Sulfuric acid ($$\text{H}_2\text{SO}_4)$$

Ethane ($$\text{C}_2\text{H}_6)$$

Tetrasubstituted alkene ($$\text{R}_2\text{C}=\text{CR}_2)$$

Acetylene ($$\text{HC}\equiv\text{CH})$$

Question 1

Which of the following best describes the stereochemistry and configuration of (2R,3E)-3-Penten-2-ol?

Accepted Answer

The molecule has a chiral center at C-2 and a trans double bond between C-3 and C-4.

Question 2

Arrange the following alkenes in order of increasing stability: 1-butene, cis-2-butene, trans-2-butene, 2-methylpropene.

Accepted Answer

1-butene \u003c cis-2-butene \u003c trans-2-butene \u003c 2-methylpropene

Question 3

Which carbocation is stabilized by hyperconjugation and alkyl group inductive effects?

Accepted Answer

A tertiary carbocation adjacent to a double bond, such as $$	ext{(CH}_3)_2C^+	ext{=CH}_2$$

Question 4

What is the role of sodium ethoxide ($$	ext{NaOCH}_2	ext{CH}_3) in $$the dehydrohalogenation of alkyl halides?

Accepted Answer

It acts as a strong base to abstract a proton, facilitating E2 elimination.

Question 5

Which acid is commonly used to dehydrate ethyl alcohol to ethylene?

Accepted Answer

Sulfuric acid ($$	ext{H}_2	ext{SO}_4)$$

Question 6

When cyclohexanol is dehydrated with $$	ext{H}_2	ext{SO}_4 at 140$$°C, what is the major organic product?

Accepted Answer

Cyclohexene

Question 7

In the dehydration of 2-methyl-2-butanol with $$	ext{H}_2	ext{SO}_4$$, which alkene is the major product?

Accepted Answer

2-Methyl-2-butene

Question 8

During the dehydration of 3-pentanol, which isomer is formed as the major product?

Accepted Answer

trans-2-pentene

Question 9

Which alkyl halide undergoes E2 elimination fastest with sodium ethoxide in ethanol?

Accepted Answer

2-Bromo-2-methylbutane

Question 10

Which halide undergoes dehydrohalogenation at the fastest rate?

Accepted Answer

Alkyl iodide ($$	ext{RI})$$

Question 11

Why does cis-4-tert-butylcyclohexyl bromide undergo E2 elimination faster than the trans isomer?

Accepted Answer

Because the H and Br are anti-coplanar in the cis isomer, allowing for proper E2 geometry.

Question 12

What is the major product when ethylene reacts with hydrogen in the presence of a nickel catalyst?

Accepted Answer

Ethane ($$	ext{C}_2	ext{H}_6)$$

Question 13

Which type of alkene is the most stable according to the heat of hydrogenation trend?

Accepted Answer

Tetrasubstituted alkene ($$	ext{R}_2	ext{C}=	ext{CR}_2)$$

Question 14

What is the product when calcium carbide reacts with water?

Accepted Answer

Acetylene ($$	ext{HC}\equiv	ext{CH})$$

Question 15

Which of the following is the correct IUPAC name for $$	ext{HC}\equiv	ext{CCH}_2	ext{CH}_3$$?

Accepted Answer

1-Butyne

Question 16

What is the result of treating a geminal dihalide with excess sodium amide ($$	ext{NaNH}_2) in $$ammonia?

Accepted Answer

Formation of an alkyne

Question 17

What is the major organic product when 1-octyne reacts with water in the presence of $$	ext{H}_2	ext{SO}_4$$ and $$	ext{HgSO}_4$$?

Accepted Answer

2-Octanone

Question 18

What is the product of ozonolysis of 1-hexyne followed by hydrolysis?

Accepted Answer

Pentanoic acid and carbonic acid

Question 19

Which mechanism is most likely for the dehydration of tertiary alcohols in acid?

Accepted Answer

E1 elimination

Alkenes and Alkynes: Nomenclature, Stability, and Reactions

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