15. Analytical Techniques:IR, NMR, Mass Spect

Propose a structure for the following compound that fits the following 1H NMR data: 

Formula:C₃H₈O₂                                                  ¹H NMR:3.36 δ (6H, singlet) 

                                                                                         4.57 δ (2H, singlet)

Propose a structure for the following compound that fits the following ¹H NMR data: 

Formula:C₂H₄O₂                                            ¹H NMR:2.1 δ (singlet, 1.2 cm) 

                                                                                   11.5 δ (0.5 cm, D2O exchange)

Propose a structure for the following compound that fits the following ¹H NMR data: 

Formula:C₁₀H₁₄                                      ¹H NMR:1.2 ppm (6H, doublet) 

                                                                             2.3 ppm (3H, singlet) 

                                                                             2.9 ppm (1H, septet) 

                                                                             7.0 ppm (4H, doublet)

Propose a structure for the following compound, C₅H₁₀O with the given ¹³C NMR spectral data: 

Fully Broadband decoupled ¹³C NMR and DEPT:206.0 δ (↑); 55.0 δ (↑); 21.0 δ (↓)& 11.0 δ (↑).

Provide the structure of the unknown compound from the given information. 

Formula:C₄H₁₀O            IR:3200-3600 cm^{-1           1}H NMR:0.9 ppm (6H, doublet) 

                                                                                               1.8 ppm (1H, nonatet) 

                                                                                               2.4 ppm (1H, singlet) 

                                                                                               3.3 ppm (2H, doublet)

Provide the structure of the unknown compound from the given information. 

Formula:C₄H₉N              IR:2950 cm^-1, 3400 cm^{-1           1}H NMR:1.0 ppm (4H, triplet) 

                                                                                                         2.1 ppm (4H, triplet) 

                                                                                                         3.2 ppm (1H, singlet)

Show how you would distinguish among the following three compounds

(a) using infrared spectroscopy and no other information.

(b) using proton NMR spectroscopy and no other information.

(c) using ¹³C NMR, including DEPT, and no other information.

When 2-chloro-2-methylbutane is treated with a variety of strong bases, the products always seem to contain two isomers (A and B) of formula C₅H₁₀. When sodium hydroxide is used as the base, isomer A predominates. When potassium tert-butoxide is used as the base, isomer B predominates. The ¹H and ¹³C NMR spectra of A and B are given below.

(a) Determine the structures of isomers A and B.

(b) Explain why A is the major product when using sodium hydroxide as the base and why B is the major product when using potassium tert-butoxide as the base.

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A compound of molecular formula C₈H₈O gives the IR and NMR spectra shown here. Propose a structure, and show how it is consistent with the observed absorptions.

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Given the ¹H NMR spectrum and the molecular formula, suggest a structure for each molecule. [The IR spectrum suggests the presence of two C=O bonds.]

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The spectral data below are presented in a manner similar to what you would find in a chemistry research journal. Identify the structure for each set of data.

(c) C₇H₁₄O₂ : ¹H NMR: δ 0.91 (3H, t, J = 7.0 Hz), 1.11 (6H, d, J = 7.0 Hz), 1.82 (2H, sextet), 2.40 (1H, sept, J = 7.0 Hz), 4.14 (2H, t, J = 7.1 Hz); IR (cm ⁻¹) : 1745, 1200

A compound gives the following IR spectrum. Upon reaction with sodium borohydride followed by acidification, it forms the product with the ¹H NMR spectrum shown below. Identify the starting material and the product.

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Shown below is the ¹H NMR spectrum of the alkyl bromide used to make the phosphonium ylide that reacts with a ketone in a Wittig reaction to form a compound with molecular formula C₁₁H₁₄. What product is obtained from the Wittig reaction?

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An aromatic hydrocarbon with a molecular formula of C₁₃H₂₀ has an ¹H NMR spectrum with a signal at ~7 ppm that integrates to 5H. It also has two singlets; one of the singlets has 1.5 times the area of the second. What is the structure of the aromatic hydrocarbon?

The proton and ¹³C NMR spectra of a compound of formula C₄H₁₁N are shown here. Determine the structure of this amine, and give peak assignments for all of the protons in the structure.

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