Question 1

Which of the following m/z values corresponds to the molecular ion for benzyl alcohol ($$C_7H_8O$$)?

Accepted Answer

$$108$$

Question 2

A compound with the formula $$C_3H_5Cl_3$$ shows two singlets in its $$^1H$$ NMR spectrum at $$\delta = 2.2$$ ppm and $$\delta = 4.0$$ ppm. Which structure is most consistent with this data?

Accepted Answer

$$\mathrm{CH_2ClCCl_2CH_3}$$

Question 3

Which of the following compounds would have three signals in its $$^1H$$ NMR spectrum?

Accepted Answer

A straight-chain alkane with three different types of hydrogens

Question 4

What can we say regarding the intensity of the $$M+2$$ ion in the mass spectrum of ethyl chloride, $$\mathrm{CH_3CH_2Cl}$$? (The two isotopes of Cl are $$^{35}\mathrm{Cl}$$ and $$^{37}\mathrm{Cl})$$

Accepted Answer

The $$M+2$$ ion will occur at $$m/z = 66$$ and will be one-third the intensity of the ion at $$m/z = 64.$$

Question 5

A diene reacts with HBr to give two products, A and B. At $$40^\circC$$, A is the major product; at $$-80^\circC$$, B is the major product. Thermodynamic data shows A is more stable. What can we conclude?

Accepted Answer

We can say that A is the thermodynamic product and B is the kinetic product.

Question 6

Which of the following spectroscopic clues is evidence for the acyl group, $$\mathrm{CH_3CO-}$$?

Accepted Answer

They are all clues to the presence of an acyl group.

Question 7

Which of the following compounds would be expected to show IR absorption at $$2250\ \mathrm{cm}^{-1}$$?

Accepted Answer

A nitrile ($$\mathrm{C\equiv N})$$

Question 8

Which nitrogen is the LEAST basic in the purine derivative shown below?

Accepted Answer

$$N7$$

Question 9

Which of the following statements best explains the information we can gain from infrared spectroscopy?

Accepted Answer

It allows us to determine the kinds of functional groups in a compound, based on the frequency at which bonds stretch or bend.

Question 10

Which of the following spectroscopic clues is evidence for an alcohol hydroxyl group, $$\mathrm{R-OH}$$?

Accepted Answer

A signal in a $$^1H $$NMR spectrum that disappears when $$\mathrm{D_2O} is $$added.

Question 11

Which of the following statements concerning benzene are true?

Accepted Answer

All the carbon-carbon bonds in benzene are the same length, and are shorter than carbon-carbon single bonds but longer than carbon-carbon double bonds.

Question 12

A compound with the formula $$C_7H_{14}O$$ gives a mass spectrum with a molecular ion at $$m/z = 114$$, an IR spectrum with a strong absorption near $$1710\ \mathrm{cm}^{-1}$$, and a $$^1H $$NMR spectrum with a singlet at $$\delta = 2.1$$ ppm integrating to 6H and a quartet at $$\delta = 2.4$$ ppm integrating to 2H. What is the most likely structure?

Accepted Answer

2,2-Dimethyl-3-pentanone

Question 13

Which of the following molecules or ions are aromatic?

Accepted Answer

Only Z

Question 14

Which of the following would NOT be a product in the reaction of 1,3,5-trimethylbenzene with chlorine in the presence of light?

Accepted Answer

A compound with a chlorine atom added to the aromatic ring

Question 15

Which compound would be an especially poor diene to use in a Diels-Alder reaction?

Accepted Answer

A diene locked in the trans conformation

Question 16

Which of the following compounds represents a phenol?

Accepted Answer

A benzene ring with an $$-OH$$ group directly attached

Question 17

How many signals would you see in principle in the $$^{13}C $$NMR spectrum of toluene?

Accepted Answer

$$5$$

Question 18

Which of the following is a real-world application of the Diels-Alder reaction?

Accepted Answer

Synthesis of vitamin K

Question 19

Which splitting pattern is observed in the proton NMR spectrum for a hydrogen atom adjacent to two equivalent hydrogens?

Accepted Answer

Triplet

Question 20

A compound shows a molecular ion at $$m/z = 98 in $$its mass spectrum. Which of the following is a possible molecular formula?

Accepted Answer

$$C_6H_{10}O$$

Organic Chemistry Exam Study Guide: Spectroscopy, Structure, and Reactivity

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