) is(are) true? Select all that apply: When two atoms are bonded together, the distance between atoms is the same all the time. In the IR spectrum, carbonyl groups (C=O) have strong sharp peaks ranging from 1700 cm 1 to 1750 cm-1. When a molecule absorbs an IR radiation, electrons are excited within the molecule and each absorbed electron creates a band in the molecules IR spectrum. IR spectroscopy is useful in confirming the structure of the analyzed compound. Molecule N2 does not absorb IR radiation

. Deduce the structure of an unknown compound with the molecular formula of C5H₁2O using the information given by its infrared spectrum. ANSWER A) НО. B) D) Intensity Frequency (peak): (cm): 3300 m EEEEE m m m m m 2900 2800 1465 1450 1375

a) Shown below is the 1H NMR (CDCl3 is the solvent) of butanal. The splitting pattern of each of the four peaks is provided. For each of the four peaks determine the number of hydrogens that belongs to each peak from the red integral line. Provide the number of the hydrogens in the order A, B, C, D. b) What happens when the radiofrequncy pulse in the NMR instrument matches the Larmor Frequncy of an NMR active nucleus?   A. The electrons transition to the LUMO   B. The nuclei undergoes a spin flip   C. Nothing   D. The bonds in the molecule stretch and vibrate

Which of the following statements is incorrect regarding IR spectroscopy?   options:   The diagnostic region contain all signals that arise from double bonds, triple bonds and X-H bonds   The fingerprint region contains signals resulting from the vibrational excitation of most single bonds (stretching and bending)   The intensity of a signal is dependent on the dipole moment of bond giving rise to the signal   A conjugated C=O bond produce a high energy signal than an unconjugated C=O bond   The wavenumber of each signal is determined primarily by bond strength and the masses of the atoms sharing the bonds

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