Deck 11: Alkynes

Question 1

Give the IUPAC name for the following compound.

A) 4,4-Diethyl-1-octyne
B) 4,4-Dipropyl-1-heptyne
C) 4,4-Dipropyl-6-heptyne
D) 4,4-Diethyl-6-octyne

Answer 1

4,4-Dipropyl-1-heptyne

Question 2

Which of the following molecular formulas is consistent with the formula for a molecule containing one alkyne and no other degrees of unsaturation? $$\begin{array} { c c c l } \mathrm { C } _ { 10 } \mathrm { H } _ { 20 } & \mathrm { C } _ { 10 } \mathrm { H } _ { 22 } & \mathrm { C } _ { 10 } \mathrm { H } _ { 18 } & \mathrm { C } _ { 10 } \mathrm { H } _ { 19 } \\\text { I } & \text { II } & \text { III } & \text { IV }\end{array}$$

A) I
B) II
C) III
D) IV

Answer 2

III

Question 3

Give the IUPAC name for the following compound.

A) trans-2-Acetylenecyclohexanol
B) trans-2-Ethynylcyclohexanol
C) trans-2-Acetylene-1-cyclohexanol
D) trans-2-Ethylenecyclohexanol

Answer 3

trans-2-Ethynylcyclohexanol

Question 4

Which of the following alkynes is a symmetrical alkyne?

A) I
B) II
C) III
D) IV

Question 5

Give the IUPAC name for the following compound.

A) 3-sec-Butyl-1,4-octadiyne
B) 3-Isopropyl-1,5-octadiyne
C) 3-Isopropyl-1,5-nonadiyne
D) 3-sec-Butyl-1,4-nonadiyne

Question 6

Which of the following represents a terminal alkyne?

A) Only I and II
B) Only II and III
C) Only I and III
D) Only II and IV

Question 7

What is the product of the following reaction?

A) I
B) II
C) III
D) IV

Question 8

Which of the following explains why 1-pentyne has a slightly higher boiling point than 1-pentene?

A) 1-Pentyne has more carbons than 1-pentene.
B) 1-Pentyne has more carbons per hydrogen than 1-pentene.
C) 1-Pentyne is linear while 1-pentene is trigonal planar.
D) The C-C triple bond in 1-pentyne is more polar than the C-C double bond in 1-pentene.

Question 9

What is the product of the following reaction?

A) I
B) II
C) III
D) IV

Question 10

Give the IUPAC name for the following compound.

A) 4-Chloro-4-methyl-2-heptyne
B) 3-Chloro-3-methyl-4-heptyne
C) 3-Chloro-3-methyl-4-hexyne
D) 4-Chloro-4-methyl-2-hexyne

Question 11

What is the product of the following sequence of reactions?

A) I
B) II
C) III
D) IV

Question 12

Give the IUPAC name for the following compound.

A) 6,6-Dimethyl-3-octyne
B) 3,3-Dimethyl-3-octyne
C) 3,3-Dimethy-5-octyne
D) 6-Ethyl-6-methyl-3-heptyne

Question 13

Which of the following represents an internal alkyne?

A) Only I and II
B) Only I and III
C) Only II and IV
D) Only II and III

Question 14

How many  bonds and  bonds are present in a triple bond?

A) One  bond and one  bond.
B) One  bond and two  bonds.
C) Two  bonds and one  bond.
D) Two  bonds and two  bonds.

Question 15

Which method would work the best in accomplishing the following transformation?

A) [1] HBr; [2] 2eq. NaNH₂
B) [1] Br₂; [2] 2eq. NaNH₂
C) [1] Br₂, H₂O; [2] NaNH₂
D) [1]BH₃, THF; [2] H₂O₂, NaOH; [3] NaNH₂

Question 16

Give the IUPAC name for the following compound.

A) 2,5-Dimethyl-3-heptyne
B) 3,6-Dimethy-4-heptyne
C) 2,5-Dimethyl-3-octyne
D) 3,6-Dimethyl-4-octyne

Question 17

How many degrees of unsaturation are introduced by a triple bond?

A) 0
B) 1
C) 2
D) 3

Question 18

Give the IUPAC name for the following compound.

A) 4-Methyl-4-penten-1-yne
B) 2-Methyl-2-hexen-5-yne
C) 5-Methyl-4-hexen-1-yne
D) 2-Methyl-2-penten-4-yne

Question 19

Which of the following statements about alkynes is not true?

A) Alkynes undergo many addition reactions.
B) Alkynes are more polarizable than alkenes.
C) Both  bonds of a C-C triple bond are weaker than a C-C  bond.
D) The electrons in the  bonds of alkynes are more tightly held than those of alkenes.

Question 20

Which of the following about the physical properties of alkynes is not true?

A) Alkynes have low melting and boiling points.
B) Melting and boiling points increase as the number of carbons increases.
C) Alkynes are soluble in organic solvents.
D) Alkynes are soluble in water.

Question 21

In the addition of HBr to 1-butyne, the electrophile in the first step of the mechanism is:

A) The Csp-H1s bond of 1-butyne.
B) The C-C triple bond of 1-butyne.
C) The H atom in HBr.
D) The Br ion.

