Question 1

Which of the following statements best describes Markovnikov's rule as it applies to the addition of HBr to an unsymmetrical alkene?

Accepted Answer

The H atom adds to the carbon with the most hydrogens, and the Br atom adds to the carbon with the fewest hydrogens.

Question 2

During the halogenation of an alkene with Br$$_2 in $$CCl$$_4$$, which of the following is true about the stereochemistry of the product?

Accepted Answer

Only anti addition occurs, resulting in a pair of enantiomers.

Question 3

Which reagent and conditions would you use to convert an alkene to a vicinal diol via syn addition?

Accepted Answer

$$\mathrm{$$OsO_4$$}$$, $$\mathrm{H_2O_2}$$

Question 4

Which of the following best explains why terminal alkynes are more acidic than terminal alkenes or alkanes?

Accepted Answer

Alkynes have more p character in their C-H bond, making the conjugate base more stable.

Question 5

In the hydroboration-oxidation of an alkene, which of the following statements is correct?

Accepted Answer

The reaction proceeds via anti-Markovnikov addition and syn addition of H and OH.

Question 6

Which of the following is the correct order of bond strength (kcal/mol) for C–C bonds in ethyne, ethene, and ethane?

Accepted Answer

$$\mathrm{C \equiv C} \u003e \mathrm{C = C} \u003e \mathrm{C - C}$$

Question 7

A student treats 1-butene with $$\mathrm{HBr} in $$the presence of peroxides ($$\mathrm{ROOR}). $$What is the major product and why?

Accepted Answer

1-bromobutane, due to anti-Markovnikov (radical) addition.

Question 8

Which of the following best describes the product(s) of ozonolysis of 2-methyl-2-butene followed by reductive workup ($$\mathrm{Zn, CH_3CO_2H}$$)?

Accepted Answer

A ketone and an aldehyde

Question 9

Which of the following statements about the hydration of alkynes is correct?

Accepted Answer

Hydration of terminal alkynes with $$\mathrm{$$HgSO_4$$}$$ and $$\mathrm{H_2SO_4}$$ gives a methyl ketone via Markovnikov addition.

Question 10

Which of the following is true regarding the halogenation of alkynes?

Accepted Answer

Halogenation of alkynes proceeds via anti addition, and the two additions can be separated.

Question 11

Which of the following best explains why the addition of Br$$_2 to $$cyclohexene in CCl$$_4 is $$both stereospecific and anti-addition?

Accepted Answer

The reaction proceeds through a bromonium ion intermediate, forcing the two Br atoms to add to opposite faces.

Question 12

Which of the following reagents would you use to convert a terminal alkyne to a trans-alkene?

Accepted Answer

$$\mathrm{Na}$$, $$\mathrm{NH_3$} ($$liq)

Question 13

Which of the following is a correct statement about the hydrohalogenation of alkynes?

Accepted Answer

The addition of HX to a terminal alkyne follows Markovnikov's rule, with the halide adding to the more substituted carbon.

Question 14

Which of the following best describes the product of hydroboration-oxidation of a terminal alkyne?

Accepted Answer

An aldehyde via anti-Markovnikov addition.

Question 15

Which of the following is the correct IUPAC name for the compound shown below?

CH$$_3C$$≡CCH$$_2CH$_2OH$$

Accepted Answer

2-pentyn-1-ol

Question 16

Which of the following statements about the acidity of terminal alkynes is correct?

Accepted Answer

Terminal alkynes have a p$$K_a$$ around 25, making them more acidic than most hydrocarbons.

Question 17

Which of the following best describes the product of the reaction of 1,3-butadiene with HBr at low temperature?

Accepted Answer

The 1,2-addition product is favored due to kinetic control.

Question 18

Which of the following is true about the reaction of an alkene with mCPBA?

Accepted Answer

It forms an epoxide via a concerted mechanism.

Alkene, Alkyne, and Conjugated Pi System Chemistry: Addition Reactions, Mechanisms, and Properties

Guida di studio - Domande di pratica