Below is the mass spectrum of an unknown hydrocarbon. In addition, this hydrocarbon shows characteristic absorption at 2100 cm−1 in its IR spectrum. Give the structure of this unknown. (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/)

The formula weight of 54 corresponds to

Exam 10: Structure Determination: Mass Spectrometry, Infrared Spectroscopy, and Ultraviolet Spectroscopy

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Cyclohexene and hex-2-yne both have the molecular formula, C₆H₁₀. a)How would you use infrared spectroscopy to distinguish between the two compounds? b)How could the mass spectrum be used to distinguish between the two compounds?

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Question 1

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a)
To use IR spectroscopy to distinguish between isomers, find a strong IR absorption present in one isomer that is absent in the other isomer. alkene peak at 3020−3100 cm−¹ and at 1650−1670 cm−¹
no alkene peaks
no alkyne peaks
alkyne peak of medium intensity at 2100−2260 cm−¹
b)Although the M⁺ peak (82) for both would be the same, the fragmentation pattern would be different.
Mass spectrum: 2-hexyne Mass spectrum: Cyclohexene (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/)

Which of the following does not involve the interaction of molecules with electromagnetic energy?

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Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/) -Refer to instructions. What peak represents the base peak?

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Question 3

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The peak at m/z = 43 is the base peak.

What are the units for electromagnetic radiation used in infrared spectroscopy?

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Question 4

Match each of the following groups of bond-types to the region of the infrared spectrum in which their absorptions occur. -N−H, C−H, and O−H stretching and bending motions.

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Question 5

Below is the mass spectrum of an unknown hydrocarbon. In addition, this hydrocarbon shows characteristic absorption at 2100 cm−¹ in its IR spectrum. Give the structure of this unknown. (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/)

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Question 6

Which of the following compounds would have the longest λ_max in the UV region of the electromagnetic spectrum? A B C

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Question 7

What is the horizontal axis of a mass spectrum?

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Question 8

Which of the following compounds gives an infrared spectrum with peaks at 3300 cm−¹ (sharp peak) and 2150 cm−¹ (sharp peak)?

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Question 9

At what approximate positions might the compound below show IR absorptions?

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Question 10

Loratidine is the active ingredient in the antihistamine Claritin. Mass spectral analysis of loratidine shows M⁺ at m/z = 382. Loratidine is known to contain nitrogen. What is the minimum number of nitrogens in loratidine?

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Question 11

Which of the following bonds undergoes stretching at the highest frequency?

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Question 12

Refer to instructions. M⁺ at m/z = 216

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Question 13

What are the masses of the charged fragments produced by the dehydration of the following compound?

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Question 14

What is the vertical axis of a mass spectrum?

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Question 15

Which type of spectroscopy (IR, UV, or MS) will best distinguish between the pair of compounds below? Give a brief reason.

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Question 16

Which of the following statements best describes the base peak in a mass spectrum?

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Question 17

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/) -Refer to instructions. Propose structures for fragment ions at m/z = 57, 43, and 29.

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Question 18

What region of the IR spectrum would be the most useful in distinguishing between the following two compounds?

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Question 19

Which of the following peaks is not prominent in the mass spectrum of 2-methylbutan-2-ol?

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Question 20

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Exam 10: Structure Determination: Mass Spectrometry, Infrared Spectroscopy, and Ultraviolet Spectroscopy

Cyclohexene and hex-2-yne both have the molecular formula, C6H10. a)How would you use infrared spectroscopy to distinguish between the two compounds? b)How could the mass spectrum be used to distinguish between the two compounds?

Which of the following does not involve the interaction of molecules with electromagnetic energy?

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/) -Refer to instructions. What peak represents the base peak?

What are the units for electromagnetic radiation used in infrared spectroscopy?

Match each of the following groups of bond-types to the region of the infrared spectrum in which their absorptions occur. -N−H, C−H, and O−H stretching and bending motions.

Below is the mass spectrum of an unknown hydrocarbon. In addition, this hydrocarbon shows characteristic absorption at 2100 cm−1 in its IR spectrum. Give the structure of this unknown. (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/)

Which of the following compounds would have the longest λmax in the UV region of the electromagnetic spectrum? A B C ​

What is the horizontal axis of a mass spectrum?

Which of the following compounds gives an infrared spectrum with peaks at 3300 cm−1 (sharp peak) and 2150 cm−1 (sharp peak)?

At what approximate positions might the compound below show IR absorptions?

Loratidine is the active ingredient in the antihistamine Claritin. Mass spectral analysis of loratidine shows M+ at m/z = 382. Loratidine is known to contain nitrogen. What is the minimum number of nitrogens in loratidine?

Which of the following bonds undergoes stretching at the highest frequency?

Refer to instructions. M+ at m/z = 216

What are the masses of the charged fragments produced by the dehydration of the following compound?

What is the vertical axis of a mass spectrum?

Which type of spectroscopy (IR, UV, or MS) will best distinguish between the pair of compounds below? Give a brief reason.

Which of the following statements best describes the base peak in a mass spectrum?

Refer to the mass spectrum of 2-methylbutane shown below to answer the following question(s). (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/) -Refer to instructions. Propose structures for fragment ions at m/z = 57, 43, and 29.

What region of the IR spectrum would be the most useful in distinguishing between the following two compounds?

Which of the following peaks is not prominent in the mass spectrum of 2-methylbutan-2-ol?

Structure and Bonding

Polar Covalent Bonds; Acids and Bases

Organic Compounds: Alkanes and Their Stereochemistry

Organic Compounds: Cycloalkanes and Their Stereochemistry

Stereochemistry at Tetrahedral Centers

An Overview of Organic Reactions

Alkenes and Alkynes

Reactions of Alkenes and Alkynes

Aromatic Compounds

Structure Determination: Mass Spectrometry, Infrared Spectroscopy, and Ultraviolet Spectroscopy

Structure Determination: Nuclear Magnetic Resonance Spectroscopy

Organohalides: Nucleophilic Substitutions and Eliminations

Alcohols, Phenols, and Thiols; Ethers and Sulfides

Aldehydes and Ketones: Nucleophilic Addition Reactions

Carboxylic Acids and Nitriles

Carboxylic Acid Derivatives: Nucleophilic Acyl Substitution Reactions

Carbonyl Alpha-Substitution and Condensation Reactions

Amines and Heterocycles

Biomolecules: Amino Acids, Peptides, and Proteins

Amino Acid Metabolism

Biomolecules: Carbohydrates

Carbohydrate Metabolism

Biomolecules: Lipids and Their Metabolism

Biomolecules: Nucleic Acids and Their Metabolism

Orbitals and Organic Chemistry: Pericyclic Reactionse

Synthetic Polymerse

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Cyclohexene and hex-2-yne both have the molecular formula, C₆H₁₀. a)How would you use infrared spectroscopy to distinguish between the two compounds? b)How could the mass spectrum be used to distinguish between the two compounds?

Below is the mass spectrum of an unknown hydrocarbon. In addition, this hydrocarbon shows characteristic absorption at 2100 cm−¹ in its IR spectrum. Give the structure of this unknown. (Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/)

Which of the following compounds would have the longest λ_max in the UV region of the electromagnetic spectrum? A B C

Which of the following compounds gives an infrared spectrum with peaks at 3300 cm−¹ (sharp peak) and 2150 cm−¹ (sharp peak)?

Loratidine is the active ingredient in the antihistamine Claritin. Mass spectral analysis of loratidine shows M⁺ at m/z = 382. Loratidine is known to contain nitrogen. What is the minimum number of nitrogens in loratidine?

Refer to instructions. M⁺ at m/z = 216