Question 1

Which of the following statements best explains why alkenes are more reactive than alkanes?

Accepted Answer

Alkenes contain a C=C double bond, which is a region of high electron density and can participate in addition reactions.

Question 2

What is the molecular geometry and approximate bond angle around each carbon in ethene ($$C_2H_4$$)?

Accepted Answer

Trigonal planar, 120°

Question 3

Which of the following best describes the difference in bond length between the C–C bond in ethane and ethene?

Accepted Answer

The C–C bond in ethene is shorter because the pi bond brings the carbons closer together.

Question 4

A compound has the molecular formula $$C_5H_8. $$How many elements of unsaturation does it have?

Accepted Answer

2

Question 5

How many elements of unsaturation are present in nicotine ($$C_{10}H$$_{12}$$N_2$$)?

Accepted Answer

5

Question 6

Which of the following is the correct IUPAC name for the compound $$(CH_3$)_2CHCH=C(CH_3$)CH_2CH_3$$?

Accepted Answer

4-methyl-2-heptene

Question 7

Which of the following alkenes will NOT exhibit cis-trans (geometric) isomerism?

Accepted Answer

CH$$_2=CH$_2$$

Question 8

According to Zaitsev's rule, which alkene is the major product in the E1 elimination of 3-iodo-2,2-dimethylbutane?

Accepted Answer

The alkene with the double bond between C-2 and C-3 (most substituted)

Question 9

Which statement about the E2 elimination mechanism is correct?

Accepted Answer

The C–H and C–X bonds that break must be anti-coplanar.

Question 10

Which base would favor formation of the Hofmann product in an E2 elimination?

Accepted Answer

Potassium tert-butoxide ($$KO^tBu)$$

Question 11

Which of the following statements about cycloalkenes is TRUE?

Accepted Answer

Trans-cycloalkenes are not stable unless the ring has at least eight carbons.

Question 12

Which of the following alkenes has the lowest heat of hydrogenation ($$\Delta H_{hyd}) $$and is therefore the most stable?

Accepted Answer

trans-2-butene

Question 13

What is the major product when 2-bromo-2-methylpentane is treated with sodium ethoxide in ethanol?

Accepted Answer

2-methylpent-2-ene

Question 14

Which of the following is the most reactive substrate in an E2 reaction?

Accepted Answer

$$CH_3Br$$

Question 15

Which of the following best describes the physical properties of cis-2-butene compared to trans-2-butene?

Accepted Answer

Cis-2-butene has a higher boiling point and a greater dipole moment than trans-2-butene.

Question 16

Which of the following reagents would you use to convert cyclopentane to cyclopentene?

Accepted Answer

Concentrated $$H_2SO_4$$ and heat

Question 17

A compound with the formula $$C_6H_6Cl_6$$ has how many elements of unsaturation?

Accepted Answer

2

Question 18

Which of the following best describes the geometry about the carbon-carbon double bond in ethene ($$C_2H_4$$)?

Accepted Answer

Trigonal planar

Question 19

Which of the following statements about the E1 reaction mechanism is correct?

Accepted Answer

The rate-determining step is carbocation formation.

Question 20

Which of the following is a correct application of Bredt's Rule?

Accepted Answer

A double bond cannot be placed at the bridgehead of a bicyclic compound unless one ring has at least eight carbons.

Structure and Synthesis of Alkenes (Chapter 7 Study Notes)

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