Question 22

What is the major product of the following reaction?

A) Only I
B) Only II
C) Only III
D) I, II, III

Question 23

What is the major organic product of the following reaction?

A) I
B) II
C) III
D) IV

Question 24

Which of the following represents a keto-enol tautomeric pair?

A) I
B) II
C) III
D) IV

Question 25

What is (are) the product(s) of the following reaction?

A) Only I
B) Only II
C) Only III
D) I, II, III

Question 26

Which of the indicated hydrogen in the following compounds is the least acidic?

A) I
B) II
C) III
D) IV

Question 27

Which of the following compounds can be an enol tautomer of 1,3-cyclohexandione?

A) Only I and II
B) Only I and III
C) Only II and III
D) I, II, III

Question 28

Which of the following statements about tautomers is true?

A) Tautomers differ in the position of a single bond and a hydrogen atom.
B) Tautomers differ in the position of a double bond and a carbon atom.
C) Tautomers differ in the position of a double bond and a hydrogen atom.
D) Tautomers differ in the position of a single bond and a carbon atom.

Question 29

Which of the following statements about the reactions of alkynes is not true?

A) Alkynes contain easily broken  bonds.
B) Alkynes undergo addition reactions.
C) When alkynes undergo two sequential addition reactions, four new  bonds are formed.
D) When alkynes undergo two sequential addition reactions, two new  bonds and a  bond are formed.

Question 30

What is the reagent required to accomplish the following transformation?

A) SOCl₂
B) 2eq. HCl
C) Cl₂
D) Br₂/CCl₄

Question 31

Rank the following compounds in order of decreasing basicity, putting the most basic first.

A) I > II > III
B) III > II > I
C) III > I > II
D) II > III > I

Question 32

What is the major organic product of the following reaction?

A) I
B) II
C) III
D) IV

Question 33

What is the relationship between the keto and enol forms of acetone, CH₃COCH₃?

A) Same compounds
B) Diastereomers
C) Enantiomers
D) Constitutional isomers

Question 34

Which of the following bases cannot deprotonate acetylene? You are given the pK_a values of the conjugate acids in parentheses. $\mathrm { CH } _ { 3 } \mathrm { NH } ^ { - } \left( \mathrm { p } K _ { a } = 40 \right) \quad \mathrm { CO } _ { 3 } ^ { 2 - } \left( \mathrm { p } K _ { a } = 10.2 \right) \quad \mathrm { CH } _ { 2 } = \mathrm { CH } ^ { - } \left( \mathrm { p } K _ { a } = 44 \right) \quad \left( \mathrm { CH } _ { 3 } \right) _ { 3 } \mathrm { CO } ^ { - } \left( \mathrm { p } K _ { a } = 18 \right)$
I $\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad$ II $\quad\quad\quad\quad\quad\quad\quad\quad\quad$ III $\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad$ IV

A) Only I and II
B) Only I and III
C) Only II and III
D) Only II and IV

Question 35

In the addition of HBr to 1-butyne, the nucleophile in the first step of the mechanism is:

A) The Csp-H1s bond of 1-butyne.
B) The C-C triple bond of 1-butyne.
C) The H atom in HBr.
D) The Br ion.

Question 36

Which of the indicated hydrogen in the following compounds is the most acidic?

A) I
B) II
C) III
D) IV

Question 37

Which of the following bases can deprotonate acetylene? You are given the pK_a values of the conjugate acids in parentheses. $\mathrm { CH } _ { 3 } \mathrm { NH } ^ { - } \left( \mathrm { p } K _ { a } = 40 \right) \quad \mathrm { CO } _ { 3 } ^ { 2 - } \left( \mathrm { p } K _ { a } = 10.2 \right) \quad \mathrm { CH } _ { 2 } = \mathrm { CH } ^ { - } \left( \mathrm { p } K _ { a } = 44 \right) \quad \left( \mathrm { CH } _ { 3 } \right) _ { 3 } \mathrm { CO } ^ { - } \left( \mathrm { p } K _ { a } = 18 \right)$
I $\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad$ II $\quad\quad\quad\quad\quad\quad\quad\quad\quad$ III $\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad$ IV

A) Only I and II
B) Only I and III
C) Only II and III
D) Only II and IV

Question 38

What is the major organic product of the following reaction?

A) I
B) II
C) III
D) IV

Question 39

Which of the following compounds is a tautomer of 2-hexanone?

A) Only I and II
B) Only I and III
C) Only II and III
D) I, II, III

Question 40

Which of the following anions is the most basic?

A) I
B) II
C) III
D) IV

Question 41

What is the major organic product of the following reaction?

A) I
B) II
C) III
D) IV

Question 42

What is the starting material in the following reaction?

A) I
B) II
C) III
D) IV

Question 43

What is (are) the major organic product(s) of the following reaction?

A) Only I and II
B) Only II and III
C) Only I and III
D) I, II, III

Question 44

What is the major organic product of the following reaction?

A) I
B) II
C) III
D) IV

Question 45

Determine the product of the following reaction.

A) I
B) II
C) III
D) IV