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15. Analytical Techniques:IR, NMR, Mass Spect

Structure Determination without Mass Spect

15. Analytical Techniques:IR, NMR, Mass Spect

Structure Determination without Mass Spect

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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 ¹H 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 ¹H NMR:1.0 ppm (4H, triplet)

2.1 ppm (4H, triplet)

3.2 ppm (1H, singlet)

Textbook Question

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.

Textbook Question

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.

Textbook Question

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. <

Textbook Question

(•••) 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.] (b)

Textbook Question

(•••) 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

Textbook Question

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.

Textbook Question

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?

Textbook Question

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?

Textbook Question

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. <

Textbook Question

Identify each of the following compounds from its molecular formula and its IR and 1H NMR spectra: b. C6H12O2

Textbook Question

Identify each of the following compounds from its molecular formula and its IR and 1H NMR spectra: b.C6H14O

Textbook Question

A compound with molecular formula C5H10O2 gives the following IR spectrum. When it undergoes acid-catalyzed hydrolysis, the compound with the 1^H NMR spectrum shown below is formed. Identify the compounds.

Textbook Question

An unknown compound (C3H2NCl) shows moderately strong IR absorptions around 1650 cm-1 and 2200 cm-1. Its NMR spectrum consists of two doublets (J = 14 Hz) at d5.9 and d7.1. Propose a structure consistent with these data.

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