Carvone is an unsaturated ketone responsible for the odor of spearmint. If carvone has

Where in the IR spectrum would you expect each of the following molecules to absorb?

Show the structures of the likely fragments you would expect in the mass spectra of the following molecules:

Propose structures for compounds that fit the following mass-spectral data: (a) A hydrocarbon with M1 5 132 (b) A hydrocarbon with M1 5 166 (c) A hydrocarbon with M1 5 84

Write molecular formulas for compounds that show the following molecular ions in their high-resolution mass spectra, assuming that C, H, N, and O might be present. The exact atomic masses are: 1.007 83 (1H) 12.000 00 (12C), 14.003 07 (14N), 15.994 91 (16O). (a) M1 5 98.0844 (b) M1 5 123.0320

Camphor, a saturated monoketone from the Asian camphor tree, is used among other things as a moth repellent and as a constituent of embalming fluid. If camphor has M1 5 152.1201 by high-resolution mass spectrometry, what is its molecular formula? How many rings does camphor have?

The nitrogen rule of mass spectrometry says that a compound containing an odd number of nitrogens has an odd-numbered molecular ion. Conversely, a compound containing an even number of nitrogens has an even-numbered M1 peak. Explain.

In light of the nitrogen rule mentioned in Problem 12.17, what is the molecular formula of pyridine, M1 5 79?

Nicotine is a diamino compound isolated from dried tobacco leaves. Nicotine has two rings and M1 5 162.1157 by high-resolution mass spectrometry. Give a molecular formula for nicotine, and calculate the number of double bonds.

The hormone cortisone contains C, H, and O, and shows a molecular ion at M1 5 360.1937 by high-resolution mass spectrometry. What is the molecular formula of cortisone? (The degree of unsaturation of cortisone is 8.)

Halogenated compounds are particularly easy to identify by their mass spectra because both chlorine and bromine occur naturally as mixtures of two abundant isotopes. Chlorine occurs as 35Cl (75.8%) and 37Cl (24.2%); bromine occurs as 79Br (50.7%) and 81Br (49.3%). At what masses do the molecular ions occur for the following formulas? What are the relative percentages of each molecular ion? (a) Bromomethane, CH3Br (b) 1-Chlorohexane, C6H13Cl

By knowing the natural abundances of minor isotopes, its possible to calculate the relative heights of M1 and M11 peaks. If 13C has a natural abundance of 1.10%, what are the relative heights of the M1 and M11 peaks in the mass spectrum of benzene, C6H6?

Propose structures for compounds that fit the following data: (a) A ketone with M1 5 86 and fragments at m/z 5 71 and m/z 5 43 (b) An alcohol with M1 5 88 and fragments at m/z 5 73, m/z 5 70, and m/z 5 59

2-Methylpentane (C6H14) has the mass spectrum shown. Which peak represents M1? Which is the base peak? Propose structures for fragment ions of m/z 5 71, 57, 43, and 29. Why does the base peak have the mass it does?

Assume that you are in a laboratory carrying out the catalytic hydrogenation of cyclohexene to cyclohexane. How could you use a mass spectrometer to determine when the reaction is finished?

What fragments might you expect in the mass spectra of the following compounds?

How might you use IR spectroscopy to distinguish among the three isomers 1-butyne, 1,3-butadiene, and 2-butyne?

Would you expect two enantiomers such as (R)-2-bromobutane and (S)-2-bromobutane to have identical or different IR spectra? Explain.

Would you expect two diastereomers such as meso-2,3-dibromobutane and (2R,3R)-dibromobutane to have identical or different IR spectra? Explain.

Propose structures for compounds that meet the following descriptions: (a) C5H8, with IR absorptions at 3300 and 2150 cm21 (b) C4H8O, with a strong IR absorption at 3400 cm21 (c) C4H8O, with a strong IR absorption at 1715 cm21 (d) C8H10, with IR absorptions at 1600 and 1500 cm21

How could you use infrared spectroscopy to distinguish between the following pairs of isomers? (a) HCqCCH2NH2 and CH3CH2CqN (b) CH3COCH3 and CH3CH2CHO

Two infrared spectra are shown. One is the spectrum of cyclohexane, and the other is the spectrum of cyclohexene. Identify them, and explain your answer

At what approximate positions might the following compounds show IR absorptions? (a) (d) (b) (c) O (e) O O CO2H CO2CH3 C HO N CH3CCH2CH2COCH3

How would you use infrared spectroscopy to distinguish between the following pairs of constitutional isomers? CH3C CHCH3 CHOCH3 O (a) CCH3 CH3CH2C CH CH3CCH CH2 O CH3CCH2CH (b) (c) H2C and and and CH3CH2CHO

At what approximate positions might the following compounds show IR absorptions? CH3CH2CCH3 (a) O CH3CH2CH2COCH3 (d) O (e) C O CH3CHCH2C CH3 (b) CH CH3CHCH2CH CH3 (c) CH2 CH3 (f) C O H

Assume that you are carrying out the dehydration of 1-methylcyclohexanol to yield 1-methylcyclohexene. How could you use infrared spectroscopy to determine when the reaction is complete?

Assume that you are carrying out the base-induced dehydrobromination of 3-bromo-3-methylpentane (Section 11.7) to yield an alkene. How could you use IR spectroscopy to tell which of two possible elimination products is formed?

Which is stronger, the C5O bond in an ester (1735 cm21) or the C5O bond in a saturated ketone (1715 cm21)? Explain.

Carvone is an unsaturated ketone responsible for the odor of spearmint. If carvone has M1 5 150 in its mass spectrum and contains three double bonds and one ring, what is its molecular formula?

Carvone (Problem 12.39) has an intense infrared absorption at 1690 cm21. What kind of ketone does carvone contain?

The mass spectrum (a) and the infrared spectrum (b) of an unknown hydrocarbon are shown. Propose as many structures as you can.

The mass spectrum (a) and the infrared spectrum (b) of another unknown hydrocarbon are shown. Propose as many structures as you can.

Propose structures for compounds that meet the following descriptions: (a) An optically active compound C5H10O with an IR absorption at 1730 cm21 (b) A nonoptically active compound C5H9N with an IR absorption at 2215 cm21

4-Methyl-2-pentanone and 3-methylpentanal are isomers. Explain how you could tell them apart, both by mass spectrometry and by infrared spectroscopy. 4-Methyl-2-pentanone 3-Methylpentanal

Grignard reagents undergo a general and very useful reaction with ketones. Methylmagnesium bromide, for example, reacts with cyclohexanone to yield a product with the formula C7H14O. What is the structure of this product if it has an IR absorption at 3400 cm21? ? Cyclohexanone 1. CH3MgBr 2. H3O

Ketones undergo a reduction when treated with sodium borohydride, NaBH4. What is the structure of the compound produced by reaction of 2-butanone with NaBH4 if it has an IR absorption at 3400 cm21 and M1 5 74 in the mass spectrum? 2-Butanone CH3CH2CCH3 O ? 1. NaBH4 2

Nitriles, R]CqN, undergo a hydrolysis reaction when heated with aqueous acid. What is the structure of the compound produced by hydrolysis of propanenitrile, CH3CH2CqN, if it has IR absorptions at 25003100 cm21 and 1710 cm21 and has M1 5 74?